Abstract 3415: PAICS is the prognostic marker in colorectal cancer patients with stage III

Abstract

Abstract PAICS (Phosphoribosylaminoimidazole carboxylase/phosphoribosylaminoimidazole succinocarboxamide synthetase) is an important bifunctional enzyme in de novo purine biosynthesis. It could be an attractive target for anticancer drug design, since rapidly dividing cancer cells rely on the purine through de novo pathway for synthesis of adenine and guanine, whereas normal cells favor the salvage pathway. Previous reports demonstrated that PAICS expression was up-regulated in ALL, lung cancer, and glioblastoma. In the present study, we first performed the comparison of PAICS mRNA expression between cancer tissue and normal colonic mucosa in 83 colorectal cancer (CRC) patients by realtime RT-PCR. We further investigated PAICS expression by immunohistochemical staining in 258 CRC patients and analyzed the association between PAICS expression and clinicopathological factors and prognosis. To understand the biological significance of PAICS expresssion, knockdown experiments of PAICS expression were performed by a siRNA method using the colon cancer cell line, HCT116. We analyzed the relationship between PAICS mRNA expression and genetic status and prognosis using several databases. PAICS mRNA expression in CRC tissue was significantly enhanced when compared to that in normal tissue. In immunohistochemical examination, PAICS expression was observed in cytoplasm of cancer cells. PAICS expression was detected in 55% cases of colorectal cancer patients. There were significant association between PAICS expression and histology (p = 0.049). There was not significant correlation between PAICS expression and overall survival in CRC patients. Regarding CRC patients with stage III, patients with positive expression of PAICS had significantly good prognosis as compared to those with negative expression (p = 0.015). Knockdown of PAICS expression acquired the ability of cellular invasion using colon cancer cell lines, HCT116 and SW480. In all CRC databases we analyzed, stage III patients with high expression of PAICS had good prognosis as compared to those with low expression of PAICS. We concluded that PAICS expression was up-regulated in approximately 55% CRC, and higher level of PAICS expression might serve as a good prognostic marker in advanced CRC patients. Citation Format: Yusuke Kobayashi, Kensuke Kumamoto, Yoshiko Matsumoto, Motonobu Saito, Tatsuo Shimura, Seiichi Takenoshita. PAICS is the prognostic marker in colorectal cancer patients with stage III. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3415. doi:10.1158/1538-7445.AM2015-3415