Induction of the RNA Regulator LIN28A Is Required for the Growth and Pathogenesis of RESTless Breast Tumors

Gunsalus, Kearney T. W.; Wagoner, Matthew P.; Meyer, Keith; Potter, Wyatt B.; Schoenike, Barry; Kim, Soyoung; Alexander, Caroline M.; Friedl, Andreas; Roopra, Avtar

doi:10.1158/0008-5472.can-11-1639

Cited by 13 publications

(14 citation statements)

References 37 publications

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“…Although we observed reduced IRS1 mRNA levels upon overexpression of REST in MDA-MB-231 cells, this reduction does not lead to a concomitant reduction in axis in regulating components of the IGF1R/IRS pathway has been reported (54). Lin28, a REST target that becomes upregulated in human breast tumors, regulates let-7 microRNA (miRNA) processing (2,55,56). Several genes in the IGF1R pathway have conserved let-7 target sequences, including IGF1, IGF1R, IRS2, PIK3IP1, AKT2, and IGFBP2.…”

Section: Discussionmentioning

confidence: 48%

“…3B and C). Indeed, the ChIP signal at IRS1 was similar to that found at BDNF, a well-characterized REST target gene (2,39).…”

Section: Irs1 Protein Is Upregulated In Restless Tumorsmentioning

confidence: 60%

“…Viral infections were conducted according to standard Addgene protocols by using psPAX2 (Addgene plasmid 12260) and pMD2.G (Addgene plasmid 12259) viral packaging particles. Stable REST knockdown in MCF7 cells was accomplished with a Dharmacon Smart vector lentiviral shRNA delivery system, as previously described (1,2). A second stable REST knockdown in MCF7 cells was achieved by using the above-mentioned methods with TRC REST shRNA from Open Biosystems (catalog number TRCN0000014784).…”

mentioning

confidence: 99%

“…Cells were seeded in triplicate into PRFM for 1 day, followed by serum deprivation for 2 days. RNA was extracted with TRIzol (Invitrogen) according to the manufacturer's protocol and reversed transcribed for quantitative real-time PCR (RT-PCR) as previously described (2). The primer set consisting of forward primer 5=-CAGAGGACCGTCAGTAGCTCAA-3= and reverse primer 5=-GGAA GATATGAGGTCCTAGTTGTGAAT-3= was used for the amplification of IRS1.…”

mentioning

confidence: 99%

“…Chromatin immunoprecipitation (ChIP) was conducted as previously described (2,8). ChIP was conducted by using 2 g of REST antibody (Millipore) or rabbit IgG (Sigma) with 300 g of protein.…”

mentioning

confidence: 99%

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Type 1 Insulin-Like Growth Factor Receptor/Insulin Receptor Substrate 1 Signaling Confers Pathogenic Activity on Breast Tumor Cells Lacking REST

Meyer

Albaugh

Schoenike

et al. 2015

Molecular and Cellular Biology

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Loss of repressor element 1 silencing transcription factor (REST) occurs in 20% of breast cancers and correlates with a poor patient prognosis. However, the molecular basis for enhanced malignancy in tumors lacking REST (RESTless) is only partially understood. We used multiplatform array data from the Cancer Genome Atlas to identify consistent changes in key signaling pathways. Of the proteins screened in the reverse-phase protein array, we found that insulin receptor substrate 1 (IRS1) is the most highly upregulated protein in RESTless breast tumors. Analysis of breast tumor cell lines showed that REST directly represses IRS1, and cells lacking REST have increased levels of IRS1 mRNA and protein. We find that the upregulation of IRS1 function is both necessary and sufficient for enhanced signaling and growth in breast cancer cells lacking REST. IRS1 overexpression is sufficient to phenocopy the enhanced activation of the signaling hubs AKT and mitogen-activated protein kinase (MAPK) of MCF7 cells lacking REST. Loss of REST renders MCF7 and MDA-MB-231 breast tumor cells dependent on IRS1 activity for colony formation in soft agar. Inhibition of the type 1 insulin-like growth factor receptor (IGF1R) reduces the enhanced signaling, growth, and migration in breast tumor cells that occur upon REST loss. We show that loss of REST induces a pathogenic program that works through the IGF1R/IRS1 pathway. We recently identified a novel subset of breast cancers that lack the repressor element 1 (RE-1) silencing transcription factor (REST). Loss of REST occurs in ϳ20% of all human breast cancers (termed RESTless), regardless of hormone receptor status (1). Patients with tumors lacking REST function have decreased disease-free survival and an aggressive disease course compared to those of patients with tumors expressing REST (RESTfl) (1). MCF7 cells lacking REST give rise to significantly more tumors in mouse xenografts and correlate with enhanced soft-agar colony formation in vitro, illustrating that REST acts as a bona fide tumor suppressor for breast epithelia (2).REST represses ϳ2,000 target genes by recruiting chromatinmodifying complexes to RE-1 sites in the regulatory region of its target genes (3-10). REST was first identified as a breast tumor suppressor in a screen for factors whose loss conferred anchorageindependent growth in human mammary epithelial cells (11). Knockdown of REST in MCF7 cells increases clonogenicity, enhances cell proliferation, and suppresses apoptosis (2, 12). However, the mechanisms by which REST regulates these oncogenic pathways are only partially understood (1, 2).An understanding of the mechanisms that promote tumor growth and metastasis is key to developing effective treatment programs for patients. We previously developed a biomarker assay that identifies a subgroup of aggressive tumors based on immunohistological staining and a gene signature comprised of 24 REST target genes (1). However, there is no targeted therapeutic approach to treat this set of tumors. To identify key effectors ...

