Induction of apoptosis by vitamin D3 analogue EB1089 in NCI-H929 myeloma cells via activation of caspase 3 and p38 MAP kinase

Vitamin D receptor gene polymorphisms and multiple myeloma: a meta-analysis

Vitamin D acts through the vitamin D receptor (VDR), and vitamin D level decreases in multiple myeloma (MM) patients. Single nucleotide polymorphisms in VDR alter its functions to affect the vitamin D status. This raises the question of whether VDR gene polymorphisms are associated with MM risk, which has been investigated in case‒control studies, but the results have been inconsistent. This meta-analysis aimed to investigate the relationship between VDR gene polymorphisms and MM risk. The PubMed, Web of Science, Medline, Embase, Chinese National Knowledge Infrastructure (CNKI), Chinese Scientific Journal (VIP), Wanfang Databases (WANFANG) were searched from inception to June 1, 2023, without language restriction or publication preference. Pooled odds ratio (OR) and 95% confidence interval (CI) for each variable were calculated. Leave-one-out sensitivity analysis was performed to determine the source of heterogeneity. Publication bias was assessed using Begg' and Egger's tests, and the trim-and-fill method was used to compensate for publication bias. The correlation meta-analysis was conducted using Comprehensive Meta-Analysis 3.0 and STATA 12.0 software. All the included studies were based on Asian populations and involved four VDR gene polymorphisms, TaqI (rs731236), ApaI (rs7975232), BsmI (rs1544410) and FokI (rs2228570). The results showed that TaqI (C vs. T: OR = 1.487, 95% CI 1.052, 2.104, P = 0.025; CC + CT vs. TT: OR = 1.830, 95% CI 1.138, 2.944, P = 0.013), ApaI (T vs. G: OR = 1.292, 95% CI 1.101, 1.517, P = 0.002; TT vs. GG: OR = 1.600, 95% CI 1.106, 2.314, P = 0.013; TG vs. GG: OR 1.305, 95% CI 1.050, 1.622; P = 0.016; TT + TG vs. GG: OR = 1.353, 95% CI 1.103, 1.662, P = 0.004), BsmI (GG vs. AA: OR = 1.918, 95% CI 1.293, 2.844, P = 0.001; GA vs. AA: OR = 1.333, 95% CI 1.058, 1.679, P = 0.015; G vs. A: OR = 1.398, 95% CI 1.180, 1.657, P = 0.000; GG vs. AA + GA: OR = 1.686, 95% CI 1.174, 2.423, P = 0.005), and FokI (T vs. C: OR = 1.687, 95% CI 1.474, 1.931, P = 0.000; TT vs. CC: OR = 2.829, 95% CI 2.066, 3.872, P = 0.000; TC vs. CC: OR = 1.579, 95% CI 1.304, 1.913, P = 0.000, TT + TC vs. CC: OR = 1.771, 95% CI 1.477, 2.125, P = 0.000; TT vs. CC + TC: OR = 2.409, 95% CI 1.814, 3.200, P = 0.000) are associated with MM risk. VDR gene polymorphisms including ApaI, BsmI, TaqI, and FokI are associated with MM risk in Asian populations. Additional studies with large sample sizes and different ethnicities are needed.

Vitamin D and K Supplementation Is Associated with Changes in the Methylation Profile of U266-Multiple Myeloma Cells, Influencing the Proliferative Potential and Resistance to Bortezomib

Multiple myeloma (MM) is a plasma cell malignancy that, despite recent advances in therapy, continues to pose a major challenge to hematologists. Currently, different classes of drugs are applied to treat MM, among others, proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies. Most of them participate in an interplay with the immune system, hijacking its effector functions and redirecting them to anti-MM activity. Therefore, adjuvant therapies boosting the immune system may be potentially beneficial in MM therapy. Vitamin D (VD) and vitamin K (VK) have multiple so called "non-classical" actions. They exhibit various anti-inflammatory and anti-cancer properties. In this paper, we investigated the influence of VD and VK on epigenetic alterations associated with the proliferative potential of MM cells and the development of BTZ resistance. Our results showed that the development of BTZ resistance is associated with a global decrease in DNA methylation. On the contrary, both control MM cells and BTZ-resistant MM cells exposed to VD alone and to the combination of VD and VK exhibit a global increase in methylation. In conclusion, VD and VK in vitro have the potential to induce epigenetic changes that reduce the proliferative potential of plasma cells and may at least partially prevent the development of resistance to BTZ. However, further ex vivo and in vivo studies are needed to confirm the results and introduce new supplementation recommendations as part of adjuvant therapy.

