Microsatellite instability(MSI) in non-small cell lung cancer(NSCLC) is highly associated with transforming growth factor-beta type II receptor(TGF-beta RII) frameshift mutation

Background: TGF-beta type II receptor (TGF-beta RII) mutations associated w ith microsatellite instability(MSI) are characteristically frameshift mutat ions within a 10 bp poly-A tract. These frameshift mutations have been repo rted to be common in colorectal and gastric cancers with MSI, though, rarel y reported in non-small cell lung cancel (NSCLC). Materials and Method: In this study, we analysed MSI and TGF-beta RII frameshift mutations in 7 NSCL C cell lines and 21 surgically resected NSCLC tissues. Determination of MSI in NSCLC was performed using. primer sets for BAT-25, BAT-26 and BAT-40. I n order to examine the presence of the frameshift mutations of TGF-beta RII in samples with MSI, sequencing for TGF-beta RII poly-A tract was pet-form ed. Results : MSI was observed in 5 out of 7 NSCLC cell lines and 3 out of 21 NSCLC tissues. Six out of 8 samples with MSI(75%) showed frameshift muta tions in TGF-beta RII poly-A tract. Conclusion: These results suggest that MSI is highly associated with TGF-beta RII frameshift mutations in NSCLC an d further support the hypothesis that TGF-beta RII plays an important role in NSCLC carcinogenesis.