Induction of more aggressive tumoral phenotypes in LNCaP and PC3 cells by serum exosomes from prostate cancer patients.

Prostate cancer (PCa) is the second most frequent and sixth most fatal cancer in men worldwide. Despite its high prevalence, our understanding of its etiology and the molecular mechanisms involved in the progression of the disease is substantially limited. In recent years, the potential participation of exosomes in this process has been suggested. Therefore, we aim to study the effect of exosomes isolated from the serum of patients with PCa on various cellular processes associated with increased tumor aggressiveness in two PCa cell lines: LNCaP-FGC and PC3. The exosomes were isolated by filtration wand ultracentrifugation. Their presence was confirmed by immunodetection of specific markers and their size distribution was analyzed by Dynamic Light Scattering (DLS). The results obtained demonstrated that serum exosomes from PCa patients increased migration of PC3 cells and neuroendocrine differentiation of LNCaP-FGC cells regardless of the grade of the tumor. PCa serum exosomes also enhanced the secretion of enzymes related to invasiveness and resistance to chemotherapeutics, such as extracellular matrix metalloproteases 2 and 9, and gamma-glutamyltransferase in both cell lines. Altogether, these findings support the pivotal participation of exosomes released by tumoral cells in the progression of PCa. Future studies on the molecular mechanisms involved in the observed changes could provide crucial information on this disease and help in the discovery of new therapeutic targets.

Carbohydrate effect of novel arene Ru(II) phenanthroline-glycoconjugates on metastatic biological processes.

Novel water-soluble half-sandwich ruthenium(II) polypyridyl-glycoconjugates [Ru(p-cymene)Cl{N-(1,10-phenanthroline-5-yl)-ß-glycopyranosylamine}][Cl] (glycopyranosyl = d-glucopyranosyl (1), D-mannopyranosyl (2), L-rhamnopyranosyl (3) and l-xylopyranosyl (4)) have been synthesized and fully characterized. Their behaviour in water under physiological conditions has been studied by nuclear magnetic resonance spectroscopy, revealing their hydrolytic stability. Interactions of the novel compounds with duplex-deoxiribonucleic acid (dsDNA) were investigated by different techniques and the results indicate that, under physiological pH and saline conditions, the metal glycoconjugates bind DNA in the minor groove and/or through external, electrostatic interactions, and by a non-classical, partial intercalation mechanism in non-saline phosphate buffered solution. Effects of compounds 1-4 on cell viability have been assessed in vitro against two human cell lines (androgen-independent prostate cancer PC-3 and non-tumorigenic prostate RWPE-1), showing moderate cytotoxicities, with IC50 values higher than those found for free ligands [N-(1,10-phenanthroline-5-yl)-ß-glycopyranosylamine] (glycopyranosyl = d-glucopyranosyl (a), D-mannopyranosyl (b), L-rhamnopyranosyl (c) and l-xylopyranosyl (d)) or corresponding metal-aglycone. Cell viability was assayed in the presence and absence of the glucose transporters (GLUTs) inhibitor [N4-{1-(4-cyanobenzyl)-5-methyl-3-(trifluoromethyl)-1H-pyrazol-4-yl}-7-fluoroquinoline-2,4-dicarboxamide] (BAY-876), and the results point to a negligible impact of the inhibition of GLUTs on the cytotoxicity caused by Ru(II) compounds 1-4. Remarkably, glycoconjugates 1-4 potently affect the migration pattern of PC-3 cells, and the wound healing assay evidence that the presence of the carbohydrate and the Ru(II) center is a requisite for the anti-migratory activity observed in these novel derivatives. In addition, derivatives 1-4 strongly affect the matrix metalloproteinase MMP-9 activities of PC-3 cells, while proMMP-2 and especially proMMP-9 were influenced to a much lesser extent.

Tumorigenic transformation of human prostatic epithelial cell line RWPE-1 by growth hormone-releasing hormone (GHRH).