Sunlight, vitamin D, vitamin D receptor polymorphisms, and risk of multiple myeloma: A systematic review

This systematic review examines the relationship with multiple myeloma (MM) risk for sunlight and vitamin D related exposures, including vitamin D supplementation, circulating 25-hydroxyvitamin D concentration, personal ultraviolet B radiation exposure, ambient solar irradiance and vitamin D receptor (VDR) gene polymorphisms We conducted a search for terms related to multiple myeloma, vitamin D, vitamin D receptor, ultraviolet radiation, sunlight, and single nucleotide polymorphism (SNP) using Ovid MEDLINE, Ovid EMBASE, Web of Science and Cochrane CENTRAL. Studies were assessed for risk of bias and quality using the RoB 2.0, ROBINS-E or Q-Genie tools. We identified 13 eligible studies: one randomised controlled trial, two cohort studies, and ten case-control studies, including one nested case-control study and one meta-analysis of genome-wide association studies. We conducted a qualitative synthesis; quantitative synthesis was not appropriate due to study heterogeneity and the small number of studies identified. There was insufficient evidence to support an effect of any sunlight or vitamin D related exposure on MM risk. No polymorphisms in VDR were found to be strongly related to risk for people of European ancestry. Of the identified studies, many had high risk of bias or were of lower quality. Few studies have investigated the association between sunlight and vitamin D related exposures and multiple myeloma risk. The scarcity of high-quality studies makes it difficult to evaluate potential effects of these exposures on MM risk. Further research is necessary to investigate the influence of vitamin D related exposures on risk of multiple myeloma..

Prevalence and clinical outcomes of vitamin D deficiency among Japanese multiple myeloma patients: a single-center observational study

PURPOSE

Vitamin D plays a crucial role in skeletal metabolism and holds significant importance in the pathophysiology of multiple myeloma (MM). This study aimed to determine the prevalence of vitamin D deficiency among Japanese MM patients and its correlation with clinical outcomes.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) levels were assessed in 68 MM patients at a single institution in Japan, analyzing their association with clinical status, laboratory parameters including procollagen type 1 N-propeptide (P1NP) and tartrate-resistant acid phosphatase 5b (TRACP-5b), health-related quality of life (HR-QOL) scores, and overall survival. Additionally, patients with suboptimal 25(OH)D levels received cholecalciferol supplementation (1000 IU/day), and changes in laboratory parameters were monitored.

RESULTS

The median 25(OH)D level was 22 ng/ml, with 32% and 51% of patients exhibiting vitamin D deficiency (< 20 ng/ml) and insufficiency (20-29 ng/ml), respectively. The 25(OH)D levels were unrelated to sex, age, MM stage, or bone lesions, but the vitamin D-deficient group showed a tendency towards lower HR-QOL scores. Among patients achieving complete remission, vitamin D supplementation increased P1NP, while TRACP-5b remained unchanged. Overall survivals from vitamin D measurement and from MM diagnosis were significantly worse in the vitamin D-deficient group compared to the vitamin D-insufficient/-sufficient group.

CONCLUSION

The study identified a considerable number of Japanese MM patients with insufficient serum vitamin D levels, with one-third being deficient. Additionally, vitamin D deficiency predicted poor overall survival in Japanese MM patients. Further investigation is required to determine whether vitamin D supplementation can improve the frailty and survival of vitamin D-deficient MM patients.

Dietary and microbiome evidence in multiple myeloma and other plasma cell disorders

Multiple Myeloma (MM) remains an incurable plasma cell neoplasm. Although little is known about the etiology of MM, several metabolic risk factors such as obesity, diabetes mellitus, diet, and the human intestinal microbiome have been linked to the pathogenesis of MM. In this article, we provide a detailed review of dietary and microbiome factors involved in the pathogenesis of MM and their impact on outcomes. Concurrent with treatment advancements that have improved survival in MM, focused efforts are needed to reduce the burden of MM as well as improve MM specific and overall outcomes once MM is diagnosed. The findings presented in this review will provide a comprehensive guide on the evidence available to date of the impact of dietary and other lifestyle interventions on the gut microbiome and on MM incidence, outcomes, and quality of life. Data generated from such studies can help formulate evidence-based guidelines for healthcare providers to counsel individuals at risk such as those with Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Multiple Myeloma (SMM) as well as MM survivors with respect to their dietary habits.

