Project description:Although the estrogen receptor (ER) positive variant of breast cancer is touted as the most indolent and favorable, the majority of breast cancer deaths are in fact from this subtype. There are several features of this category of breast cancers that likely account for this outcome. The first is that metastatic relapse can occur many years after initial diagnosis of primary disease. The second is that once the cancer cells awaken into full-blown metastatic disease, they are largely resistant to ER-directed therapies (i.e. hormonal therapy, HT). The third is that when metastases do occur, they are invariably in many locations. This observation suggests that these dormant/sleeping metastatic cells are “globally” awakened as if by a “systemic” infection. We suggest that these three processes be not only linked, but underlie the lethal features of metastatic disease. We hypothesized that mtDNA is necessary for the escape from therapy induced tumor dormancy of luminal breast cancer cells
Project description:Limited knowledge of the changes in estrogen receptor (ER) signaling during the transformation of the normal mammary gland to breast cancer hinders the development of effective prevention and treatment strategies. Differences in estrogen signaling between normal human primary breast epithelial cells and primary breast tumors obtained immediately following surgical excision were explored. Transcriptional profiling of normal ER+ mature luminal mammary epithelial cells and ER+ breast tumors revealed significant difference in the response to estrogen stimulation. Consistent with these differences in gene expression, the normal and tumor ER cistromes were distinct and sufficient to segregate normal breast tissues from breast tumors. The selective enrichment of the DNA binding motif GRHL2 in the breast cancer-specific ER cistrome suggests that it may play a role in the differential function of ER in breast cancer. Depletion of GRHL2 resulted in altered ER binding and differential transcriptional responses to estrogen stimulation. Furthermore, GRHL2 was demonstrated to be essential for estrogen-stimulated proliferation of ER+ breast cancer cells. DLC1 was also identified as an estrogen-induced tumor suppressor in the normal mammary gland with decreased expression in breast cancer. In clinical cohorts, loss of DLC1 and gain of GRHL2 expression are associated with breast cancer and are independently predictive for worse survival. This study suggests that normal ER signaling is lost and tumor-specific ER signaling is gained during breast tumorigenesis. Unraveling these changes in ER signaling during breast cancer progression should aid the development of more effective prevention strategies and targeted therapeutics. SIGNIFICANCE STATEMENT: Abnormal estrogen receptor (ER) signaling drives the majority of breast cancers and is targeted by endocrine therapies. However, in normal breast tissue, ER signaling has been demonstrated to promote benign functions such as development and differentiation. Using genomic techniques to characterize ER function in normal breast and breast tumors, this study reveals differential patterns of ER signaling, suggesting that normal ER signaling is lost and tumorigenic ER signaling gained during breast tumor formation. Better understanding of this process can aid the development of improved breast cancer prevention strategies and therapies.
Project description:The mainstay of treatment for hormone responsive breast tumors is chemotherapy, followed by targeted endocrine therapy. The vast majority (80%) of estrogen receptor positive tumors also express wild type p53 protein that is the main determinant of the DNA damage response. Tumors that are ER+ and p53WT respond poorly to chemotherapy, although the underlying mechanisms are not completely understood. We describe a novel link between store independent Ca2+ entry (SICE) and resistance to DNA damaging drugs, mediated by the secretory pathway Ca2+-ATPase, SPCA2. In luminal ER+/PR+ breast cancer subtypes, SPCA2 levels are high and correlate with poor survival prognosis. Independent of ion pump activity, SPCA2 elevates baseline Ca2+ levels through SICE and drives cell proliferation. Attenuation of SPCA2 led to increased mitochondrial ROS production, DNA damage and activation of the ATM/ATR-p53 axis leading to G0/G1 phase cell cycle arrest and apoptosis. Resistance to DNA damaging agents including doxorubicin, carboplatin, and ionizing radiation could be reversed by downregulation of SPCA2 expression using curcumin. In conclusion, elevated SPCA2 drives pro-survival and chemotherapy resistance in ER+ p53WT breast tumors by suppressing the DNA damage response. Attenuation of SPCA2 expression by curcumin may have therapeutic potential in treating receptor positive breast cancer. The goal of this study is to investigate store Independent Ca2+ entry regulation of the DNA Damage Response pathway in breast cancer cells
Project description:In lobular breast cancer, metachronous distant metastasis may become evident many years after primary tumor diagnosis and often affect the ovary. Little is known about tumor dormancy and intratumoral heterogeneity of DNA methylation in metastasis from lobular breast cancer. In this exploratory analysis, DNA methylation patterns were studied in six spacially separated regions of an ovarian metastasis from lobular breast cancer.
Project description:Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. By integrating pre-clinical models and clinical specimens, we show that signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancer-elements shared with ER and its pioneer factor FOXA1. Although IL6 activated STAT3 and ER/FOXA1 share cis-regulatory regions, STAT3 drives transcription independent of ER and FOXA1 function, and the IL6/STAT3 gene program is not influenced by ER-targeted therapies, decoupling these two important pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but independent actionable pathways controlling breast cancer progression.
Project description:Estrogen receptor-alpha (ER) drives tumour development and metastasis in ER positive (ER+) breast cancer. GATA3 is a transcription factor that has been closely linked to ER function, but the role of GATA3 in ER-transcriptional activity is not clear. We sought to identify the contribution of GATA3 to the ER complex, by conducting quantitative multiplexed rapid immunoprecipitation mass spectrometry of endogenous proteins (qPLEX-RIME), to assess changes to the ER complex in response to GATA3 depletion. Unexpectedly, very few proteins were dissociated from the ER complex in the absence of GATA3, with the only major change being loss of TET2 in the ER complex. In breast cancer cells and Patient-Derived Xenograft (PDX) tissue, TET2 binding events were shown to constitute a near-total subset of ER binding events, and loss of TET2 was functionally associated with reduced activation of proliferative pathways. To investigate the TET2-ER relationship, the role of TET2 in regulating DNA modifications in ER+ breast cancer cells was examined. TET2 knockdown did not appear to result in changes to global DNA methylation, however, oxidation of methylated DNA to 5-hydroxymethylcytosine (5hmC) was significantly reduced after TET2 depletion and these events occurred at ER enhancers. These findings implicate TET2 in the production and maintenance of 5hmC at ER sites, providing a potential mechanism for TET2-mediated regulation of ER target genes.
Project description:Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor a positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. In pre-clinical models and clinical specimens, signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancers shared with ER and its pioneer factor FOXA1. However, STAT3 drives transcription independent of ER and FOXA1 function from these enhancers, and the IL6/STAT3 pathway is therefore resistant to ER-targeted therapies, decoupling these two important oncogenic pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but functionally independent and actionable pathways controlling breast cancer progression.
Project description:Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. By integrating pre-clinical models and clinical specimens, we show that signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancer-elements shared with ER and its pioneer factor FOXA1. Although IL6 activated STAT3 and ER/FOXA1 share cis-regulatory regions, STAT3 drives transcription independent of ER and FOXA1 function, and the IL6/STAT3 gene program is not influenced by ER-targeted therapies, decoupling these two important pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but independent actionable pathways controlling breast cancer progression.
Project description:Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. By integrating pre-clinical models and clinical specimens, we show that signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancer-elements shared with ER and its pioneer factor FOXA1. Although IL6 activated STAT3 and ER/FOXA1 share cis-regulatory regions, STAT3 drives transcription independent of ER and FOXA1 function, and the IL6/STAT3 gene program is not influenced by ER-targeted therapies, decoupling these two important pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but independent actionable pathways controlling breast cancer progression.