Vasoactive intestinal peptide induces cyclooxygenase-2 expression through nuclear factor-kappaB in human prostate cell lines Differential time-dependent responses in cancer progression

Heparin Oligosaccharides as Vasoactive Intestinal Peptide Inhibitors via their Binding Process Characterization

BACKGROUND

It has been proven that vasoactive intestinal peptide (VIP) was involved in the pathogenesis of prostate cancer. Cardin et al. found that by an alanine scan, the heparin- binding site on VIP was exactly the same sequence in VIP and its receptor. Therefore, heparin could competitively block the binding of VIP and its receptor. However, the structure-activity relationship between heparin and VIP has not been reported, especially in terms of the sequence and sulfation patterns of heparin oligosaccharides upon binding to VIP.

OBJECTIVE

A variety of experiments were designed to study the binding process and structure-activity relationship between heparin oligosaccharides and VIP.

METHODS

Heparin was enzymatically digested and purified to produce heparin oligosaccharides, and the structures were characterized by NMR. The binding capacity between heparin oligosaccharides and VIP was analyzed by GMSA and ITC experiments. The binding between heparin oligosaccharides and VIP was simulated using a molecular docking program to show the complex. ELISA assay was used to investigate the effect of non-anticoagulant heparin oligosaccharides on the VIP-mediated cAMP/PKA signaling pathway in vitro.

RESULTS

The results indicated that both the length and the sulfation pattern of heparin oligosaccharides affected its binding to VIP. VIP could induce the expression of cAMP at a higher level in PC3 cells, which could be regulated by the interaction of heparin oligosaccharides and VIP.

CONCLUSION

The binding between heparin oligosaccharides and VIP could block the binding between VIP and its receptor on tumor cells. Downloading the regulation of the expression level of cAMP could possibly further affect the subsequent activation of PKA. These non-anticoagulant heparin oligosaccharides may block the VIP-mediated cAMP/PKA signaling pathway and thus exert their antitumor activity.

The prostaglandin synthases, COX-2 and L-PGDS, mediate prostate hyperplasia induced by low-dose bisphenol A

This study aimed to identify prostaglandin synthases (PGS) that mediate bisphenol A (BPA)-induced prostatic hyperplasia and explore their underlying mechanisms. In an in vivo study, male adult Sprague–Dawley rats were treated with different concentrations of BPA (10, 30, 90, or 270 μg/kg, i.g., daily), or with vehicle for 4 weeks. Results revealed that low-dose BPA induced prostatic hyperplasia with increased PCNA/TUNEL ratio. It significantly upregulated the expression of cyclooxygenase-2 (COX-2) and NF-κB in the dorsolateral prostate (P < 0.05) and the expression of lipocalin-type prostaglandin D synthase (L-PGDS) in ventral prostate (P < 0.05). The level of estradiol (E₂)/testosterone (T) and expression of androgen receptor (AR) and estrogen receptor α (ERα) were also altered. In vitro studies showed that low-dose BPA (0.1–10 nM) promoted the proliferation of human prostate fibroblasts and epithelial cells, and significantly upregulated the expression of COX-2 and L-PGDS in the cells. The two types of cell proliferation induced by BPA were inhibited by COX-2 inhibitor (NS398) and L-PGDS inhibitor (AT56), with increased apoptosis level. These findings suggested that COX-2 and L-PGDS could mediate low-dose BPA-induced prostatic hyperplasia through pathways involved in cell proliferation and apoptosis, which might be related to the functions of ERα and AR. The role of COX-2/NF-κB pathway in dorsolateral prostate requires further research.

Vasoactive intestinal peptide/pituitary adenylate cyclase activating polypeptide, and their receptors and cancer

PURPOSE OF REVIEW

To summarize the roles of vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase activating polypeptide (PACAP) and their receptors (VPAC1, VPAC2, PAC1) in human tumors as well as their role in potential novel treatments.

RECENT FINDINGS

Considerable progress has been made in understanding of the effects of VIP/PACAP on growth of various tumors as well as in the signaling cascades involved, especially in the role of transactivation of the epidermal growth factor family. The overexpression of VPAC1/2 and PAC1 on a number of common neoplasms (breast, lung, prostate, central nervous system and neuroblastoma) is receiving increased attention both as a means of tumor imaging the location and extent of these tumors, as well as for targeted directed treatment, by coupling cytotoxic agents to VIP/PACAP analogues.

SUMMARY

VIP/PACAP has prominent growth effects on a number of common neoplasms, which frequently overexpressed the three subtypes of their receptors. The increased understanding of their signaling cascades, effect on tumor growth/differentiation and the use of the overexpression of these receptors for localization/targeted cytotoxic delivery are all suggesting possible novel tumor treatments.