The Evidence That 25(OH)D3 and VK2 MK-7 Vitamins Influence the Proliferative Potential and Gene Expression Profiles of Multiple Myeloma Cells and the Development of Resistance to Bortezomib

Multiple myeloma (MM) remains an incurable hematological malignancy. Bortezomib (BTZ) is a proteasome inhibitor widely used in MM therapy whose potent activity is often hampered by the development of resistance. The immune system is vital in the pathophysiology of BTZ resistance. Vitamins D (VD) and K (VK) modulate the immune system; therefore, they are potentially beneficial in MM. The aim of the study was to evaluate the effect of BTZ therapy and VD and VK supplementation on the proliferation potential and gene expression profiles of MM cells in terms of the development of BTZ resistance. The U266 MM cell line was incubated three times with BTZ, VD and VK at different timepoints. Then, proliferation assays, RNA sequencing and bioinformatics analysis were performed. We showed BTZ resistance to be mediated by processes related to ATP metabolism and oxidative phosphorylation. The upregulation of genes from the SNORDs family suggests the involvement of epigenetic mechanisms. Supplementation with VD and VK reduced the proliferation of MM cells in both the non-BTZ-resistant and BTZ-resistant phenotypes. VD and VK, by restoring proper metabolism, may have overcome resistance to BTZ in vitro. This observation forms the basis for further clinical trials evaluating VD and VK as potential adjuvant therapies for MM patients.

Cholecalciferol induces apoptosis via autocrine metabolism in epidermoid cervical cancer cells

The anti-cancer effects of vitamin D are of fundamental interest. Cholecalciferol is sequentially hydroxylated endogenously to calcidiol and calcitriol. Here, SiHa epidermoid cervical cancer cells were treated with cholecalciferol (10 - 2600 nM). Cell count and viability were assayed using crystal violet and trypan blue, respectively. Apoptosis was assessed using flow cytometry for early and late biomarkers along with brightfield microscopy and transmission electron microscopy. Autocrine vitamin D metabolism was analysed by qPCR and immunoblotting for activating enzymes; 25-hydroxylases (CYP2R1 and CYP27A1) and 1α-hydroxylase (CYP27B1); the catabolic 24-hydroxylase (CYP24A1); and the vitamin D receptor (VDR). Data were analysed using one-way ANOVA and Bonferroni post hoc test, and p<0.05 was considered significant. After cholecalciferol, cell count (p=0.011) and viability (p<0.0001) decreased, apoptotic biomarkers were positive, mitochondrial membrane potential decreased (p=0.0145), and phosphatidylserine externalisation (p=0.0439); terminal caspase activity (p=0.0025) and nuclear damage (p=0.004) increased. Microscopy showed classical features of apoptosis. Gene and protein expression were concordant. Immunoblots revealed increased CYP2R1 (p = 0.021), VDR (p=0.04) and CYP24A1 (p=0.0274) and decreased CYP27B1 (p=0.031). We conclude that autocrine activation of cholecalciferol to calcidiol may mediate VDR signalling of growth inhibition and apoptosis in SiHa cells.

Vitamin D as a Potential Player in Immunologic Control over Multiple Myeloma Cells: Implications for Adjuvant Therapies

Multiple myeloma (MM) is a plasma cell malignancy with multifactorial etiology. One of the underlying mechanisms is immune system dysregulation. Immunotherapy is being widely introduced into various MM treatment protocols. Nevertheless, little is known about boosting the immune system with supportive treatment. Although classical actions of vitamin D (VD) are very well established, their non-classical actions related to the modulation of the immune system in MM are still a subject of ongoing research. In this literature review, we intend to summarize research conducted on VD and MM, both in vitro and in vivo, with particular emphasis on immune system modulation, the induction of the differentiation of malignant MM cells, synergic activity with anti-MM drugs, and MM-associated peripheral neuropathy.

Anti-tumor effects of vitamin D in glioblastoma: mechanism and therapeutic implications