BACKGROUND: Growth hormone-releasing hormone (GHRH) and its receptors have been implicated in the progression of various tumors. In this study, we analyzed the carcinogenetic potential of exposure to GHRH of a nontumor human prostate epithelial cell line (RWPE-1) as well as its transforming effect in a xenograft model. METHODS: We performed cell viability, cell proliferation, adhesion and migration assays. In addition, metalloprotease (MMP)-2 activity by means gelatin zymography, GHRH-R subcellular location using confocal immunofluorescence microscopy and vascular endothelial growth factor (VEGF) levels by enzyme-linked immunoassay were assessed. Besides, we developed an in vivo model in order vivo model to determine the role of GHRH on tumorigenic transformation of RWPE-1 cells. RESULTS: In cell cultures, we observed development of a migratory phenotype consistent with the gelatinolytic activity of MMP-2, expression of VEGF, as well as E-cadherin-mediated cell-cell adhesion and increased cell motility. Treatment with 0.1 µM GHRH for 24 h significantly increased cell viability and cell proliferation. Similar effects of GHRH were seen in RWPE-1 tumors developed by subcutaneous injection of GHRH-treated cells in athymic nude mice, 49 days after inoculation. CONCLUSIONS: Thus, GHRH appears to act as a cytokine in the transformation of RWPE-1 cells by mechanisms that likely involve epithelial-mesenchymal transition, thus reinforcing the role of GHRH in tumorigenesis of prostate.

Cyclopentadienyl ruthenium(II) carbosilane metallodendrimers as a promising treatment against advanced prostate cancer.

In searching for efficient and selective antitumour drugs, a new family of carbosilane metallodendrimers functionalized with [Ru(η5-C5H5)(PTA)Cl] (PTA = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1] decane) is reported. Experiments of the biophysical characterization showed an ability to interact with biological membranes, as well as with proteins (e.g. human serum albumin) without affecting their usual biological activity. These metallodendrimers possessed potent and selective anticancer activity in vitro in a panel of tumour cell lines. Importantly, the first generation metallodendrimer, bearing 4 Ru(II) complexes, was remarkably active towards resistant prostate cancer cells, inhibiting both cell proliferation and metastasis to bone tissues. Such promising antitumour activity can be further improved when given with docetaxel, with in vitro cytotoxicity being in the nanomolar range. Furthermore, its intravenous administration to an advanced prostate cancer mice model inhibited tumour growth up to 25% and 45% when given 10 mg/kg/week and 7.5 mg/kg/4-5 days, respectively.

Stimulation of neuroendocrine differentiation in prostate cancer cells by GHRH and its blockade by GHRH antagonists.

Prostate cancer is the second leading cause of cancer-related deaths among men in developed countries. Neuroendocrine prostate cancer, in particular, is associated with an aggressive phenotype and a poor prognosis. Neuroendocrine cells produce and secrete peptide hormones and growth factors in a paracrine/autocrine manner which promote the progression of the disease. Recent studies have demonstrated that extracellular vesicles or exosomes are released by prostate cancer cells, supporting the spread of prostate cancer. Hence, the aim of this study was to investigate the effect of growth hormone-releasing hormone (GHRH) on neuroendocrine differentiation (NED) in the androgen-dependent prostate cancer cell line LNCaP and the molecular mechanisms underlying these effects. GHRH induced an increase in the percentage of neurite-bearing cells and in the protein levels of Neuron-Specific Enolase. Both effects were blocked by the GHRH receptor antagonist MIA-690. In addition, pretreatment of these cells with the calcium chelator BAPTA, the EGFR inhibitor AG-1478 or the HER2 inhibitor AG-825 reduced the effect of GHRH, suggesting that the GHRH-induced stimulation of NED involves calcium channel activation and EGFR/HER2 transactivation. Finally, PC3-derived exosomes led to an increase in NED, cell proliferation and cell adhesion. Altogether, these findings suggest that GHRH antagonists should be considered for in the management of neuroendocrine prostate cancer.

