Inactivating mutations of KILLER/DR5 gene in gastric cancers

Background & Aims: The KILLER/death receptor (DR)5 has been identified as a potent inducer of apoptosis, and mapped to chromosome 8p21-22, showing frequent allelic loss in gastric cancer. The p53-induced apoptosis is an important biological process to prevent the development of cancer, and is mediated in part by expression of KILLER/DR5 only in cells with wild-type p53 protein, but not in those lacking p53 function. The aim of this study was to determine whether genetic alterations of KILLER/DR5 could be involved in the tumorigenesis of gastric cancer. Methods: We analyzed the genetic alterations of KILLER/DR5 and p53 in 43 gastric cancers and the loss of function of KILLER/DR5 mutants, detected in this study. Results: We found 3 KILLER/DR5 missense mutations (7%), and 2 of them showed allelic loss in the remaining allele. Interestingly, all the mutants inhibit apoptotic cell death in transfection studies. We also found 6 p53 mutations (14%). Interestingly, the tumors containing the KILLER/DR5 mutation did not carry the p53 mutation. Conclusions: These results suggest that inactivation of KILLER/DR5 caused by mutations of KILLER/DR5 may be one of the possible escaping mechanisms against KILLER/DR5-mediated apoptosis and that inactivating mutation of KILLER/DR5 may contribute to the development or progression of a subset of gastric cancers.