Glioma is the most prevalent primary brain tumor in adults among which glioblastoma is the most malignant and lethal subtype. Its common resistance to conventional chemotherapeutics calls for the development of alternative or concomitant treatment. Taking advantage of its endocrine function as a neurosteroid, vitamin D has become a target of interest to be used in conjunction with different chemotherapies. In this article, we review the mechanisms through which vitamin D and its analogs induce anti-tumor activity in glioblastoma, and the practical issues relevant to their potential application based on in vitro and in vivo studies. Vitamin D has largely been reported to promote cell cycle arrest and induce cell death to suppress tumor growth in glioblastoma. Glioblastoma cells treated with vitamin D have also shown reduced migratory and invasive phenotypes, and reduced stemness. It is worth noting that vitamin D analogs are able to produce similar inhibitory actions without causing adverse effects such as hypercalcemia in vivo. Upregulation of vitamin D receptors by vitamin D and its analogs may also play a role in enhancing its anti-tumor activity. Based on current findings and taking into consideration its potential cancer-protective effects, the clinical application of vitamin D in glioblastoma treatment and prevention will be discussed. With some study findings subject to controversy, further investigation is warranted to elucidate the mechanism of action of vitamin D and to evaluate relevant issues regarding its treatment efficacy and potential clinical application.

Reviewing the Significance of Vitamin D Substitution in Monoclonal Gammopathies

Vitamin D is a steroid hormone that is essential for bone mineral metabolism and it has several other effects in the body, including anti-cancer actions. Vitamin D causes a reduction in cell growth by interrupting the cell cycle. Moreover, the active form of vitamin D, i.e., 1,25-dihydroxyvitamin D, exerts various effects via its interaction with the vitamin D receptor on the innate and adaptive immune system, which could be relevant in the onset of tumors. Multiple myeloma is a treatable but incurable malignancy characterized by the growth of clonal plasma cells in protective niches in the bone marrow. In patients affected by multiple myeloma, vitamin D deficiency is commonly correlated with an advanced stage of the disease, greater risk of progression, the development of pathological fractures, and a worse prognosis. Changes in the vitamin D receptor often contribute to the occurrence and progress of deficiencies, which can be overcome by supplementation with vitamin D or analogues. However, in spite of the findings available in the literature, there is no clear standard of care and clinical practice varies. Further research is needed to better understand how vitamin D influences outcomes in patients with monoclonal gammopathies.

Unveiling molecular associations of polymorphic variants of VDR gene (FokI, BsmI and ApaI) in multiple myeloma patients of Indian population

Multiple myeloma (MM) is a plasma cell malignancy frequently accompanied with skeletal co-morbidity. Vitamin D (1,25(OH)₂D) is an important mediator of skeletal homeostasis that mediates its effect by binding to vitamin D receptor (VDR), a steroid family receptor and modulates various downstream pathways. Multiple polymorphisms have been determined in VDR gene that witnessed significant association with cancer development and progression. Therefore, in this maiden study, we recruited 75 newly diagnosed MM patients and 75 control subjects. 25-hydroxy vitamin D (25(OH)D) levels were measured in all recruited study subjects. Further, PCR-RFLP was performed in DNA samples of recruited study subjects. Results demonstrated significantly decreased 25(OH)D levels in MM patients compared to controls. Additionally, decreased 25(OH)D levels in MM patients inversely associated with disease severity. Further, single nucleotide polymorphism (SNP) analysis of VDR gene showed significantly higher risk of MM disease development in Ff + ff, Aa + aa, and Bb + bb genotypes. Additionally, FokI f, ApaI a and BsmI b alleles were significantly associated with MM occurrence. In conclusion, this study provided initial evidences of association between 25(OH)D insufficiency, VDR gene polymorphism and MM development. Thus, we suggest that a study involving assessment of 25(OH)D levels and VDR gene polymorphism in large patients' cohort might substantiate their role in MM development which would further provide impetus to give 25(OH)D supplementation along with conventional chemotherapeutic agents for myeloma treatment in future.

A phase 1, open-label, dose escalation study of intravenous paricalcitol in combination with gemcitabine in patients with advanced malignancies

BACKGROUND

Calcitriol, the active analogue of vitamin D, is antiproliferative and enhances the cytotoxicity of several anticancer agents, including gemcitabine. The vitamin D receptor (VDR) is expressed in the tumor stroma and treatment with VDR ligands results in stromal remodeling and increased intratumoral gemcitabine delivery. Furthermore, calcitriol can decrease the activity of the gemcitabine deactivating enzyme cytidine deaminase (CDD). Because hypercalcemia has been the most worrisome calcitriol-related adverse event, the less hypercalcemic agent paricalcitol may be preferred for further investigation.

METHODS

The authors undertook a phase 1 study of gemcitabine in combination with escalating doses of paricalcitol administered weekly intravenously in patients with advanced cancers. A standard 3+3 dose escalation schema was used. Pharmacokinetic assessment of gemcitabine and its metabolite 2',2'-difluorodeoxyuridine (dFdU) was performed. Pharmacodynamic assessment of paricalcitol was performed by measurement of CDD activity in peripheral blood mononuclear cells.

