Ectopic expression of p33ING1b suppresses proliferation and induces apoptosis in colonic adenocarcinoma cells

Inhibitor of growth 1b (ING1b) is considered to be a class II tumor suppressor gene. Although decreased expression of p33 ING1b has previously been reported in colorectal cancer (CRC), its role in CRC has remained to be elucidated. The present study was designed to assess the function of p33 ING1b in CRC and to further evaluate its underlying mechanisms of action. Western blot analysis confirmed that ING1b gene expression was significantly decreased in CRC tissues compared with that of adjacent non-tumorous colorectal tissues. Furthermore, recombinant adenovirus-mediated ectopic expression of p33 ING1b resulted in growth inhibition, G1-phase cell cycle arrest and apoptosis in the SW480, HT29 and LoVo colorectal adenocarcinoma cell lines. The results suggested that the downregulation of ING1b contributes to colorectal carcinogenesis and that ectopic expression of ING1b may be a potentially useful therapeutic approach for CRC.