STOML2 Knockdown Amplifies PINK1/Parkin-Dependent Mitophagy in Colorectal Cancer.

Colorectal cancer (CRC) remains a major cause of cancer death. STOML2 can orchestrate mitophagy in pancreatic cancer cells. Herein, this study probed whether STOML2 modulated cell mitophagy in CRC. STOML2 expression in CRC was analyzed using databases and measured in CRC cells and tissues. Following STOML2 knockdown in CRC cells, CCK-8 assay was utilized for detecting cell viability, Transwell assay for measuring cell invasion and migration, and flow cytometry for testing apoptosis. Meanwhile, mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels were examined using JC-1 probes and kits. PINK1, Parkin, LC3II/I, and p62 protein levels were determined by Western blot, and Bax, Bcl-2, and Caspase 3 mRNA levels were analyzed by RT-qPCR. TOM20 and LC3 co-expression was tested by immunofluorescence. Rescue experiments were conducted with an inhibitor of mitophagy (3-methyladenine) and STOML2 knockdown. STOML2 was highly expressed in CRC. STOML2 knockdown diminished CRC cell proliferation, invasion, and migration while augmenting apoptosis. Additionally, STOML2 knockdown reduced MMP, ATP contents, and p62 expression and enhanced LC3II/I, PINK1, and Parkin expression and co-expression of TOM20 and LC3II/I in CRC cells. Treatment with 3-MA reversed the promotion of mitophagy in CRC cells caused by STOML2 knockdown. Simultaneous knockdown of PINK1 in STOML2-knockdown cells effectively reversed STOML2-induced decreases in p62, increases in the LC3II/I ratio, and enhanced co-localization of mitochondria and autophagosomes. STOML2 knockdown suppresses cell proliferation, invasion, and migration and promotes mitophagy and apoptosis by inhibiting the PINK1/Parkin pathway.