Calcitriol inhibits the growth of MHCC97 heptocellular cell lines by down-modulating c-met and ERK expressions

Vitamin D and reproductive disorders: a comprehensive review with a focus on endometriosis

Vitamin D is a fat-soluble steroid hormone that was initially known only for regulating calcium and phosphorus levels and maintaining bone health. However, it was later discovered that many organs express vitamin D metabolizing enzymes and have a ligand for vitamin D, which regulates the expression of an extensive assortment of genes. As a result, vitamin D is indispensable for the proper function of organs, and its deficiency is believed to be a critical factor in symptoms and disorders such as cardiovascular diseases, autoimmune diseases, and cancers. The significance of vitamin D in reproductive tissues was recognized later, and studies have revealed its crucial role in male and female fertility, as well as proper reproductive function during pregnancy. Vitamin D deficiency has been identified as a risk factor for infertility, gonadal cancers, pregnancy complications, polycystic ovary syndrome, and endometriosis. However, data investigating the association between vitamin D levels and reproductive disorders, including endometriosis, have encountered inconsistencies. Therefore, the present study aims to review existing research on the effect of vitamin D on proper reproductive function, and the role of deficiency in reproductive diseases and specifically focuses on endometriosis.

Changes in MCP-1, HGF, and IGF-1 expression in endometrial stromal cells, PBMCs, and PFMCs of endometriotic women following 1,25(OH)2D3 treatment

1,25(OH)2D3 has anti‐inflammatory and growth inhibitory effects. Our study explored the effect of 1,25(OH)2D3 treatment on the expression of monocyte chemotactic protein‐1 (MCP‐1), hepatocyte growth factor (HGF), and insulin‐like growth factor‐1 (IGF‐1) by peripheral blood mononuclear cells (PBMCs), peritoneal fluid mononuclear cells (PFMCs), endometrial stromal cells (ESCs), and its effect on the proliferation of PBMCs and PFMCs of patients with endometriosis compared with controls. PBMCs, PFMCs, and ESCs were obtained from 10 endometriosis patients and 10 non‐endometriotic individuals. After treating cells with 0.1 μM of 1,25(OH)2D3 for 6, 24, and 48 h, the gene and protein expression of mentioned factors were evaluated by real‐time PCR and ELISA methods, respectively. 1,25(OH)2D3 treatment significantly reduced the protein expression of MCP‐1, HGF, and IGF‐1 in PBMCs and PFMCs of endometriotic patients at 48 h (p < 0.05–<0.01). Also, this treatment significantly reduced MCP‐1, HGF, and IGF‐1 gene and/or protein expression in EESCs and EuESCs at 24 and 48 h (p < 0.05–<0.01). 1,25(OH)2D3 treatment also reduced the proliferation of PBMCs and PFMCs of endometriotic patients compared with controls (p < 0.01). 1,25(OH)2D3 can be considered as a potentially effective agent in the prevention and treatment of endometriosis along with other therapies.

Vitamin D in liver cancer: novel insights and future perspectives

Vitamin D has been a focus of attention in liver cancer due to its direct and indirect antineoplastic effects. This review critically evaluates data from recently published basic and clinical studies investigating the role of vitamin D in liver cancer. Basic studies indicate that vitamin D plays an important role in liver cancer development by suppressing the activity of hepatic stellate cells and Kupffer cells. Furthermore, vitamin D has a direct anti-proliferative, anti-angiogenic, proapoptotic, and prodifferentiative effect on liver cancer cells. Recent investigation suggested several interesting mechanisms of these actions, such as inactivation of Notch signaling, p27 accumulation, and tyrosine-protein kinase Met/extracellular signal-regulated kinases inhibition. On the other hand, data from clinical observational studies, although promising, are still inconclusive. Unfortunately, studies on the effect of vitamin D supplementation were generally focused on short-term outcomes of chronic liver diseases (liver enzyme levels or elastographic finding); therefore, there are still no reliable data on the effect of vitamin D supplementation on liver cancer occurrence or survival.

