This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Prostate cancer (PCa) is the second most prevalent cancer (and the fifth most common cause of death in men) worldwide; in 2020, an estimation of 1.4 million cases and 375,000 deaths were reported globally [1]. These deaths are predominantly associated with resistance to treatments that ultimately lead to therapy failure and cancer progression. Among the causes associated with the failure of therapy against the tumor in PCa is a poor immune response. The predominant immune cells of the prostate microenvironment are T cells, B cells, and a small infiltrate of natural killer cells (NK) [2]; Since their discovery, it has been well known that NK cells play a decisive role in antitumor activity [3]. Specifically, in PCa, Marumo et al. were the first to describe the importance of the activity of NK cells against prostate cancer cells by observing a reduction in the functional capacity of NK cells in patients with metastatic prostate cancer compared to patients with localized tumors and healthy controls [4]. Other studies have reported that an increase in NK cell activity directly correlates with a better prognosis for patients and a lower risk of prostate cancer progression [2, 5]. Additionally, NK cells with high activity have been correlated with an increase in metastasis-free survival in patients with localized prostate cancer [6].
Moreover, it has been observed that the PCa microenvironment plays an essential role in regulating the activity of immune cells, including NK cells; this is mainly because the microenvironment is predominantly immunosuppressive [7]. The prostate cancer microenvironment has been reported to be characterized by a high secretion of regulatory molecules, such as TGF-β, IL-10, and IL-6 [8, 9]. Also, the presence of regulatory cells, such as Tregs, M2 macrophages, and MDSCs [10], as well as the expression of immunomodulatory ligands, such as PDL-1, and the secretion of potentially suppressive exosomes that contain MICA/B and ULBPs have been reported in the PCa mircroenvironment [11]. All these factors are determinants in the activity of NK cells against tumor cells.
In addition, it has been observed that STAT-3 is an important regulator of NK cell activity; some reports have demonstrated that STAT-3 signaling in tumor cells decreases the function of neighboring NK cells by inducing in tumor cells a lower expression of NK activating ligands (MICA/B and ULBPs) and chemoattractant factors (RANTES, IP-10, CCL2, CCL9, and CCL17). All of this leads to a decrease in the migration and activation of NK cells, with a corresponding decrease in cytotoxic mechanisms, and the downregulation of cytokine secretion (IFN-γ and TNF-α) and activating receptors (NKG2D and DNAM-1) [12].
Recently, poliovirus receptors (PVRs) have been identified as receptors present at an mRNA level in healthy tissues but with a low or absent protein expression, while in the tumor cells, this family of receptors (which also function as ligands) is overexpressed. These receptors are involved in processes such as tumor promotion and generation of metastasis; overexpression of these ligands contributes to immunological evasion through their interaction with T cell immunoglobulin and ITIM domain (TIGIT), an inhibitory receptor present on some NK and T cells [13–16].
Several studies have shown an overexpression of TIGIT in different types of cancer. This receptor is expressed predominantly on NK cells and plays an essential role in regulating their cytotoxic mechanisms in cancer, affecting NK cell proliferation and cytokine production, and directly disrupting their cytotoxicity activity; furthermore, TIGIT signaling has been associated with the generation of an exhausted condition on both CD8+ lymphocytes and NK cells [17–20]. Currently, around ten inhibitors directed against TIGIT have been developed; however, the utility of TIGIT as a target has not been verified completely, as these inhibitors are still being evaluated as possible therapeutic agents for different neoplasms in clinical trials from phases 1 to 3 [21].
In prostate cancer, high expression of PVR receptors (CD155 and CD112) has been reported in patients with resistant and castration-sensitive prostate cancer; for this reason, these receptors were proposed as potential targets in prostate cancer [22, 23]. Furthermore, a correlation between elevated expression of TIGIT and high-risk recurrence after radical prostatectomy has been shown [24]. However, no studies have currently reported using a strategy to combat prostate cancer using both blockade of TIGIT and the disruption of the IL6R/STAT-3 axis. Therefore, this study determines if the combined blockade of IL6R/STAT-3 and TIGIT enhances NK cell cytotoxicity against prostate cancer cells.
2. Material and Methods
2.1. Cell Culture Lines
The prostate cancer (PCa) cell lines DU145/ATCC® HTB-81™ (metastatic tumor and castration-resistant), LNCaP clone FGC/ATCC® CRL1740™ (metastatic tumor and androgen-dependent), and 22Rv1/ATCC® CRL2505™ (non-metastatic tumor) were obtained from the ATCC® (Manassas, VA, USA). All cell lines were cultured in RPMI 1640 medium (Life Technologies; Carlsbad, CA, USA) supplemented with 10% fetal bovine serum (FBS) (Gibco™, Thermo Fisher Scientific, Waltham, MA, USA) and 1% penicillin-streptomycin-neomycin (PSN) antibiotic mixture (Gibco™, Thermo Fisher Scientific Waltham, MA,USA). NK-92®/ATCC® CRL2407™ was cultured in a medium supplemented with 12.5% FBS together with 12.5% horse serum in addition to recombinant human IL-2 (PREPOTECH, Cranbury, NJ, USA) at 10 ng/mL concentration. Finally, RWPE1/ATCC® CRL11609™ (non-neoplastic prostate epithelial) was cultured with keratinocyte serum-free medium (KSFM) supplemented with 0.05 mg/mL bovine pituitary extract and 5 ng/mL EGF. The cells were kept in an environment of 95% air with 5% CO2 and a temperature of 37 °C. Adherent cells were treated with trypsin 0.25% (Gibco™, Thermo Fisher Scientific, Waltham, MA, USA) to detach the cells before passage or assay. The cell lines were cultured around 80-90% confluence to perform all the assays.
2.2. Antibodies and Reagents
Alexa Fluor® 647 antihuman TIGIT mAb (clone MBSA43) was obtained from BioLegend® (San Diego, CA, USA). The antibodies to evaluate CD155 (Alexa Fluor® 647, clone SKII.4), CD112 (PE, clone R2.525), PDL-1 (PerCP-Cy5.5, clone 29E.2A3), NKp30 (PE, clone P30-15), NKp44 (PE, clone P44-8), NKp46 (PE, clone 9E2), CD226 (PE, clone DX11), and NKG2D (PE, clone 1D11) were obtained from BioLegend® and MICA (PE, clone 159227), MICB (FITC, clone 236511), ULBP1 (PerCP, clone 170818), ULBP2-5-6 (PE, clone 165903), and B7-H6 (APC, clone 875002) from R & D Systems (Minneapolis, MN, USA). In addition, Ultra-LEAF ™ purified antihuman TIGIT antibody (clone A15153A, mouse IgG2a, BioLegend®) and anti-IL6R antibody (Tocilizumab/Actemra®; Roche, Basil, Switzerland) were used for functional blocking assays at 50 μg/mL and 10 μg/mL, respectively. Stattic (STAT-3 inhibitor; CAS 19983-44-9) was purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA). This reagent was reconstituted in dimethyl sulfoxide (DMSO, Sigma-Merck, Darmstadt, Germany) as 50 mM stock solutions and stored at −20 °C until use.
