BackgroundNerves are key factors in prostate cancer (PCa), but the functional role of innervation in prostate cancer is poorly understood. PCa induced neurogenesis and perineural invasion (PNI), are associated with aggressive disease.MethodWe denervated rodent prostates chemically and physically, before orthotopically implanting cancer cells. We also performed a human neoadjuvant clinical trial using botulinum toxin type A (Botox) and saline in the same patient, before prostatectomy.ResultBilateral denervation resulted in reduced tumor incidence and size in mice. Botox treatment in humans resulted in increased apoptosis of cancer cells in the Botox treated side. A similar denervation gene array profile was identified in tumors arising in denervated rodent prostates, in spinal cord injury patients and in the Botox treated side of patients. Denervation induced exhibited a signature gene profile, indicating translation and bioenergetic shutdown. Nerves also regulate basic cellular functions of non‐neoplastic epithelial cells.ConclusionNerves play a role in the homeostasis of normal epithelial tissues and are involved in prostate cancer tumor survival. This study confirms that interactions between human cancer and nerves are essential to disease progression. This work may make a major impact in general cancer treatment strategies, as nerve/cancer interactions are likely important in other cancers as well. Targeting the neural microenvironment may represent a therapeutic approach for the treatment of human prostate cancer.

BACKGROUND Semaphorin 4F (S4F) has roles in embryological axon guidance and is expressed in adults. S4F is involved in cancer-induced neurogenesis. METHODS Prostate cells were transfected with S4F retrovirus. Cells and controls were used for a BrdU incorporation assay (proliferation) and in vitro scratch and matrigel transwell chamber invasion assay (migration). Monoclonal antibodies were developed using baculovirus expressed recombinant GST-S4F and used to immunostain tissue microarrays. Slides were imaged using deconvolution and analyzed using tissue segmentation. Data was correlated with clinico-pathological parameters, other biomarkers and survival analysis performed. Heterogeneity of S4F expression was analyzed with unsupervised clustering algorithms. RESULTS Proliferation rates measured by BrdU incorporation were higher in all S4F transfected cells. S4F over-expression was associated with increased motility of the cancer cells. S4F expression was over expressed in HGPIN/PCa than normal epithelium. S4F expression correlated with seminal vesicle invasion. Patients with high values of S4F in PCa cytoplasm are at significantly higher risk of biochemical recurrence, by univariate and multivariate analysis. S4F cytoplasmic expression in PCa cells also correlates with nerve density in PCa and perineural invasion diameter. Correlations were identified with NFkB and inversely with apoptosis in PNI. CONCLUSION This data demonstrates that S4F is significantly involved in human PCa progression. S4F is a key regulator of the interactions between nerves in the tumor microenvironment and cancer cells. Because of the importance of cancer nerve interaction in the biology of cancer and its clinical implication, S4F can be considered a major therapeutic target.