Vasoactive intestinal peptide induces CD14+HLA-DR‑/low myeloid-derived suppressor cells in gastric cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of cells, which have been revealed to inhibit T-cell responses in tumor-bearing mice. In addition, a number of immune suppressive mechanisms have linked MDSCs and the development of human cancer. However, the role of MDSCs in human gastric cancer tissue remains to be elucidated as specific markers are lacking. Therefore, the aim of the present study was to investigate the frequency and immune suppressive function of MDSCs denoted in the present study as cluster of differentiation 14 (CD14)+human leukocyte antigen (HLA)-DR-/low in gastric cancer patients. In the present study, MDSCs were directly isolated and characterized from the tumor and adjacent normal tissue of gastric cancer patients. Functional analysis of the CD14+HLA-DR-/low MDSCs co-cultured with allogeneic CD4+ T cells were performed and compared with controls. In addition, the interferon-γ (IFN-γ) and interleukin (IL)-2 production was compared in order to investigate the capacity of vasoactive intestinal peptide (VIP) to induce CD14+HLA-DR(-/low) MDSC-mediated CD4+ T-cell dysfunction and whether IL-10 secretion is involved in this mechanism. As a result, the quantity of CD14+HLA-DR(-/low) cells in tumor tissue from gastric cancer patients was significantly higher than that in the adjacent normal tissue. In addition, CD14+HLA-DR-/low MDSCs isolated from tumor tissue were observed to inhibit the CD4+ T-cells' immune responses in comparison with those from the adjacent normal tissue. Furthermore, VIP was able to induce the differentiation of CD14+ mononuclear cells isolated from healthy donor peripheral blood mononuclear cells into activated MDSC cells. Of note, the immunosuppressive effect of VIP-induced CD14+HLA-DR(-/low) MDSCs on CD4+ T cells was mediated by IL-10 secretion, which was demonstrated in the subsequent decrease of IFN-γ and IL-2 production. In conclusion, CD14+HLA-DR(-/low) cells were significantly increased in gastric cancer tissue and were shown to have a critical role in CD4+T-cell immunosuppression. In addition, VIP as a novel cytokine may induce the differentiation of CD14+ mononuclear cells towards CD14+HLA-DR(-/low) MDSCs. An improved understanding of phenotypic heterogeneity and the mechanism of generation of MDSCs in gastric cancer patients is important in the design of effective immunotherapeutic strategies.

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.

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 β-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.

Antioxidant activity of vasoactive intestinal peptide in HK2 human renal cells

Oxidative stress is a major mediator of tissue and cell injuries. The injury in chronic nephrotic syndrome, acute renal failure, myeloma kidney injury and other kidney diseases is initiated by oxidative stress. We have previously demonstrated that vasoactive intestinal peptide (VIP) acts as an antiproliferative agent in renal cancer cells. This study was designed to evaluate the renoprotective activity of VIP against H(2)O(2)-induced oxidative damage in a proximal tubule kidney cell line (human, non-tumor, HK2 cells) in order to investigate the potential usefulness of this peptide in the treatment of oxidative-stress related kidney diseases. HK2 cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Propidium iodide was used to identify cells undergoing apoptosis. Western blotting was performed with anti-Bcl-2, anti-Bax and anti-formyl peptide receptor (low-affinity variant FPRL-1) monoclonal antibodies whereas 2,7-dichlorofluorescein diacetate was used for measurement of levels of intracellular reactive oxygen species (ROS). HK2 cells were injured with H(2)O(2) in order to induce apoptosis: the effect was time- and dose-dependent. VIP increased the levels of the antiapoptotic protein Bcl-2 and decreased those of the proapoptotic protein Bax. VIP decreased the intracellular ROS levels reached by H(2)O(2)-induced oxidative stress. VIP effect on ROS levels involved FPLR-1 but not VPAC(1,2) receptors as evidenced by the use of the respective antagonists WRW4 and JV-1-53. Thus, VIP protects HK2 cells from apoptosis by increasing Bcl-2 levels and this effect is initiated through FPLR1 receptor. In conclusion, VIP might exert a renoprotective effect by the suppression of oxidative stress.

Vasoactive intestinal peptide (VIP) inhibits human renal cell carcinoma proliferation

Clear renal cell carcinoma (cRCC) is an aggressive and fatal neoplasm. The present work was undertaken to investigate the antiproliferative potential of vasoactive intestinal peptide (VIP) exposure on non-tumoral (HK2) and tumoral (A498, cRCC) human proximal tubular epithelial cell lines. Reverse transcription and semiquantitative PCR was used at the VIP mRNA level whereas enzyme immunoanalysis was performed at the protein level. Both renal cell lines expressed VIP as well as VIP/pituitary adenylate cyclase-activating peptide (VPAC) receptors whereas only HK2 cells expressed formyl peptide receptor-like 1 (FPRL-1). Receptors were functional, as shown by VIP stimulation of adenylyl cyclase activity. Treatment with 0.1μM VIP (24h) inhibited proliferation of A498 but not HK2 cells as based on a reduction in the incorporation of [(3)H]-thymidine and BrdU (5'-Br-2'-deoxyuridine), PCNA (proliferating-cell nuclear antigen) expression and STAT3 (signal transducer and activator of transcription 3) expression and activation. VPAC(1)-receptor participation was established using JV-1-53 antagonist and siRNA transfection. Growth-inhibitory response to VIP was related to the cyclic adenosine monophosphate (cAMP)/exchange protein directly activated by cAMP (EPAC)/phosphoinositide 3-kinase (PI3-K) signaling systems as shown by studies on adenylate cyclase stimulation, and using the EPAC-specific compound 8CPT-2Me-cAMP and specific kinase inhibitors such as H89, wortmannin and PD98059. The efficacy of VIP on the prevention of tumor progression was confirmed in vivo using xenografted athymic mouse. These actions support a potential role of this peptide and its agonists in new therapies for cRCC.