2.3. Quantification of Growth Factors and Cytokines in Prostate Cancer Supernatants
22Rv1, LNCaP, and DU145 prostate cancer cells (
2.4. Determination of NK Ligand Expression on Prostate Cancer Cells
22Rv1, LNCaP, and DU145 prostate cancer cells (
2.5. Metabolic Activity Assessment Assay
The effect of stattic on metabolism was determined using the WST-1 assay, a colorimetric technique based on the reduction of tetrazolium salts to formazan, which has been previously used to determine the metabolic activity of neoplastic and non-neoplastic prostatic cells [25–27]. For this, DU145 prostate cancer cells (
2.6. Determination of Viability in DU145 Cells and NK Cells Treated with Stattic and Tocilizumab
NK-92 (
2.7. Evaluation of IL6R, STAT-3, and pSTAT-3 Expression on Prostate Cancer Cells by Western Blot
22Rv1 (
2.8. Dephosphorylation of STAT-3 by In-Cell Western (ICW)
The DU145 prostate cancer cells (
2.9. Evaluation of Expression of NK Cell Receptors (NKG2D, NKp30, NKp44, NKp46, CD226, and TIGIT) by Flow Cytometry
NK-92 (
2.10. Real-Time NK Cell Cytotoxicity Monitoring in Coculture with Prostate Cancer Cells
DU145 target cells (
2.11. Quantification of Cytotoxicity Soluble Molecules from Coculture Supernatants
After finalizing the coculture experiments, the supernatant was collected at 4 and 24 h. The secretion of cytotoxicity molecules (IL-2, 4, 6, 10, 17A, IFN-γ, TNF-α, soluble Fas, soluble FasL, granzyme A, granzyme B, perforin, and granulysin) was determined using the human CD8/NK panel (13-plex) through the LEGENDplex™ Multi-Analyte Flow Assay Kit (BioLegend®, San Diego, CA, USA), according to the manufacturer’s protocol for this kit by flow cytometry. After the experiment, 2100 events were acquired from region Beads Size A in the Attune Acoustic Focusing Cytometer (Applied Biosystems®, Waltham, MA, USA). All data were analyzed using the Biolegend LEGENDplex™ version 8.0 Data Analysis Software (San Diego, CA, USA). The data are shown as the
2.12. Statistical Analysis
Normality, homogeneity of variance, and data independence were determined before every analysis. The data analysis was carried out using descriptive statistics. Mixed effects two-way ANOVA was used to evaluate two variables and was performed with the Bonferroni test (post hoc) for cytotoxicity assays. In addition, parametric variables were analyzed with unpaired
3. Results
3.1. High IL-6, IL-8, and VEGF Secretion in DU145 Metastatic Castration-Resistant Prostate Cancer Cells
We assessed the secretion of growth factors, cytokines, and chemokines in 22Rv1, LNCaP, and DU145 cells at 12 h, 24 h, and 48 h (Figures 1(a) and 1(b), heat maps). We observed a higher secretion of IL-8, IL-6, M-CSF, and VEGF in DU145 prostate cancer cells when compared to 22Rv1 and LNCaP prostate cancer cells (
[figure(s) omitted; refer to PDF]
3.2. DU145 Cells Have Increased Expression of CD155 (the Principal Ligand for TIGIT)
Since tumor cells are recognized by NK cells through an interplay of activating and inhibitory ligands, we decided to evaluate the expression of CD155, CD112, MICA, MICB, ULBP1-2-5-6, PDL-1, and B7-H6 on 22Rv1, LNCaP, and DU145 prostate cancer cells (Figure 2(a) and 2(d)). We observed that CD155 and CD112 were expressed at higher levels than MICA, MICB, ULBP1-2-5-6, PDL-1, and B7-H6 on all the prostate cancer cells (Figure 2(b) and 2(c),
[figure(s) omitted; refer to PDF]
3.3. Stattic and Tocilizumab Decreased Phosphorylation of STAT-3 in Metastatic Castration-Resistant DU145 Prostate Cancer Cells
We first assessed the basal expression of the IL6R, STAT-3, and pSTAT-3 in 22Rv1, LNCaP, and DU145 prostate cancer cells. Interestingly, we observed that the DU145 cells exhibited a higher expression of the IL6R and a constitutive expression of pSTAT-3 when compared with the 22Rv1 and LNCaP prostate cancer cells (Figure 3(a)). Due to their high secretion of IL-6, IL6R, pSTAT-3 constitutive expression, and the high expression of the CD155 receptor, the main ligand of TIGIT, we decided to work with the DU145 cells in the following assays. First, we evaluated the effects of stattic (Stt) and tocilizumab (Tcz) on the viability and metabolic activity of the DU145 cells. We did not observe significant changes with Stt and Tcz in viability (Figure 3(b)); however, Stt concentrations higher than 5 μM decreased metabolic activity in DU145 cells (Figure 3(b),
[figure(s) omitted; refer to PDF]
3.4. Combined Treatment with Stattic and Tocilizumab Decreases the Expression of TIGIT and Increases the Expression of NKp46 in NK Cells
We evaluated the effects of exposure to Stt and Tcz on NK cells (Figure 4(a)). First, we observed that Tcz did not affect viability in the NK-92 cells, whereas Stt at concentrations of 5 μM significantly decreased viability (Figure 4(b),
[figure(s) omitted; refer to PDF]
3.5. Stattic plus Tocilizumab and Anti-TIGIT Increases the Cytotoxicity of NK-92 Cells against DU145 Prostate Cancer Cells
The percentage of cytolysis at 4 h (short time activity) and 24 h (long time activity) was determined in NK-92 cells in coculture with DU145 cells treated or not with Stt and/or Tcz and/or anti-TIGIT using the effector : target ranges (E : T) 5 : 1 (Figure S2(a) and S2(b)) and 10 : 1 (Figures S2(c) and S2(d)). Interestingly, we observed a significant decrease in killing time 50 (KT50) in cocultures treated with Stt + Tcz and anti-TIGIT compared to other treatments in both E : T ranges; in particular, at 4 h, a decrease in KT50 was shown in cocultures with Stt + Tcz and anti-TIGIT (Figures 5(a) and 5(b),
[figure(s) omitted; refer to PDF]
3.6. Combined Treatment with Stattic, Tocilizumab, and Anti-TIGIT Increases Cytotoxicity in NK-92 Cell Coculture with DU145 Cells
We evaluated molecules related to the cytotoxic activity of NK cells (Figure 6(a)). In comparison with the basal group, we found a significant increase in soluble FasL, granzyme A, granzyme B, and granulysin in the Tcz + anti-TIGIT and Stt + Tcz + anti-TIGIT groups at 4 h of coculture (Figure 6(b),
[figure(s) omitted; refer to PDF]
4. Discussion
The immune response to prostate cancer, particularly in CRPC, has been characterized by poor cytotoxic activity; additionally, an immunosuppressive tumor microenvironment is often reported [31]. Our study found that cell models of advanced prostate cancer demonstrated constitutive expression of STAT-3, and also exhibited characteristics such as a high secretion of growth factors, such as VEGF and cytokines, such as IL-6 and CXCL8. These factors are closely related to the activation of this transcription factor and regulation of the immune response mediated by NK cells. For instance, studies have reported that constitutive activation of STAT-3 is an essential mediator for the secretion of VEGF, CXCL8, and IL-6, creating autocrine feedback (when these molecules bind their receptors, increased STAT-3 signaling is observed) [32, 33]. Additionally, the presence of TGF-β contributes to the activation of STAT-3 through phosphorylation of SHP-2 and is an important regulator of immune responses in this pathology [34, 35]. Furthermore, understanding the complex role of the tumor microenvironment is vital in order to propose and develope new treatment approaches in these cancers; this is mainly because some tumor environment-secreted factors, such as VEGF and TGF-β, are important regulators of therapeutic antibody blocking efficiency at certain immune checkpoints [36]. Simultaneously, comprehending all this is crucial, due mainly to the microenvironment’s repercussions directly affecting NK cell cytotoxicity and functional capacity in this type of tumor [37–40]. Ultimately, recent research has reported that the presence of IL-6 and CXCL8 modulates the activity of NK cells by downregulating the expression of activating receptors and impairs the functional cytotoxic activity of these cells [41],and can induce the polarization of NK cells into an angiogenic phenotype, which also has been associated with the recruitment and polarization of macrophages to an M2 phenotype [42].
