2-Pyridin-4-yl-methylene-beta-boswellic Acid-A Potential Candidate for Targeting O6-Methylguanine-DNA Methyltransferase Epi-transcriptional Reprogramming in KRAS G13D-Microsatellite Stable, G12V-Microsatellite Instable Mutant Colon Cancer

Arem Qayum; Jasvinder Singh; Arvind Kumar; Syed Mohmad Shah; Shubham Srivastava; Manoj Kushwaha; Asmita Magotra; Utpal Nandi; Ruchi Malik; Bhahwal Ali Shah; Shashank Kumar Singh

doi:10.1021/acsptsci.1c00228

2-Pyridin-4-yl-methylene-beta-boswellic Acid-A Potential Candidate for Targeting O⁶-Methylguanine-DNA Methyltransferase Epi-transcriptional Reprogramming in KRAS G13D-Microsatellite Stable, G12V-Microsatellite Instable Mutant Colon Cancer

ACS Pharmacol Transl Sci. 2022 Apr 18;5(5):306-320. doi: 10.1021/acsptsci.1c00228. eCollection 2022 May 13.

Authors

Arem Qayum^{1

2}, Jasvinder Singh^{1

2}, Arvind Kumar³, Syed Mohmad Shah⁴, Shubham Srivastava⁵, Manoj Kushwaha⁶, Asmita Magotra⁷, Utpal Nandi⁷, Ruchi Malik⁵, Bhahwal Ali Shah³, Shashank Kumar Singh¹

Affiliations

¹ Cancer Pharmacology Division, Indian Institute of Integrative Medicine, CSIR, Jammu 180001, India.
² Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
³ Natural Product Microbes Division, Indian Institute of Integrative Medicine, CSIR, Jammu 180001, India.
⁴ Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Srinagar 190001, India.
⁵ Department of Pharmacy, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, Ajmer 305817, Rajasthan, India.
⁶ Microbial Biotechnology Division, Indian Institute of Integrative Medicine, CSIR, Jammu 180001, India.
⁷ PK-PD, Toxicology and Formulation Division, Indian Institute of Integrative Medicine, CSIR, Jammu 180001, India.

Abstract

PMBA (2-Pyridin-4-yl-methylene-beta-boswellic acid), screened from among the 21 novel series of semisynthetic analogues of β-boswellic acid, is being presented as a lead compound for integrative management of KRAS mutant colorectal cancer (CRC), upon testing and analysis for its anticancerous activity on a panel of NCI-60 cancer cell lines and in vivo models of the disease. PMBA (1.7-29 μM) exhibited potent proliferation inhibition on the cell lines and showed sensitivity in microsatellite instability and microsatellite stable (GSE39582 and GSE92921) subsets of KRAS gene (Kirsten rat sarcoma viral oncogene homolog)-mutated colon cell lines, as revealed via flow cytometry analysis. A considerable decrease in mitogen-activated protein kinase pathway downstream effectors was observed in the treated cell lines via the western blot and STRING (Search tool for the retrieval of interacting genes/proteins) analysis. PMBA was further found to target KRAS at its guanosine diphosphate site. Treatment of the cell lines with PMBA showed significant reduction in MGMT promoter methylation but restored MGMT (O⁶-methylguanine-DNA methyltransferase) messenger ribonucleic acid expression via significant demethylation of the hypermethylated CpG (Cytosine phosphate guanine) sites in the MGMT promoter. A significant decrease in dimethylated H3K9 (Dimethylation of lysine 9 on histone 3) levels in the MGMT promoter in DNA hypo- and hypermethylated HCT-116^G13D and SW-620^G12V cells was observed after treatment. In the MNU (N-methyl-N-nitrosourea)-induced CRC in vivo model, PMBA instillation restricted and repressed polyp formation, suppressed tumor proliferation marker Ki67 (Marker of proliferation), ablated KRAS-associated cytokine signaling, and decreased mortality. Clinical trial data for the parent molecule revealed its effectiveness against the disease, oral bioavailability, and system tolerance. Comprehensively, PMBA represents a new class of KRAS inhibitors having a therapeutic window in the scope of a drug candidate. The findings suggest that the PMBA analogue could inhibit the growth of human CRC in vivo through downregulation of cancer-associated biomarkers as well as reactivate expression of the MGMT gene associated with increased H3K9 acetylation and H3K4 methylation with facilitated transcriptional activation, which might be important in silencing of genes associated with upregulation in the activity of KRAS.