SEPT5 overexpression predicts poor prognosis and promotes progression through feedback regulation of HIF-1α in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC), a predominant subtype of renal cell carcinoma, significantly contributes to the heightened morbidity and mortality in individuals diagnosed with urologic tumors. The challenges posed by high malignancy at the initial diagnosis of ccRCC, therapeutic resistance, and unfavorable patient prognosis remain largely unresolved. Our findings indicate that SEPT5 is upregulated in ccRCC and this upregulation is associated with an adverse prognosis for ccRCC patients. Furthermore, we demonstrate that overexpression of SEPT5 promotes proliferation of ccRCC cells, alters their cell cycle distribution, and enhances their migratory and invasive capabilities. Additionally, we observe a positive correlation between SEPT5 overexpression and resistance to sorafenib and sunitinib in ccRCC cells. Further mechanistic investigations have revealed that SEPT5 serves as a novel direct transcriptional target of HIF-1α, leading to subsequent reduction in protein expression and nuclear translocation of HIF-1α. This establishes a feedback loop in ccRCC tumorigenesis. Ultimately, knockdown of SEPT5 significantly inhibits xenografted tumor growth in vivo. Overall, this study provides compelling evidence that directly targeting the HIF-1α-SEPT5 feedback axis may be an effective approach for suppressing the proliferation and progression of ccRCC, offering new insights into the diagnosis and treatment of ccRCC patients.