Likewise, the expression of ligands that limit the activity of NK cells in the microenvironment also suffers alterations during tumor progression. Thus, we mainly found that CD155, a receptor belonging to the PVR family and the principal ligand of the TIGIT immunoreceptor, is increased in the metastatic CRPC cell line. Previously, some studies have reported the implications of this ligand in the tumor microenvironment as it is directly involved with different factors, which are usually related to decreased patient survival [15, 43, 44]. Therefore, CD155 has been proposed as a potential therapeutic target in this disease [22]. Furthermore, some studies have observed that expression of CD155 could be induced by pathways such as Raf-MEK-ERK-AP-1 and through the Sonic Hedgehog pathway, which is highly active in advanced prostate cancer and can be indirectly mediated by STAT-3 via regulation of the TTF-1 promoter [44–46]. For this reason, it is essential to observe the pattern of CD155 expression in this pathology due to its implications for the regulation of immune checkpoint blockade through its combined expression with other ligands such as PDL-1 [47]. This combined expression of CD155 and other checkpoint ligands may prove to be an important variable that might help predict TIGIT blockade efficacy and thus enable the suitable selection of patients with advanced prostate cancer most likely to benefit from such a treatment.
Studies have reported that the tumor cells with constitutive expression of STAT-3 maintain the activity of this pathway through positive autocrine feedback between IL-6 and the IL6R [48, 49]. We observed by Western blot that the castration-resistant DU145 cells that maintain active STAT-3 exhibited a higher expression of the IL6R compared to the other cell lines; In this sense, some studies have observed, particularly in breast cancer, that constitutive expression of STAT-3 is increased in the tumor tissue and is even associated with risk factors such as mammographic density, which is why it has been proposed as a prognostic factor for determining risk in patients [50]. This highlights the feasibility of generating a therapy directed against the IL6R/STAT-3 axis in advanced stages of prostate cancer with these characteristics. We also evaluated the inhibition of this entire axis. We observed a reduction in metabolic activity and the dephosphorylation of STAT-3 when both inhibitors were administered. This effect was observed using lower concentrations of Stt than needed when Stt alone was used; here, the anti-IL6R seems to be sensitizing these tumor cells. In addition, various groups have described the effects of Stt (alone and/or in combination with other drugs) on the proliferative capacity, reduction of metastasis, and sensitization of tumor cells to drugs or immune responses in both in vitro and in vivo studies [51–55]. For example, it has been reported that inhibition of the IL-6-JAK/STAT-3 signaling pathway in CRPC cells (C4-2 and CWR22Rv1) sensitizes tumor cells to NK cell-mediated cytotoxic action through changes in the PDL-1 ligand interaction and the expression of NKG2D [56]. Additionally, tocilizumab has already been used in some cancer models with important effects in different tumor cell models, mainly on the proliferation, invasion, and sensitization to drugs through dephosphorylation of STAT-3 [29, 57–59]. Recently, tocilizumab has been proposed as a component of combination therapy with other targeted monoclonal antibodies against immune checkpoints in phase I/II studies against multiple myeloma (NCT04910568) and melanoma (NCT03999749); interestingly, there is no such combined therapy targeted directly to prostate cancer as of yet. However, a recent study confirmed that combined inhibition of the JAK1-2/STAT-3 pathway and PD-L1 blockade decreases the escape of CRPC cells from the cytotoxic action of NK cells under hypoxic conditions [60], indicating the importance of implementing STAT-3 inhibitors in combination with blockers directed against highly expressed targets in prostate cancer.
Other research has shown the implications of STAT-3 on the immune response of NK cells, mainly on the regulation of cytotoxic mechanisms and on the expression of activation receptors [12]. For this reason, we decided to evaluate the effects of the treatments on these immune response cells. Interestingly, we observed that the use of stattic and tocilizumab in combination increases the expression of NKp46 in NK-92 cells. This activating receptor has previously been reported as an essential mediator of the immune response of cytotoxic cells in prostate cancer [8]. However, NKp46 can be regulated by STAT-3 mainly because this transcription factor can bind to promoter regions of the gene for this activating receptor [61]. So, we propose that using these treatments can avoid this regulation. Likewise, we observed a decrease in the expression of TIGIT, which has not been previously reported, and which allows us to hypothesize a direct interaction between the IL6R/STAT-3 axis and the regulation of this inhibitory receptor.
Based on the above, we evaluated the response of NK-92 cells against DU145 castration-resistant prostate cancer cells using the xCELLigence system, which allows a more accurate and robust observation of the efficacy of treatments and the response of cytotoxic cells, BiTES, and CAR-T cells in in vitro studies [28]. Additionally, the use of the xCELLigenceplatform has allowed us to accurately observe the effect of both treatments and the cytotoxic activity of the NK cells from short times to prolonged times of activity, which allows us to predict more accurately the possible behavior of these treatments in future in vivo studies.
