IL-6 is associated to IGF-1Ec upregulation and Ec peptide secretion, from prostate tumors.

BACKGROUND: Ec peptide (PEc), resulting from the proteolytic cleavage of the IGF-1Ec isoform, is involved in prostate cancer progression and metastasis, whereas in muscle tissue, it is associated with the mobilization of satellite cells prior to repair. Our aim is to determine the physiological conditions associated to the IGF-1Ec upregulation and PEc secretion in prostate tumors, as well as, the effect of tumor PEc on tumor repair. METHODS: IGF-1 (mature and isoforms) expression was examined by qRT-PCR, both in prostate cancer cells co-incubated with cells of the immune response (IR) and in tumors. PEc secretion was determined by Multiple Reaction Monitoring. The effect of PEc, on mesenchymal stem cell (MSC) mobilization and repair, was examined using migration and invasion assays, FISH and immunohistochemistry (IHC). The JAK/STAT signaling pathway leading to the IGF1-Ec expression was examined by western blot analysis. Determination of the expression and localization of IL-6 and IGF-1Ec in prostate tumors was examined by qRT-PCR and by IHC. RESULTS: We documented that IL-6 secreted by IR cells activates the JAK2 and STAT3 pathway through IL-6 receptor in cancer cells, leading to the IGF-1Ec upregulation and PEc secretion, as well as to the IL-6 expression and secretion. The resulting PEc, apart from its oncogenic role, also mobilizes MSCs towards the tumor, thus promoting tumor repair. CONCLUSIONS: IL-6 leads to the PEc secretion from prostate cancer cells. Apart from its oncogenic role, PEc is also involved in the mobilization of MSCs resulting in tumor repair.

Increased expression of IGF-1Ec with increasing colonic polyp dysplasia and colorectal cancer.

PURPOSE: IGF-1Ec is an isoform of Insulin-like growth factor 1 (IGF-1) and has recently been identified to be overexpressed in cancers including prostate and neuroendocrine tumours. The aim of this paper is to investigate the expression of IGF-1Ec in colorectal cancer and polyps compared to normal colon tissues and its association with recurrent disease using semi-quantitative immunohistochemistry. METHODS: Immunohistochemistry for IGF-1Ec expression was performed for colorectal cancer, colorectal polyps and normal colonic tissues. The quantification of IGF-1Ec expression was performed with the use of Image J software and the IHC profiler plugin. Following ethics approval from the National Research Ethics Service (Reference 11/LO/1521), clinical information including recurrent disease on follow-up was collected for patients with colorectal cancer. RESULTS: Immunohistochemistry was performed in 16 patients with colorectal cancer and 11 patients with colonic polyps and compared to normal colon tissues and prostate adenocarcinoma (positive control) tissues. Significantly increased expression of IGF-1Ec was demonstrated in colorectal cancer (p < 0.001) and colorectal polyps (p < 0.05) compared to normal colonic tissues. Colonic adenomas with high-grade dysplasia had significantly higher expression of IGF-1Ec compared to low-grade dysplastic adenomas (p < 0.001). Colorectal cancers without lymph node metastases at the time of presentation had significantly higher IGF-1Ec expression compared to lymph node-positive disease (p < 0.05). No correlation with recurrent disease was identified with IGF-1Ec expression. CONCLUSION: IGF-1Ec is significantly overexpressed in colorectal cancer and polyps compared to normal colon tissues offering a potential target to improve colonoscopic identification of colorectal polyps and cancer and intraoperative identification of colorectal tumours.

The structure-function relationships of insulin-like growth factor 1 Ec in C2C12 cells.

Insulin-like growth factor 1 (IGF1) is a crucial growth factor, that regulates skeletal muscles development during cell growth and repair. Recently, its alternative splicing variant, named IGF1Ec, also named mechano-growth factor (MGF), has gained attentions as a new damage repair factor. However, the structure-function relationships of IGF1Ec have not been fully clarified due to contradictory reports. In this study, we systematically investigated physiologic responses of C2C12 muscle cells to IGF1Ec, IGF1 and MGF E peptide. Our data indicate that while the N-terminal sequence of IGF1Ec, which is homolog in part with IGF1, promotes proliferation; the C-terminal sequence of IGF1Ec, which is identical to MGF E, promotes differentiation and migration of C2C12 cells. Our results suggest that MGF E cannot completely replace all the functions of IGF1Ec on muscle repair and regeneration, and elucidate the relationships between structure and function of IGF1Ec.

The COOH-terminus of the IGF-1Ec Isoform Enhances the Proliferation and Migration of Human MCF-7 Breast Cancer Cells.

