Human X-box binding protein-1 (XBP1) is an alternatively spliced transcription factor that participates in the unfolded protein response (UPR), a stress signaling pathway that allows cells to survive the accumulation of unfolded proteins in the endoplasmic reticulum lumen. We have previously demonstrated that XBP1 expression is increased in antiestrogen-resistant breast cancer cell lines, and is co-expressed with estrogen receptor alpha (ER) in breast tumors. The purpose of this study is to investigate the role of XBP1 and the UPR in estrogen and antiestrogen responsiveness in breast cancer. Overexpression of spliced XBP1 (XBP1(S)) in ER-positive breast cancer cells leads to estrogen-independent growth and reduced sensitivity to growth inhibition induced by the antiestrogens Tamoxifen and Faslodex in a manner independent of functional p53. Data from gene expression microarray analyses imply that XBP1(S) acts through regulating the expression of ER, the anti-apoptotic gene BCL2, and several other genes associated with control of the cell cycle and apoptosis.
Human X-box binding protein-1 confers both estrogen independence and antiestrogen resistance in breast cancer cell lines.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrated molecular analysis of Tamoxifen-resistant invasive lobular breast cancer cells identifies MAPK and GRM/mGluR signaling as therapeutic vulnerabilities.
Treatment
View SamplesInvasive lobular breast cancer (ILC) is an understudied malignancy with distinct clinical, pathological, and molecular features that distinguish it from the more common invasive ductal carcinoma (IDC). Mounting evidence suggests that estrogen receptor-alpha positive (ER+) ILC has a poor response to Tamoxifen (TAM), but the mechanistic drivers of this are undefined. In the current work, we comprehensively characterize the SUM44/LCCTam ILC model system through integrated analysis of gene expression, copy number, and mutation, with the goal of identifying actionable alterations relevant to clinical ILC that can be co-targeted along with ER to improve treatment outcomes. We show that TAM has several distinct effects on the transcriptome of LCCTam cells, that this resistant cell model has acquired copy number alterations and mutations that impinge on MAPK and metabotropic glutamate receptor (GRM/mGluR) signaling networks, and that pharmacological inhibition of either improves or restores the growth-inhibitory actions of endocrine therapy.
Integrated molecular analysis of Tamoxifen-resistant invasive lobular breast cancer cells identifies MAPK and GRM/mGluR signaling as therapeutic vulnerabilities.
Treatment
View SamplesOne-third of all ER+ breast tumors treated with endocrine therapy fail to respond, and the remainder are likely to relapse in the future. Almost all data on endocrine resistance has been obtained in models of invasive ductal carcinoma (IDC). However, invasive lobular carcinomas (ILC) comprise up to 15% of newly diagnosed invasive breast cancers diagnosed each year and, while the incidence of IDC has remained relatively constant during the last 20 years, the prevalence of ILC continues to increase among postmenopausal women. We report a new model of Tamoxifen (TAM)-resistant invasive lobular breast carcinoma cells that provides novel insights into the molecular mechanisms of endocrine resistance. SUM44 cells express ER and are sensitive to the growth inhibitory effects of antiestrogens. Selection for resistance to 4-hydroxytamoxifen led to the development of the SUM44/LCCTam cell line, which exhibits decreased expression of estrogen receptor alpha (ER) and increased expression of the estrogen-related receptor gamma (ERR). Knockdown of ERR in SUM44/LCCTam cells by siRNA restores TAM sensitivity, and overexpression of ERR blocks the growth-inhibitory effects of TAM in SUM44 and MDA-MB-134 VI lobular breast cancer cells. ERR-driven transcription is also increased in SUM44/LCCTam, and inhibition of activator protein 1 (AP1) can restore or enhance TAM sensitivity. These data support a role for ERR/AP1 signaling in the development of TAM resistance, and suggest that expression of ERR may be a marker of poor Tamoxifen response.
ERRgamma mediates tamoxifen resistance in novel models of invasive lobular breast cancer.
No sample metadata fields
View SamplesExpression data from CD34+ hematopoietic cells transduced with control or anti-SLPI shRNA, serum starved and treated with G-CSF.
A lack of secretory leukocyte protease inhibitor (SLPI) causes defects in granulocytic differentiation.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
A novel KLF6-Rho GTPase axis regulates hepatocellular carcinoma cell migration and dissemination.
Specimen part
View SamplesWe performed whole genome expression profiling using a murine HCC cell line that was either infected with a virus containing shRNA targeting KLF6 or GFP. 3 sets of infections were performed for both shGFP and shKLF6 samples. RNA was isolated from these samples and subsequently analyzed.
A novel KLF6-Rho GTPase axis regulates hepatocellular carcinoma cell migration and dissemination.
Specimen part
View SamplesWe determined whole genome expression changes in 2 migratory cell lines that were derived from a parent HCC cell line.
A novel KLF6-Rho GTPase axis regulates hepatocellular carcinoma cell migration and dissemination.
Specimen part, Cell line
View SamplesType I interferon-stimulated genes (ISGs) have critical roles in inhibiting virus replication and dissemination. Despite advances in understanding the molecular basis of ISG restriction, the antiviral mechanisms of many remain unclear. The 20 kDa ISG, ISG20, is a nuclear 3''-5''exonuclease with preference for single stranded RNA (ssRNA) and has been implicated in the IFN-mediated restriction of several RNA viruses. Although the exonuclease activity of ISG20 has been shown to degrade viral RNA in vitro, evidence has yet to be presented that virus inhibition in cells requires this activity. Here, we utilized a combination of an inducible, ectopic expression system and newly generated Isg20-/- mice to investigate mechanisms and consequences of ISG20-mediated restriction. Ectopically expressed ISG20 localized primarily to Cajal bodies in the nucleus and restricted replication of chikungunya and Venezuelan equine encephalitis viruses. Although restriction by ISG20 was associated with inhibition of translation of infecting genomic RNA, degradation of viral RNAs was not observed. Instead, translation inhibition of viral RNA was associated with ISG20-induced upregulation of over 100 other genes, many of which encode known antiviral effectors. ISG20 modulated the production of IFIT1, an ISG that suppresses translation of alphavirus RNAs. Consistent with this observation, the pathogenicity of IFIT1-sensitive alphaviruses was increased in Isg20-/- mice compared to wild-type viruses, but not in ISG20 ectopic-expressing cells. Our findings establish an indirect role for ISG20 in the early restriction of RNA virus replication by regulating expressionof other ISGs that inhibit translation and possibly other activities in the replication cycle. Overall design: Two clones each of tet-inducible MEFs overexpressing eGFP (control), Isg20, and Isg20(D94G) were induced by tetracycline removal for 72 hours. rRNA was depleted with RiboMinus Eukaryote kit (Life Technologies) and prepared for Illumina directional 100bp paired-end HiSeq2000 reads.
The Interferon-Induced Exonuclease ISG20 Exerts Antiviral Activity through Upregulation of Type I Interferon Response Proteins.
Specimen part, Cell line, Subject
View SamplesKnockdown of HCLS1 mRNA in CD34+ hematopoietic cells resulted in a severe diminished in vitro myeloid differentiation which was in line with downregulation of a set of genes, e.g., of Wnt or PI3K/Akt signaling cascades. We performed microarrays to evaluate specific genes and signaling systems regulated by HCLS1 in hematopoietic cells.
Interactions among HCLS1, HAX1 and LEF-1 proteins are essential for G-CSF-triggered granulopoiesis.
Specimen part, Disease, Disease stage, Treatment
View Samples