Abstract
BackgroundDrug resistance is a major cause of therapeutic failure that is often associated with elevated autophagy and apurinic/apyrimidinic endonuclease 1 (APE1) expression. Herein, we investigated the role of APE1 and autophagy in A549 cells treated with cisplatin.MethodsSILAC proteomics was applied to obtain a panoramic view of cisplatin treatment in KRASG12S-mutant A549 cells. Quantity analysis of cellular apoptosis and autophagy was based on flow cytometry. Western blotting was used to examine the expression levels of apoptosis- and autophagy-related proteins, as well as those of APE1. Knockdown of APE1 was achieved by RNA interference. Immunoprecipitation was further employed to reveal the molecular interaction of APE1, p53, and LC3 when A549 cells were exposed to cisplatin.ResultsSILAC proteomics revealed that 72 canonical pathways, including base excision repair (BER) and autophagy signalling pathways, were regulated after cisplatin treatment in A549 cells. Cisplatin markedly induced autophagy and apoptosis in A549 cells, accompanied by remarkable APE1 increase. Suppression of autophagy enhanced the inhibition effect of cisplatin on cell growth, proliferation, and colony formation; however, APE1 inhibition enhanced the expression of LC3-I/II, suggesting that APE1 and autophagy are compensatory for cell survival to evade the anticancer action of cisplatin. Immunoprecipitation results revealed the triple complex of APE1-p53-LC3 in response to cisplatin plus CQ in A549 cells. Dual inhibition of APE1 and autophagy significantly enhanced cisplatin-induced apoptosis, which eventually overcame drug resistance in cisplatin-resistant A549 cells.ConclusionsDual inhibition of APE1 and autophagy greatly enhances apoptosis in parental KRASG12S-mutant A549 cells and cisplatin-resistant A549 cells via regulation of APE1-p53-LC3 complex assembly, providing therapeutic vulnerability to overcome cisplatin resistance in the context of KRASG12S-mutant lung cancer.
Highlights
Drug resistance is a major cause of therapeutic failure that is often associated with elevated autophagy and apurinic/apyrimidinic endonuclease 1 (APE1) expression
We evaluated the proteomic responses to cisplatin (5 μM) treatment and identified at least 3262 protein molecules responding to cisplatin treatment, including APE1, p53, LC3-I/II, and many other functional proteins involved in DNA damage repair, cell proliferation, cell cycle, cellular metabolism, apoptosis, and autophagy
We speculated that both base excision repair (BER) and autophagy pathways are involved in cisplatin-stimulated cellular responses in KRASG12S-mutant A549 cells
Summary
Drug resistance is a major cause of therapeutic failure that is often associated with elevated autophagy and apurinic/apyrimidinic endonuclease 1 (APE1) expression. We investigated the role of APE1 and autophagy in A549 cells treated with cisplatin. Lung cancer is the leading cause of cancer-related death and remains a major clinical challenge with increasing incidence and mortality [1, 2]. Recurrence, and metastasis, the treatment efficacy of lung cancer remains unsatisfactory. Somatic gene mutations, including KRAS, EGFR, and TP53 mutations, is a major driver of lung cancer initiation [3]. Given the feature of allele specificity and the pivotal role of RAS in cellular events, including cell growth, cell survival, cell senescence, and cell death, novel strategies in a RAS allele-dependent manner are still required
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