LACK OF EVIDENCE FOR EXPRESSION OF FAS LIGAND IN FAS-BEARING TUMORS

Interaction of Fas and its ligand plays an important role in the cell death by means of apoptosis in a variety of cell types. We recently de monstrated the frequent expression of Fas in female reproductive tract tumors, which prompted us to examine the local production of Fas liga nd by the Fas-bearing tumors. Human endometrial and ovarian carcinomas , surgically removed, were studied. No expression of Fas ligand messen ger ribonucleic acid (mRNA) as assessed by reverse transcription-polym erase chain reaction using oligonucleotide primers according to publis hed sequences were observed; Fas ligand mRNA was detected in lymphocyt es. Immunoblotting of membrane proteins with the specific antibody fai led to demonstrate any substantial level of immunoreactive Fas ligand in these tumors. The results for both mRNA expression and immunoreacti vity suggest that human ovarian and endometrial carcinomas lack the Fa s ligand. The demonstration of absence of Fas ligand expression raises the possibility that the stimulated proliferation of the Fas ligand-a bsent tumors may occurs by release of Fas-Fas ligand system-associated apoptosis.