Project description:Epigenetic reprogramming using demethylating drugs is a promising approach for cancer therapy, but its efficacy is highly dependent on the dosing regimen. Low-dose treatment for a prolonged period shows a high therapeutic efficacy, despite its small demethylating effect. Here, we aimed to reveal the mechanisms of how such low-dose treatment shows high efficacy by focusing on epigenetic reprograming at the single-cell level. Single-cell RNA-sequencing of HCT116 cells treated with decitabine (DAC) revealed that up-regulated genes were highly variable at the single-cell level. To analyze functional consequences at the single-cell level, DAC-treated HCT116 cells were cloned. While only partial reduction of methylation levels was observed in bulk cells, complete demethylation of specific cancer-related genes was observed, depending upon clones. For example, p16 was completely demethylated in the H3-32 clone out of 9 clones, and this clone showed slower proliferation than other clones without demethylation. In addition, in this clone, the fraction of cells with tetraploid became much larger, indicating that cellular senescence was induced. These results showed that epigenetic reprogramming of specific cancer-related pathways at the single-cell level is likely to underlie the high efficacy of low-dose DNA demethylating therapy.
Project description:We found frequent epigenetic silencing of microRNA-34b/c in human colorectal cancer. Introduction of miR-34b/c into a colorectal cancer cell line induced significant changes in gene expression profile. We also found overlap between the genes downregulated by miR-34b/c and those downregulated by DAC. Keywords: dose response A colorecal cancer cell line HCT116 was transfected with miR-34b or -c precursor or negative control. Also, HCT116 was treated with 5-aza-2'-deoxycytidine (DAC) or mock. Genes up- or downregulated by miR-34b/c and those by DAC was compared.
Project description:A derivative cell line of HCT116, HML58-3, was established to detect DNA demethylating agents [Okochi-Takada E, Epigenetics. 2018;13:147-55.]. HML58-3 cells were treated with DNA demethylating agents (DAC, OR-2003, and OR-2100). Genome-wide DNA methylation was analyzed using the Infinium Human MethylationEPIC BeadChip.
Project description:Reversal of gene promoter DNA hypermethylation and associated abnormal gene silencing is an attractive approach to cancer therapy. The DNA methylation inhibitor, decitabine (5-aza-2'-deoxycitidine), is proving efficacious for hematological neoplasms especially at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, but these may not explain the prolonged time to response seen in patients. Transient exposure of leukemic and solid tumor cells to clinically-relevant nanomolar doses, without causing immediate cytotoxicity or apoptosis, produces sustained reduced tumorigenicity, and for leukemia cells, diminished long-term self-renewal. These effects appear triggered by cellular reprogramming and include sustained decreases in promoter DNA methylation with associated gene re-expression, and anti-tumor changes in multiple key cellular regulatory pathways, most of which are high priority targets for pharmacologic anti-cancer strategies. Thus, low dose decitabine regimens appear to have broad applicability for cancer management. [Gene expression profiling] Leukemia cell lines Kasumi-1 and KG1A are treated with 10nM DAC during 72 hours and gene expression was assayed at day 3, 7 and 14 after the start of the treatment. Appropriate mock treated samples were used as control in each case. In addition, Kasumi-1 cells were also treated with a higher dose of DAC (500nM), 100nM ARA-C and 300 nM TSA, again controlled against mock treated Kasumi-1 cells, to separate dose and agent dependent effects. MCF7 was studied as an example of a solid tumor cell line. Therefore MCF7 cells were treated with 100nM DAC and results were assayed at day 1, day 3 and day 10. [Methylation profiling] The effects of the demethylating agent DAC were studied in the leukemia cell line Kasumi-1 over a 28 day time course. Intermediate time points were studied at days 3, 7, 14 and 21. These results were verfied in KG1A and KG1 leukemia cell lines, at one selected time point. The effects on one primary sample were also studied. Four normal leukemia samples (PL1, 2, 4 and 5) were used as general controls. The effect of DAC was compared to ARA-C, TSA. Both mock treated and day 3 DAC treated Kasumi-1 cells were repeated. These results were verified at one selected time point for the DAC treated MCF7 breast cancer cell line.
Project description:To identify genes responsible for the synergistic effect of DAC with Dex, we performed cDNA microarray analyses using cDNA prepared from Dex-resistant OPM1 cells treated with/without Dex, DAC or DAC+Dex.
Project description:A derivative cell line of HCT116, HML58-3, was established to detect DNA demethylating agents [Okochi-Takada E, Epigenetics. 2018;13:147-55.]. HML58-3 cells were treated with DNA demethylating agents (decitabine, OR-2003, and OR-2100) or mock. A genome-wide gene expression analysis was performed using SurePrint G3 Human Gene Expression 8 x 60K v2 Microarray.
Project description:Epigenetic reprogramming using demethylating drugs is a promising approach for cancer therapy, but its efficacy is highly dependent on the dosing regimen. Low-dose treatment for a prolonged period shows a high therapeutic efficacy, despite its small demethylating effect. Here, we aimed to reveal the mechanisms of how such low-dose treatment shows high efficacy by focusing on epigenetic reprograming at the single-cell level. Single-cell RNA-sequencing of HCT116 cells treated with decitabine (DAC) revealed that up-regulated genes were highly variable at the single-cell level. To analyze functional consequences at the single-cell level, DAC-treated HCT116 cells were cloned. While only partial reduction of methylation levels was observed in bulk cells, complete demethylation of specific cancer-related genes was observed, depending upon clones. For example, p16 was completely demethylated in the H3-32 clone out of 9 clones, and this clone showed slower proliferation than other clones without demethylation. In addition, in this clone, the fraction of cells with tetraploid became much larger, indicating that cellular senescence was induced. These results showed that epigenetic reprogramming of specific cancer-related pathways at the single-cell level is likely to underlie the high efficacy of low-dose DNA demethylating therapy.