The mechanism of m6A methyltransferase METTL3-mediated autophagy in reversing gefitinib resistance in NSCLC cells by \u03b2-elemene

Shuiping Liu,Xinbing Sui,Mingming Zhang,Xuemeng Han,Guohua Li,Xiaying Chen,Qiujie Li,Qin Zhang,Ting Jin,Lvjia Zhuo,Jianjun Wang,Qun Lv,Lili Yan,Tian Xie,Ting Pan

doi:10.1038/s41419-020-03148-8

Abstract

N6-methyladenosine (m6A) modification can alter gene expression by regulating RNA splicing, stability, translocation, and translation. Emerging evidence shows that m6A modification plays an important role in cancer development and progression, including cell proliferation, migration and invasion, cell apoptosis, autophagy, and drug resistance. Until now, the role of m6A modification mediated autophagy in cancer drug resistance is still unclear. In this study, we found that m6A methyltransferase METTL3-mediated autophagy played an important role in reversing gefitinib resistance by β-elemene in non-small cell lung cancer (NSCLC) cells. Mechanistically, in vitro and in vivo studies indicated that β-elemene could reverse gefitinib resistance in NSCLC cells by inhibiting cell autophagy process in a manner of chloroquine. β-elemene inhibited the autophagy flux by preventing autophagic lysosome acidification, resulting in increasing expression of SQSTM1 and LC3B-II. Moreover, both β-elemene and gefitinib decreased the level of m6A methylation of gefitinib resistance cells. METTL3 was higher expressed in lung adenocarcinoma tissues than that of paired normal tissues, and was involved in the gefitinib resistance of NSCLC cells. Furthermore, METTL3 positively regulated autophagy by increasing the critical genes of autophagy pathway such as ATG5 and ATG7. In conclusion, our study unveiled the mechanism of METTL3-mediated autophagy in reversing gefitinib resistance of NSCLC cells by β-elemene, which shed light on providing potential molecular-therapy target and clinical-treatment method in NSCLC patients with gefitinib resistance.

Highlights

Lung cancer is one of the most common malignant tumors in the world, and its incidence and mortality consistently rank first among malignant tumors[1]
We used chloroquine as a positive control to study the mechanism of β-elemene in the following experiments. All these results indicated that β-elemene could reverse gefitinib resistance in non-small cell lung cancer (NSCLC) cells by inhibiting autophagy, and that autophagy plays a critical role in gefitinib resistance by protecting resistant cells from death
In order to analyze the autophagy flux in tumors treated with indicated drugs, we investigated the expression of LC3B and SQSTM1 by immunohistochemistry

Summary

Introduction

Lung cancer is one of the most common malignant tumors in the world, and its incidence and mortality consistently rank first among malignant tumors[1]. Liu et al Cell Death and Disease (2020)11:969 that β-elemene has played a huge physiological and pathological role in the treatment of lung cancer, leukemia, liver cancer, cervical cancer, and gastric cancer, though many functional mechanisms of β-elemene have not been discovered. Autophagy is a physiological phenomenon widely existing in eukaryotic cells, which is characterized by transporting abnormal proteins and organelles to lysosomes for degradation[12]. It plays an important role in maintaining cellular metabolism, internal environmental stability, and genomic integrity, whose dysfunction is closely related to the occurrence of various human diseases[13]. An increasing number of evidence shows that cell autophagy is closely related to drug resistance of cancer cells[14]. The roles and mechanism of autophagy in reversing gefitinib resistance mediated by β-elemene is still unclear

Methods

Results

Conclusion