Water soluble, optically active monofunctional Pd(ii) and Pt(ii) compounds: promising adhesive and antimigratory effects on human prostate PC-3 cancer cells.

New water soluble, enantiopure palladium and platinum compounds RN-[M{(1S,4R)-κNOH,κ2NH(2-pic)}Cl]Cl and SN-[M{(1R,4S)-κNOH,κ2NH(2-pic)}Cl]Cl (2-pic = 2-picolyl, M = Pd 1 and 1', Pt 2 and 2', respectively), and heterometallic Pd/Ti [(η5-C5H5)2Ti{(1S,4R)-κON,κ2NH(2-pic)}(PdCl)]Cl (3) have been synthesized. These novel compounds were fully characterized by NMR spectroscopy and CHN elemental analysis and 1, 1', 2 and 2' were further evaluated by polarimetry, ultra-violet and circular dichroism spectroscopy. The aqueous stability of novel compounds was studied by NMR spectroscopy under physiological conditions and the new species detected under such conditions have been characterized by NMR techniques and HR-ESI-MS (High-Resolution Electrospray Ionization Mass Spectrometry). Compound-DNA interactions have been investigated for the palladium and platinum compounds by equilibrium dialysis, Fluorescence Resonance Energy Transfer (FRET) DNA melting assays and viscometric titrations, revealing a better binding affinity and ability to affect duplex DNA of the palladium compounds. Metal derivatives have been tested in vitro against three cancer (prostate PC-3, cervical HeLa and breast MCF-7) and one non-tumorigenic (human prostate RWPE-1) cell lines. The highest anticancer activities were shown by palladium compounds 1 and 1' in all cancer lines, although their toxicity was lower than that found for cisplatin. Most importantly, the effect of the compounds on the cell adhesion and migration of the androgen-independent prostate cancer PC-3 cells has been assessed, and the efficacy of Pd enantiomers to affect the invasive phenotype of PC-3 cells has been demonstrated.

Insight into the antitumor activity of carbosilane Cu(ii)-metallodendrimers through their interaction with biological membrane models.

Current cancer therapies present serious drawbacks including severe side-effects and development of drug resistance. Strategies based on nanosized metallodrugs combine the structural diversity and non-classical modes of action of metal complexes with the selectivity arising from the unique interaction of nanoparticles with biological membranes. A new family of water-soluble copper(ii) carbosilane metallodendrimers was synthesized and characterized as a nanotechnological alternative to current therapies. The interactions occurring over time between the dendrimers, at different generations (G0 to G2) and with different Cu(ii) counter-ions (nitrate vs. chloride), and cell-membrane models (cethyl-trimethylammonium bromide (CTAB) micelles and lecithin liposomes) were investigated using a computer-aided analysis of the electron paramagnetic resonance (EPR) spectra. The EPR analysis provided structural and dynamical information on the systems indicating that the increase in generation and the change of the Cu(ii) contra-ion - from nitrate to chloride - produce an increased relative amount and strength of interaction of the dendrimer with the model membranes. Interestingly, the stabilization effect produced a lower toxicity towards cancer cells. The cytotoxic effect of Cu(ii) metallodendrimers was verified by an in vitro screening in a selection of tumor cell lines, revealing the impact of multivalency on the effectivity and selectivity of the metallodrugs. As a proof-of-concept, first-generation dendrimer G1-Cu(ONO2)2 was selected for in-depth in vitro and in vivo antitumor evaluation towards resistant prostate cancer. The Cu(ii)-metallodendrimers produced a significant tumor size reduction with no signs of toxicity during the experiment, confirming their promising potential as anticancer metallodrugs.

Growth hormone-releasing hormone receptor antagonists modify molecular machinery in the progression of prostate cancer.

