Topographic distribution of bcl-2 protein in feline tissues in health and neoplasia

The bcl-2 family of genes encodes proteins that influence apoptosis. In the present immunohistochemical study, the topographic distribution of bcl-2 p rotein was examined in healthy feline fetal, neonatal, and adult tissues, a feline renal cell line, and feline tumors obtained from a veterinary hospi tal. The topographic distribution of bcl-2 in healthy tissues was similar t o that described in human tissues. Ln lymphoid tissues, follicular mantle c ells strongly expressed bcl-2. In complex and differentiating epithelium, b cl-2 expression was detected in stem cell and proliferation zones. Bcl-2 ex pression was also detected in lower crypts of the intestine and in skin bas al layers. The feline Crandell kidney cells expressed bcl-2 diffusely throu ghout the cytoplasm. Of 180 tumors examined, bcl-2 was expressed almost uni formly in cutaneous basal cell tumors, thyroid adenomas, and mammary carcin omas and in 50% of the lymphomas examined. Bcl-2 may play a role in blockin g apoptotic cell death in a broad range of normal feline tissues, whereas d ysregulated bcl-2 may extend the life of certain tumors or render certain t umors resistant to therapy because most chemotherapeutic and radiotherapeut ic agents eliminate tumor cells by triggering apoptosis.