KRAS mutants confer platinum resistance by regulating ALKBH5 posttranslational modifications in lung cancer
Fang Yu, … , Tongjun Gu, Zhijian Qian
Fang Yu, … , Tongjun Gu, Zhijian Qian
Published February 17, 2025
Citation Information: J Clin Invest. 2025;135(6):e185149. https://doi.org/10.1172/JCI185149.
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Research Article Cell biology Oncology

KRAS mutants confer platinum resistance by regulating ALKBH5 posttranslational modifications in lung cancer

Abstract

Constitutively active mutations of KRAS are prevalent in non–small cell lung cancer (NSCLC). However, the relationship between these mutations and resistance to platinum-based chemotherapy and the underlying mechanisms remain elusive. In this study, we demonstrate that KRAS mutants confer resistance to platinum in NSCLC. Mechanistically, KRAS mutants mediate platinum resistance in NSCLC cells by activating ERK/JNK signaling, which inhibits AlkB homolog 5 (ALKBH5) N6-methyladenosine (m6A) demethylase activity by regulating posttranslational modifications (PTMs) of ALKBH5. Consequently, the KRAS mutant leads to a global increase in m6A methylation of mRNAs, particularly damage-specific DNA-binding protein 2 (DDB2) and XPC, which are essential for nucleotide excision repair. This methylation stabilized the mRNA of these 2 genes, thus enhancing NSCLC cells’ capability to repair platinum-induced DNA damage and avoid apoptosis, thereby contributing to drug resistance. Furthermore, blocking KRAS-mutant–induced m6A methylation, either by overexpressing a SUMOylation-deficient mutant of ALKBH5 or by inhibiting methyltransferase-like 3 (METTL3) pharmacologically, significantly sensitizes KRAS-mutant NSCLC cells to platinum drugs in vitro and in vivo. Collectively, our study uncovers a mechanism that mediates KRAS-mutant–induced chemoresistance in NSCLC cells by activating DNA repair through the modulation of the ERK/JNK/ALKBH5 PTM-induced m6A modification in DNA damage repair–related genes.

Authors

Fang Yu, Shikan Zheng, Chunjie Yu, Sanhui Gao, Zuqi Shen, Rukiye Nar, Zhexin Liu, Shuang Huang, Lizi Wu, Tongjun Gu, Zhijian Qian

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Figure 2

The constitutively active KRAS mutant regulates global mRNA m6A methylation via controlling ALKBH5 phosphorylation and SUMOylation.

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The constitutively active KRAS mutant regulates global mRNA m6A methylat...
(A) Denaturing IP analysis suggests overexpression of the constitutively active KRAS mutant significantly induces ALKBH5 phosphorylation and SUMOylation in BEAS-2B cells. (B) IP analysis suggesting the KRAS-mutant mediates ALKBH5 phosphorylation at serine residue 325. (C) Denaturing IP analysis suggests that overexpression of the constitutively active KRAS-mutant induces ALKBH5 SUMOylation at lysine residues 86 and 321. (D) Dot-blot analysis suggests global mRNA m6A methylation could be induced by overexpression of the constitutively active KRAS-mutant. (E) Heatmap showing mRNA transcripts with significant m6A modification alterations upon KRAS G12V overexpression in NCI-H522 cells identified by m6A-seq analysis. (F) The frequency distribution of m6A peaks across the length of mRNA transcripts shown by metagene analysis in empty vector and KRAS G12V–overexpressed NCI-H522 cells. (G) GO analysis of genes, of which m6A methylation was significantly upregulated by KRAS G12V overexpression. (H) Dot-blot analysis indicating global mRNA m6A methylation in KRAS WT and -mutant NSCLC cells with or without cisplatin treatment. (I) Western blot analysis suggests that overexpression of the ALKBH5 phosphorylation-deficient mutant significantly sensitizes KRAS-mutant harboring NCI-H23 cells to cisplatin-induced DNA damage. (J) Western blot analysis suggests that overexpression of the ALKBH5 SUMOylation-deficient mutant significantly sensitizes KRAS-mutant harboring NCI-H23 cells to cisplatin-induced DNA damage. (K) Western blot analysis indicates that overexpression of the phosphorylation-mimic mutant ALKBH5 S325D significantly enhances the cisplatin sensitivity of KRAS WT H522 cells. (L) Denaturing IP analysis showing ALKBH5 phosphorylation and SUMOylation in KRAS WT and -mutant NSCLC cells with or without cisplatin treatment.