Frequent expression of soluble Fas and Fas ligand in Chinese stomach cancer and its preneoplastic lesions

To investigate the frequency and pattern of Fas and FasL expression in the gastric mucosa at different stages of gastrocarcinogenesis, the combined examinations of pathology, immunocytochemistry and Western blot hybridisation were performed on the cancer specimens as well as their preneoplastic and non-cancerous counterparts. The frequencies of Fas and FasL expression were found to be 6.3% (1/16) and 62.5% (10/16) in non-cancerous mucosa, 60% (6/10) and 80% (8/10) in atrophic gastritis, 75% (9/12) and 83% (10/12) in intestinal metaplasia, 100% in both dysplasia Grades II (20/20) and Grade III (15/15) and 4 types of gastric carcinomas (74/74). Two forms of FasL protein in 37 kDa and 26 kDa were detected in all FasL+ cases. Soluble Fas (30 kDa) but not the membrane-type (43 kDa) is predominantly expressed in the Fas+ cases. Our data thus suggest a close correlation of soluble Fas with stomach tumour progression P<0.01. The sFas protein, together with the tumor-derived soluble and membrane FasL, may confer on the transforming and transformed gastric epithelial cells an immune advantage enabling escape from endogenous and exogenous suicide signal(s).