RESULTS

A total of 44 patients were enrolled. Somnolence was the main dose-limiting toxicity. The highest dose of paricalcitol administered was 10.5 µg/kg. Hypercalcemia was infrequent and mild in severity. Paricalcitol did not appear to affect the pharmacokinetics of gemcitabine and dFdU. Evaluation of CDD activity was available for 9 patients; no clear trend for CDD activity after treatment with paricalcitol was established. The overall response rate was 4%; the rate of disease control was 67% in patients who were pretreated with gemcitabine. Progression-free and overall survival were 3.4 months and 6.5 months, respectively.

CONCLUSIONS

Paricalcitol can be administered safely in doses up to 7 µg/kg weekly with fixed dose rate gemcitabine without dose-limiting hypercalcemia. To the best of the authors' knowledge, the maximum tolerated dose has not been formally established to date. Preliminary clinical activity deserves further exploration.

Vitamin D in hematological disorders and malignancies

Commonly known for its critical role in calcium homeostasis and bone mineralization, more recently vitamin D has been implicated in hematological cancer pathogenesis and shows promise as an anti-cancer therapy. Serum levels of 25(OH)D₃ , the precursor to the active form of vitamin D, calcitriol, are frequently lower in patients with hematological disease compared to healthy individuals. This often correlates with worse disease outcome. Furthermore, diseased cells typically highly express the vitamin D receptor, which is required for many of the anti-cancer effects observed in multiple in vivo and in vitro cancer models. In abnormal hematological cells, vitamin D supplementation promotes apoptosis, induces differentiation, inhibits proliferation, sensitizes tumor cells to other anti-cancer therapies, and reduces the production of pro-inflammatory cytokines. Although the dosage of vitamin D required to achieve these effects may induce hypercalcemia in humans, analogs and combinatorial treatments have been developed to circumvent this side effect. Vitamin D and its analogs are well tolerated in clinical trials, and thus, further investigation into the use of these agents in the clinic is warranted. Here, we review the current literature in this field.

Tumor-suppressive activity of 1,25-dihydroxyvitamin D3 against kidney cancer cells via up-regulation of FOXO3

1,25-Dihydroxyvitamin D3 has been known to have the tumor-suppressive activity in various kinds of tumors. However, the exact effect and working mechanism of 1,25-dihydroxyvitamin D3 on the tumor-suppressive activity in human kidney cancer cells remains poorly understood. 1,25-Dihydroxyvitamin D3 has cytotoxicity to ACHN cells and inhibited ACHN cell proliferation compared to the vehicle control. 1,25-Dihydroxyvitamin D3 increased the expression of the cleaved PARP1, active Caspase3, Bax, and Bim but decreased the expression of Bcl2 in ACHN cells. Moreover, 1,25-dihydroxyvitamin D3 down-regulated the phosphorylated Akt and Erk which might lead to apoptosis through activation of FOXO3 in ACHN cells. Transfection of siRNA against FOXO3 attenuated the pro-apoptotic BimEL expression in ACHN cells treated with 1,25-dihydroxyvitamin D3. These results suggest that FOXO3 is involved in the apoptosis induced by 1,25-dihydroxyvitamin D3.

Fish consumption and risk of myeloma: a meta-analysis of epidemiological studies

PURPOSE

The relationship between fish consumption and multiple myeloma (MM) risk has not been consistent across epidemiological studies. We quantitatively assessed the aforementioned association through a systematic review and meta-analysis.

METHODS

PubMed was searched through the end of March 2015 for eligible studies. Fixed or random effects models were used to pool risk estimates. Five case-control studies that involved 1,366 cases and 8,259 controls were identified. Three studies had high methodological quality, and two studies had low quality based on the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

After pooling all risk estimates, a significant inverse association was found between the highest category versus lowest category of fish consumption and MM risk (relative risk = 0.65, 95% confidence interval = 0.46-0.91), with relatively high heterogeneity (I(2) = 55.6%). No evidence of publication bias was detected. The inverse association persisted in all subgroups according to study quality, type, location, and whether there were adjustments for confounders, although statistical significance was not detected in all strata. The dose-response analysis suggested a nonlinear dose-response relationship for the association, with the lowest risk linked to fish consumption once per week.

CONCLUSION

This meta-analysis suggests that the highest versus lowest category of fish consumption is inversely associated with MM risk. Furthermore, a nonlinear dose-response relationship was suggested for the association. Because this evidence is based on a small number of retrospective studies with mixed quality and because high heterogeneity was detected, further prospective studies are warranted to validate our findings and better characterize the relationship.