BACKGROUND: Therapeutic strategies should be designed to transform aggressive prostate cancer phenotypes to a chronic situation. To evaluate the effects of the new growth hormone-releasing hormone receptor (GHRH-R) antagonists: MIA-602, MIA-606, and MIA-690 on processes associated with cancer progression as cell proliferation, adhesion, migration, and angiogenesis. METHODS: We used three human prostate cell lines (RWPE-1, LNCaP, and PC3). We analyzed several molecules such as E-cadherin, ß-catenin, Bcl2, Bax, p53, MMP2, MMP9, PCNA, and VEGF and signaling mechanisms that are involved on effects exerted by GHRH-R antagonists. RESULTS: GHRH-R antagonists decreased cell viability and provoked a reduction in proliferation in LNCaP and PC3 cells. Moreover, GHRH-R antagonists caused a time-dependent increase of cell adhesion in all three cell lines and retarded the wound closure with the highest value with MIA-690 in PC3 cells. GHRH-R antagonists also provoked a large number of cells in SubG0 phase revealing an increase in apoptotic cells in PC3 cell line. CONCLUSIONS: Taken all together, GHRH-R antagonists of the MIAMI series appear to be inhibitors of tumor progression in prostate cancer and should be considered for use in future therapeutic strategies on this malignancy.

Biological evaluation of water soluble arene Ru(II) enantiomers with amino-oxime ligands.

New water soluble, enantiopure arene ruthenium compound SRuSN-(1R,4S)-[(η6-p-cymene)Ru{ĸNH(Bn),ĸNOH}Cl]Cl (Bn = benzyl, 1a') has been synthesized. The novel compound along with that previously described RRuRN-(1S,4R)-[(η6-p-cymene)Ru{ĸNH(Bn),ĸNOH}Cl]Cl (1a) was evaluated by polarimetry, ultra-violet and circular dichroism spectroscopy. The structure of novel ruthenium derivative 1a' was determined by single crystal X-ray crystallography. Both enantiomers have been tested against several cancer cell lines in vitro: prostate PC-3, lung A-549, pancreas MIA PaCa-2, colorectal HCT-116, leukemia Jurkat and cervical HeLa. Both enantiomers are active and versatile cytotoxic agents, showing IC50 values from 2 to 12 times lower than those found for cisplatin in the different cell lines evaluated. The mechanism of cell death induced by the metal compounds was analyzed in A-549 and Jurkat cell lines. Derivatives 1a and 1a' induced apoptotic cell death of A-549 cells while dose-dependent cell death mechanisms have been found in the Jurkat cell line. Compound-DNA interactions have been investigated by equilibrium dialysis, Fluorescence Resonance Energy Transfer (FRET) melting assays and viscometric titrations, revealing moderate binding affinity of 1a and 1a' towards duplex DNA. Finally, the efficacy of 1a in a preliminary in vivo assay of PC-3 xenografts in nude mice has been evaluated, resulting in a promising inhibition of tumor growth by 45%. Analysis of tumor tissue also showed a significant decrease of levels of crucial molecules in the invasive phenotype of PC-3 cells.

Growth hormone-releasing hormone (GHRH) promotes metastatic phenotypes through EGFR/HER2 transactivation in prostate cancer cells.

The involvement of growth hormone-releasing hormone (GHRH) in several relevant processes that contribute to prostate cancer progression was analyzed. Firstly, we evaluated GHRH effects on cell proliferation and adhesion in human cancer prostate cell lines, LNCaP and PC3, by using specific assays (BrdU incorporation and collagen adhesion). The expression levels of the main marker molecules of these processes were measured by RT-PCR, Western blotting and zymography assays. GHRH increased both cell proliferation and proliferating cell nuclear antigen (PCNA) levels in LNCaP cells and in PC3 cells; however, such a rise was faster in the PC3 cells that represent the most aggressive stage of prostate cancer. Furthermore, GHRH significantly reduced cell adhesion and E-cadherin levels in LNCaP and PC3 cells and up-regulated the total and nuclear expression of ß-catenin in PC3 cells. In addition, we assessed cell cycle, cell migration and VEGF secretion in PC3 cells. GHRH augmented the number of cells in G2/M-phase but diminished that corresponding to G1-phase. Cell-cycle specific markers were evaluated since GHRH effects may be related to their differential expression; we observed a decrease of p53, p21, and Bax/Bcl2 ratio. Furthermore, GHRH increased the expression of CD44, c-myc and cyclin D1, MMP-2 and MMP-9 activity, and VEGF secretion. We also observed that EGFR and/or HER2 transactivation is involved in cell adhesion, cell migration and VEGF secretion produced by GHRH. Consequently, present results define GHRH as a proliferative, anti-apoptotic and migratory agent in prostate cancer.

