Project description:Disruptor of telomeric silencing 1-like (DOT1L) expression is elevated in many cancer types including ovarian cancer. Therefore, we analyzed the role of DOT1L in ovarian cancer. Pharmacological inhibition of DOT1L expression in ovarian cancer cell lines resulted in decreased proliferation, and increased cell death.
Project description:Estrogen Receptor alpha (ERα), a nuclear receptor with transcriptional activity, is a master regulator of estrogen signaling, widely known as therapeutic target in hormone-responsive breast cancer (BC). Moreover, ERα is highly expressed in approximately 80% of High Grade Serous Ovarian Cancer (HGSOC), the most common epithelial ovarian carcinoma. Despite some promising clinical trials evaluating endocrine therapy in this type of tumor, the role of ERα is still unknown. Epigenetic changes, such as DNA methylation, are emerging as key contributing factors to carcinogenesis. Disruptor of telomeric silencing-1-like (DOT1L), the only known histone methyl transferase capable to produce H3K79 mono, di and tri-methylation, modulates ERα actions in hormone-responsive BC. Considering this evidence, ERα-DOT1L association was confirmed in ERα-positive OC cells, PEO1 and PEO4, by Co-IP. DOT1L pharmacological inhibition by EPZ004777 (EPZ) revealed the involvement of this epigenetic enzyme in cell proliferation, cell cycle progression and apoptosis. Transcriptome profiling after ICI (a Selective Estrogen Receptor Degrader) and EPZ treatment, in both cell lines, has underlined a deep impact of both compounds on ERα-modulated genes, including the down-regulation of ERα itself. On the other hand, functional analysis showed that commonly affected transcripts are involved in different cellular processes, such as cancer cell survival, chemoresistance and cell cycle progression. Moreover, ChIP-qPCR performed on ERα promoter highlighted ERα and DOT1L co-localization, both in PEO1 and in PEO4 cells, which was reduced after EPZ treatment, suggesting a role of this complex on receptor transcriptional activity. In addition, drug combination studies performed with EPZ and ICI showed an additive effect in cell growth inhibition. Taken together, these results suggest DOT1L as a potential therapeutic target in the treatment of OC.
Project description:Many repetitive DNA elements are packaged in heterochromatin, but depend on occasional transcription to maintain long-term silencing. The factors that promote transcription of repeat elements in heterochromatin are largely unknown. Here, we show that DOT1L, a histone methyltransferase that modifies lysine 79 of histone H3 (H3K79), is required for transcription of major satellite repeats to maintain pericentromeric heterochromatin (PCH), and that this function is essential for preimplantation development. DOT1L is a transcriptional activator at single-copy genes but does not have a known role in repeat element transcription. We show that H3K79me3 is specifically enriched at repetitive elements, that loss of DOT1L compromises pericentromeric major satellite transcription, and that this function depends on interaction between DOT1L and the chromatin remodeler SMARCA5. DOT1L inhibition causes chromosome breaks and cell cycle defects, and leads to embryonic lethality. Together, our findings uncover a vital new role for DOT1L in transcriptional activation of heterochromatic repeats.
Project description:In order to understand the role of H3K79me2 and DOT1L during CNS development, we analysed neural stem cells after pharmacological inhibition of DOT1L (5 µM SGC0946). To identify target genes of DOT1L in the cortex, we determined the transcriptome of cortical progenitor cells derived from E14.5 NMRI mice after interference with DOT1L activity for three days in vitro (DIV3). Therefore, three independent experiments were performed (ctrl1 – inh1, ctrl2 – inh2, ctrl3 – inh3).
Project description:Biomarkers that predict disease progression might assist the development of better therapeutic strategies for aggressive cancers, such as ovarian cancer. Here, we investigated the role of collagen type XI alpha 1 (COL11A1) in cell invasiveness and tumor formation and the prognostic impact of COL11A1 expression in ovarian cancer. Microarray analysis suggested that COL11A1 is a disease progression-associated gene that is linked to ovarian cancer recurrence and poor survival.
Project description:Exogenous 17β-estradiol (E2) accelerates the progression of ovarian cancer in the transgenic tgCAG-LS-TAg mouse model of the disease. We hypothesized that E2 has direct effects on ovarian cancer cells and this study was designed to determine the molecular mechanisms by which E2 accelerates ovarian tumour progression. Mouse ovarian cancer ascites (MASE2) cell lines were derived from tgCAG-LS-TAg mice. Following intraperitoneal engraftment of MASE2 into SCID mice, exogenous E2 significantly decreased the survival time and increased the tumour burden. Microarray analysis performed on cells derived from mouse ovarian cancer ascites (MASE2) treated with and without E2 indicated that E2 treatment caused the upregulation and downregulation of genes involved in cell differentiation, proliferation and migration. In particular, Greb1 that has been also identified as a hormone-responsive gene in breast cances, was upregulated in mouse tumour cells treated with E2. Three biological replicates (MASE2 tumours grown in SCID mice, see growth protocol) were analyzed for both conditions of addition of E2 or placebo.