Vitamin D and Cancer: An Historical Overview of the Epidemiology and Mechanisms

This is a narrative review of the evidence supporting vitamin D’s anticancer actions. The first section reviews the findings from ecological studies of cancer with respect to indices of solar radiation, which found a reduced risk of incidence and mortality for approximately 23 types of cancer. Meta-analyses of observational studies reported the inverse correlations of serum 25-hydroxyvitamin D [25(OH)D] with the incidence of 12 types of cancer. Case-control studies with a 25(OH)D concentration measured near the time of cancer diagnosis are stronger than nested case-control and cohort studies as long follow-up times reduce the correlations due to changes in 25(OH)D with time. There is no evidence that undiagnosed cancer reduces 25(OH)D concentrations unless the cancer is at a very advanced stage. Meta-analyses of cancer incidence with respect to dietary intake have had limited success due to the low amount of vitamin D in most diets. An analysis of 25(OH)D-cancer incidence rates suggests that achieving 80 ng/mL vs. 10 ng/mL would reduce cancer incidence rates by 70 ± 10%. Clinical trials have provided limited support for the UVB-vitamin D-cancer hypothesis due to poor design and execution. In recent decades, many experimental studies in cultured cells and animal models have described a wide range of anticancer effects of vitamin D compounds. This paper will review studies showing the inhibition of tumor cell proliferation, dedifferentiation, and invasion together with the sensitization to proapoptotic agents. Moreover, 1,25-(OH)₂D₃ and other vitamin D receptor agonists modulate the biology of several types of stromal cells such as fibroblasts, endothelial and immune cells in a way that interferes the apparition of metastases. In sum, the available mechanistic data support the global protective action of vitamin D against several important types of cancer.

Vitamin D: Possible Therapeutic Roles in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a unique type of liver cancer instigated by underlying liver diseases. Pre-clinical evidence suggests that HCC progression, like other cancers, could be aided by vitamin D deficiency. Vitamin D is a lipid-soluble hormone usually obtained through sunlight. Vitamin D elucidates its biological responses by binding the vitamin D receptor; thus, promoting skeletal mineralization, and maintain calcium homeostasis. Other reported Vitamin D functions include specific roles in proliferation, angiogenesis, apoptosis, inflammation, and cell differentiation. This review highlighted studies on vitamin D's functional roles in HCC and discussed the specific therapeutic targets from various in vivo, in vitro and clinical studies over the years. Furthermore, it described recent advancements in vitamin D's anticancer effects and its metabolizing enzymes' roles in HCC development. In summary, the review elucidated specific vitamin D-associated target genes that play critical functions in the inhibition of tumorigenesis through inflammation, oxidative stress, invasion, and apoptosis in HCC progression.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Vitamin D reverts resistance to the mTOR inhibitor everolimus in hepatocellular carcinoma through the activation of a miR-375/oncogenes circuit

Primary or acquired resistant mechanisms prevent the employment of individualized therapy with target drugs like the mTOR inhibitor everolimus (EVE) in hepatocellular carcinoma (HCC). The current study evaluated the effect of 1,25(OH)₂Vitamin D (VitD) treatment on EVE sensitivity in established models of HCC cell lines resistant to everolimus (EveR). DNA content and colony formation assays, which measure the proliferative index, revealed that VitD pre-treatment re-sensitizes EveR cells to EVE treatment. The evaluation of epithelial and mesenchymal markers by western blot and immunofluorescence showed that VitD restored an epithelial phenotype in EveR cells, in which prolonged EVE treatment induced transition to mesenchymal phenotype. Moreover, VitD treatment prompted hepatic miRNAs regulation, evaluated by liver miRNA finder qPCR array. In particular, miR-375 expression was up-regulated by VitD in EveR cells, in which miR-375 was down-regulated compared to parental cells, with consequent inhibition of oncogenes involved in drug resistance and epithelial-mesenchymal transition (EMT) such as MTDH, YAP-1 and c-MYC. In conclusion, the results of the current study demonstrated that VitD can re-sensitize HCC cells resistant to EVE treatment triggering miR-375 up-regulation and consequently down-regulating several oncogenes responsible of EMT and drug resistance.

