Vitamin D analogs combined with 5-fluorouracil in human HT-29 colon cancer treatment

Abstract

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.

Vitamin D in cancer chemoprevention

“…These effects appeared to be the consequence of a suppression of gene transcriptional activities and protein expression of survivin and thymidylate synthase, to the enhanced E-cadherin localization in cell membranes and the complex formation of Ecadherin and b-catenin, and repression TCF4 transcriptional activation. Consistent with these observations, on one hand, recent findings by Milczarek et al (2014) showed that calcipotriol may potentiate the antitumor activity of 5-FU in HT-29 colon tumor-bearing mice. These studies also showed that the mechanism of potentiation of 5-FU antitumor was related to the increased expression of p21 and decreased expression of pERK1/2 level which may lead to a decreased expression of thymidylate synthase.…”

“…Experimental observations show that this molecule exerts important effects on cellular differentiation and proliferation in vitro while its effect on calcium metabolism in vivo is negligible (Binderup & Bramm, 1988;Cho et al, 1996). In vitro studies showed that this molecule may regulate cell differentiation and proliferation and exhibits growth-inhibiting effects against several human cancer cell lines including HL-60 and HL60/MX2 promyelocytic leukemia, U937 histiocytic lymphoma, MCF-7, T47D human breast cancer, HT-29 human colon cancer, and human SCC (Colston et al, 1992;Meephansan et al, 2012;Milczarek et al, 2013aMilczarek et al, , 2014. Regarding the possible mechanisms underlying the growth inhibiting and pro-differentiating effects of calcipotriol on tumor cells, in vitro studies highlighted the fact that a 20-h exposure of LNCaP prostate cancer cells and MCF-7 breast cancer cells to this analogue or to BGP-15, a new calcipotriene-derived vitamin D 3 analogue, generated procaspase-3 cleavage and ultimately, apoptosis (Berkovic et al, 2010).…”

Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

“…In this paper, we report the differential anti-proliferative responses of pigmented and non-pigmented rodent melanoma cells to classical metabolites of Vitamin D (1,25(OH) 2 D 3 and 25(OH)D 3 ) and novel 20(OH)D 3 [ 61 ] and calcipotriol [ 62 ], as well as short-side chain secosteroids, pD [ 63 ], 20(OH)pD, 20(OH)pL [ 64 ] and 21(OH)pD [ 36 ]. It should be noted that 20(OH)D 3 , pD, 20(OH)pD and 21(OH)pD are non- or low- calcemic secosteroids that may represent therapeutic alternatives to 1,25(OH) 2 D 3 , which is highly calcemic [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ].…”

Apolipoprotein M increases the expression of vitamin D receptor mRNA in colorectal cancer cells detected with duplex fluorescence reverse transcription-quantitative polymerase chain reaction

“…VDR functions as a transcription factor that regulates various biological processes including the regulation of proliferation, differentiation, apoptosis, angiogenesis, immunity and miRNAs ( 9 ). Studies have reported an antineoplastic effect of VDR, particularly in colorectal cancer; VDR expression is increased in well-differentiated or moderately differentiated colorectal cancer tissues, however is decreased in poorly differentiated tumors ( 20 ), and high VDR expression is correlated with an advantageous prognosis in colorectal patients ( 21 ). In addition, studies in different animal models and cell lines of colorectal cancer support the antineoplastic effect of VDR via various mechanisms ( 22 – 24 ).…”