Epigenetically Down-Regulated BRCA2 through Acetyltransferase KAT2B Increases the Sensitivity of Colorectal Cancer to Olaparib
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PROVIDER: PRJNA1034603 | ENA |
REPOSITORIES: ENA
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Project description:Sequencing of olaparib-resistant PEO1 derivatives (C4, C5, C10 and C18) and parental PEO1 (P1 and P2) cells was performed in order to determine mechanisms of acquired resistance in the resistant cell lines. PEO1 parental cell lines were authenticated prior to sequencing. PEO1 parental were confirmed to be BRCA2-mutated (5139C>G). Olaparib PEO1 resistant cells were generated through a step-wise escalation of olaparib (10nM to 8uM olaparib). In olaparib resistant lines an increase canonical Wnt signaling and loss of of non-canonical Wnt signaling was observed.
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Project description:The Endoplasmic Reticulum (ER) unfolded protein response (UPRer) pathway plays an important role for pancreatic β cells to adapt their cellular responses to environmental cues and metabolic stress. Although altered UPRer gene expression appears in rodent and human type 2 diabetic (T2D) islets, the underlying molecular mechanisms remain unknown. We show here that germ-line and β-cell specific disruption of the lysine acetyltransferase 2B (Kat2b) gene in mice leads to impaired insulin secretion and glucose intolerance. Genome wide analysis of Kat2b-regulated genes and functional assays revealed a critical role for KAT2B in maintaining UPRer gene expression and subsequent β-cell function. Importantly, Kat2b expression was decreased in db/db and in human T2D islets and correlated with UPRer genes in normal human islets. In conclusion, KAT2B is a crucial transcriptional regulator for adaptive β-cell function during metabolic stress by controlling UPRer and represents a promising target for T2D prevention and treatment
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Project description:During fasting, increases in circulating pancreatic glucagon maintain glucose balance by up-regulating hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates the gluconeogenic program through the phosphorylation of CREB and via the de-phosphorylation of the CREB coactivator CRTC2. Hormonal and nutrient signals are also thought to modulate gluconeogenic genes by promoting epigenetic changes that facilitate assembly of the transcriptional machinery, although the nature of these modifications is unclear. Here we show that histone H3 acetylation at Lys 9 (H3K9Ac) is elevated over gluconeogenic genes during fasting and in diabetes, where it contributes to increases in hepatic glucose production. Following its dephosphorylation, CRTC2 promoted increases in H3K9Ac by mediating the recruitment of the lysine acetyltransferase 2B (KAT2B) and WD repeat-containing protein 5 (WDR5), a core subunit of histone methyltransferase (HMT) complexes. In turn, KAT2B and WDR5 stimulated the gluconeogenic program through a self-reinforcing cycle whereby increases in H3K9Ac further potentiated CRTC2 occupancy at CREB binding sites. Breaking this cycle, by depletion of KAT2B or WDR5, decreased gluconeogenic gene expression. As administration of a small molecule KAT2B antagonist lowered circulating blood glucose concentrations in insulin resistance, our results demonstrate how this enzyme may be a useful target for diabetes treatment. A subset of cAMP responsive genes depend on specific recruitment of KAT2B (pcaf), which in concert with WDR5 acetylates H3K9. By selectively depleting hepatocytes for KAT2B or WDR5 prior to glucagon stimulation we explore, which genes rely on KAT2B and WDR5 activity. mKAT2B or mWDR5 were knocked down in primary mouse hepatocytes using adenoviral transduction with appropriate shRNAs. Control cells were transduced with a non-specific (NS) shRNA. 72 hours post transduction some cells were stimulated for 90 minutes with 100nM glucagon and others with PBS. Total RNA was purified and subjected to micro-RNA analysis. All samples are pools of RNA from three sepearate dishes. One replicate is included for most samples.
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Project description:During fasting, increases in circulating pancreatic glucagon maintain glucose balance by up-regulating hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates the gluconeogenic program through the phosphorylation of CREB and via the de-phosphorylation of the CREB coactivator CRTC2. Hormonal and nutrient signals are also thought to modulate gluconeogenic genes by promoting epigenetic changes that facilitate assembly of the transcriptional machinery, although the nature of these modifications is unclear. Here we show that histone H3 acetylation at Lys 9 (H3K9Ac) is elevated over gluconeogenic genes during fasting and in diabetes, where it contributes to increases in hepatic glucose production. Following its dephosphorylation, CRTC2 promoted increases in H3K9Ac by mediating the recruitment of the lysine acetyltransferase 2B (KAT2B) and WD repeat-containing protein 5 (WDR5), a core subunit of histone methyltransferase (HMT) complexes. In turn, KAT2B and WDR5 stimulated the gluconeogenic program through a self-reinforcing cycle whereby increases in H3K9Ac further potentiated CRTC2 occupancy at CREB binding sites. Breaking this cycle, by depletion of KAT2B or WDR5, decreased gluconeogenic gene expression. As administration of a small molecule KAT2B antagonist lowered circulating blood glucose concentrations in insulin resistance, our results demonstrate how this enzyme may be a useful target for diabetes treatment. A subset of cAMP responsive genes depend on specific recruitment of KAT2B (pcaf), which in concert with WDR5 acetylates H3K9. By selectively depleting hepatocytes for KAT2B or WDR5 prior to glucagon stimulation we explore, which genes rely on KAT2B and WDR5 activity.
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Project description:PARP inhibitor and platinum based drugs such as cisplatin are promising therapies for triple negative breast cancer and exploit the deficiencies in BRCA1 or BRCA2, or homologous recombination repair defects. However, PARP inhibitor resistance is proven to be a major clinical problem. Acquired PARP inhibitor resistance has been linked with co-resistance to platinum-based drugs. To determine how acquired olaparib resistance affects cisplatin response and whether this is influenced by their BRCA1 status, we performed RNAseq transcriptome analysis of isogenic triple negative breast cancer models of olaparib resistance with normal and mutant BRCA1.
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Project description:Cancer cells undergo transcriptional reprogramming to drive tumorigenesis and caner progression. Here, we identified the transcriptional complex, NELF (Negative elongation factor), as an important regulator of this process. Using cancer cell lines and patient-derived tumor organoids, we demonstrated that loss of NELF inhibits breast cancer. Specifically, we found that epithelial-mesenchymal transition (EMT) and stemness-associated genes are downregulated in NELF-depleted breast cancer cells. Afterwards, we pinpointed that SLUG, a key EMT transcription factor, was a top hit of NELF interactome during EMT progression. Furthermore, ChIP-seq analysis revealed that loss of NELF led to impaired SLUG binding on chromatin. Through integrative transcriptomic and genomic analyses, we identified the histone acetyltransferase, KAT2B, as a key functional target of NELF-E-SLUG. Genetic and pharmacological inactivation of KAT2B ameliorate expression of critical EMT marker genes, phenocopying NELF ablation. Elevated NELF-E and KAT2B expressions are associated with poorer prognosis in breast cancer patients, highlighting the clinical relevance of our findings. Taken together, we uncovered a crucial role of the NELF-E-KAT2B epigenetic axis in breast cancer carcinogenesis.
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Project description:Divergent Functions of Histone Acetyltransferase Paralogs KAT2A and KAT2B in Keratinocyte Stemness and Differentiation
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