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Introduction
The vasohibin (VASH) family consists of two members, VASH1 and VASH2 (1). VASH1 was initially identified as a regulator of negative feedback in angiogenesis induced by vascular endothelial growth factor (VEGF) or fibroblast growth factor 2 (FGF2) (2,3). VASH2 is a VASH1 homolog expressed in mononuclear cells that has been demonstrated to act as an angiogenesis stimulator in a mouse model of hypoxia-induced subcutaneous angiogenesis (3). VASH2 is also involved in the proliferation of hepatic (4) and ovarian (5,6) cancer.
It was previously demonstrated that there are two types of VASH2: Nuclear and cytoplasmic (7). In the present study, the focus was on cytoplasmic VASH2, thus all subsequent mention of VASH2 refers to the cytoplasmic form. VASH2 expression was investigated in human breast cancer in the current study; rabbit polyclonal anti-human VASH2 antibodies were produced and successfully used in immunoblotting and immunohistochemical analysis (7).
In the present study, VASH2 expression levels were indicated to be higher in grade 3 vs. grade 1–2 tissues, and in tissues with a level of Ki67 ≥14%. Ki67 is a marker for breast cancer proliferation. It was hypothesized that VASH2 is associated with cell proliferation in breast cancer, and in order to investigate the proliferative function of VASH2 in breast cancer cells and the underlying mechanism, VASH2 overexpression and knockdown in vitro and in vivo models were established. VASH2 produced a significant proliferative effect in vitro and in vivo. Human growth factor array demonstrated that VASH2 promoted proliferation in breast cancer cells via the upregulation of FGF2 and growth/differentiation factor-15 (GDF15) expression. The present study identified a novel role for VASH2 in human breast cancer, and this knowledge may lead to the possibility of VASH2 as a novel target in breast cancer treatment.
Materials and methods
Clinical samples
Human breast cancer tissue and adjacent non-cancerous tissue were obtained from 99 patients who underwent surgical resection at The First Affiliated Hospital of Nanjing Medical University (Nanjing, China) in accordance with institutional policy. All patients provided written informed consent.
Animals
Five-week-old female BALB/cA-nu (nu/nu) nude mice were obtained from Vital River Laboratories (Beijing, China). The Animal Care and Use Subcommittee of Nanjing Medical University approved all experimental procedures, which were performed in accordance with the standards established by the 1964...