Project description:Indole-3-carbinol (I3C) is a natural anti-carcinogenic compound found at high concentrations in Brassica vegetables. ER-positive cell lines demonstrated the greatest sensitivity to the anti-tumor effects of I3C compared to ER-negative breast cancer cell lines. Gene expression analysis was performed to identify genes and pathways that accounted for sensitivity to I3C. Microarray analysis performed using Illumina HT-12 v4 expression arrays A total of 36 samples were analyzed with six breast cancer cell lines treated with either the vehicle control or the drug Indole-3-carbinol in triplicate. The cell lines were: MCF-7, T47D, ZR751(sensitive to the drug, apoptosis/growth arrest) and MDA-MB-231, MDA-MB-157, and MDA-MB-436 (insensitive to the drug). Sensitive cell lines are of the luminal subtype and insensitive cell lines are of the basal subtype.
Project description:Indole-3-carbinol is used as a dietary supplement and has potential use as a therapeutic agent for the prevention of various types of cancer. While substantial evidence exists that indole-3-carbinol can reduce the risk of cancers induced by several known carcinogens when administered to animals, indole-3-carbinol can also function as an initiator and tumor promoter in certain models. The carcinogenic potential of indole-3-carbinol has not been studied in a 2-year bioassay. The objective of the microarray study was to evaluate the transcriptional changes in liver from rats exposed to 0 or 300 mg/kg indole-3-carbinol. At 3 months, livers were analyzed from female Harlan Sprague Dawley rats in the 2-year gavage study of indole-3-carbinol. Female rats were administered 300 mg indole-3-carbinol/kg body weight in corn oil by gavage, 5 days per week in a 2 year toxicology study of indole-3-carbinol. Gene expression studies were performed on rat liver with samples hybridized to whole rat genome RG230_2.0 rat GeneChip arrays (Affymetrix, CA).
Project description:Indole-3-carbinol is used as a dietary supplement and has potential use as a therapeutic agent for the prevention of various types of cancer. While substantial evidence exists that indole-3-carbinol can reduce the risk of cancers induced by several known carcinogens when administered to animals, indole-3-carbinol can also function as an initiator and tumor promoter in certain models. The carcinogenic potential of indole-3-carbinol has not been studied in a 2-year bioassay. The objective of the microarray study was to evaluate the transcriptional changes in liver from rats exposed to 0 or 300 mg/kg indole-3-carbinol. At 3 months, livers were analyzed from female Harlan Sprague Dawley rats in the 2-year gavage study of indole-3-carbinol.
Project description:Indole-3-carbinol (I3C) is a natural anti-carcinogenic compound found at high concentrations in Brassica vegetables. ER-positive cell lines demonstrated the greatest sensitivity to the anti-tumor effects of I3C compared to ER-negative breast cancer cell lines. Gene expression analysis was performed to identify genes and pathways that accounted for sensitivity to I3C. Microarray analysis performed using Illumina HT-12 v4 expression arrays
Project description:Dysregulated estrogen and estrogen receptor (ER)-induced gene transcription is tightly associated with estrogen receptor alpha (ERα)-positive breast carcinogenesis. ERα-occupied enhancers, particularly super enhancers, have been suggested to play a vital role in such transcriptional events. However, the landscape of ERα-occupied super enhancers (ERSEs) as well as key super enhancer-associated genes remain to be fully characterized. Here, we defined the landscape of ERSEs in MCF7, a ERα-positive breast cancer cell line, and demonstrated that bromodomain protein BRD4 is a master regulator of the transcriptional activation of ERSE and cognate ERα-target genes. Furthermore, RET, a member of the tyrosine protein kinase family of proteins, was identified to be a key target gene of BRD4-regulated ERSEs, which is vital for estrogen/ ERα-induced gene transcriptional activation and malignant phenotypes through activating the Ras-Raf-MEK-ERK-p90RSK-ERα phosphorylation cascade. Accordingly, combination therapy with BRD4 and RET inhibitors exhibited synergistic effects on suppressing ERα-positive breast cancer both in vitro and in vivo. Taken together, our data uncovered the critical role of a super enhancer-associated BRD4/ERα-RET-ERα positive feedback loop in ERα-positive breast cancer, and targeting components in this loop will provide new therapeutic avenue for treating ERα-positive breast cancer in the clinic.
Project description:Dysregulated estrogen and estrogen receptor (ER)-induced gene transcription is tightly associated with estrogen receptor alpha (ERα)-positive breast carcinogenesis. ERα-occupied enhancers, particularly super enhancers, have been suggested to play a vital role in such transcriptional events. However, the landscape of ERα-occupied super enhancers (ERSEs) as well as key super enhancer-associated genes remain to be fully characterized. Here, we defined the landscape of ERSEs in MCF7, a ERα-positive breast cancer cell line, and demonstrated that bromodomain protein BRD4 is a master regulator of the transcriptional activation of ERSE and cognate ERα-target genes. Furthermore, RET, a member of the tyrosine protein kinase family of proteins, was identified to be a key target gene of BRD4-regulated ERSEs, which is vital for estrogen/ ERα-induced gene transcriptional activation and malignant phenotypes through activating the Ras-Raf-MEK-ERK-p90RSK-ERα phosphorylation cascade. Accordingly, combination therapy with BRD4 and RET inhibitors exhibited synergistic effects on suppressing ERα-positive breast cancer both in vitro and in vivo. Taken together, our data uncovered the critical role of a super enhancer-associated BRD4/ERα-RET-ERα positive feedback loop in ERα-positive breast cancer, and targeting components in this loop will provide new therapeutic avenue for treating ERα-positive breast cancer in the clinic.