Growth hormone-releasing hormone induced transactivation of epidermal growth factor receptor in human triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) is a subset of breast cancers which is negative for expression of estrogen and progesterone receptors and human epidermal growth factor receptor-2 (HER2). Chemotherapy is currently the only form of treatment for women with TNBC. Growth hormone-releasing hormone (GHRH) and epidermal growth factor (EGF) are autocrine/paracrine growth factors in breast cancer and a substantial proportion of TNBC expresses receptors for GHRH and EGF. The aim of this study was to evaluate the interrelationship between both these signaling pathways in MDA-MB-468 human TNBC cells. We evaluated by Western blot assays the effect of GHRH on transactivation of EGF receptor (EGFR) as well as the elements implicated. We assessed the effect of GHRH on migration capability of MDA-MB-468 cells as well as the involvement of EGFR in this process by means of wound-healing assays. Our findings demonstrate that in MDA-MB-468 cells the stimulatory activity of GHRH on tyrosine phosphorylation of EGFR is exerted by two different molecular mechanisms: i) through GHRH receptors, GHRH stimulates a ligand-independent activation of EGFR involving at least cAMP/PKA and Src family signaling pathways; ii) GHRH also stimulates a ligand-dependent activation of EGFR implicating an extracellular pathway with an important role for metalloproteinases. The cross-talk between EGFR and GHRHR may be impeded by combining drugs acting upon GHRH receptors and EGFR family members. This combination of GHRH receptors antagonists with inhibitors of EGFR signalling could enhance the efficacy of both types of agents as well as reduce their doses increasing therapeutic benefits in management of human breast cancer.

Anti-proliferative and pro-apoptotic effects of GHRH antagonists in prostate cancer.

Growth hormone-releasing hormone (GHRH) and its receptors have been implicated in the progression of various tumors. In vitro and in vivo studies have demonstrated that GHRH antagonists inhibit the growth of several cancers. GHRH antagonists, JMR-132 and JV-1-38 inhibit the growth of androgen-independent prostate tumors. Here we investigated the involvement of GHRH antagonists in proliferative and apoptotic processes. We used non-tumoral RWPE-1 and tumoral LNCaP and PC3 human prostatic epithelial cells, as well as an experimental model of human tumor PC3 cells. We evaluated the effects of JMR-132 and JV-1-38 antagonists on cell viability and proliferation in the three cell lines by means of MTT and BrdU assays, respectively, as well as on cell cycle and apoptotic process in PC3 cells. The expression levels of PCNA, p53, p21, CD44, Cyclin D1, c-myc, Bax and Bcl2 were determined in both in vivo and in vitro models by means of Western-blot and RT-PCR. GHRH antagonists suppressed cell proliferation and decreased the levels of the proliferation marker, PCNA, in the three cell lines and in PC3 tumor. GHRH antagonists led to an increase of cells in S-phase and a decrease in G1 and G2/M phases, and induced S-phase arrest and increase of apoptotic cells. The effects of GHRH-antagonists on cell cycle could be due to the changes observed in the expression of p21, p53, Bax, Bcl2, CD44, Cyclin D1, c-myc and caspase 3. Present results confirm and extend the role of GHRH antagonists as anti-proliferative and pro-apoptotic molecules in prostate cancer.

Novel enantiopure cyclopentadienyl Ti(IV) oximato compounds as potential anticancer agents.