Using the xCELLigence plates, we observed that combined therapy against the IL6R/STAT-3 axis and TIGIT increased the cytotoxicity of NK cells against tumor cells. We observed this increased cytotoxicity beginning from the first hours of coculture and continuing through the full 24 h of the experiment. In agreement with our results, some trials have demonstrated an enhanced NK cytotoxic response after the silencing of IL-6 in prostate cancer cells [56]. Likewise, other studies have observed positive effects on the cytotoxicity of NK cells after the inhibition of STAT-3 and the use of monoclonal antibodies directed against immune checkpoints [52, 62]. For example, the blockade of TIGIT was found to positively regulate the response of NK cells against breast cancer cell lines [63]. Furthermore, another study proposed the importance of NK cells on the efficacy of TIGIT blockade by observing a preventive effect on exhaustion in NK cells, which increased the response of CD8+ cells against colon CT26 cancer cells [64]. Another group recently observed that blocking TIGIT allows the reconstitution of antitumor activity when used together with an inhibitor of HIF-1α, a critical mediator of the immune response, which in turn is regulated by STAT-3 [65, 66]. Together, the evidence denotes the importance of using these treatments directed against IL6R/STAT-3 and TIGIT in combination in future animal models and patient studies. We expect that the positive antitumor effect would be mainly due to the regulation of the NK-mediated response and enhancement of CD8+ cells.
When we evaluated the supernatant from the coculture groups, we observed a significant increase in the secretion of cytotoxic molecules, mainly in the group treated with all inhibitors in the first hours of activity. Additionally, the increased secretion was maintained significantly in some of the groups treated in combination, even at the longest time points of the experiment. Previous studies have observed that inhibitors against IL-6, the main activator of STAT-3, recover the production of granzyme B [41]; another research demonstrated that silencing of STAT-3 enhances the production of granzyme B and perforin in NK cells [67], so we propose that using tocilizumab, stattic, and anti-TIGIT in combination allows these mechanisms to be reconstituted to a greater degree than using only a single inhibitor of the IL6R/STAT-3 axis for a more prolonged time.
Understanding the roles of these receptors, ligands, and pathways is essential for hypothesizing the possible mechanisms mediating the NK cells’ activity. Therefore, we propose that inhibition of the IL6R/STAT-3 axis allows the regeneration of natural mechanisms directly involved in the cytotoxic and functional capacity of NK cells via a decrease in the expression of TIGIT, an inhibitory receptor with a high affinity for ligands present in these tumor cells. Supporting this, some researchers have observed that NK cells with high expression of TIGIT have a low cytotoxic capacity, mainly due to their greater affinity for CD155 and that the TIGIT/CD155 binding avoids interaction with the activating receptor CD226 and prevents its homodimerization [68, 69]; thus, the use of a monoclonal antibody against TIGIT could avoid the interaction with this inhibitory ligand and improve the response against these tumor cells. Likewise, we determined that using these treatments in combination with anti-TIGIT increases and maintains the expression of some factors such as NKp46 and secretion of granzyme A, granzyme B, perforin, and granulysin which may regulate cytotoxicity against DU145 prostate cancer cells.
5. Conclusion
In conclusion, this is the first study to propose a potential combination therapy directed against the IL6R/STAT-3 axis and TIGIT. Targeting these three factors simultaneously in a model of advanced castration resistance prostate cancer revealed a significant improvement in the functional activity of NK cells against these tumor cells, which is determinant for the design of future studies or clinical trials examining the in vivo efficacy of these treatments.
Authors’ Contributions
G-O S, T-B MC, and O-L PC designed the protocol and methodology; M-C A, G-O S, and P-M LA carried out the experimental work. B-C A, P-B EJ, and S-R K performed the statistical analysis; G-O S, H-F G, H-J, T-B MC, and O-L PC discussed and drafted the manuscript.
[1] H. Sung, J. Ferlay, R. L. Siegel, M. Laversanne, I. Soerjomataram, A. Jemal, F. Bray, "Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries," CA: a Cancer Journal for Clinicians, vol. 71 no. 3, pp. 209-249, DOI: 10.3322/caac.21660, 2021.
[2] C. Solinas, N. M. Chanzá, A. Awada, M. Scartozzi, "The immune infiltrate in prostate, bladder and testicular tumors: an old friend for new challenges," Cancer Treatment Reviews, vol. 53, pp. 138-145, DOI: 10.1016/j.ctrv.2016.12.004, 2017.
[3] R. Kiessling, E. Klein, H. Pross, H. Wigzell, "“Natural” killer cells in the mouse. II. Cytotoxic cells with specificity for mouse Moloney leukemia cells. Characteristics of the killer cel," European Journal of Immunology, vol. 5 no. 2, pp. 117-121, DOI: 10.1002/eji.1830050209, 1975.
[4] K. Marumo, K. Ikeuchi, S. Baba, M. Ueno, H. Tazaki, "Natural killer cell activity and recycling capacity of natural killer cells in patients with carcinoma of the prostate," The Keio Journal of Medicine, vol. 38 no. 1, pp. 27-35, DOI: 10.2302/kjm.38.27, 1989.
[5] C. Pasero, G. Gravis, S. Granjeaud, M. Guerin, J. Thomassin-Piana, P. Rocchi, N. Salem, J. Walz, A. Moretta, D. Olive, "Highly effective NK cells are associated with good prognosis in patients with metastatic prostate cancer," Oncotarget, vol. 6 no. 16, pp. 14360-14373, DOI: 10.18632/oncotarget.3965, 2015.
[6] A. B. Weiner, T. Vidotto, Y. Liu, A. A. Mendes, D. C. Salles, F. A. Faisal, S. Murali, M. McFarlane, E. L. Imada, X. Zhao, Z. Li, E. Davicioni, L. Marchionni, A. M. Chinnaiyan, S. J. Freedland, D. E. Spratt, J. D. Wu, T. L. Lotan, E. M. Schaeffer, "Plasma cells are enriched in localized prostate cancer in black men and are associated with improved outcomes," Nature Communications, vol. 12 no. 1,DOI: 10.1038/s41467-021-21245-w, 2021.
[7] K. D. Runcie, M. C. Dallos, "Prostate cancer immunotherapy–finally in from the cold?," Current Oncology Reports, vol. 23 no. 8,DOI: 10.1007/s11912-021-01084-0, 2021.
[8] C. Pasero, G. Gravis, M. Guerin, S. Granjeaud, J. Thomassin-Piana, P. Rocchi, M. Paciencia-Gros, F. Poizat, M. Bentobji, F. Azario-Cheillan, J. Walz, N. Salem, S. Brunelle, A. Moretta, D. Olive, "Inherent and tumor-driven immune tolerance in the prostate microenvironment impairs natural killer cell antitumor activity," Cancer Research, vol. 76 no. 8, pp. 2153-2165, DOI: 10.1158/0008-5472.CAN-15-1965, 2016.
[9] G. M. Konjević, A. M. Vuletić, K. M. M. Martinović, A. K. Larsen, V. B. Jurišić, "The role of cytokines in the regulation of NK cells in the tumor environment," Cytokine, vol. 117, pp. 30-40, DOI: 10.1016/j.cyto.2019.02.001, 2019.