Antineoplastic effects of 1,25(OH)2D3 and its analogs in breast, prostate and colorectal cancer

The active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is mostly known for its importance in the maintenance of calcium and phosphate homeostasis. However, next to its classical effects on bone, kidney and intestine, 1,25(OH)2D3 also exerts antineoplastic effects on various types of cancer. The use of 1,25(OH)2D3 itself as treatment against neoplasia is hampered by its calcemic side effects. Therefore, 1,25(OH)2D3-derived analogs were developed that are characterized by lower calcemic side effects and stronger antineoplastic effects. This review mainly focuses on the role of 1,25(OH)2D3 in breast, prostate and colorectal cancer (CRC) and the underlying signaling pathways. 1,25(OH)2D3 and its analogs inhibit proliferation, angiogenesis, migration/invasion and induce differentiation and apoptosis in malignant cell lines. Moreover, prostaglandin synthesis and Wnt/b-catenin signaling are also influenced by 1,25(OH)2D3 and its analogs. Human studies indicate an inverse association between serum 25(OH)D3 values and the incidence of certain cancer types. Given the literature, it appears that the epidemiological link between vitamin D3 and cancer is the strongest for CRC, however more intervention studies and randomized placebo-controlled trials are needed to unravel the beneficial dose of 1,25(OH)2D3 and its analogs to induce antineoplastic effects.

Role of vitamin D receptor (VDR) polymorphisms in susceptibility to multiple myeloma in ethnic Kashmiri population

BACKGROUND

Vitamin D regulates many biological processes including bone metabolism, innate immune response, and cell proliferation and differentiation by binding to its receptor VDR. Vitamin D receptor (VDR) gene polymorphisms have been associated with many cancers like breast, colorectal, prostate, and skin. The main aim of this study was to determine whether VDR polymorphisms (ApaI, BsmI and FokI) are associated with increased risk of multiple myeloma.

METHODS

We designed a case control study where 75 multiple myeloma cases were studied for VDR polymorphisms (ApaI, BsmI and FokI) against 150 controls taken from general population. The polymorphisms of VDR gene were investigated using PCR-RFLP method.

RESULTS

We did not find any significant association between ApaI and BsmI polymorphisms and multiple myeloma risk (P>0.05), but FokI polymorphism was significantly associated with increased risk for multiple myeloma. We also found a significant association between the ff variant genotype with creatinine levels, albumin levels, and Durie-Salmon stage III.

CONCLUSION

Our findings suggest that the FokI polymorphism is involved in the increased susceptibility to development and progression in multiple myeloma in the ethnic Kashmiri population. Furthermore these results suggest that ff genotype is associated with higher risk for developing multiple myeloma.

The role of vitamin D in cancer prevention and treatment

Considerable data described in the first part of this review suggest that there is a role for vitamin D in cancer therapy and prevention. Although the preclinical data are persuasive and the epidemiologic data intriguing, no well-designed clinical trial of optimal administration of vitamin D as a cancer therapy has ever been conducted. Had there been the opportunity and insight to develop calcitriol as any other cancer drug, the following studies would have been completed: 1. Definition of the MTD. 2. Definition of a phase II dose, as a single agent and in combination with cytotoxic agents. 3. Studies to define a biologically optimal dose. 4. Phase II (probably randomized phase II) studies of calcitriol alone and chemotherapy ± calcitriol. 5. Then, randomized phase III trials would be conducted and designed such that the only variable was the administration of calcitriol. Prerequisites 1 to 5 have not been completed for calcitriol. Preclinical data provide considerable rationale for continued development of vitamin D analogue-based cancer therapies. However, design of future studies should be informed by good clinical trials design principles and the mistakes of the past not repeated. Such studies may finally provide compelling data to prove whether or not there is a role for vitamin D analogues in cancer therapy.

