Differential expression of new splice variants of the neurotensin receptor 1 gene in human prostate cancer cell lines

Article (PDF Available)inPeptides 31(2):242-7 · December 2009with35 Reads
DOI: 10.1016/j.peptides.2009.12.007 · Source: PubMed
Neurotensin is a neuroendocrine peptide acting as a trophic factor in a variety of cells in vivo but it can also function as an autocrine growth factor in human prostate cancer cells in vitro. In addition, the high-affinity G protein-coupled NT receptor (NTS1) is overexpressed in prostate cancer cell lines. Increasing evidence argues for a direct correlation between specific alternative splice variants and cancer. We detected four splice variants of the NTS1 receptor in human prostate cancer cell lines. These isoforms include one or more exons skipping as well as an alternative 5' splice donor site and are expressed in the late-stage androgen independent prostate cancer cell lines PC3 and DU145, but not in the early-stage androgen-sensitive LNCaP or in normal prostate tissue, which only express the normal transcript. This result shows new splice variants of NTS1 for the first time. The differential expression observed among prostate cancer cell lines and normal prostate tissue opens the interesting possibility of a new role of NT/NTS1 pathway in prostate cancer.

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Available from: Ricardo Reyes
    • "These mRNA would encode two truncated forms of 336 amino acids and 280 aminoacids, respectively, which coexist with the native protein (418 aminoacids). Functional studies performed on truncated isoforms of G protein-coupled receptor structurally similar to those described here found that they are able to bind agonists, can couple to intracellular signaling pathways, and can associate both with themselves and with the native receptor to form homo-and heterodimer species, respectively [17]. We are currently conducting experiments to determine the function of the different NTSR1 isoforms. "
    Dataset · Sep 2013 · BMC Cancer
    • "Similarly, relative strong inductions in the in vivo setting were observed for NTSR1 in LNCaP and PC-3 cells (Fig. 3E andTable III). The NTSR1 receptor is over-expressed in numerous types of solid tumors and NTSR1 receptor binding to neurotensin (NT) has been reported to increase proliferation of several types of cancer cells, including prostate cancer cells [19,34]. Further, NT functions via autocrine, paracrine, and endocrine actions in prostate cancer tissues [35,36] . "
    [Show abstract] [Hide abstract] ABSTRACT: Membrane receptors are frequent targets of cancer therapeutic and imaging agents. However, promising in vitro results often do not translate to in vivo clinical applications. To better understand this obstacle, we measured the expression differences in receptor signatures among several human prostate cancer cell lines and xenografts as a function of tumorigenicity. Messenger RNA and protein expression levels for integrin α(ν) β(3), neurotensin receptor 1 (NTSR1), prostate specific membrane antigen (PSMA), and prostate stem cell antigen (PSCA) were measured in LNCaP, C4-2, and PC-3 human prostate cancer cell lines and in murine xenografts using quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and immunohistochemistry. Stable expression patterns were observed for integrin α(ν) and PSMA in all cells and corresponding xenografts. Integrin β(3) mRNA expression was greatly reduced in C4-2 xenografts and greatly elevated in PC-3 xenografts compared with the corresponding cultured cells. NTSR1 mRNA expression was greatly elevated in LNCaP and PC-3 xenografts. PSCA mRNA expression was elevated in C4-2 xenografts when compared with C4-2 cells cultured in vitro. Furthermore, at the protein level, PSCA was re-expressed in all xenografts compared with cells in culture. The regulation of mRNA and protein expression of the cell-surface target proteins α(ν) β(3), NTSR1, PSMA, and PSCA, in prostate cancer cells with different tumorigenic potential, was influenced by factors of the microenvironment, differing between cell cultures and murine xenotransplants. Integrin α(ν) β(3), NTRS1 and PSCA mRNA expression increased with tumorigenic potential, but mRNA expression levels for these proteins do not translate directly to equivalent expression levels of membrane bound protein.
    Full-text · Article · Apr 2012
    • "Experiments using a specific antagonist or knockdown of the NTSR1 using short interfering RNA suggest that NTSR1 mediates the effects of neurotensin on cancer cells, although NTSR3/ sortilin, which is often coexpressed in cancer cells, may modulate NTSR1 signalling [14,16]. Splice variants of the NTSR1 were recently detected in prostate cancer cell lines, however, no functional studies of these have been conducted [17]. Recent data have suggested that the NTSR1 receptor gene may be a downstream target of the extracellular signal-regulated kinase (ERK) and Tcf/b-catenin pathways [18,19] , and increased expression of NTSR1 during progression of colon tumorigenesis has been reported [20,21]. "
    [Show abstract] [Hide abstract] ABSTRACT: Neurotensin has been found to promote colon carcinogenesis in rats and mice, and proliferation of human colon carcinoma cell lines, but the mechanisms involved are not clear. We have examined signalling pathways activated by neurotensin in colorectal and pancreatic carcinoma cells. Colon carcinoma cell lines HCT116 and HT29 and pancreatic adenocarcinoma cell line Panc-1 were cultured and stimulated with neurotensin or epidermal growth factor (EGF). DNA synthesis was determined by incorporation of radiolabelled thymidine into DNA. Levels and phosphorylation of proteins in signalling pathways were assessed by Western blotting. Neurotensin stimulated the phosphorylation of both extracellular signal-regulated kinase (ERK) and Akt in all three cell lines, but apparently did so through different pathways. In Panc-1 cells, neurotensin-induced phosphorylation of ERK, but not Akt, was dependent on protein kinase C (PKC), whereas an inhibitor of the β-isoform of phosphoinositide 3-kinase (PI3K), TGX221, abolished neurotensin-induced Akt phosphorylation in these cells, and there was no evidence of EGF receptor (EGFR) transactivation. In HT29 cells, in contrast, the EGFR tyrosine kinase inhibitor gefitinib blocked neurotensin-stimulated phosphorylation of both ERK and Akt, indicating transactivation of EGFR, independently of PKC. In HCT116 cells, neurotensin induced both a PKC-dependent phosphorylation of ERK and a metalloproteinase-mediated transactivation of EGFR that was associated with a gefitinib-sensitive phosphorylation of the downstream adaptor protein Shc. The activation of Akt was also inhibited by gefitinib, but only partly, suggesting a mechanism in addition to EGFR transactivation. Inhibition of PKC blocked neurotensin-induced DNA synthesis in HCT116 cells. While acting predominantly through PKC in Panc-1 cells and via EGFR transactivation in HT29 cells, neurotensin used both these pathways in HCT116 cells. In these cells, neurotensin-induced activation of ERK and stimulation of DNA synthesis was PKC-dependent, whereas activation of the PI3K/Akt pathway was mediated by stimulation of metalloproteinases and subsequent transactivation of the EGFR. Thus, the data show that the signalling mechanisms mediating the effects of neurotensin involve multiple pathways and are cell-dependent.
    Full-text · Article · Oct 2011
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