Moran-Jones K, Grindlay J, Jones M et al.hnRNP A2 regulates alternative mRNA splicing of TP53INP2 to control invasive cell migration. Cancer Res 69:9219-9227

Beatson Institute for Cancer Research, Glasgow, United Kingdom.
Cancer Research (Impact Factor: 9.33). 11/2009; 69(24):9219-27. DOI: 10.1158/0008-5472.CAN-09-1852
Source: PubMed


Largely owing to widespread deployment of microarray analysis, many of the transcriptional events associated with invasive cell migration are becoming clear. However, the transcriptional drives to invasive migration are likely modified by alternative splicing of pre-mRNAs to produce functionally distinct patterns of protein expression. Heterogenous nuclear ribonucleoprotein (hnRNP A2) is a known regulator of alternative splicing that is upregulated in a number of invasive cancer types. Here, we report that although siRNA of hnRNP A2 had little influence on the ability of cells to migrate on plastic surfaces, the splicing regulator was clearly required for cells to move effectively on three-dimensional matrices and to invade into plugs of extracellular matrix proteins. We used exon-tiling microarrays to determine that hnRNP A2 controlled approximately six individual splicing events in a three-dimensional matrix-dependent fashion, one of which influenced invasive migration. Here, we show that alternative splicing of an exon in the 5' untranslated region of a gene termed TP53INP2 is a key event downstream of hnRNP A2 that is necessary for cells to invade the extracellular matrix. Furthermore, we report that the consequences of altered TP53INP2 splicing on invasion are likely mediated via alterations in Golgi complex integrity during migration on three-dimensional matrices.

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    • "Furthermore, in a PCa cell line (LNCaP) the drug Genistein, normally used to treat PCa, was shown to up-regulate TP53INP2, among other genes 62. Moreover, it has also been proposed that the occurrence of a specific splice variant of TP53INP2 might be a necessary event in order for malignant cells to invade the ECM 63. Finally, in 2007 a patent was filed that described using measurements of TP53INP2, among other targets, as part of a multivariate signature to monitor the progression of PCa 64. "
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    ABSTRACT: Globally, Prostate cancer (PCa) is the most frequently occurring non-cutaneous cancer, and is the second highest cause of cancer mortality in men. Serum prostate specific antigen (PSA) has been the standard in PCa screening since its approval by the American Food & Drug Administration (FDA) in 1994. Currently, PSA is used as an indicator for PCa - patients with a serum PSA level above 4ng/mL will often undergo prostate biopsy to confirm cancer. Unfortunately fewer than ~30% of these men will biopsy positive for cancer, meaning that the majority of men undergo invasive biopsy with little benefit. Despite PSA's notoriously poor specificity (33%), there is still a significant lack of credible alternatives. Therefore an ideal biomarker that can specifically detect PCa at an early stage is urgently required. The aim of this study was to investigate the potential of using deregulation of urinary proteins in order to detect Prostate Cancer (PCa) among Benign Prostatic Hyperplasia (BPH). To identify the protein signatures specific for PCa, protein expression profiling of 8 PCa patients, 12 BPH patients and 10 healthy males was carried out using LC-MS/MS. This was followed by validating relative expression levels of proteins present in urine among all the patients using quantitative real time-PCR. This was followed by validating relative expression levels of proteins present in urine among all the patients using quantitative real time-PCR. This approach revealed that significant the down-regulation of Fibronectin and TP53INP2 was a characteristic event among PCa patients. Fibronectin mRNA down-regulation, was identified as offering improved specificity (50%) over PSA, albeit with a slightly lower although still acceptable sensitivity (75%) for detecting PCa. As for TP53INP2 on the other hand, its down-regulation was moderately sensitive (75%), identifying many patients with PCa, but was entirely non-specific (7%), designating many of the benign samples as malignant and being unable to accurately identify more than one negative.
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    • "Despite the fact that hnRNP D suppresses expression of many cell cycle regulatory factors by promoting degradation of their mRNAs (57), overexpression of hnRNP D has also been shown to prevent cellular senescence (53) and to lead to tumorigenesis (72). Expression of hnRNP A2/B1 protein is deregulated and overexpressed in many different cancer forms and has been shown to drive tumorigenesis (73) and control invasive cell migration (74) and epithelial-mesenchymal transition (75). This is interesting as high levels of hnRNP A2/B1 enhances splicing of the HPV-16 early pre-mRNAs to generate E7 mRNAs and inhibits HPV-16 late mRNAs splicing, thereby creating the HPV-16 gene expression profile seen in HPV-16 high grade lesions or cancers in which the HPV-16 genome has not integrated into the host cell chromosomes. "
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    • "The ability of hnRNP A1 to control hnRNP A2/B1 expression appears to be relevant for the biology of the cell because increased expression of hnRNP A1 in cancer cells has been shown to correlate with downregulation of hnRNP A2/B1 (42). Several observations indicate a prominent role of hnRNP A2/B1 in the alternative splicing of genes implicated in cellular migration and invasion (13,30,63). Indeed, upregulation of hnRNP A2/B1 correlates with poor prognosis in patients with glioma and its overexpression is sufficient to confer to mouse fibroblasts the ability to form high-grade sarcomas in nude mice (13). "
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