[10] K. S. Sfanos, T. C. Bruno, C. H. Maris, L. Xu, C. J. Thoburn, A. M. DeMarzo, A. K. Meeker, W. B. Isaacs, C. G. Drake, "Phenotypic analysis of prostate-infiltrating lymphocytes reveals TH17 and Treg skewing," Clinical Cancer Research, vol. 14 no. 11, pp. 3254-3261, DOI: 10.1158/1078-0432.CCR-07-5164, 2008.
[11] M. Lundholm, M. Schröder, O. Nagaeva, V. Baranov, A. Widmark, L. Mincheva-Nilsson, P. Wikström, "Prostate tumor-derived exosomes down-regulate NKG2D expression on natural killer cells and CD8+ T cells: mechanism of immune evasion," PLoS One, vol. 9 no. 9, article e108925,DOI: 10.1371/journal.pone.0108925, 2014.
[12] N. A. Cacalano, "Regulation of natural killer cell function by STAT3," Frontiers in Immunology, vol. 7,DOI: 10.3389/fimmu.2016.00128, 2016.
[13] H. L. MacGregor, A. Sayad, A. Elia, B. X. Wang, S. R. Katz, P. A. Shaw, B. A. Clarke, S. Q. Crome, C. Robert-Tissot, M. Q. Bernardini, L. T. Nguyen, P. S. Ohashi, "High expression of B7-H3 on stromal cells defines tumor and stromal compartments in epithelial ovarian cancer and is associated with limited immune activation," Journal for Immunotherapy of Cancer, vol. 7 no. 1,DOI: 10.1186/s40425-019-0816-5, 2019.
[14] E. Picarda, K. C. Ohaegbulam, X. Zang, "Molecular pathways: targeting B7-H3 (CD276) for human cancer immunotherapy," Clinical Cancer Research, vol. 22 no. 14, pp. 3425-3431, DOI: 10.1158/1078-0432.CCR-15-2428, 2016.
[15] K. E. Sloan, B. K. Eustace, J. K. Stewart, C. Zehetmeier, C. Torella, M. Simeone, J. E. Roy, C. Unger, D. N. Louis, L. L. Ilag, D. G. Jay, "CD155/PVR plays a key role in cell motility during tumor cell invasion and migration," BMC Cancer, vol. 4 no. 1,DOI: 10.1186/1471-2407-4-73, 2004.
[16] N. Negishi, T. Sato, Y. Yamashita-Kanemaru, K. Shibuya, K. Uchida, Y. Kametani, H. Yagita, J. Kitaura, K. Okumura, S. Habu, "CD155-transducing signaling through TIGIT plays an important role in transmission of tolerant state and suppression capacity," Immunohorizons, vol. 2 no. 10, pp. 338-348, DOI: 10.4049/immunohorizons.1800033, 2018.
[17] K. B. Lupo, S. Matosevic, "CD155 immunoregulation as a target for natural killer cell immunotherapy in glioblastoma," Journal of Hematology & Oncology, vol. 13 no. 1,DOI: 10.1186/s13045-020-00913-2, 2020.
[18] W. He, H. Zhang, F. Han, X. Chen, R. Lin, W. Wang, H. Qiu, Z. Zhuang, Q. Liao, W. Zhang, Q. Cai, Y. Cui, W. Jiang, H. Wang, Z. Ke, "CD155T/TIGIT signaling regulates CD8+ T-cell metabolism and promotes tumor progression in human gastric cancer," Cancer Research, vol. 77 no. 22, pp. 6375-6388, DOI: 10.1158/0008-5472.CAN-17-0381, 2017.
[19] R. Liang, X. Zhu, T. Lan, D. Ding, Z. Zheng, T. Chen, Y. Huang, J. Liu, X. Yang, J. Shao, H. Wei, B. Wei, "TIGIT promotes CD8+ T cells exhaustion and predicts poor prognosis of colorectal cancer," Cancer Immunology, Immunotherapy, vol. 70 no. 10, pp. 2781-2793, DOI: 10.1007/s00262-021-02886-8, 2021.
[20] F. Wang, H. Hou, S. Wu, Q. Tang, W. Liu, M. Huang, B. Yin, J. Huang, L. Mao, Y. Lu, Z. Sun, "TIGIT expression levels on human NK cells correlate with functional heterogeneity among healthy individuals," European Journal of Immunology, vol. 45 no. 10, pp. 2886-2897, DOI: 10.1002/eji.201545480, 2015.
[21] J. Yeo, M. Ko, D.-H. Lee, Y. Park, H.-s. Jin, "TIGIT/CD226 Axis regulates anti-tumor immunity," Pharmaceuticals, vol. 14 no. 3,DOI: 10.3390/ph14030200, 2021.
[22] A. Papanicolau-Sengos, Y. Yang, S. Pabla, F. L. Lenzo, S. Kato, R. Kurzrock, P. DePietro, M. Nesline, J. Conroy, S. Glenn, G. Chatta, C. Morrison, "Identification of targets for prostate cancer immunotherapy," The Prostate, vol. 79 no. 5, pp. 498-505, DOI: 10.1002/pros.23756, 2019.
[23] H. Zhang, Z. Yang, G. Du, L. Cao, B. Tan, "CD155-prognostic and immunotherapeutic implications based on multiple analyses of databases across 33 human cancers," Technology in Cancer Research & Treatment, vol. 20,DOI: 10.1177/1533033820980088, 2021.
[24] D. Lv, X. Wu, X. Chen, S. Yang, W. Chen, M. Wang, Y. Liu, D. Gu, G. Zeng, "A novel immune-related gene-based prognostic signature to predict biochemical recurrence in patients with prostate cancer after radical prostatectomy," Cancer Immunology, Immunotherapy, vol. 70 no. 12, pp. 3587-3602, DOI: 10.1007/s00262-021-02923-6, 2021.
[25] M. V. Berridge, P. M. Herst, A. S. Tan, "Tetrazolium dyes as tools in cell biology: new insights into their cellular reduction," Biotechnology Annual Review, vol. 11, pp. 127-152, DOI: 10.1016/S1387-2656(05)11004-7, 2005.
[26] J. S. Diallo, B. Péant, L. Lessard, N. Delvoye, C. le Page, A. M. Mes-Masson, F. Saad, "An androgen-independent androgen receptor function protects from inositol hexakisphosphate toxicity in the PC3/PC3(AR) prostate cancer cell lines," The Prostate, vol. 66 no. 12, pp. 1245-1256, DOI: 10.1002/pros.20455, 2006.
[27] K. F. Chambers, E. M. Mosaad, P. J. Russell, J. A. Clements, M. R. Doran, "Correction: 3D cultures of prostate cancer cells cultured in a novel high-throughput culture platform are more resistant to chemotherapeutics compared to cells cultured in monolayer," PLoS One, vol. 10 no. 4, article e0125641,DOI: 10.1371/journal.pone.0125641, 2015.
