Differential expression of apoptosis-associated genes in canine mammary tumors

B-cell lymphoma 2 (Bcl-2) and heat shock protein (HSP) families are implicated in various processes of carcinogenesis, owing to their role in regulation of apoptosis and cell cycle, respectively. mRNA expression of Bcl-2, myeloid cell leukemia 1 (Mcl-1), B-cell lymphoma-extra-large (Bcl-xl), Bcl2-associated X (Bax), HSP70 and HSP90-β genes were studied in 30 clinical canine mammary tumors (CMTs). Histological ‘type’ and ‘grade’ were assigned to CMTs and expression was evaluated by SYBR-Green real-time PCR assay. Overall, the tumors exhibited the maximum expression of Bcl-2 amongst the Bcl-2 family members. Sarcoma and carcinosarcoma showed relatively higher expression of Mcl-1, whereas Bcl-2 was over-expressed in carcinoma. In relation to the cancer grades, Bcl-2/Bax ratio tend to increase as the tumor differentiation progressed from well to poorly differentiated. HSP90-β exhibited significantly high expression in carcinoma, carcinosarcoma and all grades of CMTs were suggestive of their elemental role in tumor progression. In conclusion, this study underpins the conjecture that Bcl-2, Mcl-1 and HSP90-β can be used as potential targets of inhibition in future mammary tumor therapeutics.