RIZ, the retinoblastoma protein interacting zinc finger gene, is mutated in genetically unstable cancers of the pancreas, stomach, and colorectum.
The retinoblastoma protein interacting zinc finger (RIZ) gene is a candidate tumor suppressor gene on 1p36, a region frequently rearranged in a wide variety of human tumors. As the RIZ gene harbors several microsatellites within its coding region, it is a candidate for an inactivating mutation in microsatellite instability (MSI) mediated carcinogenesis. In this study, we examined mutations of two poly adenine tracts, A(8) and A(9), within the coding region of the RIZ gene, in MSI-high (MSI-H) primary cancers occurring in the pancreas, stomach, and colorectum. Frameshift mutations were found in one (10%) of 10 pancreatic, four (36%) of 11 gastric, and two (25%) of eight colorectal cancers. These results indicate that mutations of the RIZ gene play an important role in the pathogenesis of some MSI-H cancers.