Multifunctional role of VIP in prostate cancer progression in a xenograft model: suppression by curcumin and COX-2 inhibitor NS-398

We used an in vivo model of human experimental prostate cancer in order to shed a new light on the effects of vasoactive intestinal peptide (VIP) on tumor growth as well as its pro-metastatic potential in this disease. We used nude mice subcutaneously injected with prostate cancer androgen-independent PC3 cells for 30 days. The regulatory role of VIP on cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) expression as well as on matrix metalloproteinase-2 and 9 (MMP-2 and 9) activities was examined. A selective COX-2 inhibitor, NS-398, and curcumin were used to block VIP effects. Xenografts of VIP-treated PC3 prostate cancer cells in nude mice gave tumors that grew significantly faster than those in the untreated group. It is conceivably a result of both the trophic effect of VIP on prostate cancer cells and the proangiogenic action of the neuropeptide in the growing tumor. We show the overexpression at mRNA and/or protein levels of VIP, its main receptor VPAC(1), the major angiogenic factor VEGF, and the pro-inflammatory enzyme COX-2 as well as the increased activity of MMP-2 and 9 in tumors derived from VIP-treated PC3 cells as compared with control group. The overexpression of the above biomarkers was suppressed in tumors derived from VIP-treated PC3 cells that had been previously incubated with curcumin or NS-398. Thus, the potential therapeutic role of curcumin and selective COX-2 inhibitors in combination with available VIP antagonists should be considered in prostate cancer therapy as supported by their inhibitory activities on tumor cell growth.

Vasoactive intestinal peptide behaves as a pro-metastatic factor in human prostate cancer cells

BACKGROUND

There is little known on the involvement of vasoactive intestinal peptide (VIP) in the metastatic cascade of human prostate cancer, that is, cell proliferation, cell-cell adhesion, extracellular-matrix degradation, and migration/invasion. Here we evaluated the expression of related biomarker proteins (cyclin D1, metalloproteinases MMP-2 and MMP-9, and E-cadherin) in human androgen-dependent (LNCaP) and independent (PC3) prostate cancer cells.

METHODS

Reverse transcriptase (RT)-polymerase chain reaction (PCR), gelatin zymography, Western blotting, confocal immunofluorescence microscopy, and assays on cell proliferation, adhesion, wound-healing, migration and random homing were performed.

RESULTS

VIP increased cell proliferation and cyclin D1 expression whereas it decreased cell adhesion and E-cadherin expression in LNCaP and PC3 cells. VIP enhanced the gelatinolytic activity of MMP-2 and MMP-9. Semiquantitative RT-PCR assays showed that VIP stimulated mRNA levels of these MMPs and suppressed mRNA levels of its inhibitory protein RECK. VIP promoted cell invasion and migration, and the responses were faster according to the most aggressive status in cancer progression (androgen-independence). The involvement of nuclear factor-kappaB (NF-kappaB) was demonstrated since the anti-inflammatory agent curcumin blocked VIP effects on the above biomarkers in both cell lines.

CONCLUSIONS

Taken together, these results and the presence of kappaB sites on gene promoter of cyclin D1, MMPs and, possibly, E-cadherin suggest that VIP may act as a cytokine in an early metastatic stage of human prostate cancer through the NF-kappaB/MMPs-RECK/E-cadherin system. Our findings may help to define novel targets and agents with potential usefulness in prostate cancer therapy.

The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis

Osteoarthritis (OA) is one of the most common and disabling chronic joint disorders affecting horses, dogs and humans. Synovial inflammation or synovitis is a frequently observed phenomenon in osteoarthritic joints and contributes to the pathogenesis of OA through formation of various catabolic and pro-inflammatory mediators altering the balance of cartilage matrix degradation and repair. Catabolic mediators produced by the inflamed synovium include pro-inflammatory cytokines, nitric oxide, prostaglandin E(2) and several neuropeptides, which further contribute to the pathogenesis of OA by increasing cartilage degradation. Recent studies suggest that substance P, corticotropin-releasing factor, urocortin and vasoactive intestinal peptide may also be involved in OA development, but the precise role of these neuropeptides in the pathogenesis of OA is not known. Since increased production of matrix metalloproteinases by the synovium is stimulated by pro-inflammatory cytokines, future anti-inflammatory therapies should focus on the synovium as a means of controlling subsequent inflammatory damage.