HSP90AA1 restrains clear cell renal cell carcinoma progression by promoting CADM1 expression and suppressing the PI3K-AKT pathway through interaction with FBXO7.

Recent studies have shown that heat shock protein 90 alpha family class A member 1 (HSP90AA1) interacts with various tumor-associated proteins, regulates their biological activity and stability, and plays an important role in various tumors. However, the role of HSP90AA1 in clear cell renal cell carcinoma (ccRCC) remains unclear. In the study, GEO and TCGA-KIRC databases were used to analyze the expression pattern and clinical significance of HSP90AA1 in ccRCC; immunohistochemistry and Western blot were used to validate HSP90AA1 expression in ccRCC tissues and cell lines; colony formation assays, EdU and TUNEL methods, cell migration and invasion experiments, and a mouse renal orthotopic xenograft tumor model were used to detect the effects of HSP90AA1 overexpression on the biological function of ccRCC; Co-IP and RNA-seq experiments were utilized to explore the downstream regulatory mechanism of HSP90AA1. Our results showed that HSP90AA1 expression was significantly downregulated in ccRCC, and its reduced expression was associated with tumor metastasis. HSP90AA1 overexpression markedly inhibited the proliferation and metastasis ability of ccRCC cells. HSP90AA1 bound to F-box only protein 7 (FBXO7) and accelerated its protein expression. FBXO7 was expressed at low level in ccRCC, and its decreased expression was closely related to unfavorable pathological features of tumors and poor patient prognosis. FBXO7 overexpression promoted cell adhesion molecule 1 (CADM1) expression and suppressed the PI3K-AKT signaling pathway. Knocking down FBXO7 expression on the basis of HSP90AA1 overexpression significantly reversed the cell phenotype inhibition caused by HSP90AA1 overexpression, downregulated CADM1 expression, and activated the PI3K-AKT signaling pathway. In summary, HSP90AA1 exhibited a low expression pattern in ccRCC, and HSP90AA1 overexpression promoted CADM1 expression and inhibited the PI3K-AKT pathway, thereby suppressing the proliferation and metastasis of ccRCC.