Project description:Breast cancer is genetically heterogeneous, and recent studies have underlined a prominent contribution of epigenetics to the development of this disease. To uncover new synthetic lethalities with known breast cancer oncogenes, we screened an epigenome-focused short hairpin RNA library on a panel of engineered breast epithelial cell lines. Here we report a selective interaction between the NOTCH1 signaling pathway and the SUMOylation cascade. Knockdown of the E2-conjugating enzyme UBC9 (UBE2I) as well as inhibition of the E1-activating complex SAE1/UBA2 using ginkgolic acid impairs the growth of NOTCH1-activated breast epithelial cells. We show that upon inhibition of SUMOylation NOTCH1-activated cells proceed slower through the cell cycle and ultimately enter apoptosis. Mechanistically, activation of NOTCH1 signaling depletes the pool of unconjugated small ubiquitin-like modifier 1 (SUMO1) and SUMO2/3 leading to increased sensitivity to perturbation of the SUMOylation cascade. Depletion of unconjugated SUMO correlates with sensitivity to inhibition of SUMOylation also in patient-derived breast cancer cell lines with constitutive NOTCH pathway activation. Our investigation suggests that SUMOylation cascade inhibitors should be further explored as targeted treatment for NOTCH-driven breast cancer. We treated MCF10A and NOTCH1 cells with either DMSO or ginkgolic acid 30 uM for 3 days. Two replicates have been analysed for each condition.
Project description:Breast cancer is genetically heterogeneous, and recent studies have underlined a prominent contribution of epigenetics to the development of this disease. To uncover new synthetic lethalities with known breast cancer oncogenes, we screened an epigenome-focused short hairpin RNA library on a panel of engineered breast epithelial cell lines. Here we report a selective interaction between the NOTCH1 signaling pathway and the SUMOylation cascade. Knockdown of the E2-conjugating enzyme UBC9 (UBE2I) as well as inhibition of the E1-activating complex SAE1/UBA2 using ginkgolic acid impairs the growth of NOTCH1-activated breast epithelial cells. We show that upon inhibition of SUMOylation NOTCH1-activated cells proceed slower through the cell cycle and ultimately enter apoptosis. Mechanistically, activation of NOTCH1 signaling depletes the pool of unconjugated small ubiquitin-like modifier 1 (SUMO1) and SUMO2/3 leading to increased sensitivity to perturbation of the SUMOylation cascade. Depletion of unconjugated SUMO correlates with sensitivity to inhibition of SUMOylation also in patient-derived breast cancer cell lines with constitutive NOTCH pathway activation. Our investigation suggests that SUMOylation cascade inhibitors should be further explored as targeted treatment for NOTCH-driven breast cancer.
Project description:Senescence, a persistent form of cell cycle arrest, is often associated with a diverse secretome, which provides complex downstream functionality for senescent cells within the tissue microenvironment. We show that oncogene-induced senescence (OIS) is accompanied by a dynamic fluctuation of NOTCH1 activity, which drives a TGF-β-rich secretome, whilst suppressing the senescence-associated pro-inflammatory secretome through inhibition of C/EBPβ. NOTCH1 and NOTCH1-driven TGF-β contribute to ‘lateral induction of senescence’ through a juxtacrine NOTCH-JAG1 pathway. In addition, NOTCH1 inhibition during senescence facilitates upregulation of pro-inflammatory cytokines, promoting lymphocyte recruitment and senescence surveillance in vivo. Because enforced activation of NOTCH1 signalling confers a near mutually exclusive secretory profile compared to typical senescence, our data collectively indicate that the dynamic alteration of NOTCH1 activity during senescence dictates a functional balance between these two distinct secretomes: one representing TGF-β and the other pro-inflammatory cytokines, highlighting that NOTCH1 is a temporospatial controller of secretome composition.
Project description:We report the development of a second-generation AKT degrader INY-05-040, which outperformed catalytic AKT inhibition both with respect to biochemical and cellular suppression of AKT/mTORC1-driven phenotypes in diverse breast cancer cell lines. Using multi-omic profiling and causal network integration, we demonstrate that the enhanced efficacy of INY-05-040 relies in part on potent downstream activation of stress mitogen activated protein kinase (MAPK) signaling. Systematic measurements of growth inhibition across 288 cancer cell lines confirmed the substantial improvement in potency for INY-05-040 compared to the first-generation AKT degrader (INY-03-041) and catalytic AKT inhibition with GDC-0068. Subsequent integration of breast cancer cell line-specific data with publicly available transcriptomic, proteomic and reverse phase protein array (RPPA) measurements revealed that decreased sensitivity to INY-05-040 correlates with a high baseline activation of inflammatory/stress signaling pathways. Collectively, our data uncover a unique mechanism of breast cancer cell line sensitivity to AKT degradation, further suggesting that the efficacy of catalytic AKT inhibition may be enhanced by activation of stress MAPKs in breast cancer cells with low baseline activity of these components.
