HERC1 attenuates gemcitabine resistance of lung cancer cells by inhibiting autophagy through KAT2A ubiquitination.

Abstract

Lung cancer, a leading cause of death, is challenging to treat due to gemcitabine resistance. Dysregulated autophagy is associated with chemoresistance. Here, we aimed to study the mechanism of how HERC1 modulates autophagy and gemcitabine sensitivity in lung cancer. Paired tumor and adjacent normal tissues were collected from 30 patients with lung cancer. The viability, proliferation, apoptosis, migratory, and invasive capacity of gemcitabine-resistant A549 and H1299 cells (A549/R and H1299/R) were evaluated using Cell Counting Kit-8 (CCK-8), EdU staining, flow cytometry, wound healing, and Transwell assays, respectively. The interactions among HECT and RLD domain-containing E3 ubiquitin protein ligase family member 1 (HERC1)-lysine acetyltransferase 2A (KAT2A)-phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta (PIK3CB) were verified by co-immunoprecipitation. A mouse xenograft tumor model was established. Ki-67 expression was determined by immunohistochemistry. Our data showed that HERC1 expression was downregulated in gemcitabine-resistant tumor tissues and A549/R cells, correlating with poor prognosis. Overexpressing HERC1 suppressed proliferation and migration, enhanced apoptosis in A549/R or H1299/R cells, and simultaneously inhibited autophagy. Mechanistically, HERC1 promoted KAT2A ubiquitination and degradation, which enhanced gemcitabine sensitivity by inhibiting autophagy. Further investigation revealed that KAT2A depletion inhibited the lysine acetylation modification of PIK3CB, leading to inactivation of the PI3K/AKT axis. Additionally, HERC1 suppressed autophagy and gemcitabine resistance in A549/R cells by KAT2A-dependent inactivation of the PI3K/AKT axis. Furthermore, HERC1 overexpression enhanced the inhibition of gemcitabine on tumor growth by suppressing autophagy in vivo. In conclusion, HERC1 inhibited autophagy by inactivating PIK3CB-mediated PI3K/AKT signaling via promoting KAT2A degradation, thereby enhancing the gemcitabine sensitivity in lung cancer.