Carbonic Anhydrase IX Expression in Renal Cell Carcinoma: An Immunohistochemical Study

Introduction: Over the past two decades, Renal cell carcinoma (RCC) has become one of the lethal tumors of growing concern among the Indian population due to its heterogenic pattern. It is asymptomatic and chemoradioresistant. Most patients present with metastasis at the time of diagnosis. The treatment is limited. The inactivation of von Hippel-Lindau (VHL) gene produces Hypoxia Inducible Factor-1α. In response to hypoxia, Carbonic anhydrase IX (CA IX) modifies intracellular pH to aid tumor progression by regulating cell proliferation and invasiveness. CAIX is over-expressed in VHL mutated ccRCC. It is essential to improve the host immunity by targeting the CAIX, thereby destroying the tumor progressionto improve the survival rate.

Aim: To evaluate the CAIX expression in renal carcinoma tissue and adjacent normal tissue and to compare its expressions with the tumor characteristics.

Method and Materials: This study was conducted using 150 tissue blocks of histopathologicallyproven RCC patients. Ethical clearance was obtained from the institute Ethics Committee. CAIX was analyzed by Biotin Streptavidin Immunoperoxidase method. Q scoring was done.

Results: 74% of RCC cases were CA IX positive whereas the adjacent normal tissue area showed n/0976-5506.2019.03977.9egative staining. In this study, most of the CcRCC patients (91.7%) expressed strong and diffuse /0976-5506.2019.03977.9staining and the other subtypes were weak and focally stained. Collecting Duct and sarcomatoid Carcinoma subtypes showed negative staining. The intensity of staining was inversely proportional to grading.

Conclusion: CAIX was strongly expressed in low grade clear cell RCC. CAIX could play a role as potential diagnostic marker in renal cell carcinoma, assessing prognosis and designing therapy.