Somatic mutations of caspase-2 gene in gastric and colorectal cancers

There is mounting evidence that evasion of apoptosis is a hallmark of cancer. Caspase-2, which plays roles in both extrinsic and intrinsic apoptosis pathways, is considered a candidate tumor suppressor. The aim of this study was to explore the possibility that genetic alterations of caspase-2 gene are present in human cancers. In this study, we analyzed the entire coding sequences of human caspase-2 gene for the detection of somatic point mutations in 90 gastric carcinomas and 100 colorectal carcinomas by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP). Of the cancers analyzed, two gastric cancers (2/90; 2.2%) and two colorectal cancers (2/100; 2.0%) harbored somatic missense mutations of caspase-2. The mutations consisted of p.V46M (at prodomain), p.S157L (at prodomain), p.R357K (at p13 subunit), and p.R397L (at p13 subunit). We expressed these tumor-derived mutants in 293 T cells and found that three of the mutants decreased cell death activity of caspase-2. Our data indicate that somatic mutation of caspase-2 is rare in gastric and colorectal carcinomas. However, functional data of the caspase-2 mutations also suggest that caspase-2 gene mutation might affect the pathogenesis of some gastric and colorectal cancers by inactivating cell death function of caspase-2.