Project description:We report the development of a second-generation AKT degrader INY-05-040, which outperformed catalytic AKT inhibition both with respect to biochemical and cellular suppression of AKT/mTORC1-driven phenotypes in diverse breast cancer cell lines. Using multi-omic profiling and causal network integration, we demonstrate that the enhanced efficacy of INY-05-040 relies in part on potent downstream activation of stress mitogen activated protein kinase (MAPK) signaling. Systematic measurements of growth inhibition across 288 cancer cell lines confirmed the substantial improvement in potency for INY-05-040 compared to the first-generation AKT degrader (INY-03-041) and catalytic AKT inhibition with GDC-0068. Subsequent integration of breast cancer cell line-specific data with publicly available transcriptomic, proteomic and reverse phase protein array (RPPA) measurements revealed that decreased sensitivity to INY-05-040 correlates with a high baseline activation of inflammatory/stress signaling pathways. Collectively, our data uncover a unique mechanism of breast cancer cell line sensitivity to AKT degradation, further suggesting that the efficacy of catalytic AKT inhibition may be enhanced by activation of stress MAPKs in breast cancer cells with low baseline activity of these components.
Project description:NOTCH activation has been recently implicated in human basal-like breast cancers associated with a poor prognosis. To address the role of Notch1 in mammary transformation and mammary tumor initiating cell activity, we developed a doxycycline-regulated model of Notch1-mediated mammary transformation. These mice develop mammary adenocarcinomas that express cytokeratin (CK) 8/18 and contain rare cells that also express keratin 14. In vivo limiting dilution analyses reveal that these mammary tumors exhibit functional heterogeneity and harbor a rare (1/2978) mammary tumor initiating cell population. Using this dox-regulated Notch1 mammary tumor model, we demonstrate that Notch1 inhibition results in mammary tumor regression in vivo and prevents disease recurrence in 4 of 6 tumors tested. Consistent with the in vivo data, Notch1 inhibition reduces mammary tumorsphere forming activity in vitro. Using doxycycline-responsive tumor derived cell lines, we also identify the embryonic stem cell transcription factor Nanog as a novel Notch1-regulated gene in mammospheres. These data indicate that Notch1 contributes to mammary tumor initiating activity and raises the possibility that NOTCH therapeutics may have efficacy in human basal-like breast cancers associated with NOTCH activation.
Project description:NOTCH activation has been recently implicated in human basal-like breast cancers associated with a poor prognosis. To address the role of Notch1 in mammary transformation and mammary tumor initiating cell activity, we developed a doxycycline-regulated model of Notch1-mediated mammary transformation. These mice develop mammary adenocarcinomas that express cytokeratin (CK) 8/18 and contain rare cells that also express keratin 14. In vivo limiting dilution analyses reveal that these mammary tumors exhibit functional heterogeneity and harbor a rare (1/2978) mammary tumor initiating cell population. Using this dox-regulated Notch1 mammary tumor model, we demonstrate that Notch1 inhibition results in mammary tumor regression in vivo and prevents disease recurrence in 4 of 6 tumors tested. Consistent with the in vivo data, Notch1 inhibition reduces mammary tumorsphere forming activity in vitro. Using doxycycline-responsive tumor derived cell lines, we also identify the embryonic stem cell transcription factor Nanog as a novel Notch1-regulated gene in mammospheres. These data indicate that Notch1 contributes to mammary tumor initiating activity and raises the possibility that NOTCH therapeutics may have efficacy in human basal-like breast cancers associated with NOTCH activation. Primary mammary tumors were isolated from two different MMTV-tTA/TOP-ICN1 transgenic mice, minced, enzymatically digested and converted to culture. To identify changes in gene expression in response to ICN1 suppression, tumor-derived cell lines 8534 and 8542 were left untreated (8534-Untreated; 8542-Untreated) or treated with 2ug/ml doxycycline for 24 hours (8534-Dox; 8542-Dox). Cells were collected by scraping and total RNA was isolated, followed by real-time PCR validation of NOTCH1 target gene modulation. RNA samples were further hybridized to Affymetrix mouse genome 430A2.0 arrays.
Project description:CDK4/6 inhibition is the standard of care for estrogen receptor positive (ER+) breast cancer, although cytostasis is frequently observed, and new treatment strategies that enhance efficacy are required. We performed a genome-wide CRISPR screen to identify genetic determinants of CDK4/6 inhibitors sensitivity. Multiple genes involved in oxidative stress and ferroptosis modulated palbociclib sensitivity. Depletion or inhibition of GPX4 increased sensitivity to palbociclib in ER+ breast cancer models, and sensitised triple negative breast cancer models to palbociclib, with GPX4 null xenografts being highly sensitive to palbociclib. Palbociclib induced oxidative stress and disordered lipid metabolism with lipid peroxidation, leading to a ferroptosis-sensitive state. Lipid peroxidation relied on a peroxisome AGPAT3-dependent pathway in ER+ breast cancer models, rather than the classical ACSL4 pathway. Our data demonstrate that CDK4/6 inhibition creates vulnerability to ferroptosis that could be exploited through combination with GPX4 inhibitors, enhancing sensitivity to CDK4/6 inhibition in breast cancer.