Project description:Dysregulated estrogen and estrogen receptor (ER)-induced gene transcription is tightly associated with estrogen receptor alpha (ERα)-positive breast carcinogenesis. ERα-occupied enhancers, particularly super enhancers, have been suggested to play a vital role in such transcriptional events. However, the landscape of ERα-occupied super enhancers (ERSEs) as well as key super enhancer-associated genes remain to be fully characterized. Here, we defined the landscape of ERSEs in MCF7, a ERα-positive breast cancer cell line, and demonstrated that bromodomain protein BRD4 is a master regulator of the transcriptional activation of ERSE and cognate ERα-target genes. Furthermore, RET, a member of the tyrosine protein kinase family of proteins, was identified to be a key target gene of BRD4-regulated ERSEs, which is vital for estrogen/ ERα-induced gene transcriptional activation and malignant phenotypes through activating the Ras-Raf-MEK-ERK-p90RSK-ERα phosphorylation cascade. Accordingly, combination therapy with BRD4 and RET inhibitors exhibited synergistic effects on suppressing ERα-positive breast cancer both in vitro and in vivo. Taken together, our data uncovered the critical role of a super enhancer-associated BRD4/ERα-RET-ERα positive feedback loop in ERα-positive breast cancer, and targeting components in this loop will provide new therapeutic avenue for treating ERα-positive breast cancer in the clinic.
Project description:To identify microRNAs impacting estrogen receptor ERα expression in breast cancer, we have screened ER-positive breast cancer cells with a library of pre-miRs, and systematically monitored the ERα expression by protein lysate microarrays. There was a significant enrichment of the in silico predicted ERα targeting microRNAs among the hits. The most potent pre-miRs miR-18a/b, miR-193b, miR-206, and miR-302c, were confirmed to directly target ERα and to repress estrogen-responsive genes. The effect of miRNA overexpression on gene expression profile of MCF-7 cells was studied. Furthermore, miR-18a and miR-18b showed increased expression in ERα-negative as compared to ERα-positive clinical tumors. In summary, we present systematic and direct functional and correlative clinical evidence on microRNAs inhibiting ERα signaling in breast cancer.
Project description:PI3K/AKT pathway plays one of pivotal roles in breast cancer development and maintenance. PIK3CA, coding PIK3 catalytic subunit, is the oncogene which shows the high frequency of gain-of-function mutations leading to the PI3K/AKT pathway activation in breast cancer. In particular in the ERα-positive breast tumors PIK3CA mutations have been observed in 30% to 40%. However, genes expressed in connection to the pathway activation in breast tumorigenesis remain largely unknown. To identify downstream relevant target genes (and signaling pathways) turned on by the aberrant PI3K/AKT signal in breast tumors, we analyzed gene expression by pangenomic oligonucleotide microarray in a series of 43 ERα-positive tumors with and without PIK3CA mutations. 43 ERα-positive breast tumors including 14 tumors with PIK3CA mutations and 29 tumors without PIK3CA mutattions were used as screening set for microarray.
Project description:Estrogen receptor alpha (ERα) is highly expressed in most breast cancers. Consequently, ERα modulators, such as tamoxifen, are successful in breast cancer treatment, although tamoxifen resistance is commonly observed. While tamoxifen resistance may be caused by altered ERα signaling, the molecular mechanisms regulating ERα signaling and tamoxifen resistance are not entirely clear. Here, we found that PAK4 expression was consistently correlated to poor patient outcome in endocrine treated and tamoxifen-only treated breast cancer patients. Importantly, while PAK4 overexpression promoted tamoxifen resistance in MCF-7 human breast cancer cells, pharmacological treatment with a group II PAK (PAK4, 5, 6) inhibitor, GNE-2861, sensitized tamoxifen resistant MCF-7/LCC2 breast cancer cells to tamoxifen. Mechanistically, we identified a regulatory positive feedback loop, where ERα bound to the PAK4 gene, thereby promoting PAK4 expression, while PAK4 in turn stabilized the ERα protein, activated ERα transcriptional activity and ERα target gene expression. Further, PAK4 phosphorylated ERα-Ser305, a phosphorylation event needed for the PAK4 activation of ERα-dependent transcription. In conclusion, PAK4 may be a suitable target for perturbing ERα signaling and tamoxifen resistance in breast cancer patients.