Ricardo Rodrigues Giorgi

Thalidomide treatment down-regulates SDF-1α and CXCR4 expression in multiple myeloma patients

The chemokine stromal-derived factor-1alpha (SDF-1alpha) and its receptor CXCR4 are critically involved in directional migration and homing of plasma cells in multiple myeloma. Here, we show that the expression of SDF-1alpha and CXCR4 was significantly down-regulated in patients treated with thalidomide (n=10) as compared to newly diagnosed MM patients (n=31) and MM patients treated with other drugs (n=38). SDF-1 alpha and CXCR4 expression was also significantly decreased in a RPMI 8226 cell line treated with 10 and 20micromol/L of thalidomide. Our findings indicate that thalidomide therapy induces down-regulation of CXCR4 and its ligand SDF-1alpha in multiple myeloma.

HOXB7 mRNA is overexpressed in pancreatic ductal adenocarcinomas and its knockdown induces cell cycle arrest and apoptosis

BackgroundHuman homeobox genes encode nuclear proteins that act as transcription factors involved in the control of differentiation and proliferation. Currently, the role of these genes in development and tumor progression has been extensively studied. Recently, increased expression of HOXB7 homeobox gene (HOXB7) in pancreatic ductal adenocarcinomas (PDAC) was shown to correlate with an invasive phenotype, lymph node metastasis and worse survival outcomes, but no influence on cell proliferation or viability was detected. In the present study, the effects arising from the knockdown of HOXB7 in PDAC cell lines was investigated.MethodsReal time quantitative PCR (qRT-PCR) (Taqman) was employed to assess HOXB7 mRNA expression in 29 PDAC, 6 metastatic tissues, 24 peritumoral tissues and two PDAC cell lines. siRNA was used to knockdown HOXB7 mRNA in the cell lines and its consequences on apoptosis rate and cell proliferation were measured by flow cytometry and MTT assay respectively.ResultsOverexpression of HOXB7 mRNA was observed in the tumoral tissues and in the cell lines MIA PaCa-2 and Capan-1. HOXB7 knockdown elicited (1) an increase in the expression of the pro-apoptotic proteins BAX and BAD in both cell lines; (2) a decrease in the expression of the anti-apoptotic protein BCL-2 and in cyclin D1 and an increase in the number of apoptotic cells in the MIA PaCa-2 cell line; (3) accumulation of cell in sub-G1 phase in both cell lines; (4) the modulation of several biological processes, especially in MIA PaCa-2, such as proteasomal ubiquitin-dependent catabolic process and cell cycle.ConclusionThe present study confirms the overexpression of HOXB7 mRNA expression in PDAC and demonstrates that decreasing its protein level by siRNA could significantly increase apoptosis and modulate several biological processes. HOXB7 might be a promising target for future therapies.

Rosiglitazone prevents sirolimus-induced hypomagnesemia, hypokalemia, and downregulation of NKCC2 protein expression

Sirolimus, an antiproliferative immunosuppressant, induces hypomagnesemia and hypokalemia. Rosiglitazone activates renal sodium- and water-reabsorptive pathways. We evaluated whether sirolimus induces renal wasting of magnesium and potassium, attempting to identify the tubule segments in which this occurs. We tested the hypothesis that reduced expression of the cotransporter NKCC2 forms the molecular basis of this effect and evaluated the possible association between increased urinary excretion of magnesium and renal expression of the epithelial Mg2+ channel TRPM6. We then analyzed whether rosiglitazone attenuates these sirolimus-induced tubular effects. Wistar rats were treated for 14 days with sirolimus (3 mg/kg body wt in drinking water), with or without rosiglitazone (92 mg/kg body wt in food). Protein abundance of NKCC2, aquaporin-2 (AQP2), and TRPM6 was assessed using immunoblotting. Sirolimus-treated animals presented no change in glomerular filtration rate, although there were marked decreases in plasma potassium and magnesium. Sirolimus treatment reduced expression of NKCC2, and this was accompanied by greater urinary excretion of sodium, potassium, and magnesium. In sirolimus-treated animals, AQP2 expression was reduced. Expression of TRPM6 was increased, which might represent a direct stimulatory effect of sirolimus or a compensatory response. The finding that rosiglitazone prevented or attenuated all sirolimus-induced renal tubular defects has potential clinical implications.