Association of 25-Hydroxyvitamin D with Liver Cancer Incidence and Chronic Liver Disease Mortality in Finnish Male Smokers of the ATBC Study

Background: Although circulating 25-hydroxyvitamin D [25(OH)D] concentrations were linked to liver cancer and chronic liver disease (CLD) in laboratory studies, few epidemiologic studies have addressed the associations.Methods: Within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, we measured 25(OH)D in baseline serum of 202 incident liver cancer cases and 225 CLD deaths that occurred during nearly 25 years of follow-up, and 427 controls. ORs and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. We examined predetermined clinically defined cut-points, and season-specific and season-standardized quartiles.Results: Low serum 25(OH)D concentrations were associated with higher risk of liver cancer (<25 nmol/L vs. ≥50 nmol/L: 1.98; 95% CI, 1.22-3.20; P_trend across categories = 0.003) and CLD mortality (1.93; 95% CI, 1.23-3.03; P_trend = 0.006) in models adjusted for age and date of blood draw. After additional adjustment for body mass index, diabetes, smoking, and other potential confounders, the association remained statistically significant for liver cancer (1.91; 95% CI, 1.16-3.15; P_trend = 0.008), but was somewhat attenuated for CLD mortality (1.67; 95% CI, 1.02-2.75; P_trend = 0.05). Associations were similar for analyses using season-specific and season-standardized quartiles, and after excluding participants with diabetes, or hepatitis B or C.Conclusions: Our results suggest a possible preventive role for vitamin D against liver cancer and CLD, although the importance of the liver for vitamin D metabolism and the lack of information about underlying liver disease makes reverse causality a concern.Impact: Future studies are needed to evaluate associations of vitamin D with liver cancer and liver disease in other populations, particularly those with a different constellation of risk factors. Cancer Epidemiol Biomarkers Prev; 27(9); 1075-82. ©2018 AACR.

1,25-Dihydroxy vitamin D prevents tumorigenesis by inhibiting oxidative stress and inducing tumor cellular senescence in mice

Human epidemiological studies suggest that 1,25(OH)₂ D₃ deficiency might increase cancer incidence, but no spontaneous tumors have been reported in mice lacking 1,25(OH)₂ D₃ or deficient in its receptor. In our study, we detected, for the first time, diverse types of spontaneous tumors in l,25(OH)₂ D₃ deficient mice more than 1 year of age. This was associated with increased oxidative stress, cellular senescence and senescence-associated secretory phenotype molecules, such as hepatocyte growth factor, mediated via its receptor c-Met. Furthermore, 1,25(OH)₂ D₃ prevented spontaneous tumor development. We also demonstrated that l,25(OH)₂ D₃ deficiency accelerates allograft tumor initiation and growth by increasing oxidative stress and DNA damage, activating oncogenes, inactivating tumor suppressor genes, stimulating malignant cell proliferation and inhibiting their senescence; in contrast, supplementation with exogenous l,25(OH)₂ D₃ or antioxidant, or knock-down of the Bmi1 or c-Met oncogene, largely rescued the phenotypes of allograft tumors. Results from our study suggest that 1,25(OH)₂ D₃ deficiency enhances tumorigenesis by increasing malignant cell oxidative stress and DNA damage, stimulating microenvironmental cell senescence and a senescence-associated secretory phenotype, and activating oncogenes and inactivating tumor suppressor genes, thus increasing malignant cell proliferation. Our study provides direct evidence supporting the role of vitamin D deficiency in increasing cancer incidence. Conversely, 1,25(OH)₂ D₃ prevented spontaneous tumor development, suggesting that this inhibitory effect prevents the initiation and progression of tumorigenesis, thus provides a mechanistic basis for 1,25(OH)₂ D₃ to prevent tumorigenesis in an aging organism.