[28] F. Cerignoli, Y. A. Abassi, B. J. Lamarche, G. Guenther, D. Santa Ana, D. Guimet, W. Zhang, J. Zhang, B. Xi, "In vitro immunotherapy potency assays using real-time cell analysis," PLoS One, vol. 13 no. 3, article e0193498,DOI: 10.1371/journal.pone.0193498, 2018.
[29] N. N. Alraouji, F. H. Al‐Mohanna, H. Ghebeh, M. Arafah, R. Almeer, T. Al‐Tweigeri, A. Aboussekhra, "Tocilizumab potentiates cisplatin cytotoxicity and targets cancer stem cells in triple‐negative breast cancer," Molecular Carcinogenesis, vol. 59 no. 9, pp. 1041-1051, DOI: 10.1002/mc.23234, 2020.
[30] I. Segatto, S. Berton, M. Sonego, S. Massarut, T. Perin, E. Piccoli, A. Colombatti, A. Vecchione, G. Baldassarre, B. Belletti, "Surgery-induced wound response promotes stem-like and tumor-initiating features of breast cancer cells, via STAT3 signaling," Oncotarget, vol. 5 no. 15, pp. 6267-6279, DOI: 10.18632/oncotarget.2195, 2014.
[31] V. Jurisic, "Multiomic analysis of cytokines in immuno-oncology," Expert Review of Proteomics, vol. 17 no. 9, pp. 663-674, DOI: 10.1080/14789450.2020.1845654, 2020.
[32] G. Niu, K. L. Wright, M. Huang, L. Song, E. Haura, J. Turkson, S. Zhang, T. Wang, D. Sinibaldi, D. Coppola, R. Heller, L. M. Ellis, J. Karras, J. Bromberg, D. Pardoll, R. Jove, H. Yu, "Constitutive Stat3 activity up-regulates VEGF expression and tumor angiogenesis," Oncogene, vol. 21 no. 13, pp. 2000-2008, DOI: 10.1038/sj.onc.1205260, 2002.
[33] Z. Culig, M. Puhr, "Interleukin-6 and prostate cancer: current developments and unsolved questions," Molecular and Cellular Endocrinology, vol. 462 no. Part A, pp. 25-30, DOI: 10.1016/j.mce.2017.03.012, 2018.
[34] A. Zehender, J. Huang, A.-H. Györfi, A. E. Matei, T. Trinh-Minh, X. Xu, Y. N. Li, C. W. Chen, J. Lin, C. Dees, C. Beyer, K. Gelse, Z. Y. Zhang, C. Bergmann, A. Ramming, W. Birchmeier, O. Distler, G. Schett, J. H. W. Distler, "The tyrosine phosphatase SHP2 controls TGF β -induced STAT3 signaling to regulate fibroblast activation and fibrosis," Nature Communications, vol. 9 no. 1,DOI: 10.1038/s41467-018-05768-3, 2018.
[35] J. Ahel, N. Hudorović, V. Vičić-Hudorović, H. Nikles, "TGF-BETA in the natural history of prostate cancer," Acta Clinica Croatica, vol. 58 no. 1, pp. 128-138, DOI: 10.20471/acc.2019.58.01.17, 2019.
[36] B. L. Russell, S. A. Sooklal, S. T. Malindisa, L. J. Daka, M. Ntwasa, "The tumor microenvironment factors that promote resistance to immune checkpoint blockade therapy," Frontiers in Oncology, vol. 11,DOI: 10.3389/fonc.2021.641428, 2021.
[37] S. Parra, R. Pinochet, R. Vargas, C. Sepúlveda, D. Miranda, J. Puente, "Natural killer cytolytic activity in renal and prostatic cancer," Revista medica de Chile, vol. 122 no. 6, pp. 630-637, 1994.
[38] J. Barkin, R. Rodriguez-Suarez, K. Betito, "Association between natural killer cell activity and prostate cancer: a pilot study," Canadian Journal of Urology, vol. 24 no. 2, 2017.
[39] M. F. Santos, V. K. Mannam, B. S. Craft, L. V. Puneky, N. T. Sheehan, R. E. Lewis, J. M. Cruse, "Comparative analysis of innate immune system function in metastatic breast, colorectal, and prostate cancer patients with circulating tumor cells," Experimental and Molecular Pathology, vol. 96 no. 3, pp. 367-374, DOI: 10.1016/j.yexmp.2014.04.001, 2014.
[40] P. O. Gannon, A. O. Poisson, N. Delvoye, R. Lapointe, A.-M. Mes-Masson, F. Saad, "Characterization of the intra-prostatic immune cell infiltration in androgen- deprived prostate cancer patients," Journal of Immunological Methods, vol. 348 no. 1-2,DOI: 10.1016/j.jim.2009.06.004, 2009.
[41] J. Wu, F.-x. Gao, C. Wang, M. Qin, F. Han, T. Xu, Z. Hu, Y. Long, X. M. He, X. Deng, D. L. Ren, T. Y. Dai, "IL-6 and IL-8 secreted by tumour cells impair the function of NK cells via the STAT3 pathway in oesophageal squamous cell carcinoma," Journal of Experimental & Clinical Cancer Research, vol. 38 no. 1,DOI: 10.1186/s13046-019-1310-0, 2019.
[42] A. Albini, D. Baci, M. Gallazzi, F. Dehò, A. Naselli, A. Guernieri, L. Mortara, D. M. Noonan, A. Bruno, "Abstract LT006: NK cells from prostate cancer patients acquire a pro-angiogenic phenotype and polarize macrophages towards a M2-like/TAM subset," Cancer Research, vol. 81, 2021.
[43] N. D. Huntington, J. Cursons, J. Rautela, "The cancer-natural killer cell immunity cycle," Nature Reviews Cancer, vol. 20 no. 8, pp. 437-454, DOI: 10.1038/s41568-020-0272-z, 2020.
[44] R. Molfetta, B. Zitti, M. Lecce, N. D. Milito, H. Stabile, C. Fionda, M. Cippitelli, A. Gismondi, A. Santoni, R. Paolini, "CD155: a multi-functional molecule in tumor progression," International Journal of Molecular Sciences, vol. 21 no. 3,DOI: 10.3390/ijms21030922, 2020.
[45] D. J. Solecki, M. Gromeier, S. Mueller, G. Bernhardt, E. Wimmer, "Expression of the human poliovirus receptor/CD155 gene is activated by sonic hedgehog," Journal of Biological Chemistry, vol. 277 no. 28, pp. 25697-25702, DOI: 10.1074/jbc.M201378200, 2002.
[46] Q. Yang, S. S. Shen, S. Zhou, J. Ni, D. Chen, G. Wang, Y. Li, "STAT3 activation and aberrant ligand-dependent sonic hedgehog signaling in human pulmonary adenocarcinoma," Experimental and Molecular Pathology, vol. 93 no. 2, pp. 227-236, DOI: 10.1016/j.yexmp.2012.04.009, 2012.