The synthesis and characterization of new enantiopure cyclopentadienyl titanium oximato compounds (S,R)-[(η(5)-C5H5)Ti{к(2)NO,(R)NH·HCl}Cl2] (R=Ph (phenyl) 1a·HCl, Bn (benzyl) 1b·HCl, 2-pic (2-picolyl) 1c·HCl), (S,R)-[(η(5)-C5H5)TiCl2{к(2)NO,(Ph)NH}] (1a) and (S,R)-[(η(5)-C5H5)2TiCl{к(2)NO,(R)NH}] (R=Ph 2a, Bn 2b, 2-pic 2c), along with studies on their behavior in D2O at different pD values are reported. The structure of previously described ammonium-oxime (2S,5R)-{NOH,(Bn)NH·HCl} (b·HCl) and novel titanium derivative 1a have been determined by single crystal X-ray crystallography. The effect of the compounds on cytotoxicity, cell adhesion and migration of the androgen-independent prostate cancer PC-3 cells has been assessed. Compounds 2b and 2c are more cytotoxic than additive doses of titanocene dichloride and free oxime proligand, probing the synergistic effect of these novel compounds. The cytotoxicity of 2b and 2c has been further evaluated against human renal Caki-1, colon DLD-1 and triple negative breast MDA-MB-231 cancer cell lines. The activity found for 2c on PC-3 and Caki-1 is higher than that of highly active Titanocene Y (bis-[(p-methoxybenzyl)cyclopentadienyl]titanium(IV) dichloride), while showing selectivity against renal cancer when compared to a non-tumorigenic human renal (HEK-293T) cell line. Compounds 2b and especially 2c are apoptotic in Caki-1 cancer cell lines. Cell adhesion and wound-healing assays confirmed that derivatives 1c·HCl, 2b and 2c affect the adhesion and migration patterns of the PC-3 cell line. Interactions of the novel compounds with plasmid (pBR322) DNA have also been studied, showing that the oximato Ti(IV) derivatives have a weak or no interaction with DNA at physiological pH.

Hydrogen bonding and anticancer properties of water-soluble chiral p-cymene Ru(II) compounds with amino-oxime ligands.

The investigation of the hydrogen-bonding effect on the aggregation tendency of ruthenium compounds [(η6-p-cymene)Ru(κNHR,κNOH)Cl]Cl (R = Ph (1a), Bn (1b)) and [(η6-p-cymene)Ru(κ2NH(2-pic),κNOH)][PF6]2 (1c), [(η6-p-cymene)Ru(κNHBn,κNO)Cl] (2b) and [(η6-p-cymene)Ru(κNBn,κ2NO)] (3b), has been performed by means of concentration dependence 1H NMR chemical shifts and DOSY experiments. The synthesis and full characterization of new compounds 1c, [(η6-p-cymene)Ru(κNPh,κ2NO)] (3a) and 3b are also reported. The effect of the water soluble ruthenium complexes 1a-1c on cytotoxicity, cell adhesion and cell migration of the androgen-independent prostate cancer PC3 cells have been assessed by MTT, adhesion to type-I-collagen and recovery of monolayer wounds assays, respectively. Interactions of 1a-1c with DNA and human serum albumin have also been studied. Altogether, the properties reported herein suggest that ruthenium compounds 1a-1c have considerable potential as anticancer agents against advanced prostate cancer.

VIP induces NF-κB1-nuclear localisation through different signalling pathways in human tumour and non-tumour prostate cells.