VDR mRNA overexpression is associated with worse prognostic factors in papillary thyroid carcinoma

The purpose of this study was to assess the relationship between vitamin D receptor gene (VDR) expression and prognostic factors in papillary thyroid cancer (PTC). mRNA sequencing and somatic mutation data from The Cancer Genome Atlas (TCGA) were analyzed. VDR mRNA expression was compared to clinicopathologic variables by linear regression. Tree-based classification was applied to find cutoff and patients were split into low and high VDR group. Logistic regression, Kaplan-Meier analysis, differentially expressed gene (DEG) test and pathway analysis were performed to assess the differences between two VDR groups. VDR mRNA expression was elevated in PTC than that in normal thyroid tissue. VDR expressions were high in classic and tall-cell variant PTC and lateral neck node metastasis was present. High VDR group was also associated with classic and tall cell subtype, AJCC stage IV and lower recurrence-free survival. DEG test reveals that 545 genes were upregulated in high VDR group. Thyroid cancer-related pathways were enriched in high VDR group in pathway analyses. VDR mRNA overexpression was correlated with worse prognostic factors such as subtypes of papillary thyroid carcinoma that are known to be worse prognosis, lateral neck node metastasis, advanced stage and recurrence-free survival.

The Effect of Serum Vitamin D on Serum ALT Levels in Healthy Individuals

BACKGROUND

Several studies have examined the relationship between vitamin D (VD) and liver disease but none have explored this relationship in adults with normal liver enzymes. Our aim was to explore an independent association of VD with alanine aminotransferase (ALT) in a large sample of the US adults with liver enzymes in normal range (≤39 U/L).

METHODS

We used the continuous National Health and Nutrition Examination Survey from 2001 to 2006. We excluded individuals with serum ALT>39 U/L. We built linear regression models to estimate unadjusted and adjusted (age, sex, race, diabetes, hypertension, alcohol use, smoking, and body mass index) effect sizes, taking into account the complex probability survey design.

RESULTS

Of the 12,155 participants, 6635 (54.6%) were women, mean±SD age was 49.9±19.4 years, VD was 21.9±9.2 ng/mL, and ALT was 20.9±6.9 U/L. In unadjusted analysis, VD was significantly associated with serum ALT (0.02 U/L/ng/mL of VD, P=0.007). After adjustment for confounders, VD remained statistically significantly associated with serum ALT levels (0.04 U/L, P<0.001). Similarly, individuals in the highest quartile of VD had significantly higher serum levels of ALT than those in the lowest quartile (unadjusted difference=0.98 U/L, P<0.001; adjusted difference=1.21 U/L, P<0.001).

CONCLUSIONS

We found a positive association between VD and ALT after excluding individuals with suspected active liver injury (ALT>39 U/L). The underlying mechanisms for this association are not known and needs further study.

The c-Met Inhibitor MSC2156119J Effectively Inhibits Tumor Growth in Liver Cancer Models

The mesenchymal-epithelial transition factor (c-Met) is a receptor tyrosine kinase with hepatocyte growth factor (HGF) as its only high-affinity ligand. Aberrant activation of c-Met is associated with many human malignancies, including hepatocellular carcinoma (HCC). We investigated the in vivo antitumor and antimetastatic efficacy of the c-Met inhibitor MSC2156119J (EMD 1214063) in patient-derived tumor explants. BALB/c nude mice were inoculated with MHCC97H cells or with tumor fragments of 10 patient-derived primary liver cancer explants selected according to c-Met/HGF expression levels. MSC2156119J (10, 30, and 100 mg/kg) and sorafenib (50 mg/kg) were administered orally as single-agent treatment or in combination, with vehicle as control. Tumor response, metastases formation, and alpha fetoprotein (AFP) levels were measured. MSC2156119J inhibited tumor growth and induced complete regression in mice bearing subcutaneous and orthotopic MHCC97H tumors. AFP levels were undetectable after 5 weeks of MSC2156119J treatment, and the number of metastatic lung foci was reduced. Primary liver explant models with strong c-Met/HGF activation showed increased responsiveness to MSC2156119J, with MSC2156119J showing similar or superior activity to sorafenib. Tumors characterized by low c-Met expression were less sensitive to MSC2156119J. MSC2156119J was better tolerated than sorafenib, and combination therapy did not improve efficacy. These findings indicate that selective c-Met/HGF inhibition with MSC2156119J is associated with marked regression of c-Met high-expressing tumors, supporting its clinical development as an antitumor treatment for HCC patients with active c-Met signaling.

