Project description:Epigenetic changes, particularly DNA methylation aberrations have been implicated in acquired resistance to platinum in ovarian cancer. A multi-institutional randomized clinical trial compared a regimen of a DNA methyl transferase (DNMT) inhibitor guadecitabine and carboplatin to physician’s choice chemotherapy for patients with recurrent platinum resistant ovarian cancer. Tumor biopsies or malignant ascites were collected at day 1 of cycle 1 (pre-guadecitabine) and after two cycles of treatment (post-decitabine). The goal of the current study was to analyze guadecitabine-induced DNA methylation and gene expression changes and correlate pretreatment levels with clinical outcomes. Epigenomic and transcriptomic profiling using the Infinium HumanMethylation450 BeadChip (HM450) and RNA sequencing revealed extensive methylation and gene expression changes induced by guadecitabine in ovarian tumors. Ninety-four gene promoters were significantly hypomethylated after treatment with guadecitabine and 949 genes were differentially expressed in pre vs. post-treatment tumors. Pathways associated with immune reactivation and DNA repair were significantly altered by guadecitabine treatment. Expression levels of 1155 genes involved in 25 networks on day 1 of cycle 1 correlated with progression free survival. Increased expression of selected genes (e.g. DOK2, miR193a) silenced through promoter methylation restored platinum sensitivity in ovarian cancer cells. Together, these results support that guadecitabine altered DNA methylation and expression of genes and gene networks correlate with re-sensitization to carboplatin in ovarian cancer patients.
Project description:Epigenetic changes, particularly DNA methylation aberrations have been implicated in acquired resistance to platinum in ovarian cancer. A multi-institutional randomized clinical trial compared a regimen of a DNA methyl transferase (DNMT) inhibitor guadecitabine and carboplatin to physician’s choice chemotherapy for patients with recurrent platinum resistant ovarian cancer. Tumor biopsies or malignant ascites were collected at day 1 of cycle 1 (pre-guadecitabine) and after two cycles of treatment (post-decitabine). The goal of the current study was to analyze guadecitabine-induced DNA methylation and gene expression changes and correlate pretreatment levels with clinical outcomes. Epigenomic and transcriptomic profiling using the Infinium HumanMethylation450 BeadChip (HM450) and RNA sequencing revealed extensive methylation and gene expression changes induced by guadecitabine in ovarian tumors. Ninety-four gene promoters were significantly hypomethylated after treatment with guadecitabine and 949 genes were differentially expressed in pre vs. post-treatment tumors. Pathways associated with immune reactivation and DNA repair were significantly altered by guadecitabine treatment. Expression levels of 1155 genes involved in 25 networks on day 1 of cycle 1 correlated with progression free survival. Increased expression of selected genes (e.g. DOK2, miR193a) silenced through promoter methylation restored platinum sensitivity in ovarian cancer cells. Together, these results support that guadecitabine altered DNA methylation and expression of genes and gene networks correlate with re-sensitization to carboplatin in ovarian cancer patients.
Project description:Genome wide DNA methylation profiling of blood and biopsy samples from recurrent, platinum resistant epithelial ovarian cancer patients before and after treatment of decitabine in combination with carboplatin. The Illumina Infinium 27k Human DNA methylation Beadchip v1.2 was used to obtain DNA methylation profiles across approximately 27,000 CpGs in PBMC (14 paired samples), tumor (8 paired samples) and ascites (6 paired samples). Bisulphite converted DNA from 56 samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip v1.2
Project description:Introduction: Although High Grade Serous Ovarian Cancer (HGSOC) is considered a chemo-responsive disease, a proportion of patients do not respond to platinum-based chemotherapy at presentation or have progression-free survival of <6 months. Validated biomarkers of lack of response would enable alternative treatment stratification for these patients and identify novel mechanisms of resistance. Methods: Differential DNA methylation was investigated in independent tumour sets using Illumina 27K HumanMethylation arrays and validated by bisulphite pyrosequencing. Gene expression was by Affymetrix arrays and qRT-PCR. The role of Msh homeobox 1 (MSX1) in drug sensitivity was investigated by gene reintroduction into ovarian cancer cell lines. Results: CpG sites at contiguous genomic locations within the MSX1 gene have significantly lower levels of methylation in HGSOC which recur by 6 months compared to after 12 months and/or with RECIST response (p<0.05, q<0.05). A decrease in methylation at these intragenic CpG sites was significantly correlated with decreased MSX1 gene expression. Low expression of MSX1 was associated with poor progression-free survival independent of known clinical prognostic features (p=0.014). Three mutant or wild-type TP53 expressing ovarian cancer cell lines, resistant to cisplatin, have reduced MSX1 expression compared to matched parental, platinum sensitive, lines. Re-expression of MSX1 in resistant lines led to cisplatin sensitisation, increased apoptosis, increased p21 and BAX expression. However, in two TP53-null cell lines, MSX1 failed to change cisplatin sensitivity. Conclusion: Hypomethylation of MSX1 is a biomarker of resistant HGSOC disease at presentation and identifies a novel mechanism of platinum drug resistance. Bisulphite converted DNA from the 86 samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip v1.2
Project description:Genome wide DNA methylation profiling of blood and biopsy samples from recurrent, platinum resistant epithelial ovarian cancer patients before and after treatment of decitabine in combination with carboplatin. The Illumina Infinium 27k Human DNA methylation Beadchip v1.2 was used to obtain DNA methylation profiles across approximately 27,000 CpGs in PBMC (14 paired samples), tumor (8 paired samples) and ascites (6 paired samples).
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.