Expression of heat shock protein D1 is up-regulated in canine mammary tumors

Abstract Background- Mammary tumors are frequently seen in female dogs. Conventionally, these tumors are diagnosed by histopathology. Differentially expressed biomarkers could aid in non-invasive diagnosis of canine mammary tumors but their number is scanty. The present investigation focuses on assessing HSPD1 as a diagnostic biomarker of canine mammary tumors. Methods and results- Expression of HSPD1 transcript was analyzed by SYBR green based real time PCR (qRT-PCR). Gene encoding immuno-dominant region of HSPD1 was cloned using the expression vector pPROEX-HTa and expressed in a prokaryotic system. Upon purification by affinity chromatography, a 60KDa recombinant protein was obtained which was confirmed by Western blotting. Hyperimmune serum was raised against the rHSPD1 in mice and immunohistochemistry was standardized to assess expression of this protein in various histotypes of canine mammary tumors. Elevated level of HSPD1 mRNA expression (4.92 ± 0.65folds) was observed in canine mammary tumors as compared to the healthy mammary tissue. Further, HSPD1 protein expression in 80% of healthy tissues showed mild immunoreactivity whereas, moderate to high expression of HSPD1 was seen in 80% CMT tissue samples. Conclusions- The findings suggest that HSPD1 could act as molecular marker for the diagnosis of mammary tumors in canines and also to assess the response to these subjects to treatment.