Expression of Neurotensin and its Receptors in Pituitary Adenomas

The neurotensin (NT) produced in the hypothalamus and in pituitary gonadotrophs and thyrotrophs participates in neuroendocrine regulation. Recently, the involvement of this peptide in normal and neoplastic cell proliferation has been postulated. In the present study, we evaluated the expression of NT and its receptors (NTR1, 2 and 3) in a series of 50 pituitary adenomas [11 growth hormone (GH)‐, eight prolactin (PRL)‐, four adrenocorticotrophic hormone (ACTH)‐ and 27 nonfunctioning adenomas]. NT mRNA expression was significantly higher in functioning compared to nonfunctioning adenomas and with normal pituitary. Nonfunctioning pituitary adenomas showed lower expression of NT mRNA than normal pituitary. In the immunohistochemical study of functioning adenomas, NT was colocalised with GH, PRL and ACTH secreting cells. In nonfunctioning adenomas, the NT immunoreactivity intensity was variable among the samples. NTR3 mRNA expression was observed in all examined samples and was higher in the adenomas, both functioning and nonfunctioning, compared to normal pituitary. By contrast, NTR1 and NTR2 mRNA were not detected in either pituitary adenomas or normal tissue. The higher expression of NTR3, as well as the expression of NT by tumoural corticotrophs, lactotrophs and somatotrophs, which are cells types that do not express this peptide in the normal pituitary, suggests that NT autocrine and/or paracrine stimulation mediated by NTR3 may be a mechanism associated with the tumourigenesis of functioning adenomas.

Association between tumoral GH-releasing peptide receptor type 1a mRNA expression and in vivo response to GH-releasing peptide-6 in ACTH-dependent Cushing's syndrome patients

OBJECTIVE GH secretagogues (GHS) produce exaggerated ACTH and cortisol responses in Cushings disease (CD) patients, attributable to their direct action on GH-releasing peptide receptor type 1a (GHSR-1a). However, there are no studies correlating the in vivo response to GHS and GHSR-1a mRNA expression in ACTH-dependent Cushings syndrome (CS) patients. The aim of this study is to correlate the patterns of ACTH and cortisol response to GH-releasing peptide-6 (GHRP-6) to GHSR-1a expression in ACTH-dependent CS patients. DESIGN Prospective study in a tertiary referral hospital center. Fifteen CD patients and two ectopic ACTH syndrome (EAS) patients were studied. METHODS Tumor fragments were submitted to RNA extraction, and GHSR-1a expression was studied through real-time qPCR and compared with normal tissue samples. The patients were also submitted to desmopressin test and vasopressin receptor type 1B (AVPR1B) mRNA analysis by qPCR. RESULTS GHSR-1a expression was similar in normal pituitary samples and in corticotrophic tumor samples. GHSR-1a expression was higher in patients (CD and EAS) presenting in vivo response to GHRP-6. Higher expression of AVPR1B was observed in the EAS patients responsive to desmopressin, as well as in corticotrophic tumors, as compared with normal pituitary samples, but no correlation between AVPR1B expression and response to desmopressin was observed in the CD patients. CONCLUSIONS Our results revealed a higher expression of GHSR-1a in the ACTH-dependent CS patients responsive to GHRP-6, suggesting an association between receptor gene expression and in vivo response to the secretagogue in both the CD and the EAS patients.

TGF-β1 expression in wound healing is acutely affected by experimental malnutrition and early enteral feeding.

Malnutrition is associated with the delay or failure of healing. We assessed the effect of experimental malnutrition and early enteral feeding with standard diet or diet supplemented with arginine and antioxidants on the levels of mRNA encoding growth factors in acute, open wound healing. Standardised cutaneous dorsal wounds and gastrostomies for enteral feeding were created in malnourished (M, n = 27) and eutrophic control (E, n = 30) Lewis male adult rats. Both M and E rats received isocaloric and isonitrogenous regimens with oral chow and saline (C), standard (S) or supplemented (A) enteral diets. On post‐trauma day 7, mRNA levels of growth factor genes were analysed in wound granulation tissue by reverse transcription polymerase chain reaction (RT‐PCR). M(C) rats had significantly lower transforming growth factor β(TGF‐β1) mRNA levels than E(C) rats (2·58 ± 0·83 versus 3·53 ± 0·57, P < 0·01) and in comparison with M(S) and M(A) rats (4·66 ± 2·49 and 4·61 ± 2·11, respectively; P < 0·05). VEGF and KGF‐7 mRNA levels were lower in M(A) rats than in E(A) rats (0·74 ± 0·16 versus 1·25 ± 0·66; and 1·07 ± 0·45 versus 1·79 ± 0·89, respectively; P≤ 0·04), but did not differ from levels in E(C) and M(C) animals. In experimental open acute wound healing, previous malnutrition decreased local mRNA levels of TGF‐β1 genes, which was minimised by early enteral feeding with standard or supplemented diets.