The nuclear factor κB (NF-κB) is a powerful activator of angiogenesis, invasion and metastasis. Transactivation and nuclear localisation of NF-κB is an index of recurrence in prostate cancer. Vasoactive intestinal peptide (VIP) exerts similar effects in prostate cancer models involving increased expression of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) which are related to NF-κB transactivation. Here we studied differential mechanisms of VIP-induced NF-κB transactivation in non-tumour RWPE-1 and tumour LNCaP and PC3 human prostate epithelial cells. Immunofluorescence studies showed that VIP increases translocation of the p50 subunit of NF-κB1 to the nucleus, an effect that was inhibited by curcumin. The signalling transduction pathways involved are different depending on cell transformation degree. In control cells (RWPE1), the effect is mediated by protein kinase A (PKA) activation and does not implicate extracellular signal-regulated kinase (ERK) or phosphoinositide 3-kinase (PI3-K) pathways whereas the opposite is true in tumour LNCaP and PC3 cells. Exchange protein directly activated by cAMP (EPAC) pathway is involved in transformed cells but not in control cells. Curcumin blocks the activating effect of VIP on COX-2 promoter/prostaglandin E2 (PGE2) production and VEGF expression and secretion. The study incorporates direct observation on COX-2 promoter and suggests that VIP effect on VEGF may be indirectly mediated by PGE2 after being synthesised by COX-2, thus amplifying the initial signal. We show that the signalling involved in VIP effects on VEGF is cAMP/PKA in non-tumour cells and cAMP/EPAC/ERK/PI3K in tumour cells which coincides with pathways mediating p50 nuclear translocation. Thus, VIP appears to use different pathways for NF-κB1 (p50) transactivation in prostate epithelial cells depending on whether they are transformed or not. Transformed cells depend on pro-survival and pro-proliferative signalling pathways involving ERK, PI3-K and cAMP/EPAC which supports the potential therapeutic value of these targets in prostate cancer.

Growth hormone-releasing hormone antagonists abolish the transactivation of human epidermal growth factor receptors in advanced prostate cancer models.

Growth hormone-releasing hormone (GHRH) and its receptors have been implicated in a variety of cellular phenotypes related with tumorigenesis process. Human epidermal growth factor receptor family members (HER) such as EGFR and HER2 are involved in mitogenic signaling pathways implicated in the progression of prostate cancer. We analyzed the cross-talk between GHRH and EGF receptors in prostate cancer. The effects of GHRH in HER signaling were evaluated on human androgen-independent PC3 prostate cancer cells in vitro and GHRH antagonist in vitro and in nude mice xenografts of PC3 prostate cancer. Time-course studies indicated that GHRH had a stimulatory activity on both the expression of EGFR and HER2. GHRH analogues, JMR-132 and JV-1-38, endowed with antagonistic activity for GHRH receptors, abrogated the response to GHRH in PC3 cells. GHRH stimulated a rapid ligand-independent activation of EGFR and HER2 involving at least cAMP/PKA and Src family signaling pathways. GHRH also stimulated a slow ligand-dependent activation of EGFR and HER2 involving an extracellular pathway with an important role for ADAM. Preliminary results also revealed an increase of mRNA for GHRH and GHRH receptor induced by EGF. The inhibition of tumor growth, in vivo, was associated with a substantial reduction in the expression of mRNA and protein levels of EGFR and HER2 in the tumors. GHRH antagonist JV-1-38, significantly decreased the phosphorylated Src levels. The cross-talk between HER and GHRH-R may be impeded by combining drugs acting upon GHRH receptors and HER family members in human advanced prostate cancer.

Signalling pathways involved in antitumoral effects of VIP in human renal cell carcinoma A498 cells: VIP induction of p53 expression.

Vasoactive intestinal peptide (VIP) decreases cell proliferation through PI3K signalling and prevents tumour progression in clear renal cell carcinoma (RCC). Here we analyzed the signalling pathways that mediate such VIP effects by using human RCC A498 cells. The effects of treatment with 1 µM VIP and/or specific protein kinase inhibitors such as H89, Wortmannin and PD98059 were studied by cell adhesion assay, ELISA of VEGF165 and ROS production assays. Semiquantitative RT-PCR and western blot were performed to study p53 expression. VIP increased cell adhesion and ROS production, and decreased VEGF165 secretion through PI3K signalling. Moreover, VIP increased nuclear expression of tumour suppressor p53. VIP effects could be blocked by cell incubation with a specific p53 inhibitor, cyclin pifithrin-α hydrobromide (CPFT-αH). In conclusion, this study provides a p53-dependent mechanism by which VIP regulates cell proliferation in RCC development. It supports a potential usefulness of VIP in new therapies of RCC.