BACKGROUND/AIM: The insulin-like growth factor-1 (IGF-1) signaling is well implicated in cancer biology, however the potential roles of the distinct IGF-1 isoforms in human malignancies are largely unknown. Recently, the carboxyl-terminal of the IGF-1Ec variant (hEc; 24aa) has been associated with osteosarcoma and prostate cancer. Herein, we investigated the potential role of hEc in breast cancer. MATERIALS AND METHODS: Synthetic hEc peptide was administrated to MCF-7 and MDA-MB-231 breast cancer cells. In addition MCF-7 cells were engineered to overexpress hEc. The proliferation and migratory capacities in response to hEc were analyzed using MTT, trypan blue and wound healing/scratch assays, while the activation of the ERK/AKT signaling pathways were investigated using phospho western blotting. RESULTS: We found that exogenous administration of hEc stimulated the proliferation of estrogen-responsive MCF-7, but not that of hormone-resistant MDA-MB-231 cells. In addition, MCF-7 cells stably-overexpressing hEc acquired an increased proliferation rate and migratory capacity, as well as, enhanced ERK1/2 phosphorylation, compared to mock and wild-type cells. CONCLUSION: hEc stimulates the proliferation and migration of MCF-7 breast cancer cells and enhances the intracellular ERK1/2 signaling.

Identification of the IGF-1 processing product human Ec/rodent Eb peptide in various tissues: Evidence for its differential regulation after exercise-induced muscle damage in humans.

OBJECTIVE: Insulin-like growth factor-1 (IGF-1) is a pleiotropic factor expressed in various tissues and plays a critical role in skeletal muscle physiology. Alternative splicing of the IGF-1 gene gives rise to different precursor polypeptides (isoforms) which could undergo post-translational cleavage, generating the common mature IGF-1 peptide and different carboxyl terminal extension (E-) peptides, with the fate of the latter being, so far, unknown. The objective if this study was to identify the IGF-1Ec forms or processing product(s), other than mature IGF-1, generated in different human and rodent tissues and particularly in human skeletal muscle after exercise-induced damage. DESIGN: Protein lysates from a wide range of human and rodent tissues were immunoblotted with a rabbit anti-human Ec polyclonal antibody raised against the last 24 amino acids of the C-terminal of the Ec peptide. This antibody can recognize the Ec peptide, both as part of IGF-1Ec and alone, and also the corresponding rodent forms, due to the high homology that the human Ec shares with the rodent Eb. RESULTS: We were able to confirm, for the first time, that the human Ec peptide and its rodent homologous Eb peptide are produced simultaneously with their precursor protein (pro-IGF-1Ec/Eb) in vivo, in a wide range of tissues (e.g. muscle, liver, heart). Proprotein convertase furin digestion of human muscle and liver protein lysates confirmed that the higher molecular form, pro-IGF-1Ec, can be cleaved to produce the free Ec peptide. Furthermore, initial evidence is provided that Ec peptide is differentially regulated during the process of muscle regeneration after exercise-induced damage in humans. CONCLUSIONS: The findings of this study possibly imply that the post-translational modification of the IGF-1Ec pro-peptide may regulate the bioavailability and activity of the processing product(s).

The role of the IGF-1 Ec in myoskeletal system and osteosarcoma pathophysiology.

Growth hormone (GH) regulated mainly liver-produced insulin-like growth factor 1 (IGF-1) is a key molecule in embryonic & post embryonic development that is also involved in cancer biology. Herein we review new insights of the role of igf-1 gene products and of the IGF-1Ec isoform in muscle and bone development/repair and its role in osteosarcoma pathophysiology, underlying the possible role of the Ec peptide as a future therapeutic target.

IGF-IEc expression is associated with advanced clinical and pathological stage of prostate cancer.

BACKGROUND: Recent evidence suggests a role for the insulin-like growth factor-1Ec (IGF-IEc) transcript variant in cancer biology. The aim of the present study was to investigate whether IGF-IEc expression is associated with prostate cancer stage. MATERIALS AND METHODS: Formalin-fixed and paraffin-embedded prostate cancer surgical specimens from 83 patients were assessed by immunohistochemistry for IGF-IEc expression. RESULTS: Normal prostate epithelium was negative or demonstrated mild IGF-IEc cytoplasmic expression whereas prostate cancer exhibited mild to strong cytoplasmic immunoexpression. The mean IGF-1Ec expression, was significantly lower (p=0.004) in localized (stage ≤ IIb) prostate cancer, compared to locally advanced tumors (stage ≥ III). Only one out of 83 (1.2%) prostate cancer samples was completely negative for IGF-IEc. A weak-positive correlation was also observed between IGF-IEc expression levels and Gleason score (r=0.247; p=0.024). CONCLUSION: The present data demonstrate that the expression of IGF-IEc is positively-associated with more advanced stage and higher Gleason score of prostate carcinomas.