Short-term specialized enteral diet fails to attenuate malnutrition impairment of experimental open wound acute healing

OBJECTIVE We assessed the effect of enteral refeeding on the morphology, gene expression, and contraction of acute open wounds in previously malnourished rats using two different enteral diets. METHODS Adult male isogenic Lewis rats divided into two groups (eutrophic, n = 30; and previously malnourished, 12-15% body weight loss, n = 27) were subjected to cutaneous dorsal wounds and gastrostomy. Control rats received a standard oral diet (AIN-93M chow) plus enteral saline solution. Subject rats received chow plus a standard enteral diet or an enteral diet enriched with arginine and antioxidants. On post-trauma days 7 and 14, wound granulation tissue samples were collected for morphologic analysis using hematoxylin and eosin and picrosirius stain or immunohistochemistry slides and real-time polymerase chain reaction for collagen I and III gene expression. Wound contraction was also evaluated by comparing wound images from days 0, 7, and 14. RESULTS Malnourished control rats had increased intensity and duration of wound inflammation, impaired increase of fibroblast cells contingent on post-trauma days 7 to 14, decreased expression of collagen III, and less wound contraction compared with eutrophic control rats. A specialized enteral diet did not improve wound healing of malnourished rats but did promote wound contraction at post-trauma day 7 in eutrophic rats. CONCLUSION Short-term enteral refeeding, even with a specialized diet, failed to protect previously wounded malnourished rats from a prolonged inflammatory phase and impaired healing.

Hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) are differentially expressed in GH-secreting adenomas

Pituitary tumors, adenomas in their vast majority, represent around 10–15% of the intracranial neoplasms. Pituitary carcinomas are exceedingly rare. Clinically, these neoplasms cause hormonal dysfunctions, and mass effect symptoms as headache and visual disorders in the case of macroadenomas. Pituitary tumorigenesis is still poorly understood. In order to investigate the expression of cancer-related genes in pituitary tumors, we employed a human cancer cDNA macroarray membrane with 1176 well-characterized human genes related to cancer and tumor biology. We were able to identify several differentially expressed genes, among them hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) which were over expressed in a pool of clinically nonfunctioning pituitary adenomas, compared with a spinal cord metastasis of a nonfunctioning pituitary carcinoma. HGS and GUK1 mRNA expression were chosen to be validated by quantitative RT-qPCR, however, only GUK1 had the differential expression confirmed between the adenomas and the metastasis of a pituitary carcinoma. We have also investigated HGS and GUK1 mRNA expressions in a series of 46 pituitary adenomas (18 nonfunctioning, 12 GH-secreting, nine PRL-secreting, and seven ACTH-secreting adenomas). HGS and GUK1 were significantly over expressed in GH-secreting adenomas, compared with ACTH-secreting adenomas and nonfunctioning tumors, and with PRL-secreting adenomas, respectively. We have shown that these genes, involved in tumorigenesis in other tissues, are as well over expressed in the pituitary tumors, however, their role in the oncogenesis of these tumors need to be further investigated.

Expression of CRABP1, GRP , and RERG mRNA in clinically non-functioning and functioning pituitary adenomas

Background: Pituitary tumors account for approximately 10–15% of intracranial neoplasms. Aim: Using the cDNA microarray method, we have previously compared expression under two distinct conditions: a pool of 4 clinically non-functioning pituitary adenomas (NFPA) and a spinal cord metastasis of a non-functioning pituitary carcinoma, in order to gain biological insights into genomic changes of pituitary neoplasias. In the present study, we further investigated the mRNA expression of 3 selected genes previously described as being involved in other neoplasias based on a series of 60 pituitary adenomas: CRABP1 (cellular retinoic acid binding protein 1), GRP (gastrin-releasing peptide), and RERG (Ras-related, estrogen-regulated, growth inhibitor). Material and methods: The expression of CRABP1, GRP, and RERG was determined by quantitative RT-PCR. Results: A significantly higher content of CRABP1 mRNA was observed in NFPA compared to functioning adenomas, and PRL-secreting adenomas showed a lower expression of this gene compared to normal pituitary. A lower expression of GRP mRNA was detected in NFPA compared to normal pituitary and also to functioning adenomas. RERG mRNA was overexpressed in NFPA in comparison to functioning adenomas and to normal pituitary. Among the functioning adenomas, only the ACTH-secreting adenomas presented a higher expression of RERG mRNA compared to normal pituitary. Conclusions: The findings of differential expression of CRABP1 in prolactinomas and of RERG in NFPA compared to normal pituitary suggests that retinoic acid and estrogen receptor, respectively, could be involved in the tumorigenesis of these adenomas subtypes. Additional studies are required to further confirm this hypothesis.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome due to a mutation in the glutamate dehydrogenase gene

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is a rare autosomal dominant disease manifested by hypoglycemic symptoms triggered by fasting or high-protein meals, and by elevated serum ammonia. HI/HA is the second most common cause of hyperinsulinemic hypoglycemia of infancy, and it is caused by activating mutations in GLUD1, the gene that encodes mitochondrial enzyme glutamate dehydrogenase (GDH). Biochemical evaluation, as well as direct sequencing of exons and exon-intron boundary regions of the GLUD1 gene, were performed in a 6-year old female patient presenting fasting hypoglycemia and hyperammonemia. The patient was found to be heterozygous for one de novo missense mutation (c.1491A>G; p.Il497Met) previously reported in a Japanese patient. Treatment with diazoxide 100 mg/day promoted complete resolution of the hypoglycemic episodes.