Prostate Cancer (PCa)-related deaths are mostly due to metastasization of poorly differentiated adenocarcinomas often endowed with neuroendocrine differentiation (NED) areas.The SNAI2/Slug gene is a major regulator of cell migration and tumor metastasization. We here assessed its biological significance in NED, and metastatic potential of PCa.SNAI2 expression was down-regulated in most PCa epithelia, in association with gene promoter methylation, except for cell clusters forming: a. the expansion/invasion front of high-grade PCa, b. NED areas, or c. lymph node metastasis.Knockdown of SNAI2 in PC3 cells down-regulated the expression of neural-tissue-associated adhesion molecules, Neural-Cadherin, Neural-Cadherin-2, Neuronal-Cell-Adhesion-Molecule, and of the NED marker Neuron-Specific Enolase, whereas it abolished Chromogranin-A expression. The metastasis-suppressor genes, Nm23-H1 and KISS1, were up-regulated, while the pluripotency genes SOX2, NOTCH1, CD44v6, WWTR1/TAZ and YAP1 were dramatically down-regulated. Over-expression of SNAI2 in DU145 cells substantiated its ability to regulate metastasis-suppressor, NED and pluripotency genes. In PCa and lymph node metastasis, expression of SOX2 and NOTCH1 was highly related to that of SNAI2.In conclusion, I. SNAI2 silencing in PCa may turn-off the expression of NED markers and pluripotency genes, while turning-on that of specific metastasis-suppressors, II. SNAI2 expression in selected PCa cells, by regulating their self-renewal, NED and metastatic potential, endows them with highly malignant properties. SNAI2 may thus constitute a key target for modern approaches to PCa progression.
Keywords: SNAI2/Slug; laser capture microdissection; neuroendocrine differentiation; prostate cancer.