Mutation analysis of the FAS and TNFR apoptotic cascade genes in hematological malignancies

Objective. The existence of properly functioning apoptotic pathways is of u tmost importance in the maintenance of a normal cell count. Several groups have searched for mutations in the FAS receptor, a well-characterized apopt otic protein carrying a death domain, and reported the existence of rare mu tations in multiple myeloma, T-acute lymphoblastic leukemia (T-ALL), and ad ult T-cell leukemia. Our aim was to expand these searches by looking for mu tations in the death domains of FAS, FADD, TNFR, TRADD, and RIP, in the pro moter region of FAS, and in the protease domain of caspase 10, in a larger variety of hematological malignancies, some of which express an apoptosis-r esistant phenotype, Methods. We extracted RNA and DNA samples from 92 hematological malignancie s: chronic lymphocytic leukemia (CLL; 31 cases), chronic myelogenous leukem ia (CML; 28 cases), essential thrombocythemia (ET; 8 cases), acute lymphocy tic leukemia (ALL; 6 cases), acute myeloblastic leukemia (ARIL; 6 cases), h airy-cell leukemia (HCL; 3 cases), Burkitt's lymphoma (3 cases), polycythem ia vera (PV; 3 cases), myelofibrosis (2 cases), and chronic myelomonocytic leukemia (CMML; 2 cases) and performed PCR-SSCP and sequence analysis on th ese samples. Results. Five polymorphic patterns were found: three in the death domain of the FAS gene in CML patients, one in the promoter of this gene in a CLL pa tient, and the fifth in the death domain of the TRADD gene in a CML patient . No mutations, altering amino acids, were found in these genes in any of t he aforementioned malignancies. Conclusions. These observations imply that mutations in the death domains o f FAS, FADD, TNFR, TRADD, and RIP and in the protease domain of caspase 10 are not a major cause for failure of apoptosis in hematological malignancie s, mainly CML and CLL. Regulatory and epigenetic abnormalities in these apo ptotic cascade members and aberrations in other components of all death mac hinery should be looked for. (C) 2001 International Society for Experimenta l Hematology. Published by Elsevier Science Inc.