Single nucleotide variants of succinate dehydrogenase A (SDHA) gene in renal cell carcinoma

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is mainly associated with a mutation in the SDHB gene and sometimes with mutations in the SDHC or SDHD genes. However, only three cases of SDHA-deficient RCC have been reported, and the relation between SDHA mutations and RCC has not been clarified. This study assessed the role of SDHA gene mutations in human RCC. We investigated SDHA/B/C/D gene mutations in 129 human RCCs. Targeted next-generation sequencing and direct Sanger sequencing revealed single nucleotide variants (SNVs) of SDHA gene with amino acid sequence variations in 11/129 tumors, while no SDHB/C/D gene mutations were found. Tumor cells with SNVs of SDHA gene were characterized by eosinophilic cytoplasm and various patterns of proliferation. Immunohistochemistry examination found that the 11 tumors with SNVs of SDHA gene showed significant reduction of SDHA protein and SDHB protein expression compared to the 19 tumors without SDHA or SDHB mutations (both p < 0.0001). Western blotting showed a greater decrease in the expression of SDHA and SDHB proteins in the 11 tumors with SNVs of SDHA gene than in the 19 tumors without (both p < 0.0001). There was a positive correlation between SDHA and SDHB protein levels (p < 0.0001). On immunohistochemistry and Western blotting, the 11 tumors with SNVs of SDHA gene had higher protein expression for nuclear factor E2-related factor 2 (Nrf2) compared to the 19 tumors without the mutation (p < 0.01). These observations suggest that SDHA gene mutations might be associated with a subset of RCC.