GLI2/Parkin-mediated mitophagy promotes pazopanib resistance in clear cell renal cell carcinoma

Abstract

Advanced clear cell renal cell carcinoma (ccRCC) treatment primarily involves targeted therapy and immunotherapy; however, many patients exhibit resistance to these modalities. Understanding the mechanisms underlying this resistance is essential for improved outcomes. Herein, we created a pazopanib-resistant 786-O-PR cell line, revealing an active mitophagy pathway and increased Parkin expression in the resistant cells. Knocking down Parkin enhanced the sensitivity of resistant cells to pazopanib, while its overexpression in parental cells induced resistance, which was partially reversed by the mitophagy inhibitor 3-Methyladenine (3-MA). In xenograft models, Parkin knockdown and pazopanib administration inhibited tumorigenesis. We further identified GLI Family Zinc Finger 2 (GLI2) as a potential Parkin regulator, with high expression correlating with advanced tumor stages and poor prognosis. Knocking down GLI2 increased pazopanib sensitivity and diminished mitophagy level in resistant cells; however, its overexpression enhanced resistance and mitophagy, with partial rescue achieved using 3-MA. Furthermore, GLI2 knockdown reduced Parkin mRNA and protein levels. In pazopanib-resistant 786-O-PR cells, GLI2 knockdown and Parkin overexpression partially restored pazopanib resistance, while GLI2 overexpression and Parkin knockdown in parental cells partially restored sensitivity. GLI2's binding sites on the Parkin promoter were identified using JASPAR database analysis and confirmed using chromatin immunoprecipitation followed by quantitative polymerase chain reaction (CHIP-qPCR) and dual-luciferase assays, indicating GLI2's role in Parkin transcription. This study demonstrated that the GLI2-Parkin mitophagy pathway may be a therapeutic target for overcoming targeted therapy resistance in ccRCC.

Keywords: GLI2; Mitophagy; Parkin; Pazopanib resistance; ccRCC.