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Section: Discussionmentioning

confidence: 48%

“…3B and C). Indeed, the ChIP signal at IRS1 was similar to that found at BDNF, a well-characterized REST target gene (2,39).…”

Section: Irs1 Protein Is Upregulated In Restless Tumorsmentioning

confidence: 60%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Chromatin immunoprecipitation (ChIP) was conducted as previously described (2,8). ChIP was conducted by using 2 g of REST antibody (Millipore) or rabbit IgG (Sigma) with 300 g of protein.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Type 1 Insulin-Like Growth Factor Receptor/Insulin Receptor Substrate 1 Signaling Confers Pathogenic Activity on Breast Tumor Cells Lacking REST

Meyer

Albaugh

Schoenike

et al. 2015

Molecular and Cellular Biology

Self Cite

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LIN28A-stabilized FBXL19-AS1 promotes breast cancer migration, invasion and EMT by regulating WDR66

Zhang

Xiao

Zhou

et al. 2019

In Vitro Cell.Dev.Biol.-Animal

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Diagnostic significance of alternative splice variants of REST and DOPEY1 in the peripheral blood of patients with breast cancer

et al. 2014

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Changes in alternative splicing have been linked to cancer development. We hypothesized that changes occurring in tumor tissue can also be detected in the peripheral blood of cancer patients leading to discovery of blood biomarkers of breast cancer. Alternative splicing profiles of 94 genes were examined in cancerous breast tissue. Discriminating splice variants were analyzed in the peripheral blood of early stage (BCI/II) (stage I-II; n = 26), neoadjuvant receiving locally advanced breast cancer patients (LABC) (stage IIb-IIIa, b; n = 10) and healthy volunteers (n = 26) using qRT-PCR analysis. Changes in marker expression during neoadjuvant therapy were analyzed at 15 timepoints. High expression of REST-N50, the alternatively spliced variant of REST, was detected in the blood of LABC patients but not in BCI/II and healthy controls (p = 0.0032 and p = 0.0029, respectively). Expression levels of DOPEY1v2, the alternative splice variant of DOPEY1, in the blood could differentiate cancer from healthy controls (p = 0.024) and discriminate between patient groups (BCI/II vs LABC, p = 0.002). Positive response to neoadjuvant therapy of REST-N50-positive LABC patients correlated with a decrease in REST-N50 levels (p < 0.0001). Assessment of REST-N50 and DOPEY1v2 may prove useful in diagnostic blood tests of breast cancer. REST-N50 shows a high potential as a blood biomarker for evaluating the effectiveness of therapy in the neoadjuvant setting.

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Induction of the RNA Regulator LIN28A Is Required for the Growth and Pathogenesis of RESTless Breast Tumors

Cited by 13 publications

References 37 publications

Type 1 Insulin-Like Growth Factor Receptor/Insulin Receptor Substrate 1 Signaling Confers Pathogenic Activity on Breast Tumor Cells Lacking REST

Type 1 Insulin-Like Growth Factor Receptor/Insulin Receptor Substrate 1 Signaling Confers Pathogenic Activity on Breast Tumor Cells Lacking REST

LIN28A-stabilized FBXL19-AS1 promotes breast cancer migration, invasion and EMT by regulating WDR66

Diagnostic significance of alternative splice variants of REST and DOPEY1 in the peripheral blood of patients with breast cancer

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