Project description:Triple negative breast cancers (TNBC) are associated with poor clinical outcomes due to a lack of targeted therapies. Here, we identified a small molecule ERX-41 with potent activity against TNBC cell lines, primary tumor explants and xenografts. ERX-41 induced endoplasmic reticulum (ER) stress and caused cell death. We identified lysosomal acid lipase A (LIPA) gene as the molecular target for ERX-41 and critical for ERX-41 to induce ER stress and cell death. Mechanistically, interaction of ERX-41 with LIPA alters expression of multiple ER-resident proteins involved in protein folding. Importantly, we defined that ER localization of LIPA but not its lipase function are necessary for ERX-41 activity in TNBC. Our study implicates a new targeted strategy for multiple solid tumors, including breast, brain, pancreatic and ovarian, whereby a small orally bioavailable molecule (ERX-41) targeting LIPA blocks protein folding, induces ER stress and causes cell death.
Project description:Triple-negative breast cancer (TNBC) has a poor clinical outcome, due to a lack of actionable therapeutic targets. Herein we define lysosomal acid lipase A (LIPA) as a viable molecular target in TNBC and identify a stereospecific small molecule (ERX-41) that binds LIPA. ERX-41 induces endoplasmic reticulum (ER) stress resulting in cell death, and this effect is on target as evidenced by specific LIPA mutations providing resistance. Importantly, we demonstrate that ERX-41 activity is independent of LIPA lipase function but dependent on its ER localization. Mechanistically, ERX-41 binding of LIPA decreases expression of multiple ER-resident proteins involved in protein folding. This targeted vulnerability has a large therapeutic window, with no adverse effects either on normal mammary epithelial cells or in mice. Our study implicates a targeted strategy for solid tumors, including breast, brain, pancreatic and ovarian, whereby small, orally bioavailable molecules targeting LIPA block protein folding, induce ER stress and result in tumor cell death.
Project description:Carcinoma cells can acquire key malignant traits by reprogramming their differentiation state via an epithelial-to-mesenchymal transition (EMT). Cancer cells that undergo EMT become invasive and resist a wide range of therapies including most chemotherapy drugs and radiation. Such cells are also able to efficiently seed primary and metastatic tumors, making them functionally indistinguishable from tumor-initiating or cancer stem-like cells (TICs or CSCs). Therefore, there is significant interest in finding vulnerabilities of cancer cells that have undergone EMT. A potent EMT-selective small molecule was discovered through a large-scale chemical screen. We used microarray analysis to understand the biological effects of this compound.
Project description:Hormone therapy targeting estrogen receptor (ER) is the principal treatment for ER-positive breast cancers but many cancers develop resistance to anti-estrogens. Cyclin-dependent kinase 8 (CDK8) is a transcriptional regulator of several oncogenic pathways. Expression levels of CDK8 and ERα are inversely correlated in breast cancers suggesting a functional association between CDK8 and ER. CDK8 inhibition by selective small-molecule inhibitors, by shRNA knockdown or by CRISPR-Cas9 knockout suppressed estrogen-induced transcription, with no significant effects on ERα protein expression or phosphorylation. CDK8 inhibition also abrogated the mitogenic effect of estrogen on ER-positive breast cancer cells and potentiated growth inhibition by the ER antagonist fulvestrant. In vivo, administration of a CDK8 inhibitor suppressed ER-positive breast cancer xenograft growth and augmented the effects of fulvestrant with no apparent toxicity. CDK8 inhibitors also suppressed the development of estrogen independence in ER-positive breast cancer cells. These results identify CDK8 as a novel drug target for breast cancer therapy.
Project description:Carcinoma cells can acquire key malignant traits by reprogramming their differentiation state via an epithelial-to-mesenchymal transition (EMT). Cancer cells that undergo EMT become invasive and resist a wide range of therapies including most chemotherapy drugs and radiation. Such cells are also able to efficiently seed primary and metastatic tumors, making them functionally indistinguishable from tumor-initiating or cancer stem-like cells (TICs or CSCs). Therefore, there is significant interest in finding vulnerabilities of cancer cells that have undergone EMT. A potent EMT-selective small molecule was discovered through a large-scale chemical screen. We used microarray analysis to understand the biological effects of this compound. HMLE_ctrl (human MECs, infected with a pBabe-shGFP retrovirus) and HMLE_Twist (human MECs, infected with a pBabe-Twist retrovirus) cells were treated with solvent control (DMSO), 5 µM or 10 µM of Cmp302 for 6 hours. Microarray analysis was performed to profile global gene expression.
Project description:Elevated expression and activity of the epidermal growth factor receptor (EGFR) is associated with development and progression of head and neck cancer (HNC) and a poor prognosis. Clinical trials with EGFR tyrosine kinase inhibitors (TKIs; eg. erlotinib) have been disappointing in HNC. To investigate the mechanisms mediating resistance to these agents, we developed a HNC cell line (HN5-ER) with acquired erlotinib resistance. In contrast to parental HN5 HNC cells, HN5-ER cells exhibited an epithelial-mesenchymal (EMT) phenotype with increased migratory potential, reduced E-cadherin and epithelial-associated miRNAs, and elevated vimentin expression. Phosphorylated RTK profiling identified Axl activation in HN5-ER cells. Growth and migration of HN5-ER cells was blocked with a specific Axl inhibitor, R428, and R428 re-sensitized HN5-ER cells to erlotinib. Microarray analysis of HN5-ER cells confirmed the EMT phenotype associated with acquired erlotinib resistance, and identified activation of gene expression associated with cell migration and inflammation pathways. Moreover, increased expression and secretion of interleukin (IL)-6 and IL-8 in HN5-ER cells suggested a role for inflammatory cytokine signaling in EMT and erlotinib resistance. Expression of the tumor suppressor miR-34a was reduced in HN5-ER cells and increasing its expression abrogated Axl expression and reversed erlotinib resistance. Finally, analysis of 302 HNC patients revealed that high tumor Axl mRNA expression was associated with poorer survival (HR 1.66, p=0.007). In summary, our results identify Axl as a key mediator of acquired erlotinib resistance in HNC and suggest that therapeutic inhibition of Axl by small molecule drugs or specific miRNAs might overcome anti-EGFR therapy resistance. Differential gene expression between parental and acquired erlotinib resistant head and neck cancer cell lines of HN5.