Frameshift mutations of a tumor suppressor gene ZNF292 in gastric and colorectal cancers with high microsatellite instability

A transcription factor-encoding gene ZNF292 is considered a candidate tumor suppressor gene (TSG). Its mutations have been identified in cancers from liver, colon, and bone marrow. However, ZNF292 inactivating mutations that might suppress the TSG functions have not been reported in gastric (GC) and colorectal cancers (CRC) with microsatellite instability (MSI). In a public database, we found that ZNF292 gene had mononucleotide repeats in the coding sequences that might be mutation targets in the cancers with MSI. In this study, we analyzed 79 GCs and 124 CRCs including high MSI (MSI-H) and microsatellite stable/low MSI (MSS/MSI-L) cases for the detection of somatic mutations in the repeats. Overall, we identified frameshift mutations of ZNF292 in 3 (8.8%) GCs and 11 (13.9%) CRCs with MSI-H (14/113), but not in MSS/MSI-L cancers (0/90) (p < 0.001). Also, we studied intratumoral heterogeneity (ITH) of the ZNF292 frameshift mutations in 16 CRCs and found that two (12.5%) had regional ITH of the mutations. Our data show that ZNF292 gene harbors not only frameshift mutations but also mutational ITH, which together may be features of GC and CRC with MSI-H. Based on this, the ZNF292 frameshift mutations may possibly contribute to tumorigenesis by altering its TSG functions in GC and CRC.