Project description:LMTK3 is an oncogenic receptor tyrosine kinase (RTK) implicated in various types of cancer including breast, lung, gastric and colorectal. It is localized in different cellular compartments but its nuclear function has not been investigated thus far. We have mapped LMTK3 binding across the genome using ChIP-seq and found that LMTK3 binding events are correlated with repressive chromatin markers. We further identified KRAB associated protein-1 (KAP1) as a binding partner of LMTK3. The LMTK3/KAP1 interaction is stabilized by PP1α, which suppresses KAP1 phosphorylation specifically at LMTK3-associated chromatin regions, inducing chromatin condensation and resulting in transcriptional repression of LMTK3-bound tumour suppressor-like genes. Furthermore, LMTK3 functions at enhancer regions in tethering the chromatin to the nuclear periphery, resulting in H3K9me3 modification and gene silencing. In summary, we propose a model where a scaffolding function of nuclear LMTK3 promotes cancer progression through chromatin remodeling, revealing a previously undescribed mechanism of RTK activity.
Project description:LMTK3 is an oncogenic receptor tyrosine kinase (RTK) implicated in various types of cancer including breast, lung, gastric and colorectal. It is localized in different cellular compartments but its nuclear function has not been investigated thus far. We have mapped LMTK3 binding across the genome using ChIP-seq and found that LMTK3 binding events are correlated with repressive chromatin markers. We further identified KRAB associated protein-1 (KAP1) as a novel binding partner of LMTK3. The LMTK3/KAP1 interaction is stabilized by PP1_, which suppresses KAP1 phosphorylation specifically at LMTK3-associated chromatin regions, inducing chromatin condensation and resulting in transcriptional repression of LMTK3-bound tumour suppressor-like genes. Furthermore, LMTK3 functions at enhancer regions in tethering the chromatin to the nuclear periphery, resulting in H3K9me3 modification and gene silencing. In summary, we propose a new model where a scaffolding function of nuclear LMTK3 promotes cancer progression through chromatin remodeling, revealing a new mechanism of RTK activity. Examination of LMTK3 binding profile in 2 cell types.
Project description:To test the hypothesis that the propensity for silencing of tumor suppressor genes in the respiratory epithelium of chronic smokers by promoter hypermethylation is influenced by sequence variations that modify the activity of genes and microRNAÕs that directly or indirectly influence de novo methylation and chromatin remodeling.
Project description:Overweight and obesity are now recognized as established risk factors for breast cancer in postmenopausal women. Reciprocal interactions have been described between adipose and cancer cells. Among the cell types present in the breast, myoepithelial cells (MECs) are considered "tumour suppressor" cells. During the transition from ductal carcinoma in situ to invasive cancer, disorganization or even the disappearance of MECs is observed. As the adipose microenvironment is now considered as a central actor in the progression of breast cancer, our objective was to evaluate if it could be involved in MEC functional modifications, leading to the transition of in situ to invasive carcinoma, particularly in obese patients. Through a co-culture model, we found that adipose cells could decrease the viability of the MECs. The adipose cells could also disrupt the expression of the genes involved in the maintenance of the extracellular matrix and to amplify the expression of leptin and inflammatory markers. The metabolite analyses revealed specific profiles that may be involved in the growth of neoplastic cells. All of these perturbations could thus be responsible for the loss of tumour suppressor status of MECs and promote the transition from in situ to invasive carcinoma.
Project description:LMTK3 is an oncogenic receptor tyrosine kinase (RTK) implicated in various types of cancer including breast, lung, gastric and colorectal. It is localized in different cellular compartments but its nuclear function has not been investigated thus far. We have mapped LMTK3 binding across the genome using ChIP-seq and found that LMTK3 binding events are correlated with repressive chromatin markers. We further identified KRAB associated protein-1 (KAP1) as a novel binding partner of LMTK3. The LMTK3/KAP1 interaction is stabilized by PP1_, which suppresses KAP1 phosphorylation specifically at LMTK3-associated chromatin regions, inducing chromatin condensation and resulting in transcriptional repression of LMTK3-bound tumour suppressor-like genes. Furthermore, LMTK3 functions at enhancer regions in tethering the chromatin to the nuclear periphery, resulting in H3K9me3 modification and gene silencing. In summary, we propose a new model where a scaffolding function of nuclear LMTK3 promotes cancer progression through chromatin remodeling, revealing a new mechanism of RTK activity.
Project description:We reported that low expression of miRNA in cancer as a recognized signature leads to loss function of TSGs in breast cancer. In 157 paired breast cancer and adjacent normal samples, tumour suppressor gene GPER1 and miR-339 are both downregulated in Luminal A/B and Triple Negative Breast Cancer subtypes. Mechanistic investigations revealed that that miR-339 upregulates GPER1 expression in breast cancer cells by switching on the GPER1 enhancer, which can be blocked by enhancer deletion through the CRISPR/Cas9 system.
Project description:Glucocorticoid receptor (GR) is a ligand-inducible transcription factor with an intricate role in cancer biology. Using an in silico designed GR activity signature we show that GR is a tumor suppressor across diverse primary cancers. In breast cancer, GR activity status determines luminal identity, and importantly, relates to patients’ outcomes. We illustrate that GR suppresses tumor growth, mediated through its engagement with the estrogen receptor-α (ER). This steroid hormone receptor cross-talk leads to redistribution of ERα on chromatin, ultimately leading to expression of ZBTB16 gene. We define ZBTB16 as a transcriptional repressor and a tumor suppressor in ER-positive breast cancer. Importantly, highly aggressive ER-positive breast cancer cells displaying absence of GR activity can be eradicated if GR-induced gene repression is mimicked by inhibitors of the epigenetic pathway. In line with this, epigenetic regulators are highly expressed upon GR activity loss, leading to vulnerability of aggressive breast cancer cells to clinically available epigenetic inhibitors. Our findings indicate that GR functions as a tumor suppressor by repositioning ER to specific sites on chromatin, modulating targetable pathways, which has important implications for patients’ prognosis and therapeutic interventions.
Project description:Cancer cells undergo transcriptional reprogramming to drive tumor progression and metastasis. 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 tumorigenesis and metastasis. Specifically, we found that epithelial-mesenchymal transition (EMT) and stemness-associated genes are downregulated in NELF-depleted breast cancer cells. Quantitative Multiplexed Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins (qPLEX-RIME) of NELF-E, a key subunit of NELF, reveals significant rewiring of NELF-E-associated chromatin partners as a function of EMT, and further illuminates a co-option of NELF-E with the key EMT transcription factor SLUG. Accordingly, loss of NELF-E 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. Importantly, KAT2B knockout mice are viable, raising the exciting prospect of targeting this dependency therapeutically. Taken together, we uncovered a crucial role of the NELF-E-KAT2B epigenetic axis in breast cancer carcinogenesis.