PMC

MiR-627 suppresses in vivo tumor growth. HCT-116 cell lines stably expressing miR-627 or negative control miRNA were established and miR-627 expression was confirmed by real-time PCR. Negative control miRNA (provided by Invitrogen, does not target any known vertebrate gene) or miR-627 expressing cells were transplanted into nude mice to establish tumor xenografts (five mice per group). Tumor volumes and body weights were measured, (**p<0.01).

Expression of miR-627 in human colon cancer specimens. (A) Total RNA samples isolated from 18 human colon adenocarcinomas and 6 non-tumor colon mucosa were analyzed for miR-627 expression by real-time PCR. Statistical analysis was done with unpaired two-tailed Student’s t-test. (B) The relative miR-627 levels in individual samples were shown compared to one of the normal colon mucosa tissue.

Calcitriol induces miR-627 expression in colon cancer cells. (A) HT-29 cells and HCT-116 cells were treated with 100 nM calcitriol for 24h and total RNA was isolated from the cells and real-time PCR analysis was performed as described in Materials and Methods. (B) HCT-116 cells were transfected with 100 nM negative control miRNA or miR-627 mimic. Cell growth was determined at various time points after transfection by WST-1 assay. (C) HCT-116 cells stably expressing the JMJD1A 3′UTR sponge (to block miR-627) or the JMJD1A 3′UTR sponge with miR-627 binding site mutation (ATTC to TGAG) were treated with various doses of calcitriol for 48h and in vitro cell growth was analyzed using WST-1 assay. (D) Untransfected or pCEP4-Flag-VDR transfected SW620 cells were treated with 100 nM calcitriol for 24 hours, total RNA was isolated and real-time PCR analysis was performed. All of the above experiments have been repeated three times, data shown are mean values + S.D. (*p<0.05, **p<0.01, ***p<0.001).

Calcitriol inhibits the in vitro growth of colon cancer cells. (A) HT-29 and HCT-116 cells were treated with various doses of calcitriol for 48h and in vitro cell growth was analyzed using WST-1 assay as described in Materials and Methods. (B) HCT-116 cells were treated with 500 nM calcitriol for 48h and cell cycle distribution was analyzed by flow cytometry. The experiment was repeated three times; representative results of three independent experiments were shown. The percentages of cells in each phase of cell cycle (mean ± S.D.) are: Control: G1 (60.6 ± 3.2), S (14.5 ± 0.4), G2 (22.5 ± 1.9); Calcitriol: G1 (65.0 ± 2.7), S (12.8 ± 0.4), G2 (21.2 ± 2.0). (C) HCT-116 cells were treated with various doses of calcitriol for 48h and the expression of cell cycle regulatory proteins was analyzed by western blots. The experiment was repeated three times. Representative images of three independent experiments were shown. (D) HCT-116 cells were treated with 500 nM of calcitriol for 48 hours, apoptosis was determined by annexin V staining and flow cytometry. The experiments have been repeated three times, representative results of three independent experiments were shown. Data shown are mean values + SD (*p<0.05, **p<0.01, ***p<0.001).

Calcitriol induces miR-627 expression in tumor xenografts and miR-627 mediates the antitumor activity of calcitriol. (A and B) Nude mice bearing HT-29 xenografts were treated with calcitriol at i.p. doses of 0.1 and 0.4 μg daily for two days. Tumor samples were collected 24h after the second dose and analyzed by real-time PCR (A) and western blotting (B) with the indicated antibodies. The experiments have been repeated three times, data shown are mean values + SD (**p<0.01). (C) Nude mice bearing HT-29 (n=9 per group) xenografts were treated with calcitriol (i.p. doses of 0.4 μg, seven times as indicated by arrows). The same volume of DMSO was administered to the control groups at the same schedule. Tumor volumes and body weights were measured as described in Materials and Methods. (D) Nude mice bearing HCT-116-3′UTR xenografts (transfected with pRNAT-CMV3.2/Puro-3′UTR to stably express the JMJD1A 3′UTR sponge to block miR-627) were treated with calcitriol (i.p. doses of 0.4 μg, seven times as indicated by arrows, the same schedule as that in (C) or DMSO for the control groups, (n=5 per group). Tumor volumes were measured. (E) Nude mice bearing HCT-116-3′UTR-mut xenografts (transfected with pRNAT-CMV3.2/Puro-3′UTR-mut to stably express the JMJD1A 3′UTR sponge with the miR-627 binding site mutated) were treated with calcitriol or DMSO for the control group (n=7 per group) as described in (D). Tumor volumes were measured at indicated time points.

miR-627 targets JMJD1A. (A) Predicted duplex formation between human JMJD1A 3′UTR and miR-627. (B) HCT-116 cells were transfected with GFP-JMJD1A 3′UTR (left) or GFP-JMJD1A 3′UTR-mut (right) plasmids together with plasmids expressing miR-627 or a negative control miRNA. Western blotting was performed with anti-GFP and anti-tubulin antibodies. Relative protein levels were quantified and shown under the gel. The experiment was repeated three times. The mean protein levels ± S.D. are: left panel, NC (1.0 ± 0), miR-627 (0.375 ± 0.007); right panel, NC (1.0 ± 0), miR-627 (0.83 ± 0.09). (C) HCT-116 cells were transfected with pcDNA6.2-GW/EmGFP-miR-negative control or pcDNA6.2-GW/EmGFP-miR627 plasmids. 48 hours after transfection, cell lysates were analyzed by western blots with the indicated antibodies. The experiment was repeated three times. The mean protein levels ± S.D. are: NC (1.0 ± 0), miR-627 (0.26 ± 0.13). (D) HT-29 and HCT-116 cells were treated with various doses of calcitriol for 48h, and western blots were done using the indicated antibodies. Relative protein levels were quantified and shown under the gel. The experiment was repeated three times. (E) HCT-116 cells were transfected with 100 nM LNA-modified miRNA inhibitor specific to miR-627 or the negative control inhibitor, and treated with 500 nM calcitriol for 48h. Total RNA and cell lysates were analyzed by real-time PCR for miR-627 and western blots with the indicated antibodies. The experiment was repeated three times. The mean protein levels ± S.D. are: left panel, Ctr (1.0 ± 0), Calcitriol (0.33 ± 0.08); right panel, Ctr (1.0 ± 0), Calcitriol (1.07 ± 0.17). (F) HCT-116 cells were treated with 500 nM calcitriol for 48 hours. ChIP assay was performed as described in Materials and Methods, using primers specific for the GDF15 promoter and the indicated antibodies. Total RNA was isolated and analyzed for GDF15 expression by real-time PCR. The experiment was repeated three times. Representative images of three independent experiments were shown.