Project description:BackgroundEpigenetic reprogramming using DNA 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 remarkable therapeutic efficacy, despite its small demethylating effect. Here, we aimed to explore the mechanisms of how such low-dose treatment shows this remarkable efficacy by focusing on epigenetic reprograming at the single-cell level.MethodsExpression profiles in HCT116 cells treated with decitabine (DAC) were analyzed by single-cell RNA-sequencing (scRNA-seq). Functional consequences and DNA demethylation at the single-cell level were analyzed using cloned HCT116 cells after DAC treatment.ResultsscRNA-seq revealed that DAC-treated cells had highly diverse expression profiles at the single-cell level, and tumor-suppressor genes, endogenous retroviruses, and interferon-stimulated genes were upregulated in random fractions of cells. DNA methylation analysis of cloned HCT116 cells revealed that, while only partial reduction of DNA methylation levels was observed in bulk cells, complete demethylation of specific cancer-related genes, such as cell cycle regulation, WNT pathway, p53 pathway, and TGF-β pathway, was observed, depending upon clones. Functionally, a clone with complete demethylation of CDKN2A (p16) had a larger fraction of cells with tetraploid than parental cells, indicating induction of cellular senescence due to normalization of cell cycle regulation.ConclusionsEpigenetic reprogramming of specific cancer-related pathways at the single-cell level is likely to underlie the remarkable efficacy of low-dose DNA demethylating therapy.
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:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2’-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2’-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2’-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy.
Project description:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2’-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2’-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2’-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy.
Project description:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2’-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2’-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2’-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy. A microarray study using genomic DNA from different DLBCL cell lines before any treatment. Two to four biological replicates by cell line. The HELP data wil be used to find genes hypermethylated in resistant cell lines compared to sensitive cell lines to doxorubicin and other drugs.
Project description:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2M-bM-^@M-^Y-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2M-bM-^@M-^Y-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2M-bM-^@M-^Y-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy. A microarray study using double-stranded cDNA from different DLBCL cell lines before any treatment. Two biological replicates by cell line. The gene expression will be used to find gene expression signatures between sensitive and resistant cell lines to chemotherapeutics.
Project description:We are investigating the response of human lymphoblastoid cells to low-dose exposure of environmental metals We used microarrays to detail the global programme of gene expression upon response to low-dose metals Keywords: dose