Content area
Full text
Introduction
Colorectal cancer (CRC) is the third most commonly diagnosed cancer in males and the second in females worldwide, and is the fourth leading cause of cancer death in males and the third in females worldwide (1). Although several molecular target therapies have been developed for CRCs, the prognosis of this disease in advanced stages is still poor. Therefore, personalized therapies using biomarkers and new molecular therapies are expected to improve current therapies. For example, cetuximab, a therapeutic antibody to an epidermal growth factor receptor (EGFR), was reported to be effective in CRC treatment. The randomized phase III study (CRYSTAL: Cetuximab Combined with Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer) and randomized phase II study (OPUS: Oxaliplatin and Cetuximab in First-Line Treatment of metastatic CRC) demonstrated that addition of cetuximab to first-line chemotherapy in patients with KRAS wild-type CRC significantly improved the treatment outcome compared with chemotherapy alone. However, the benefit of cetuximab was limited to patients with KRAS wild-type tumors. The overall survival (OS) rate in these trials was still less than two years, and adverse events such as skin reactions, infusion-related reactions and diarrhea were more frequent with cetuximab plus chemotherapy than with chemotherapy alone (2,3). Therefore, there is a need for personalized therapies that are more effective for CRCs including the KRAS mutant, but with fewer adverse events.
Oncoantigens are proteins with oncogenic functions that are overexpressed in malignant cells of various origins and in normal reproductive tissues such as the testis, ovary, and placenta (4,5). Oncoantigens are considered a candidate biomarker and therapeutic target for cancer therapy. We performed genome-wide gene expression analyses and subsequent tissue microarray analyses of solid tumor tissues using a cDNA microarray containing 25,000 genes or expressed sequence tags (ESTs) (6–10). To date, we have isolated several oncoantigens involved in development and/or progression of cancer (11–42). These data revealed that cell division cycle-associated protein 1 (CDCA1) was overexpressed in cancer tissues including CRC and lung cancer tissues. In our previous reports, CDCA1 proteins were detected in many lung cancers with varying histologic types and were associated with a poorer prognosis for patients with non-small cell lung carcinomas (NSCLC). Knockdown of CDCA1 expression with siRNA significantly suppressed growth of NSCLC cell lines (16). In addition,...