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

Enhanced Mortality to Metastatic Bladder Cancer Cell Line MB49 in Vasoactive Intestinal Peptide Gene Knockout Mice

To identify if the absence of the vasoactive intestinal peptide (VIP) gene enhances susceptibility to death from metastatic bladder cancer, two strains of mice were injected with MB49 murine bladder cancer cells. The growth and spread of the cancer was measured over a period of 4 weeks in C57BL/6 mice and 5 weeks in VIP knockout (KO) mice. A Kaplan-Meier plot was constructed to compare control C57BL/6 mice and C57BL/6 mice with MB49 vs. VIP KO controls and VIP KO mice with MB49. The wild-type (WT) strain (C57BL/6) contained the VIP gene, while the other strain, VIP knockout backcrossed to C57BL/6 (VIP KO) did not and was thus unable to endogenously produce VIP. VIP KO mice had increased mortality compared to C57BL/6 mice at 4 weeks. The number of ulcers between both groups was not statistically significant. In vitro studies indicated that the presence VIP in high doses reduced MB49 cell growth, as well as macrophage inhibitory factor (MIF), a growth factor in bladder cancer cells. These findings support the concept that VIP may attenuate susceptibility to death from bladder cancer, and that it exerts its effect via downregulation of MIF.

Neuropeptide Levels as well as Neprilysin Activity Decrease in Renal Cell Carcinoma

Calcitonin Gene-related Peptide (CGRP), Vasoactive Intestinal Peptide (VIP) and Substance P (SP) are sensory neuropeptides which may alter cancer growth through modulation of chronic inflammation. We recently reported that SP suppresses breast cancer growth and metastasis through neuroimmune modulation. These neuropeptides are hydrolyzed by Neprilysin (NEP) to bioactive fragments. Decreased activity of NEP was reported in clear cell and chromophobe type renal cell carcinoma (RCC). It is however not known how the levels of neuropeptides hydrolyzed with NEP changes in RCC. Decrease activity of SP and CGRP containing sensory nerve endings was previously reported to increase cancer metastasis in animal models. It is however not known how peptidergic nerve endings are altered in RCC. Hence we here evaluated the levels of neuronal and non-neuronal neuropeptides and NEP activity in RCC including papillary type as well as neighboring uninvolved kidney. A cross-sectional study was conducted in 57 patients undergoing radical nephrectomy and diagnosed with RCC. NEP activity, levels and expression were determined using flourogenic substrate, western blot and qPCR respectively in freshly-frozen tissues. Immunohistochemical analyses were also performed. Neuronal and non-neuronal levels of CGRP, SP and VIP levels were determined using two-step acetic acid extraction. Levels and activity of NEP were markedly decreased in RCC regardless of subtype. Similar levels of VIP were detected in first and second extractions. VIP levels were higher in clear cell and papillary RCC compared to nearby kidney tissue. VIP levels of neighboring kidney tissue of papillary type RCC was significantly lower compared to kidney samples from clear cell RCC. CGRP levels were higher in second extraction. Similar to VIP levels, CGRP levels of neighboring kidney tissue from clear cell and chromophobe type RCC was significantly lower compared to corresponding tumor samples, an effect observed in the second extraction. VIP and CGRP levels of nearby kidney tissue varied subtype dependently demonstrating that different subtypes of RCC alter their local environment differently. Furthermore NEP-induce hydrolysis of VIP creates selective VPAC-1 receptor agonist which has anti-proliferative and anti-inflammatory effects. Hence loss of NEP activity may prevent anti-tumoral effects of VIP on RCC.

Identification of downstream target genes regulated by the nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate signal pathway in pulmonary hypertension

Objective

To investigate the downstream target genes regulated by the nitric oxide–soluble guanylate cyclase–cyclic guanosine monophosphate (NO-sGC-cGMP) signal pathway and their possible roles in the pathogenesis of pulmonary hypertension (PH).

Methods

Digital gene expression tag profiling was performed to identify genes that are differentially expressed after activation of the NO-sGC-cGMP signal pathway in human pulmonary artery smooth muscles cells using 8-bromo-cyclic guanosine monophosphate, BAY 41-2272 and BAY 60-2770. Results were confirmed using real-time polymerase chain reaction. Gene ontology and signal transduction network analyses were also performed.

Results

A number of genes were differentially expressed, including MMP1, SERPINB2, GREM1 and IL8. A total of 68 gene ontology terms and seven pathways were found to be associated with these genes. Most of these genes are involved in cell proliferation, cell migration and apoptosis, which may contribute to the pathological pulmonary vascular remodelling in PH.

Conclusion

These results may provide new insights into the molecular mechanisms of PH.

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.