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Integrin ?3?1 controls mRNA splicing that determines Cox-2 mRNA stability in breast cancer cells.

ABSTRACT: It is unknown how cues from the tumor microenvironment can regulate post-transcriptional mechanisms, such as alternative splicing, that control genes that drive malignant growth. The induction of cyclooxygenase 2 (Cox-2) by integrin ?3?1 in breast cancer cells can promote tumor progression. We have used RNAi to suppress ?3?1 in human MDA-MB-231 breast cancer cells and then investigated changes in global gene expression. Numerous mRNAs, including Cox-2, show altered expression and/or alternative exon usage (AEU) in ?3?1-deficient cells. AEU included patterns predicted to render an mRNA susceptible to degradation, such as 3'-UTR variations or retention of elements that target an mRNA for nonsense-mediated decay (NMD). PCR-based analysis of ?3?1-deficient cells confirmed changes in Cox-2 mRNA that might target it for NMD, including retention of an intron that harbors premature termination codons and changes within the 3'-UTR. Moreover, Cox-2 mRNA has reduced stability in ?3?1-deficient cells, which is partially reversed by knockdown of the essential NMD factor UPF1. Our study identifies ?3?1-mediated AEU as a novel paradigm of integrin-dependent gene regulation that has potential for exploitation as a therapeutic target.

SUBMITTER: Subbaram S

PROVIDER: S-EPMC3953813 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Integrin α3β1 controls mRNA splicing that determines Cox-2 mRNA stability in breast cancer cells.

Subbaram Sita S Lyons Scott P SP Svenson Kimberly B KB Hammond Sean L SL McCabe Lorena G LG Chittur Sridar V SV DiPersio C Michael CM

Journal of cell science 20140116 Pt 6

It is unknown how cues from the tumor microenvironment can regulate post-transcriptional mechanisms, such as alternative splicing, that control genes that drive malignant growth. The induction of cyclooxygenase 2 (Cox-2) by integrin α3β1 in breast cancer cells can promote tumor progression. We have used RNAi to suppress α3β1 in human MDA-MB-231 breast cancer cells and then investigated changes in global gene expression. Numerous mRNAs, including Cox-2, show altered expression and/or alternative ...[more]

PMID: 24434582

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Project description:BackgroundHER2-driven breast cancer is correlated with poor prognosis, especially during its later stages. Numerous studies have shown the importance of the integrin α3β1 during the initiation and progression of breast cancer; however, its role in this disease is complex and often opposite during different stages and in different types of tumors. In this study, we aim to elucidate the role of integrin α3β1 in a genetically engineered mouse model of HER2-driven mammary tumorigenesis.MethodsTo investigate the role of α3β1 in HER2-driven tumorigenesis in vivo, we generated a HER2-driven MMTV-cNeu mouse model of mammary tumorigenesis with targeted deletion of Itga3 (Itga3 KO mice). We have further used several established triple-negative and HER2-overexpressing human mammary carcinoma cell lines and generated ITGA3-knockout cells to investigate the role of α3β1 in vitro. Invasion of cells was assessed using Matrigel- and Matrigel/collagen I-coated Transwell assays under static or interstitial fluid flow conditions. The role of α3β1 in initial adhesion to laminin and collagen was assessed using adhesion assays and immunofluorescence.ResultsTumor onset in mice was independent of the presence of α3β1. In contrast, the depletion of α3β1 reduced the survival of mice and increased tumor growth and vascularization. Furthermore, Itga3 KO mice were significantly more likely to develop lung metastases and had an increased metastatic burden compared to WT mice. In vitro, the deletion of ITGA3 caused a significant increase in the cellular invasion of HER2-overexpressing SKBR3, AU565, and BT474 cells, but not of triple-negative MDA-MB-231. This invasion suppressing function of α3β1 in HER2-driven cells depended on the composition of the extracellular matrix and the interstitial fluid flow.ConclusionDownregulation of α3β1 in a HER2-driven mouse model and in HER2-overexpressing human mammary carcinoma cells promotes progression and invasiveness of tumors. The invasion-suppressive role of α3β1 was not observed in triple-negative mammary carcinoma cells, illustrating the tumor type-specific and complex function of α3β1 in breast cancer.

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Integrin ?3?1 controls mRNA splicing that determines Cox-2 mRNA stability in breast cancer cells.

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Integrin α3β1 controls mRNA splicing that determines Cox-2 mRNA stability in breast cancer cells.

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