ALKBH5 promotes the proliferation of renal cell carcinoma by regulating AURKB expression in an m6A-dependent manner

Background: The modification and regulation of N6-methyladenosine (m⁶A) at mRNA level can affect the development and progression in various tumors. ALKBH5, as an m⁶A demethylase, plays different roles in tumors by regulating the m⁶A modification of mRNA. However, its role in renal cell carcinoma (RCC) remains unclear.

Methods: First, levels of ALKBH5 in RCC tissues and cell lines were verified by qRT-PCR and western blot. We analyzed the relationship between ALKBH5 and the clinicopathological characteristics of RCC patients and the influence of ALKBH5 on the prognosis of patients. Then we generated ALBKH5-overexpression, ALBKH5-knockdown stable RCC cell lines and their control cell lines. Through cell proliferation assay, colony formation assay, cell invasion and tumor migration assay, cell cycle assay and xenograft studies, we studied the ALKBH5 roles in RCC cell lines. AURKB was predicted to be its potential target based on TCGA database analysis and verified by western blot. The role of AURKB in RCC was verified by TCGA database and Kaplan-Meier analysis with TMA immunohistochemical analysis. Finally, the specific molecular mechanism of ALKBH5 targeting AURKB was explored by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), m⁶A dot-blot assay, m⁶A RNA Immunoprecipitation (MeRIP) assay, and mRNA stability assay.

Results: We found that ALKBH5 was highly expressed in both RCC tumor tissues and cell lines. Clinicopathological analysis showed that high ALKBH5 expression was associated with larger tumor volume (P=0.017) and higher TNM staging (P=0.006), and worse prognosis (log rank: P=0.0199). The cellular functional assays showed that stably overexpression ALKBH5 could promote the cell proliferation, colony formation, cell migration and cell invasion of renal cell carcinoma cells in vitro and promote tumor growth in vivo. In contrast, ALKBH5 knocked down inhibited cell proliferation, colony formation, migration and invasion of renal cell carcinoma cells in vitro. Based on TCGA database analysis, AURKB was predicted highly expressed in RCC and a potential target of ALKBH5. Both database prediction and TMA immunohistochemical analysis supported that AURKB could affect the prognosis of RCC patients (P values of 5.5e-08 and 0.0004, respectively) and was regulated by ALKBH5 expression level. Subsequent mechanism experiments showed that ALKBH5 regulated the expression of AURKB by regulating the stability of AURKB mRNA in the m⁶A-dependent manner, and finally promoted cell proliferation. Furthermore, we found that hypoxia-induced HIF could up-regulate both expressions of AURKB and ALKBH5.

Conclusions: Our findings suggest that ALKBH5 may play a carcinogenic role in renal cell carcinoma by stabilizing AURKB mRNA in a m⁶A-dependent manner. These data suggest that ALKBH5 may play a key role in RCC and targeting the ALKBH5 signaling pathway may be a promising strategy for the treatment of RCC.