Use of 1,25α dihydroxyvitamin D3 as a cryosensitizing agent in a murine prostate cancer model

Cryotherapy has emerged as a primary treatment option for prostate cancer (CaP); however, incomplete ablation in the periphery of the cryogenic lesion can lead to recurrence. Accordingly, we investigated the use of a non-toxic adjunctive agent, vitamin D3 (VD3), with cryotherapy to sensitize CaP to low temperature-induced, non-ice rupture-related cell death. VD3 (calcitriol) has been identified as a possible adjunct in the treatment of cancer because of its antiproliferative and antitumorigenic properties. This study aimed to identify the cellular responses and molecular pathways activated when VD3 (calcitriol) is combined with cryotherapy in a murine CaP model. Single freeze-thaw events above -15 °C had little effect on cancer cell viability; however, pretreatment with calcitriol in conjunction with cryo significantly increased cell death. The -15 °C calcitriol combination increased cell death to 55% following a single freeze compared with negligible cell loss by freezing or calcitriol alone. Repeated cryo combination yielded 90% cell death compared with 65% in dual freeze-only cycles. Western blot analysis following calcitriol cryosensitization regimes confirmed the activation of apoptosis. Specifically, proapoptotic Bid and procaspase-3 were found to decrease at 1 h following combination treatment, indicating cleavage to the active forms. A parallel in vivo study confirmed the increased cell death when combining cryotherapy with calcitriol pretreatment. The development of an adjunctive therapy combining calcitriol and cryotherapy represents a potentially highly effective, less toxic, minimally invasive treatment option. These results suggest a role for calcitriol and cryo as a combinatorial treatment for CaP, with the potential for clinical translation.

Rhein lysinate inhibits cell growth by modulating various mitogen-activated protein kinases in cervical cancer cells

In previous studies, we found that rhein lysinate (RHL; the salt of rhein and lysine, easily dissolved in water) inhibited the growth of tumor cells in breast and ovarian cancer and hepatocellular carcinoma. This study aimed to investigate the effect of RHL on the growth of human cervical carcinoma HeLa cells and any underlying mechanisms. RHL inhibited the growth of HeLa cells in a dose- and time-dependent manner. It was also noted that RHL induced apoptosis in HeLa cells in a dose-dependent manner. Mechanistically, RHL triggered HeLa cell apoptosis by increasing the levels of cleaved poly ADP-ribose polymerase (PARP) and caspase-3/7. In addition, the activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK) was a critical mediator in RHL-induced growth inhibition. Inhibition of the expression of p38 MAPK and JNK by pharmacological inhibitors reversed RHL-induced growth inhibition by decreasing the level of cleaved PARP and caspase-3/7. Phosphorylation of the extracellular signal-related kinase (ERK) was increased by RHL; conversely, the MEK inhibitor which inhibits ERK activity, synergistically enhanced RHL-induced growth inhibition in HeLa cells. The results showed that RHL inhibits Hela cell growth through the activation of p38 MAPK and JNK, and is a potential chemotherapeutic agent for cervical cancer.

The role of vitamin D in cancer prevention and treatment

Calcitriol (1,25-dihydroxyvitamin D(3)), the hormonally active form of vitamin D, exerts growth inhibitory and prodifferentiating effects on many malignant cells and retards tumor growth in animal models. Calcitriol is being evaluated as an anticancer agent in several human cancers. The mechanisms underlying the anticancer effects of calcitriol include inhibition of cell proliferation, stimulation of apoptosis, suppression of inflammation, and inhibition of tumor angiogenesis, invasion, and metastasis. This review discusses some of the molecular pathways mediating these anticancer actions of calcitriol and the preclinical data in cell culture and animal models. The clinical trials evaluating the use of calcitriol and its analogues in the treatment of patients with cancer are described. The reasons for the lack of impressive beneficial effects in clinical trials compared with the substantial efficacy seen in preclinical models are discussed.

Impact of vitamin D deficiency on the clinical presentation and prognosis of patients with newly diagnosed multiple myeloma

Vitamin D is a fundamental mediator of skeletal metabolism. It also has important nonskeletal actions. We hypothesized that vitamin D deficiency may play an important role in skeletal morbidity and clinical outcomes in MM. We studied 148 newly diagnosed MM patients from January 1, 2004 through December 31, 2008 who had a serum 25-hydroxyvitamin D [25(OH)D] obtained within 14 days of diagnosis. Subjects with vitamin D deficiency [25(OH)D level less than 50 nmol/L (20 ng/mL)] had higher mean values of serum C-reactive protein (CRP) (2.40 mg/L vs. 0.84 mg/L, P = 0.02) and creatinine (1.75 mg/dL vs. 1.24 mg/dL, P = 0.03) and lower serum albumin values (3.12 g/dL vs. 3.39 g/dL, P = 0.003) compared to subjects without vitamin D deficiency. The prevalence of vitamin D deficiency increased in parallel with International Staging System (ISS): 16% of subjects in Stage I, 20% in Stage II, and 37% in Stage III (P = 0.03) were vitamin D deficient. No differences were detected between the two groups in terms of skeletal morbidity. Association of vitamin D deficiency with higher serum CRP, serum creatinine and ISS stage at time of diagnosis suggests that vitamin D deficiency may portend poorer outcomes in subjects with MM. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.