Vitamin D receptor activation down-regulates the small heterodimer partner and increases CYP7A1 to lower cholesterol

BACKGROUND & AIMS

Little is known about the effects of the vitamin D receptor (VDR) on hepatic activity of human cholesterol 7α-hydroxylase (CYP7A1) and cholesterol metabolism. We studied these processes in mice in vivo and mouse and human hepatocytes.

METHODS

Farnesoid X receptor (Fxr)(-/-), small heterodimer partner (Shp)(-/-), and C57BL/6 (wild-type control) mice were fed normal or Western diets for 3 weeks and were then given intraperitoneal injections of vehicle (corn oil) or 1α,25-dihydroxyvitamin D3 (1,25[OH]2D3; 4 doses, 2.5 μg/kg, every other day). Plasma and tissue samples were collected and levels of Vdr, Shp, Cyp7a1, Cyp24a1, and rodent fibroblast growth factor (Fgf) 15 expression, as well as levels of cholesterol, were measured. We studied the regulation of Shp by Vdr using reporter and mobility shift assays in transfected human embryonic kidney 293 cells, quantitative polymerase chain reaction with mouse tissues and mouse and human hepatocytes, and chromatin immunoprecipitation assays with mouse liver.

RESULTS

We first confirmed the presence of Vdr mRNA and protein expression in livers of mice. In mice fed normal diets and given injections of 1,25(OH)2D3, liver and plasma concentrations of 1,25(OH)2D3 increased and decreased in unison. Changes in hepatic Cyp7a1 messenger RNA (mRNA) correlated with those of Cyp24a1 (a Vdr target gene) and inversely with Shp mRNA, but not ileal Fgf15 mRNA. Similarly, incubation with 1,25(OH)2D3 increased levels of Cyp24a1/CYP24A1 and Cyp7a1/CYP7A1 mRNA in mouse and human hepatocytes, and reduced levels of Shp mRNA in mouse hepatocytes. In Fxr(-/-) and wild-type mice with hypercholesterolemia, injection of 1,25(OH)2D3 consistently reduced levels of plasma and liver cholesterol and Shp mRNA, and increased hepatic Cyp7a1 mRNA and protein; these changes were not observed in Shp(-/-) mice given 1,25(OH)2D3 and fed Western diets. Truncation of the human small heterodimer partner (SHP) promoter and deletion analyses revealed VDR-dependent inhibition of SHP, and mobility shift assays showed direct binding of VDR to enhancer regions of SHP. In addition, chromatin immunoprecipitation analysis of livers from mice showed that injection of 1,25(OH)2D3 increased recruitment of Vdr and rodent retinoid X receptor to the Shp promoter.

CONCLUSIONS

Activation of the VDR represses hepatic SHP to increase levels of mouse and human CYP7A1 and reduce cholesterol.

Expression of apoptosis- and vitamin D pathway-related genes in hepatocellular carcinoma

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and therapeutic options are scarce. As they might represent future targets for cancer therapy, the expression of apoptosis-related genes in HCC is of particular interest. In this pilot study, we further examined apoptosis-related genes in human HCC and also focused on vitamin D signaling as this might be a regulator of HCC cell apoptosis.

