Reversion of malignancy in human gastric cancer MKN-45 cells through the transfection of transforming growth factor-β type Ⅱ receptor gene

Human gastric cancer MKN-45 cells which are resistant to TGF-β growth inhibition and possess TGF-β type Ⅰ and type Ⅲ receptors, but not type Ⅱ receptors, have been used as a model system to reconstitute these caflcer cells with TGF-β RII cDNA. The results of these experiments indicated that the reexpression of TGF-g RII gene in MKN-45 cells can restore their sensitivity to TGFβ growth inhibition, decrease their growth rate, reduce their cloning efficiency in soft agar and tumorigenicity in nude mice in stable transfectants, in comparison with their control MKN-45 cells. Among different RII transfectants,their difference in the changes of these parameters, as a result of the regain of autocrine negative growth control by TGF-β, is roughly proportional to their level of expression of transfected RII mRNA. From these data, it is concluded that the inactivation of TGF-β RII gene is related to the escape of growth control by TGF-β in MKN-45 cells. The importance of the study of the interplay of TGF-β and its receptor system in the negative growth control of gastric cancer, and possibly also of other cancers, is discussed.