[47] B. R. Lee, S. Chae, J. Moon, M. J. Kim, H. Lee, H. W. Ko, B. C. Cho, H. S. Shim, D. Hwang, H. R. Kim, S. J. Ha, "Combination of PD-L1 and PVR determines sensitivity to PD-1 blockade," JCI insight, vol. 5 no. 14,DOI: 10.1172/jci.insight.128633, 2020.
[48] P. Kroon, P. A. Berry, M. J. Stower, G. Rodrigues, V. M. Mann, M. Simms, D. Bhasin, S. Chettiar, C. Li, P. K. Li, N. J. Maitland, A. T. Collins, "JAK-STAT blockade inhibits tumor initiation and clonogenic recovery of prostate cancer stem-like cells," Cancer Research, vol. 73 no. 16, pp. 5288-5298, DOI: 10.1158/0008-5472.CAN-13-0874, 2013.
[49] N. Don-Doncow, F. Marginean, I. Coleman, P. S. Nelson, R. Ehrnström, A. Krzyzanowska, C. Morrissey, R. Hellsten, A. Bjartell, "Expression of STAT3 in prostate cancer metastases," European Urology, vol. 71 no. 3, pp. 313-316, DOI: 10.1016/j.eururo.2016.06.018, 2017.
[50] S. Radenkovic, G. Konjevic, D. Gavrilovic, S. Stojanovic-Rundic, V. Plesinac-Karapandzic, P. Stevanovic, V. Jurisic, "pSTAT3 expression associated with survival and mammographic density of breast cancer patients," Pathology-Research and Practice, vol. 215 no. 2, pp. 366-372, DOI: 10.1016/j.prp.2018.12.023, 2019.
[51] J. Mohammadian, O. Molavi, M. B. Pirouzpanah, A. A. R. Rahimi, N. Samadi, "Stattic enhances the anti-proliferative effect of docetaxel via the Bax/Bcl-2/cyclin B axis in human cancer cells," Process Biochemistry, vol. 69, pp. 188-196, DOI: 10.1016/j.procbio.2018.03.004, 2018.
[52] L. Zhang, L. J. Xu, J. Zhu, J. Li, B. X. Xue, J. Gao, C. Y. Sun, Y. C. Zang, Y. B. Zhou, D. R. Yang, Y. X. Shan, "ATM-JAK-PD-L1 signaling pathway inhibition decreases EMT and metastasis of androgen-independent prostate cancer," Molecular Medicine Reports, vol. 17 no. 5, pp. 7045-7054, DOI: 10.3892/mmr.2018.8781, 2018.
[53] M. H. Thulin, J. Määttä, A. Linder, S. Sterbova, C. Ohlsson, J. E. Damber, A. Widmark, E. Persson, "Inhibition of STAT3 prevents bone metastatic progression of prostate cancer in vivo," The Prostate, vol. 81 no. 8, pp. 452-462, DOI: 10.1002/pros.24125, 2021.
[54] M. Spitzner, B. Roesler, C. Bielfeld, G. Emons, J. Gaedcke, H. A. Wolff, M. Rave-Fränk, F. Kramer, T. Beissbarth, J. Kitz, J. Wienands, B. M. Ghadimi, R. Ebner, T. Ried, M. Grade, "STAT3 inhibition sensitizes colorectal cancer to chemoradiotherapy in vitro and in vivo," International Journal of Cancer, vol. 134 no. 4, pp. 997-1007, DOI: 10.1002/ijc.28429, 2014.
[55] S. Wang, Y. Wang, Z. Huang, H. Wei, X. Wang, R. Shen, W. Lan, G. Zhong, J. Lin, "Stattic sensitizes osteosarcoma cells to epidermal growth factor receptor inhibitors via blocking the interleukin 6-induced STAT3 pathway," Acta Biochimica et Biophysica Sinica, vol. 53 no. 12, pp. 1670-1680, DOI: 10.1093/abbs/gmab146, 2021.
[56] L. Xu, X. Chen, M. Shen, D. R. Yang, L. Fang, G. Weng, Y. Tsai, P. C. Keng, Y. Chen, S. O. Lee, "Inhibition of IL-6-JAK/Stat3 signaling in castration-resistant prostate cancer cells enhances the NK cell-mediated cytotoxicity via alteration of PD-L1/NKG2D ligand levels," Molecular Oncology, vol. 12 no. 3, pp. 269-286, DOI: 10.1002/1878-0261.12135, 2018.
[57] N. H. Kim, S. K. Kim, D. S. Kim, D. Zhang, J. A. Park, H. Yi, J. S. Kim, H. C. Shin, "Anti-proliferative action of IL-6R-targeted antibody tocilizumab for non-small cell lung cancer cells," Oncology letters, vol. 9 no. 5, pp. 2283-2288, DOI: 10.3892/ol.2015.3019, 2015.
[58] T. Hagi, T. Nakamura, K. Kita, T. Iino, K. Asanuma, A. Sudo, "Anti-tumour effect of tocilizumab for osteosarcoma cell lines," Bone & Joint Research, vol. 9 no. 11, pp. 821-826, DOI: 10.1302/2046-3758.911.BJR-2020-0123.R1, 2020.
[59] N. N. Alraouji, A. Aboussekhra, "Tocilizumab inhibits IL-8 and the proangiogenic potential of triple negative breast cancer cells," Molecular Carcinogenesis, vol. 60 no. 1, pp. 51-59, DOI: 10.1002/mc.23270, 2021.
[60] L. Xu, M. Shen, X. Chen, R. Zhu, D. R. Yang, Y. Tsai, P. C. Keng, Y. Chen, S. O. Lee, "Adipocytes affect castration-resistant prostate cancer cells to develop the resistance to cytotoxic action of NK cells with alterations of PD-L1/NKG2D ligand levels in tumor cells," The Prostate, vol. 78 no. 5, pp. 353-364, DOI: 10.1002/pros.23479, 2018.
[61] B. Zheng, Y. Yang, Q. Han, C. Yin, Z. Pan, J. Zhang, "STAT3 directly regulates NKp46 transcription in NK cells of HBeAg-negative CHB patients," Journal of Leukocyte Biology, vol. 106 no. 4, pp. 987-996, DOI: 10.1002/JLB.2A1118-421R, 2019.
[62] L. J. Xu, Q. Ma, J. Zhu, J. Li, B. X. Xue, J. Gao, C. Y. Sun, Y. C. Zang, Y. B. Zhou, D. R. Yang, Y. X. Shan, "Combined inhibition of JAK1, 2/Stat3-PD-L1 signaling pathway suppresses the immune escape of castration-resistant prostate cancer to NK cells in hypoxia," Molecular Medicine Reports, vol. 17 no. 6, pp. 8111-8120, DOI: 10.3892/mmr.2018.8905, 2018.
[63] F. Xu, A. Sunderland, Y. Zhou, R. D. Schulick, B. H. Edil, Y. Zhu, "Blockade of CD112R and TIGIT signaling sensitizes human natural killer cell functions," Cancer Immunology, Immunotherapy, vol. 66 no. 10, pp. 1367-1375, DOI: 10.1007/s00262-017-2031-x, 2017.
