Loss of CDCA5 Promotes Cell Apoptosis by Activating the DNA Damage Response in Clear Cell Renal Cell Carcinoma

Abstract Background: Cell division cycle-associated 5 (CDCA5) protein, which is involved in cohesion, contributes to cell cycle regulation and chromosome segregation by maintaining genomic stability. Accumulating evidence indicates that CDCA5 is upregulated in many types of cancers with poor prognoses. However, it remains largely unknown about the biological function of CDCA5 in clear cell renal cell carcinoma (ccRCC). Methods:UALCAN databases were used to display CDCA5 expression profile and its prognosis in ccRCC patients. Further，we performed immunohistochemistry (IHC) on tissue microarray (TMA) containing 137 paired ccRCC and adjacent normal tissue samples, and evaluated correlation between CDCA5 expression and clinicalpathological parameters. Survival analysis by univariate and multivariate Cox regression were applied to identify the independent risk factors. By short hairpin RNAs (shRNA) knockdown, knockdown, a series of functional assays were conducted to determine the role of CDCA5 in ccRCC malignancy in vitro. DNA damage was analyzed by immunofuorescent staining and western blot. Orthotopic ccRCC model illuminated the function of CDCA5 in tumorgenicity in vivo.Results:TCGA data mining revealed that CDCA5 was more highly expressed in ccRCCs than adjacent normal tissues. Importantly, such high expression was correlated with a higher risk of distal metastasis and poorer clinical outcomes, which we further validated via immunohistochemical analysis of tissue microarrays. Functional studies showed that CDCA5 depletion significantly inhibited the proliferation and migration of ccRCC cells and suppressed the growth of xenografts in nude mice. Mechanistically, CDCA5 knockdown induced serious DNA damage with persistent accumulation of gamma-H2AX foci, resulting in G2/M cell cycle arrest and finally chromosomal instability and apoptosis. CDCA5 knockdown significantly decreased the phosphorylation of AKT, STAT3, and NF-κB, suggesting that CDCA5 plays a role in regulating the inflammatory response.Conclusion: ccRCC cells require CDCA5 for malignant progression, and that CDCA5 inhibition may enhance the outcomes of patients with high-risk ccRCC.