HAO2 inhibits malignancy of clear cell renal cell carcinoma by promoting lipid catabolic process.

Hydroxy acid oxidase 2 (HAO2) has been reported to inhibit tumor progression through metabolic pathway. The current study was designed to evaluate the prognostic significance and probable mechanism of HAO2 in patients with clear cell renal cell carcinoma (ccRCC). The study screened The Cancer Genome Atlas Kidney Clear Cell Carcinoma (TCGA-KIRC) database for patients with ccRCC having complete clinical information and HAO2 expression. Low HAO2 was associated with shorter overall survival (OS) and shorter disease-free survival (DFS). Gene set enrichment analysis (GSEA) showed HAO2 was associated with neutral lipid catabolic process, metabolic process, lipid oxidation, epithelial-mesenchymal transition (EMT), and Kirsten rat sarcoma viral oncogene signaling (KRAS). Western blot analysis and immunohistochemistry analysis checked HAO2 expression in ccRCC cancer tissues, normal tissues, and renal cancer cell lines. HAO2 was downregulated in ccRCC cancer tissues and ccRCC cell lines when compared with their control group. Overexpression of HAO2 by plasmid promoted lipid catabolic process, eliminated lipid accumulation, inhibited KRAS expression, controlled the proliferation, migration, and invasion activity of ccRCC tumor cells. Our results indicated that HAO2 inhibits malignancy ccRCC by promoting lipid catabolic process, HAO2 could be an effective molecular marker and treatment for ccRCC.