Antitumoral effects of vasoactive intestinal peptide in human renal cell carcinoma xenografts in athymic nude mice.

We studied antitumor effect of VIP in human renal cell carcinoma (RCC) (A498 cells xenografted in immunosuppressed mice). VIP-treated cells gave resulted in p53 upregulation and decreased nuclear ß-catenin translocation and NFκB expression, MMP-2 and MMP-9 activities, VEGF levels and CD-34 expression. VIP led to a more differentiated tubular organization in tumours and less metastatic areas. Thus, VIP inhibits growth of A498-cell tumours acting on the major issues involved in RCC progression such as cell proliferation, microenvironment remodelling, tumour invasion, angiogenesis and metastatic ability. These antitumoral effects of VIP offer new therapeutical possibilities in RCC treatment.

Inhibitory effects of antagonists of growth hormone-releasing hormone on growth and invasiveness of PC3 human prostate cancer.

New approaches are needed to the therapy of advanced prostate cancer. This study determined the effect of growth hormone-releasing hormone (GHRH) antagonists, JMR-132 and JV-1-38 on growth of PC3 tumors as well as on angiogenesis and metastasis through the evaluation of various factors that contribute largely to the progression of prostate cancer. Human PC3 androgen-independent prostate cancer cells were injected subcutaneously into nude mice. The treatment with JMR-132 (10 µg/day) or JV-1-38 (20 µg/day) lasted 41 days. We also evaluated the effects of JMR-132 and JV-1-38 on proliferation, cell adhesion and migration in PC-3 cells in vitro. Several techniques (Western blot, reverse transcription polymerase chain reaction, immunohistochemistry, ELISA and zymography) were used to evaluate the expression levels of GHRH receptors and its splice variants, GHRH, vascular endothelial growth factor (VEGF), hypoxia inducible factor (HIF)-1α, metalloproteinases (MMPs) -2 and -9, ß-catenin and E-cadherin. GHRH antagonists suppressed the proliferation of PC-3 cells in vitro and significantly inhibited growth of PC3 tumors. After treatment with these analogues, we found an increase in expression of GHRH receptor accompanied by a decrease of GHRH levels, a reduction in both VEGF and HIF-1α expression and in active forms of MMP-2 and MMP-9, a significant increase in levels of membrane-associated ß-catenin and a significant decline in E-cadherin. These results support that the blockade of GHRH receptors can modulate elements involved in angiogenesis and metastasis. Consequently, GHRH antagonists could be considered as suitable candidates for therapeutic trials in the management of androgen-independent prostate cancer.

Vasoactive intestinal peptide induces oxidative stress and suppresses metastatic potential in human clear cell renal cell carcinoma.

Molecular mechanisms involved in progression of clear-cell renal-cell carcinomas (ccRCCs) are poorly understood. A common genetic mutation found in ccRCC is the loss of the von Hippel-Lindau (VHL) gene, which contributes to cancer progression and metastasis. We investigated VIP effects on metastatic and angiogenic factors in human VHL-null A498 ccRCC and HK2 renal cells. VIP increased adhesion but decreased expression of metalloproteinases, MMP2 and MMP9, as well as cell migration and VEGF expression and secretion in A498 but not in HK2 cells. VIP enhanced ROS levels and decreased nuclear levels of ß-catenin and NFκB p50-subunit in A498 cells, suggesting neuropeptide involvement in the observed decrease of metastatic ability in clear-cell carcinoma. VIP effects in A498 cells were blocked by the VPAC(1/2)-receptor antagonist JV-1-53. In conclusion, present data point to a role of VIP in preventing invasion and metastasis in ccRCCs and support its potential therapeutic usefulness in this disease.