microRNAs and DICER1 are regulated by 1,25-dihydroxyvitamin D in prostate stroma

Abstract

Vitamin D deficiency increases the risk of lethal prostate adenocarcinomas (PCa) and the majority of older men are deficient. Although PCa arises from the epithelium, the surrounding stroma has hormonal regulatory control over the epithelium and contributes to carcinogenesis. Herein, we describe regulation of microRNAs (miRs) by the active hormone dihydroxyvitamin D (1,25(OH)2D) in human prostate stroma. 1,25(OH)2D binds the vitamin D receptor (VDR) transcription factor to regulate gene expression, including miRs, which have emerged as potent regulators of protein expression. 1,25(OH)2D -regulated miRs were identified by profiling in primary human prostatic stromal cells (PrS) and three miRs, miR-126-3p, miR 154-5p and miR-21-5p were subsequently validated in laser-capture micro-dissected prostate stromal tissue from a vitamin D3 clinical trial (N=45). Regulation of these miRs by 1,25(OH)2D was VDR-dependent. Network analysis of known and putative mRNA targets of these miRs was enriched with cancer and inflammation pathways, consistent with known roles of stroma and of vitamin D in carcinogenesis. Expression of the miR processing ribonuclease, DICER1, positively correlated with vitamin D metabolite levels in the clinical trial specimens. High epithelial/stromal ratios of DICER1 were significantly associated biochemical recurrence (OR 3.1, p=0.03) in a tissue microarray of 170 matched PCa patients. In summary, these results underscore the role of the prostate stroma in regulating responses to the hormone 1,25(OH)2D and identified miRs and DICER1 as being regulated in human prostate stroma. Regulation of stromal DICER1 by 1,25(OH)2D may also have clinical relevance in protection against aggressive PCa.

High levels of PIWI‐interacting RNAs are present in the small RNA landscape of prostate epithelium from vitamin D clinical trial specimens

“…We previously reported that vitamin D upregulates miR‐100 and miR‐125b in prostate epithelium, which may contribute to its antitumor effects . In prostate stroma, vitamin D upregulated miRs, including miR‐21, and miR biogenesis gene DICER . Vitamin D has also been shown to also modulate miRNA expression in other tissues and serum .…”

“…PrE were grown in PrEGM media (Lonza), for one passage. Primary stromal cells (PrS) were isolated under the same IRB as PrE as described, grown in MCDB media (Sigma) for 1 to 3 passage. RWPE1, PC‐3, LNCaP, 22RV1, and LAPC4 were obtained through ATCC (Manassas, VA) and grown less than 20 passages.…”

Cell-type specific expression of oncogenic and tumor suppressive microRNAs in the human prostate and prostate cancer

“…For xMD, seven consecutive sections were isolated for each sample and combined for RNA 6 extraction. For LCM, prostate stroma and epithelium from benign areas was collected as described earlier by Nonn and colleagues (23,24). Briefly, formalin-fixed paraffin-embedded specimens were deparaffinized, fixed, stained (0.5 % toluidine blue) and microdissected using a LMD-6000 LCM instrument (Leica).…”

“…To further investigate these results, miRNA levels were quantified in a separate set of normal prostate tissues, which were microdissected by LCM at the University of Illinois (Figure 2A, LCM). Total RNA had been previously isolated from normal prostate stroma and epithelium (n = 6) as part of a clinical trial involving oral Vitamin D3 (24). These specimens did not include an internal control, therefore miRNA copies are normalized to RNU6B.…”

Association among plasma 1,25(OH)2D, ratio of 1,25(OH)2D to 25(OH)D, and prostate cancer aggressiveness

“…1,25(OH) 2 D in prostate epithelium positively correlated with microRNAs 100 and 125b that showed tumor suppressive properties in vitro . The same group showed that 1,25(OH) 2 D can regulate microRNAs and DICER protein in prostatic stroma that positively associates with biochemical recurrence . These data suggest that 1,25(OH) 2 D can have diverse effects on both prostatic epithelial and stromal cells and this cross‐talk may be significant in prostate cancer biology.…”