METHODS

We employed tumor tissue and serum samples from 62 HCC patients as well as 62 healthy controls for these studies. Tissue and serum specimens were analyzed by quantitative RT-PCR, immunohistochemistry and ELISA.

RESULTS

In HCC patients the apoptosis marker M30 was found to be elevated and several pro-apoptotic (TRAIL, FasL and FasR) as well as anti-apoptotic genes (Mcl-1 and Bcl-2) were simultaneously upregulated in tumor tissue and especially tumor-surrounding tissue as compared to healthy control livers. Moreover, vitamin D serum levels were decreased in HCC patients whereas vitamin D receptor mRNA expression was increased in tumor tissue and tumor-surrounding tissue as compared to healthy livers.

CONCLUSIONS

In human HCC, M30 serum levels are elevated indicating an increased cell turnover. Modulation of the vitamin D pathway might be a supportive, pro-apoptotic HCC therapy.

Interaction of vitamin D with membrane-based signaling pathways

Many studies in different biological systems have revealed that 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) modulates signaling pathways triggered at the plasma membrane by agents such as Wnt, transforming growth factor (TGF)-β, epidermal growth factor (EGF), and others. In addition, 1α,25(OH)₂D₃ may affect gene expression by paracrine mechanisms that involve the regulation of cytokine or growth factor secretion by neighboring cells. Moreover, post-transcriptional and post-translational effects of 1α,25(OH)₂D₃ add to or overlap with its classical modulation of gene transcription rate. Together, these findings show that vitamin D receptor (VDR) cannot be considered only as a nuclear-acting, ligand-modulated transcription factor that binds to and controls the transcription of target genes. Instead, available data support the view that much of the complex biological activity of 1α,25(OH)₂D₃ resides in its capacity to interact with membrane-based signaling pathways and to modulate the expression and secretion of paracrine factors. Therefore, we propose that future research in the vitamin D field should focus on the interplay between 1α,25(OH)₂D₃ and agents that act at the plasma membrane, and on the analysis of intercellular communication. Global analyses such as RNA-Seq, transcriptomic arrays, and genome-wide ChIP are expected to dissect the interactions at the gene and molecular levels.

Classical and emerging roles of vitamin D in hepatitis C virus infection

According to the Institute of Medicine, the risk of clinically significant vitamin D deficiency increases at 25-hydroxyvitamin D levels below 20 ng/mL. By this standard, most cirrhotic hepatitis C virus- (HCV-) positive patients and many noncirrhotic patients are vitamin D-deficient. The high prevalence of vitamin D deficiency among HCV patients is a cause for concern for several specific reasons. Classic studies established the importance of vitamin D and calcium in maintaining bone. Vitamin D's beneficial effects on bone are likely to be vital for HCV-infected patients because these individuals have a high prevalence of low bone mineral density. Many pharmaceutical agents reduce bone density and exposure to these drugs may increase bone disease in HCV-positive patients. Bone loss occurs following liver transplantation and bone density is often low in patients with HIV/HCV co-infection who are on combination antiretroviral therapy. Some evidence suggests that ribavirin reduces bone density, underscoring the special need to monitor vitamin D in patients receiving HCV treatment and to prescribe supplements, as appropriate. In addition to its role in calcium metabolism, vitamin D is also an immune modulator that reduces inflammation while enhancing protective immune responses. Higher vitamin D levels are associated with less liver fibrosis and less inflammation in HCV patients. Recent studies show that low vitamin D levels are associated with treatment failure among HCV-infected patients receiving pegylated-interferon and ribavirin. If confirmed, these findings will provide an additional reason to ensure adequate levels of vitamin D. Information about how to monitor vitamin D status and how to use vitamin D supplements most effectively in HCV-infected patients is provided.

Thyroid cancer resistance to vitamin D receptor activation is associated with 24-hydroxylase levels but not the ff FokI polymorphism

BACKGROUND

The vitamin D receptor (VDR) has been studied as a novel target for cancer therapy in many tissue types as VDR ligands decrease cell proliferation in vitro and decrease tumor growth in vivo in sensitive cells. The objective of this study was to analyze the response to VDR agonist therapy in a panel of validated thyroid cancer cells and assess genetic markers predicting sensitivity and resistance to calcitriol and the noncalcemic analog DP006.

