1-alpha-24-dihydroxyvitamin-d3 and Colonic-Neoplasms

This study was aimed to determine whether hypocalcemic analogs of active forms of vitamins D modulate expression of genes related to stem-like phenotype in colon cancer cell lines HT-29 and HCT-116 undergoing renewal after the treatment with 5-fluorouracil (5-FU). Both lines express vitamin D receptor, but differ in differentiation stage and vitamin D sensitivity. Cells that resisted the 5-FU exposure were treated with synthetic analog of 1,25-dihydroxyvitamin D2 (PRI-1906) and analogs of 1,25-dihydroxyvitamin D3 (PRI-2191 and PRI-2205). Proliferative activity was more profoundly affected by vitamin D analogs in HT-29/5-FU than in HCT-116/5-FU cells. In HT-29/5-FU cells, analogs PRI-1906 and PRI-2191 downregulated the expression of genes related to survival, re-growth, and invasiveness during renewal, while PRI-2205 increased expression of genes related to differentiation only. In HCT-116/5-FU cells, PRI-2191 decreased the expression of stemness- and angiogenesis-related genes, whereas PRI-1906 augmented their expression. The effects in HCT-116/5-FU cells were observed at higher concentrations of the analogs than those used for HT-29/5-FU cells. Out of the series of analogs studied, PRI-2191 might be used to counteract the renewal of both moderately and poorly differentiated cancer cells following conventional treatment.

Topics: Antimetabolites, Antineoplastic; Calcitriol; Cell Self Renewal; Cell Survival; Colonic Neoplasms; Dihydroxycholecalciferols; Drug Resistance, Neoplasm; Drug Synergism; Epithelial-Mesenchymal Transition; Ergocalciferols; Fluorouracil; Gene Expression; HCT116 Cells; HT29 Cells; Humans; Neoplastic Stem Cells; Neovascularization, Pathologic

In the present study, we evaluated the antitumor effect of two synthetic analogs of vitamin D, namely PRI-2191 [(24R)-1,24-dihydroxyvitamin D3] and PRI-2205 (5,6-trans calcipotriol), in combined human colon HT-29 cancer treatment with 5-fluorouracil (5-FU). Mice bearing HT-29 tumors transplanted subcutaneously or orthotopically were injected with vitamin D analogs and 5-FU in various schedules. A statistically significant inhibition of subcutaneous or orthotopic tumor growth was observed as a result of combined therapy. In HT-29 tumors and in cells from in vitro culture, we observed increased vitamin D receptor (VDR) expression after treatment with either PRI-2205 or 5-FU alone, or in combination. Moreover, PRI-2205 decreased the percentage of cells from intestinal tumors in G2/M and S stages and increased sub-G1. Increased VDR expression was also observed after combined treatment of mice with 5-FU and PRI-2191. Moreover, our docking studies showed that PRI-2205 has stronger affinity for VDR, DBP and CAR/RXR ligand binding domains than PRI-2191. PRI-2191 analog, used with 5-FU, increased the percentage of subcutaneous tumor cells in G0/G1 and decreased the percentage in G2/M, S and sub-G1 populations as compared to 5-FU alone. In in vitro studies, we observed increased expression of p21 and p-ERK1/2 diminution via use of both analogs as compared to use of 5-FU alone. Simultaneously, PRI-2191 antagonizes some pro-apoptotic activities of 5-FU in vitro. However, in spite of these disadvantageous effects in terms of apoptosis, the therapeutic effect expressed as tumor growth retardation by PRI-2191 is significant. Our results suggest that the mechanism of potentiation of 5-FU antitumor action by both analogs is realized via increased p21 expression and decreased p-ERK1/2 level which may lead to diminution of thymidylate synthase expression. Higher binding affinity for VDR, DBP, but also for CAR\\RXR ligand binding domain of PRI-2205 may, in part, explain its very low toxicity with sustained anticancer activity.

Topics: Animals; Antimetabolites, Antineoplastic; Calcitriol; Cell Cycle; Colonic Neoplasms; Dihydroxycholecalciferols; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Synergism; Female; Fluorouracil; Gene Expression Regulation, Neoplastic; HT29 Cells; Humans; Mice; Mice, Inbred NOD; Receptors, Calcitriol; Signal Transduction; Vitamin D; Xenograft Model Antitumor Assays

aim: The aim of this study was the evaluation of the antitumor effect of two synthetic analogs of vitamin D, PRI-2191 and PRI-2205 in combined treatment with irinotecan or oxaliplatin on mouse (MC38) and human (HT-29) colon cancer cells.. Mice bearing subcutaneous tumors were injected with vitamin D analogs and with irinotecan or oxaliplatin, according to various schedules.. Statistically significant inhibition of MC38 tumor growth by combined therapy was observed. When analogs were used in combined treatment with irinotecan, survival times of mice were significantly prolonged. We also observed improved antitumor effects in combined treatment with oxaliplatin in mice bearing HT-29 tumors, however, antagonism in life span prolongation was observed. Analog PRI-2191 increased the expression of vitamin D receptor (VDR), retinoic X receptor-α (RXRα) and phosphorylated extracellular signal regulated kinase 1/2 (p-ERK1/2) in HT-29 tumors when used alone. VDR and RXRα expressions were up-regulated by PRI-2191 analog, as compared to oxaliplatin alone.. The obtained results suggest that vitamin D analogs could be used in combined colonic cancer treatment with irinotecan or oxaliplatin. However, the regulation of ERK1/2 expression by both analogs and oxaliplatin may explain the observed antagonistic interactions.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Blotting, Western; Camptothecin; Cell Line, Tumor; Colonic Neoplasms; Dihydroxycholecalciferols; Female; HT29 Cells; Humans; Irinotecan; Mice; Mice, Inbred C57BL; Neoplasms, Experimental; Organoplatinum Compounds; Oxaliplatin; Signal Transduction; Vitamin D; Xenograft Model Antitumor Assays

Mutations in the adenomatous polyposis coli (APC) gene, which initiate almost all human colon cancers, directly target the proto-oncogene, c-myc, by elevating beta-catenin/T-cell factor (TCF) signaling. We have shown that agents ascribed chemopreventive activity for colon cancer in fact also stimulate beta-catenin/TCF activity in vitro. Their effects on c-myc transcription were assayed using a novel variant of fluorescence in situ hybridization that detects c-myc transcription sites in intact nuclei. Increased transcriptional initiation of c-myc induced by the short-chain fatty acid, butyrate, consistent with elevated beta-catenin/TCF activity, was efficiently abrogated by a block to transcriptional elongation, resulting in decreased c-myc expression. 1alpha,25-Dihydroxyvitamin D(3) also induced transcriptional blockage. In contrast, the nonsteroidal anti-inflammatory drug, sulindac, increased c-myc expression, an effect attributable at least in part to its failure to induce transcriptional blockage. We have described a novel approach for evaluating the effects of chemopreventive agents on the expression of a gene critical in colonic tumorigenesis.

Topics: Anticarcinogenic Agents; Butyrates; Colonic Neoplasms; Dihydroxycholecalciferols; DNA Probes; Drug Interactions; Gene Expression Regulation, Neoplastic; Gene Silencing; Genes, myc; Genetic Predisposition to Disease; Humans; Proto-Oncogene Mas; RNA, Messenger; Sulindac; Transcription, Genetic