A Transforming Growth Factor β Receptor Type II Gene Mutation Common in Colon and Gastric but Rare in Endometrial Cancers with Microsatellite Instability

We have recently demonstrated that mutation of the transforming growth factor-β (TGF-β) receptor type II (RH) gene is characteristic of colon cancers exhibiting microsatellite instability or replication errors (RER+). Moreover, we have shown that RH mutations in these RER+ colon cancers are characteristically frameshift mutations within a 10-bp polyadenine repeat present in the RII-coding region. We now show that RH gene mutations in this polyadenine repeat are also commonly present in RER+ gastric cancers (71%). In contrast, we find these same RH gene mutations are distinctly uncommon in RER+ endometrial cancers (17%, P < 0.02). These results suggest that RH gene mutations confer a growth advantage and are selected for in RER+ cancers of both the upper and lower gastrointestinal tract. The genesis of RER+ endometrial tumors must, however, be by a different route.