Vasoactive intestinal peptide (VIP) stimulates rat prostatic epithelial cell proliferation

Influence of sensory neuropeptides on human cutaneous wound healing process

BACKGROUND

Close interactions exist between primary sensory neurons of the peripheral nervous system (PNS) and skin cells. The PNS may be implicated in the modulation of different skin functions as wound healing.

OBJECTIVE

Study the influence of sensory neurons in human cutaneous wound healing.

METHODS

We incubated injured human skin explants either with rat primary sensory neurons from dorsal root ganglia (DRG) or different neuropeptides (vasoactive intestinal peptide or VIP, calcitonin gene-related peptide or CGRP, substance P or SP) at various concentrations. Then we evaluated their effects on the proliferative and extracellular matrix (ECM) remodeling phases, dermal fibroblasts adhesion and differentiation into myofibroblasts.

RESULTS

Thus, DRG and all studied neuromediators increased fibroblasts and keratinocytes proliferation and act on the expression ratio between collagen type I and type III in favor of collagen I, particularly between the 3rd and 7th day of culture. Furthermore, the enzymatic activities of matrix metalloprotesases (MMP-2 and MMP-9) were increased in the first days of wound healing process. Finally, the adhesion of human dermal fibroblasts and their differentiation into myofibroblasts were promoted after incubation with neuromediators. Interestingly, the most potent concentrations for each tested molecules, were the lowest concentrations, corresponding to physiological concentrations.

CONCLUSION

Sensory neurons and their derived-neuropeptides are able to promote skin wound healing.

Stereological Quantification of Nerve Fibers Immunoreactive to PGP 9.5, NPY, and VIP in Rat Prostate During Postnatal Development

This work was undertaken to study prostate innervation during the postnatal development of rats. It deals with the quantification of nervous fibers throughout all the regions of the rat prostate during the postnatal development using a general marker for nervous tissue, protein gene product 9.5, and 2 neuropeptides (NPY and VIP). Forty male Wistar rats (prepubertals, pubertals, young, and aged adults) were studied for immunohistochemistry of protein gene product (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP). They were also evaluated for length density of nerve fibers (L(V) PGP 9.5, L(V) NPY, L(V) VIP). Nerve fibers immunoreactive to the 3 antigens studied were detected in all the groups and in all the prostate zones. Periductal L(V) NPY evidenced a significant increase in the pubertal group, maintained throughout adult life. Periductal L(V) VIP showed a significant increase in young adults. The length densities of VIP and NPY fibers were significantly higher in periductal and ampular locations in comparison with dorsal and ventral sites. It can be concluded that the relative amount of nerve fibers in rat prostate, detected by PGP 9.5, does not change during postnatal development. There were significant changes in NPY and VIP fibers, showing an increase in periurethral ducts at puberty. The abundance of peptidergic innervation around the excretory ducts is related to their contractility. The development of innervation of periurethral ducts is regulated by androgens.

Autonomic nervous system overactivity in men with lower urinary tract symptoms secondary to benign prostatic hyperplasia

PURPOSE

The relationship of lower urinary tract symptoms (LUTS) to objective measures of benign prostatic hyperplasia (BPH), such as prostatic size and urodynamic parameters, has proved difficult to evaluate. Studies in animal models of BPH suggest that autonomic nervous system (ANS) activity is an important determinant of prostatic growth. We investigated the relationship of ANS activity to LUTS as well as to objective measures of BPH in men with BPH.

MATERIALS AND METHODS

This study was done in 3,047 men with LUTS secondary to BPH during screening for enrolment at 1 center in a large, multicenter, double-blind, placebo controlled trial designed to assess the long-term effects of medical therapy on BPH progression. A total of 38 men with an American Urological Association (AUA) symptom score of 8 or greater and a maximum urinary flow rate of 4 to less than 15 ml per second had ANS activity assessed based on heart rate, blood pressure, the response to circulatory stress via tilt table, and plasma and urinary catecholamine. These ANS related variables were compared with subjective measures of LUTS (AUA symptom score, quality of life score and BPH impact index), overall health measures (RAND 36-Item Health Survey) and objective clinical measures of BPH (prostate size, post-void residual volume and maximum urinary flow rate). Pearson correlation coefficients were calculated for each ANS variable vs each LUTS and BPH variable. These correlations were further assessed using stepwise multiple regression analysis to determine which BPH and LUTS variables were independently related to the ANS variable. Relationships that were identified as significant then underwent final multiple regression analysis together with control variables to exclude known extraneous and confounding influences on ANS activity.

RESULTS

After adjusting for extrinsic influences on ANS activity AUA symptom score (p <0.01), BPH impact index score (p <0.001) and quality of life score (p <0.05) were independently associated with the change in systolic and diastolic blood pressure 1 and 5 minutes after tilt. Additionally, prostate transition zone volume (p <0.001) and the RAND 36-Item Health Survey mental subscale score (p <0.001) were independently associated with the plasma norepinephrine response to tilt.

CONCLUSIONS

ANS hyperactivity is significantly associated with the most commonly used measures of LUTS, namely AUA symptom score and BPH impact index score. Also, the magnitude of the serum norepinephrine increase after tilt predicts prostate size. These relationships persist after controlling for extrinsic influences on ANS activity. The current findings may have important implications concerning the pathophysiological mechanisms underlying or influencing LUTS as well as its optimal treatment in men with BPH.