METHODS

Thyroid cancer cell lines were analyzed for VDR and RXR protein by Western blot. Cell growth after VDR agonist treatment (calcitriol or DP006) was assessed after 6 days of treatment by viable cell assay. To investigate calcitriol/DP006 resistance in VDR-expressing cells, the VDR was sequenced and 1-α and 24-hydroxylase mRNA expression was assessed.

RESULTS

VDR protein was variably expressed in the thyroid cancer cell lines and its presence was not sufficient for decreased viable cell count in response to calcitriol or DP006. The most sensitive cells (TPC1) have an ff FokI VDR polymorphism and the most resistant cells (HTh7 and 8505C) have an FF FokI VDR. This is a unique finding given that the balance of the literature of VDR polymorphisms describes an association of the ff FokI polymorphism with cancer risk and/or decreased VDR transactivation. 1-α and 24-hydroxylase mRNA expression before and after VDR agonist therapy was examined. 1-α-Hydroxylase levels did not change after calcitriol treatment. However, we found that higher baseline 24-hydroxylase levels and/or lower stimulation of 24-hydroxylase levels after calcitriol treatment were associated with relative resistance to calcitriol/DP006.

CONCLUSIONS

The VDR represents a novel therapeutic target in poorly differentiated thyroid cancer; however, the efficacy of VDR agonist therapy to decrease viable thyroid cancer cell count cannot be predicted solely on the presence of the VDR. The FF FokI VDR genotype and high baseline 24-hydroxylase levels were associated with relative resistance to calcitriol and DP006. Therefore, identifiable markers of sensitivity or resistance to VDR agonist therapy may allow for a personalized use of these agents in poorly differentiated thyroid cancer.

22-oxa-1,25-dihydroxyvitamin D3 efficiently inhibits tumor growth in inoculated mice and primary histoculture of cholangiocarcinoma

BACKGROUND

It is well known that 1α,25-Dihydroxyvitamin D3 (1,25[OH]2 D3) restrains cell proliferation and induces differentiation and apoptosis in normal and tumor cells. The authors of this report recently demonstrated that 1,25(OH)2 D3 effectively inhibits the proliferation of cholangiocarcinoma (CCA) cell lines. The antitumor activity and the underlying mechanism of 22-oxa-D3, an analog of vitamin D, in mice and in tissue cultures from patients with CCA were further explored in the current study.

METHODS

Cell growth and cell cycle distribution were examined in CCA cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Mice were injected subcutaneously with 4×10(6) CCA cells at both flank sides and intraperitoneal injections with phosphate-buffered saline or 22-oxa-D3 (15 μg/kg/day) for 17 days thereafter. Tumors were removed the next day. The expression levels of cyclin D1 and the cyclin-dependent kinase inhibitor p21 were determined by Western blot analysis and immunohistochemistry. Growth inhibition of 22-oxa-D3 in fresh tissue samples from patients with CCA was analyzed by using a histodrug response assay.

RESULTS

22-oxa-D3 effectively suppressed the growth of CCA cell lines in a time-dependent and dose-dependent manner. 22-oxa-D3 arrested CCA cells at G1 phase to S phase by the suppression of cyclin D1 expression and the up-regulation of p21. Supplementation of 22-oxa-D3 to CCA-inoculated mice significantly inhibited tumor growth without hypercalcemia or serious side effects. The treatment also induced cellular apoptosis in tissue samples from patients with CCA.

CONCLUSIONS

22-oxa-D3 effectively suppressed tumor growth in CCA-inoculated mice and induced cellular apoptosis in tissue samples from patients with CCA. The current data encourage further investigation of 1,25(OH)2 D3 or its analogues as therapeutic agents in the treatment of patients with CCA.