Inactivation of 14-3-3σ by hypermethylation is a rare event in colorectal cancers and its expression may correlate with cell cycle maintenance at the invasion front

In many kinds of cancers, 14-3-3σ, one of the cell cycle negative regulator, is inactivated by hypermethylation of the gene. In colorectal cancers, this study revealed that the hypermethylation of the 14-3-3σ gene was an uncommon event and 14-3-3σ expression was kept even in established colorectal cancer cell lines. Immunohistochemical study using surgical materials showed the expression of 14-3-3σ was localized at the deep peripheral area of the tumor, so-called invasion front. According to the results of Ki-67 and cyclin B1 immunohistochemistry, 14-3-3σ-positive cases maintained higher proliferative activity compared to 14-3-3σ-negative cases at IF. However, a significant correlation between 14-3-3σ expression and proliferative activity in CRC cells remains to be unsolved.