Recruitment of KMT2C/MLL3 to DNA Damage Sites Mediates DNA Damage Responses and Regulates PARP Inhibitor Sensitivity in Cancer

Abstract

When recruited to promoters, histone 3 lysine 4 (H3K4) methyltransferases KMT2 (KMT2A-D) activate transcription by opening chromatin through H3K4 methylation. Here we report that KMT2 mutations occur frequently in non-small cell lung cancer (NSCLC) and are associated with high mutation loads and poor survival. KMT2C regulated DNA damage responses (DDR) through direct recruitment to DNA damage sites by Ago2 and small noncoding DNA damage response RNA, where it mediates H3K4 methylation, chromatin relaxation, secondary recruitment of DDR factors, and amplification of DDR signals along chromatin. Furthermore, by disrupting homologous recombination (HR)-mediated DNA repair, KMT2C/D mutations sensitized NSCLC to Poly(ADP-Ribose) Polymerase inhibitors (PARPi), whose efficacy is unclear in NSCLC due to low BRCA1/2 mutation rates. These results demonstrate a novel, transcription-independent role of KMT2C in DDR and identify high-frequency KMT2C/D mutations as much-needed biomarkers for PARPi therapies in NSCLC and other cancers with infrequent BRCA1/2 mutations. STATEMENT OF SIGNIFICANCEThis study uncovers a critical role for KMT2C in DDR via direct recruitment to DNA damage sites, identifying high-frequency KMT2C/D mutations as biomarkers for response to PARP inhibition in cancer.

A Novel CDK4/6 and PARP Dual Inhibitor ZC-22 Effectively Suppresses Tumor Growth and Improves the Response to Cisplatin Treatment in Breast and Ovarian Cancer

“…Cell viability assay was performed as described before [ 24 ]. Briefly, 2500/well of breast or ovarian cancer cells were seeded into a 96-well plate; grown overnight; treated with indicated concentration of Olaparib, LY2835219, ZC22, LP-1, GC-24, or cisplatin alone or together for an indicated amount of time; and then incubated with Cell Counting kit-8 (CCK-8) substrate (Dojindo, Kumamoto, Kyushu Island, Japan) for 1–2 h at 37 °C.…”

“…Immunofluorescence-staining of γH2A.X was performed as described before [ 24 ]. Briefly, cells were seeded on cover glasses in 24-well plates, cultured for 24–48 h, and then treated with cisplatin alone or together with Olaparib or ZC-22 for 24 h. After washing with PBS, cells were fixed by 4% PFA, permeated with 0.5% Triton-X100 in PBS, washed thrice with 0.1% PBS-Tween (PBST), blocked with 3% BSA in PBST, and then incubated with anti-γH2A.X antibody overnight at 4 °C.…”

“…Immunohistochemical (IHC) analyses of Ki67, γH2A.X, or p-Rb in paraffin-embedded sections were performed using the Envision Kit (Dako) as described before [ 24 , 25 ]. Sections were analyzed by microscopy.…”

Cancer mutation profiles predict ICIs efficacy in patients with non-small cell lung cancer

“…Overall, DDR pathway alteration is related to tumour mutation burden and tumour-specific neoantigen load, which may be the explanation of its predictive value in ICIs efficacy in cancer. Moreover, the gene mutation disrupting the DDR pathway will present as high mutation loads and indicate benefit from ICIs, such as KMT2C mutation (Refs 122, 123).…”

Imaging the Rewired Metabolism in Lung Cancer in Relation to Immune Therapy

“…In addition, onco-immunological treatment strategies emerge that employ the metabolic vulnerabilities of cancer cells, especially at the level of mitochondria (54)(55)(56)(57)(58). These strategies include enzymatic drugs that interfere with dominant metabolic pathways in the TME (59), such as metformin, atovaquone, glucose (60), indoleamine 2,3-dioxygenase (IDO inhibitors), glutamine inhibitors (37) and AKT-mTOR inhibitors (27).…”