Transforming growth factor beta type II receptor expression in gastric cancer: evidence for two independent subgroups.

Transforming growth factor β type II receptor (TGFβ -IIR) has been found to be altered in primary gastrointestinal carcinomas. So far relatively few facts are known about the expression of TGFβ - IIR in primary gastric cancer. Therefore, in the present study, TGFβ - IIR expression was analyzed in 130 primary gastric carcinomas and correlated with clinicopathological findings, the presence of a mutator phenotype, the mutational status of the TGFβ - IIR polyadenine tract and survival. TGFβ - IIR expression was analyzed immunohistochemically. Microsatellite instability was evaluated using a PCR - based assay and the polyadenine run inside the TGFβ -IIR gene was sequenced. A complete loss of TGFβ - IIR expression could be found in 55 (42.3%) of these carcinomas. Loss of TGFβ - IIR expression was significantly correlated with diffuse - type carcinomas according to the Lauren classification as well as with signet ring cell carcinomas and a lower grade of differentiation. No correlation was found with the overall prognosis, the presence of a mutator phenotype, or a mutated TGFβ - IIR. Thus, our data suggest the existence of a further definite subgroup of diffuse - type gastric carcinomas with altered TGFβ - IIR expression, independent from a mutator phenotype with TGFβ - IIR gene mutations. However, according to our results, in gastric cancer neither loss of TGFβ - IIR expression nor mutations of the TGFβ - IIR are of prognostic value.