[64] Q. Zhang, J. Bi, X. Zheng, Y. Chen, H. Wang, W. Wu, Z. Wang, Q. Wu, H. Peng, H. Wei, R. Sun, Z. Tian, "Blockade of the checkpoint receptor TIGIT prevents NK cell exhaustion and elicits potent anti-tumor immunity," Nature Immunology, vol. 19 no. 7, pp. 723-732, DOI: 10.1038/s41590-018-0132-0, 2018.
[65] M. Fathi, S. Bahmanpour, A. Barshidi, H. Rasouli, F. Karoon Kiani, A. Mahmoud Salehi Khesht, S. Izadi, B. Rashidi, S. Kermanpour, R. Mokhtarian, V. Karpisheh, H. Hassannia, H. Mohammadi, A. Jalili, F. Jadidi-Niaragh, "Simultaneous blockade of TIGIT and HIF-1 α induces synergistic anti-tumor effect and decreases the growth and development of cancer cells," International Immunopharmacology, vol. 101 no. Part A, article 108288,DOI: 10.1016/j.intimp.2021.108288, 2021.
[66] A. Albasanz-Puig, J. Murray, M. Namekata, E. S. Wijelath, "Opposing roles of STAT-1 and STAT-3 in regulating vascular endothelial growth factor expression in vascular smooth muscle cells," Biochemical and Biophysical Research Communications, vol. 428 no. 1, pp. 179-184, DOI: 10.1016/j.bbrc.2012.10.037, 2012.
[67] D. Gotthardt, E. M. Putz, E. Straka, P. Kudweis, M. Biaggio, V. Poli, B. Strobl, M. Müller, V. Sexl, "Loss of STAT3 in murine NK cells enhances NK cell–dependent tumor surveillance," Blood, The Journal of the American Society of Hematology, vol. 124 no. 15, pp. 2370-2379, DOI: 10.1182/blood-2014-03-564450, 2014.
[68] X. Yu, K. Harden, L. C. Gonzalez, "The surface protein TIGIT suppresses T cell activation by promoting the generation of mature immunoregulatory dendritic cells," Nature Immunology, vol. 10 no. 1, pp. 48-57, DOI: 10.1038/ni.1674, 2009.
[69] R. J. Johnston, L. Comps-Agrar, J. Hackney, X. Yu, M. Huseni, Y. Yang, S. Park, V. Javinal, H. Chiu, B. Irving, D. L. Eaton, J. L. Grogan, "The immunoreceptor TIGIT regulates antitumor and antiviral CD8 + T cell effector function," Cancer Cell, vol. 26 no. 6, pp. 923-937, DOI: 10.1016/j.ccell.2014.10.018, 2014.
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
Copyright © 2022 S. González-Ochoa et al. This is an open access article distributed under the Creative Commons Attribution License (the “License”), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License. https://creativecommons.org/licenses/by/4.0/
Abstract
Background/Aims. Prostate cancer (PCa) is one of the neoplasms with the highest incidence and mortality rate in men worldwide. Advanced stages of the disease are usually very aggressive, and most are treated with chemotherapeutic drugs that generally cause side effects in these patients. However, additional therapeutic targets such as the IL6R/STAT-3 axis and TIGIT have been proposed, mainly due to their relevance in the development of PCa and regulation of NK cell-mediated cytotoxicity. Here, we evaluate the effect of inhibitors directed against these therapeutic targets primarily via an analysis of NK cell function versus prostate cancer cells. Methods. We analyzed the secretion of cytokines, chemokines, and growth factors in 22Rv1, LNCaP, and DU145 cells. In these cells, we also evaluated the expression of NK ligands, IL6R, STAT-3, and phosporylated STAT-3. In NK-92 cells, we evaluated the effects of Stattic (Stt) and tocilizumab (Tcz) on NK receptors. In addition, we assessed if the disruption of the IL6R/STAT-3 pathway and blockade of TIGIT potentiated the cytotoxicity of NK-92 cells versus DU145 cells. Results. DU145 abundantly secretes M-CSF, VEGF, IL-6, CXCL8, and TGF-β. Furthermore, the expression of CD155 was found to increase in accordance with aggressiveness and metastatic status in the prostate cancer cells. Stt and Tcz induce a decrease in STAT-3 phosphorylation in the DU145 cells and, in turn, induce an increase of NKp46 and a decrease of TIGIT expression in NK-92 cells. Finally, the disruption of the IL6R/STAT-3 axis in prostate cancer cells and the blocking of TIGIT on NK-92 were observed to increase the cytotoxicity of NK-92 cells against DU145 cells through an increase in sFasL, granzyme A, granzyme B, and granulysin. Conclusions. Our results reveal that the combined use of inhibitors directed against the IL6R/STAT-3 axis and TIGIT enhances the functional activity of NK cells against castration-resistant prostate cancer cells.
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
Details


1 Instituto Mexicano del Seguro Social (IMSS), Centro de Investigación Biomédica de Occidente (CIBO), División de Inmunología, Guadalajara, 44340, Jalisco, Mexico; Universidad de Guadalajara, Centro Universitario de Ciencias de la Salud (CUCS), Programa de Doctorado en Ciencias Biomédicas Orientación Inmunología, Guadalajara, 44340, Jalisco, Mexico
2 Universidad de Guadalajara, Centro Universitario de Ciencias de la Salud (CUCS), Programa de Doctorado en Ciencias Biomédicas Orientación Inmunología, Guadalajara, 44340, Jalisco, Mexico; Universidad de Guadalajara, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Departamento de Biología Celular y Molecular, Las Agujas, 45220, Jalisco, Mexico
3 Instituto Mexicano del Seguro Social (IMSS), Centro de Investigación Biomédica de Occidente (CIBO), División de Inmunología, Guadalajara, 44340, Jalisco, Mexico; Universidad de Guadalajara, Centro Universitario de los Altos (CUALTOS), Departamento de Ciencias de la Salud, Tepatitlán de Morelos, 47620, Jalisco, Mexico
4 Instituto Mexicano del Seguro Social (IMSS), Centro de Investigación Biomédica de Occidente (CIBO), División de Inmunología, Guadalajara, 44340, Jalisco, Mexico
5 Universidad de Guadalajara, Centro Universitario de Ciencias de la Salud (CUCS), HIV and Immunodeficiencies Research Institute, Clinical Medicine Department, Guadalajara, 44280, Jalisco, Mexico; Universidad Autónoma de Guadalajara, Departamento Académico de Aparatos y Sistemas I, Unidad Académica de Ciencias de la Salud, Zapopan, 45129, Jalisco, Mexico
6 Universidad de Guadalajara, Centro Universitario de Ciencias de la Salud (CUCS), HIV and Immunodeficiencies Research Institute, Clinical Medicine Department, Guadalajara, 44280, Jalisco, Mexico