Project description:In a 3D coculture with stroma cells derived from breast cancer patients’ brain metastasis, HER2+ breast cancer cells were protected from HER2-targeted therapies, particularly the EGFR/HER2 small molecule inhibitor neratinib. To get insight into how this protection arises, ATAC-seq on coculture cells with or without neratinib as performed.
Project description:Activated HER2 and EGFR stimulate the Ras small GTPases, which in turn primarily activate the MAPK, PI3K-Akt and RalGEF-Ral pathways. While activation of the MAPK and PI3K-Akt pathways downstream of HER2 and EGFR promote mammary tumorigenesis, little is known regarding the role of the RalGEF-Ral pathway. RalGEFs convert the small GTPases RalA and RalB to an active GTP-bound state. Of the two proteins, only activated RalA is transforming, while RalB is more important for cell motility, and hence we investigated the role of RalA in HER2-overexpressing and EGFR-positive breast cancer. We now report that shRNA-mediated knockdown of RalA reduced the in vitro transformed growth and in vivo tumorigenic growth of MDA-MB-231 human breast cancer cells, while knockdown of RalB reduced migration and invasion. Lastly, we demonstrate that expression of activated HER2 increases RalA-GTP levels, and that a number of genes associated with activated RalA are elevated in tumor compared to normal mammary tissue. Taken together, these results suggest a possible role for RalA in mammary tumorigenesis. Four independent cultures of HEK-HT cells stably infected with a retrovirus confirmed to expressed RalAQ72L and four independent cultures of HEK-HT cells stably infected with a control retrovirus RalA activation expression analysis
Project description:Transcription profiling by array of triple-negative, HER2-overexpressing and hormone-sensitive breast carcinoma cell lines after EGFR inhibition with erlotinib
Project description:In a 3D coculture with stroma cells derived from breast cancer patients’ brain metastasis, HER2+ breast cancer cells were protected from HER2-targeted therapies, particularly the EGFR/HER2 small molecule inhibitor neratinib. To get insight into how this protection arises, a Synthetic Notch (SynNotch) reporter model allowed to study the effect of direct contact between stroma and cancer cells.
Project description:Recent studies suggested that crosstalk between ERα and EGFR/HER2 pathways plays a critical role in mediating endocrine therapy resistance. Several targeting EGFR/HER2 signaling inhibitors including FDA-approved lapatinib and gefitinib as well as a novel dual tyrosine kinase inhibitor (TKI) sapitnib showed greater inhibitory efficacies. However, how a 3D chromatin landscape of the response to the inhibition to EGFR/HER2 pathway remains to be elucidated. In this study, we conducted in situ Hi-C and RNA-seq in two ERα+ breast cancer cell systems, tamoxifen-sensitive MCF7 and T47D and tamoxifen-resistant MCF7TR and T47DTR before and after the treatment of sapitnib. We identified differential response of topologically associated domains (TADs), looping genes and expressed genes. Interestingly, we found that many differential TADs and looping genes are reversible, indicating that EGFR/HER2 signaling may play a role in reshaping and rewiring the high order genome organization. We further examined and recapitulated the reversible looping genes in 3D spheroids of breast cancer cells. Our data provides a rich resource for further evaluating chromatin structural response to anti-EGFR/HER2 targeted therapies in endocrine-resistant breast cancer.
Project description:Recent studies suggested that crosstalk between ERα and EGFR/HER2 pathways plays a critical role in mediating endocrine therapy resistance. Several targeting EGFR/HER2 signaling inhibitors including FDA-approved lapatinib and gefitinib as well as a novel dual tyrosine kinase inhibitor (TKI) sapitnib showed greater inhibitory efficacies. However, how a 3D chromatin landscape of the response to the inhibition to EGFR/HER2 pathway remains to be elucidated. In this study, we conducted in situ Hi-C and RNA-seq in two ERα+ breast cancer cell systems, tamoxifen-sensitive MCF7 and T47D and tamoxifen-resistant MCF7TR and T47DTR before and after the treatment of sapitnib. We identified differential response of topologically associated domains (TADs), looping genes and expressed genes. Interestingly, we found that many differential TADs and looping genes are reversible, indicating that EGFR/HER2 signaling may play a role in reshaping and rewiring the high order genome organization. We further examined and recapitulated the reversible looping genes in 3D spheroids of breast cancer cells. Our data provides a rich resource for further evaluating chromatin structural response to anti-EGFR/HER2 targeted therapies in endocrine-resistant breast cancer.
Project description:Activated HER2 and EGFR stimulate the Ras small GTPases, which in turn primarily activate the MAPK, PI3K-Akt and RalGEF-Ral pathways. While activation of the MAPK and PI3K-Akt pathways downstream of HER2 and EGFR promote mammary tumorigenesis, little is known regarding the role of the RalGEF-Ral pathway. RalGEFs convert the small GTPases RalA and RalB to an active GTP-bound state. Of the two proteins, only activated RalA is transforming, while RalB is more important for cell motility, and hence we investigated the role of RalA in HER2-overexpressing and EGFR-positive breast cancer. We now report that shRNA-mediated knockdown of RalA reduced the in vitro transformed growth and in vivo tumorigenic growth of MDA-MB-231 human breast cancer cells, while knockdown of RalB reduced migration and invasion. Lastly, we demonstrate that expression of activated HER2 increases RalA-GTP levels, and that a number of genes associated with activated RalA are elevated in tumor compared to normal mammary tissue. Taken together, these results suggest a possible role for RalA in mammary tumorigenesis.
Project description:A Myc transcriptional program that is independent of EMT drives a poor prognosis tumor-propagating phenotype in HER2+ breast cancer