DNMT Inhibitors Increase Methylation in the Cancer Genome

Abstract

DNA methyltransferase inhibitors (DNMTi) decitabine and azacytidine are approved therapies for myelodysplastic syndrome and acute myeloid leukemia, and their combinations with other anticancer agents are being tested as therapeutic options for multiple solid cancers such as colon, ovarian, and lung cancer. However, the current therapeutic challenges of DNMTis include development of resistance, severe side effects and no or partial treatment responses, as observed in more than half of the patients. Therefore, there is a critical need to better understand the mechanisms of action of these drugs. In order to discover molecular targets of DNMTi therapy, we identified 638 novel CpGs with an increased methylation in response to decitabine treatment in HCT116 cell lines and validated the findings in multiple cancer types (e.g., bladder, ovarian, breast, and lymphoma) cell lines, bone marrow mononuclear cells from primary leukemia patients, as well as peripheral blood mononuclear cells and ascites from platinum resistance epithelial ovarian cancer patients. Azacytidine treatment also increased methylation of these CpGs in colon, ovarian, breast, and lymphoma cancer cell lines. Methylation at 166 identified CpGs strongly correlated (|r|≥ 0.80) with corresponding gene expression in HCT116 cell line. Differences in methylation at some of the identified CpGs and expression changes of the corresponding genes was observed in TCGA colon cancer tissue as compared to adjacent healthy tissue. Our analysis revealed that hypermethylated CpGs are involved in cancer cell proliferation and apoptosis by P53 and olfactory receptor pathways, hence influencing DNMTi responses. In conclusion, we showed hypermethylation of CpGs as a novel mechanism of action for DNMTi agents and identified 638 hypermethylated molecular targets (CpGs) common to decitabine and azacytidine therapy. These novel results suggest that hypermethylation of CpGs should be considered when predicting the DNMTi responses and side effects in cancer patients.

Aberrant DNA Methylation in Esophageal Squamous Cell Carcinoma: Biological and Clinical Implications

“…This makes them attractive targets for cancer therapy or chemoprevention (89). Indeed, several studies have demonstrated that TSG expression could be restored after treatment of cells with demethylating agents, and DNMT inhibitors, such as azacytidine and decitabine, are currently under preclinical and clinical investigations in various cancer types (e.g., ClinicalTrials.gov Identifier: NCT01193517, NCT03666559, and NCT04187703) (90)(91)(92)(93). Nonetheless, up until now, very limited data have been shown concerning the effectiveness of DNMT inhibitors in ESCC.…”

Epigenetic regulation of Neuregulin-1 tunes white adipose stem cell differentiation

“…Using DNA isolated from the same stem cells experiment as Figure 3, we show that while partial methylation (~ 50% at most CpG sites) could be seen in the DMSO control, it was not decreased upon treatment with 1μm DAC, and if anything the methylation increased ( Figure S1). While this is not unprecedented--DAC has been shown to increase methylation in some genomic locations [28] --it suggests that the epigenetic control point in the genome is unknown. We also cannot rule out the possibility that another epigenetically-regulated transcription factor in turn controls NRG1 type III expression; however from the microarray expression data none of the most up-regulated genes after DAC treatment were transcription factors ( Table 2) so this explanation appears less likely.…”

S‐adenosylmethionine in combination with decitabine shows enhanced anti‐cancer effects in repressing breast cancer growth and metastasis

“…The 5AzadC treatment, for the monotherapy and combination groups, was carried out for three weeks to avoid potential adverse effects. 12 In contrast, all animals treated with SAM in the monotherapy and the combination setting received SAM daily via oral gavage from the start of treatment until the experimental end-point was reached. Our results show that all animals in the control group developed tumours that continued to grow until the experimental end-point at week 10 after tumour cell injection ( Figure 2B; Appendix S1: Figure S2).…”