Increased expression of FLIP, an inhibitor of Fas-mediated apoptosis, in stomach cancer.
Despite the cell surface expression of Fas (Apo-1/CD95), many types of tumor cells, including stomach cancer cells, are resistant to Fas-mediated apoptosis, indicating the presence of inactivating mechanisms of Fas signaling. Expression of FLICE-like inhibitory protein (FLIP), one of the inhibitory proteins of Fas-mediated apoptosis, has been reported in several cancer types, but not in stomach cancer. In the present study, we analyzed the expression of Fas and FLIP in 60 advanced gastric adenocarcinomas by immunohistochemistry using a tissue microarray approach. Immunopositivity (defined as >/=30% of the neoplastic cells) was observed for Fas in 58 (97%) and FLIP in 54 (90%) of the 60 cancers. All of the tumors with FLIP immunostaining also showed Fas immunostaining. Loss of cell surface Fas immunostaining, another mechanism of Fas resistance, was observed in 45 tumors (75%). By contrast, normal gastric mucosal cells showed no or weak expression of both Fas and FLIP. Taken together, these results indicate that increased expression of FLIP is a frequent event in stomach carcinomas, and suggest that for evading apoptosis stomach carcinoma cells in vivo may need FLIP expression, which might contribute to tumor development.
Lee
Sug Hyung
SH
Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Kim
Hong Sug
HS
Kim
Su Young
SY
Lee
Yun-Sil
YS
Park
Won Sang
WS
Kim
Sang Ho
SH
Lee
Jung Young
JY
Yoo
Nam Jin
NJ
D015703:Antigens, CD / Q000032:analysis; D017209:Apoptosis; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D020411:Oligonucleotide Array Sequence Analysis; D013274:Stomach Neoplasms / Q000145:classification / Q000235:genetics / Q000473:pathology*; D019014:fas Receptor / Q000032:analysis*
D015703:Antigens, CD; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D019014:fas Receptor