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Ghrelin is a novel gastrointestinal hormone produced by rat and human gastric X-like neuroendocrine cells, which strongly stimulates GH secretion and influences energy balance, gastric motility, and acid secretion. Ghrelin is expressed in pituitary and gastrointestinal endocrine tumors. It binds to the GH secretagogue receptor (GHS-R), which is present in a wide variety of central and peripheral human tissues. The aim of the present study was 2-fold: 1) to determine, by immunohistochemistry and mRNA analysis, whether pancreatic islet cells produce ghrelin and express GHS-R; and 2) to investigate ghrelin and GHS-R expression in pancreatic endocrine tumors. Seven cases of nonneoplastic pancreatic tissue and 28 endocrine tumors were studied. In pancreatic islets, ghrelin immunoreactivity was present in all cases and confined to beta-cells. Eleven of the 28 (39%) endocrine tumors were immunoreactive for ghrelin. In situ hybridization and RT-PCR confirmed the immunohistochemical data for both tumors and islets but also revealed ghrelin mRNA in 8 and 11 additional tumors, respectively. GHS-R 1a and 1b mRNAs were present in 7 of 28 and 14 of 28 tumors, respectively, studied by RT-PCR. These findings demonstrate that ghrelin production is not restricted to the stomach but is also present in pancreatic beta-cells and endocrine tumors (regardless of the type of pancreatic hormone produced, if any). Expression of GHS-R in some of the endocrine tumors studied indicates that autocrine/paracrine circuits may be active in neoplastic conditions.

Background: Ghrelin, a natural growth hormone secretagogue (GHS), has been identified in prostate carcinoma cell lines. Objectives: To investigate the presence of ghrelin and its receptors in human prostate tumours and in DU-145, PC-3 and LNCaP prostate carcinoma cell lines, and to assesss the effects of ghrelin and its more abundant circulating form, des-octanoyl ghrelin, on cell proliferation. Methods: Ghrelin and types 1a and 1b GHS receptor (GHS-R) were determined at the mRNA and protein levels by RT-PCR, in situ hybridization, immunohistochemistry and enzyme immunoassay in tissues, cell lines and culture medium. Ghrelin binding was determined by radioreceptor assay. The effects on cell proliferation were evaluated by growth curves. Results: Ghrelin mRNA was found in prostatic carcinomas and benign hyperplasias, but immunohistochemistry was negative. GHS-R1a and 1b mRNAs were absent from carcinomas, but GHSR1b mRNA was present in 50% of hyperplasias. Ghrelin peptide and mRNA were present in PC-3 cells exclusively, whereas GHS-R1a and 1b mRNAs were expressed in DU-145 cells only. Specific [

BackgroundInvasive micropapillary carcinoma (IMPC) of the breast is a distinct and aggressive variant of luminal type B breast cancer that does not respond to neoadjuvant chemotherapy. It is characterized by small pseudopapillary clusters of cancer cells with inverted cell polarity. To investigate whether hypoxia-inducible factor-1 (HIF-1) activation may be related to the drug resistance described in this tumor, we used MCF7 cancer cells cultured as 3-D spheroids, which morphologically simulate IMPC cell clusters.MethodsHIF-1 activation was measured by EMSA and ELISA in MCF7 3-D spheroids and MCF7 monolayers. Binding of HIF-1α to MDR-1 gene promoter and modulation of P-glycoprotein (Pgp) expression was evaluated by ChIP assay and FACS analysis, respectively. Intracellular doxorubicin retention was measured by spectrofluorimetric assay and drug cytotoxicity by annexin V-FITC measurement and caspase activity assay.ResultsIn MCF7 3-D spheroids HIF-1 was activated and recruited to participate to the transcriptional activity of MDR-1 gene, coding for Pgp. In addition, Pgp expression on the surface of cells obtained from 3-D spheroids was increased. MCF7 3-D spheroids accumulate less doxorubicin and are less sensitive to its cytotoxic effects than MCF7 cells cultured as monolayer. Finally, HIF-1α inhibition either by incubating cells with 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (a widely used HIF-1α inhibitor) or by transfecting cells with specific siRNA for HIF-1α significantly decreased the expression of Pgp on the surface of cells and increased the intracellular doxorubicin accumulation in MCF7 3-D spheroids.ConclusionsMCF7 breast cancer cells cultured as 3-D spheroids are resistant to doxorubicin and this resistance is associated with an increased Pgp expression in the plasma membrane via activation of HIF-1. The same mechanism may be suggested for IMPC drug resistance.

Somatostatin receptors (SSTRs) have been extensively mapped in human tumors by means of autoradiography, reverse-transcriptase polymerase chain reaction (RT-PCR), in situ hybridization (ISH) and immunohistochemistry (IHC). We analyzed the SSTR type 1-5 expression by means of RT-PCR and/or IHC in a series of 81 functioning and non-functioning gastroenteropancreatic (GEP) endocrine tumors and related normal tissues. Moreover, we compared the results with clinical, pathological and hormonal features. Forty-six cases (13 intestinal and 33 pancreatic) were studied for SSTR 1-5 expression using RT-PCR, IHC with antibodies to SSTR types 2, 3, 5 and ISH for SSTR2 mRNA. The vast majority of tumors expressed SSTR types 1, 2, 3 and 5, while SSTR4 was detected in a small minority. Due to the good correlation between RT-PCR and IHC data on SSTR types 2, 3, and 5, thirty-five additional GEP endocrine tumors were studied with IHC alone. Pancreatic insulinomas had an heterogeneous SSTR expression, while 100% of somatostatinomas expressed SSTR5 and 100% gastrinomas and glucagonomas expressed SSTR2. Pre-operative biopsy material showed an overlapping immunoreactivity with that of surgical specimens, suggesting that the SSTR status can be detected in the diagnostic work-up. It is concluded that SSTRs 1-5 are heterogeneously expressed in GEP endocrine tumors and that IHC is a reliable tool to detect SSTR types 2, 3 and 5 in surgical and biopsy specimens.