Vasoactive intestinal peptide induces neuroendocrine differentiation in the LNCaP prostate cancer cell line through PKA, ERK, and PI3K

BACKGROUND

Neuroendocrine (NE) differentiation in prostate cancer has been correlated with unfavorable clinical outcome. The mechanisms by which prostate cancer acquires NE properties are poorly understood, but several signaling pathways have been proposed. We have previously observed that vasoactive intestinal peptide (VIP) stimulates cAMP production mainly through VPAC(1) receptor, inducing NE differentiation in LNCaP cells. The aim of this study was to analyze the mechanisms involved in this process.

METHODS

Reverse transcriptase (RT)-polymerase chain reaction (PCR), quantitative real-time RT-PCR, Western blotting, and immunocytochemistry were performed.

RESULTS

LNCaP cells produce VIP, as demonstrated by RT-PCR and immunocytochemistry. VIP induced NE differentiation of LNCaP cells at a time as short as 1 hr of treatment, and the same occurred with the expression and secretion of neuronal-specific enolase (NSE, a NE differentiation marker). These effects were faster than those exerted by serum-deprivation. VIP induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation and NE differentiation by PKA-dependent and independent pathways, since the PKA inhibitor H89 partially blocked VIP-induced NE differentiation and did not affect ERK1/2 phosphorylation. mitogen-activated protein kinase kinase (MEK) and phosphoinositide 3-kinase (PI3K) appear to be also involved since the inhibitors PD98059 and wortmannin abolished ERK1/2 phosphorylation and decreased NE differentiation induced by VIP. Moreover, VIP activated Ras suggesting the involvement of a Ras-dependent pathway.

CONCLUSIONS

VIP behaves as autocrine/paracrine factor in LNCaP cells by inducing NE differentiation through PKA, ERK1/2, and PI3K.

VIP and PACAP are autocrine factors that protect the androgen-independent prostate cancer cell line PC-3 from apoptosis induced by serum withdrawal

1. In the present study, we describe the expression of the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) as well as their receptors in PC-3 cells, a human prostate cancer cell line. In addition, we have investigated their role in apoptosis induced by serum starvation. 2. By RT-PCR and immunocytochemistry assays, we have demonstrated the production of VIP and PACAP in PC-3 cells. 3. We have demonstrated by RT-PCR and binding assays the expression of common PACAP/VIP (VPAC(1) and VPAC(2)) receptors, but not PACAP-specific (PAC(1)) receptors. The pharmacological profile of [(125)I]-VIP binding assays was as follows: VPAC(1) antagonist=VPAC(1) agonist>VIP>VPAC(2) agonist (IC(50)=1.2, 1.5, 2.3 and 30 nM, respectively). In addition, both receptor subtypes are functional since VIP, PACAP-27 or VPAC(1) and VPAC(2) agonists all increased the intracellular levels of cAMP. 4. The expression of both peptides and their receptors is similar in serum-cultured and serum-deprived PC-3 cells. The treatment of serum-deprived PC-3 cells with exogenous VIP or PACAP-27 increases cell number and viability in a dose-dependent manner, as demonstrated by cellular counting and MTT assays. The increased cell survival is exerted through the VPAC(1) receptor, since a VPAC(1), but not VPAC(2), receptor agonist, mimics the effects and a VPAC(1) receptor antagonist blocks it. Moreover, VIP and PACAP-27 inhibit genomic DNA fragmentation in PC-3 cells triggered by serum starvation, and increase the immunoreactivity of the antiapoptotic protein bcl-2. 5. Our results suggest that VIP and PACAP are autocrine/paracrine factors that protect PC-3 cells from apoptosis through VPAC1 receptors.

Inhibition of PC-3 human prostate cancers by analogs of growth hormone-releasing hormone (GH-RH) endowed with vasoactive intestinal peptide (VIP) antagonistic activity

Vasoactive intestinal peptide (VIP) stimulates the proliferation and invasiveness of malignant prostatic cells. Receptors for VIP and the closely related growth hormone-releasing hormone (GH-RH) show considerable homology and are found in prostatic and other carcinomas. Among various analogs of GH-RH synthesized, JV-1-52 is a non-selective VIP/GH-RH antagonist, whereas JV-1-53 is a VIP antagonist devoid of GH-RH antagonistic effect. In our study, nude mice bearing PC-3 human androgen-independent prostate carcinomas were treated with JV-1-52 or JV-1-53 (20 microg/day, s.c.) for 28 days. Both antagonists produced a similar reduction in tumor volume (62-67%, p < 0.01) and tumor weight (59-62%; p < 0.05) vs. controls and extended tumor doubling-time from 9.1 to about 16 days (p < 0.05). To investigate the mechanisms involved, in another study we compared the effects of JV-1-53 with those of somatostatin analog RC-160. VIP antagonist JV-1-53 reduced tumor weight by 67% (p < 0.01) and suppressed the expression of mRNA for c-fos and c-jun oncogenes by about 34% (p < 0.05), without affecting serum levels of insulin-like growth factor-I (IGF-I). In contrast, RC-160 (50 microg/day) reduced serum IGF-I by 19% (p < 0.05), but did not significantly decrease tumor weight. mRNA for VIP and high affinity receptors for VIP were detected on PC-3 tumors. Our results suggest that VIP/GH-RH antagonists can inhibit the growth of androgen-independent prostate cancer by abrogating the autocrine/paracrine mitogenic stimuli of VIP. The ability of GH-RH antagonists to block tumoral VIP receptors, in addition to GH-RH receptors, could be potentially beneficial for prostate cancer therapy.