MiRNAs are involved in the progression and regulation of inflammation and the immune response in cancer. Understanding the interplay between miRNAs and inflammation in the prostate may be beneficial for the treatment or prevention of prostate cancer (PCa) with anti-inflammatory agents such as vitamin D. We previously found that vitamin D effectively blocked inflammatory cytokine signaling and secretion in primary cultures of normal prostatic epithelial cells. Because inflammatory signaling relies on the crosstalk between epithelial, stromal, and immune cells, our new studies use a human prostate 3-dimensional co-culture model of primary human prostatic epithelial (PrE) cells and stromal (PrS) cells. Single PrE cells seeded in matrigel were grown into spheroid structures termed prostaspheres (PS). Simulating an inflammatory trigger from immune cells with TNF-α and IL-1α (T+I), we found a prolonged inflammatory response in our co-cultures that persisted beyond 24 hours as compared to the transient response in monolayer cultures. IL-6 expression increased and persisted beyond 24 hours after T+I exposure in both the PrS and PS-PrE cells. However, only in the PS-PrE cells did vitamin D blocked IL-6 expression. Cytokine array profiling revealed that vitamin D decreased expression of many T+I-induced cytokine genes, including TNF, IL-1A, IL-8, CCL7. CCL5, and CXCL10. MicroRNAs are also mediators of inflammation. A miRNA microarray demonstrated that miR-146a, -155, and -223, and other miRNAs were altered by cytokine stimulation in co-culture. MiR-146a is a known mediator of inflammation and vitamin D significantly reduced T+I-stimulated miR-146a expression in both PS-PrE and PrS cells. These data demonstrate that vitamin D is involved in the regulation of inflammation at both the mRNA and the miRNA level in a novel 3D prostasphere co-culture model. As miR-146a is found to be down-regulated in PCa, further studies will determine the role of T+I and/or vitamin D in co-cultures of PS-PrE (normal) and PS-PrECa (Cancer) on miR-146a to further understand vitamin D's inflammatory role in cancer. Our model provides a more in vivo-like method to study inflammation in PCa. We will fully validate these in vitro results in laser-capture-microdissected patient tissue from a vitamin D clinical trial, in which patients were supplemented with 400-40,000 IU/day of vitamin D3 prior to radical prostatectomy. Our results should shed light on the complex inflammatory signaling pathways in the prostate and provide further evidence for anti-inflammatory benefits of vitamin D supplementation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 584. doi:1538-7445.AM2012-584