Treatment of K562 cells with 1,25-dihydroxyvitamin D3 induces distinct alterations in the expression of apoptosis-related genes BCL2, BAX, BCLXL, and p21

Apoptosis, or programmed cell death, is a very important phenomenon in cytotoxicity induced by anticancer treatment. 1α,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)), the active metabolite of vitamin D, inhibits the growth of multiple types of cancer cells including breast, colon, and prostate cancer cell lines. We studied alterations in the mRNA expression levels of BCL2, BAX, CYC, BCL-XL, and VDR genes in the K562 chronic myeloid leukemia cell line in response to treatment with 1,25-(OH)(2)D(3). Morphological observation of K562 cells was evaluated by the staining with Wright's solution. Cell percentage at different phases of the cell cycle was measured, and apoptosis was measured by flow cytometry. The expression levels of the apoptosis-related genes were analyzed by real-time reverse transcription polymerase chain reaction. We found that treatment with 1,25-(OH)(2)D(3) down-regulates BCL2 and BCL-XL mRNA expressions, as well as up-regulates expressions of BAX and p21 mRNA. The expression pattern of CYC and VDR genes were not influenced. However, K562 cells treated with 1,25-(OH)(2)D(3) caused an arrest of cell cycle progression in G1 phase resulting in a decreased number of cells in the S phase, complemented by an accumulation of cells in the G0-G1 phases. Our data show the modulatory effects of 1,25-(OH)(2)D(3) treatment in apoptosis-related genes in K562 cells.

Vitamin D and human health: lessons from vitamin D receptor null mice

The vitamin D endocrine system is essential for calcium and bone homeostasis. The precise mode of action and the full spectrum of activities of the vitamin D hormone, 1,25-dihydroxyvitamin D [1,25-(OH)(2)D], can now be better evaluated by critical analysis of mice with engineered deletion of the vitamin D receptor (VDR). Absence of a functional VDR or the key activating enzyme, 25-OHD-1alpha-hydroxylase (CYP27B1), in mice creates a bone and growth plate phenotype that mimics humans with the same congenital disease or severe vitamin D deficiency. The intestine is the key target for the VDR because high calcium intake, or selective VDR rescue in the intestine, restores a normal bone and growth plate phenotype. The VDR is nearly ubiquitously expressed, and almost all cells respond to 1,25-(OH)(2)D exposure; about 3% of the mouse or human genome is regulated, directly and/or indirectly, by the vitamin D endocrine system, suggesting a more widespread function. VDR-deficient mice, but not vitamin D- or 1alpha-hydroxylase-deficient mice, and man develop total alopecia, indicating that the function of the VDR and its ligand is not fully overlapping. The immune system of VDR- or vitamin D-deficient mice is grossly normal but shows increased sensitivity to autoimmune diseases such as inflammatory bowel disease or type 1 diabetes after exposure to predisposing factors. VDR-deficient mice do not have a spontaneous increase in cancer but are more prone to oncogene- or chemocarcinogen-induced tumors. They also develop high renin hypertension, cardiac hypertrophy, and increased thrombogenicity. Vitamin D deficiency in humans is associated with increased prevalence of diseases, as predicted by the VDR null phenotype. Prospective vitamin D supplementation studies with multiple noncalcemic endpoints are needed to define the benefits of an optimal vitamin D status.

Diet and risk of multiple myeloma in Connecticut women

Multiple myeloma accounts for an estimated 19,900 incident cancer cases per year in the United States. A population-based case-control study, consisting of 179 incident cases and 691 controls, was conducted to examine the impact of diet on multiple myeloma risk. Diet was assessed using a food frequency questionnaire and odds ratios, 95% confidence intervals, and P-trends were calculated across quartiles of consumption. After controlling for potential confounders, we observed inverse associations for cooked tomatoes (P-trend = 0.002), cruciferous vegetables (P-trend = 0.01), fresh fish (P-trend < 0.001), alcohol (P-trend < 0.001), and vitamin A (P-trend < 0.001) with multiple myeloma risk. In contrast, consumption of cream soups (P-trend = 0.01), jello (P-trend = 0.01), ice cream (P-trend = 0.01), and pudding (P-trend < 0.001) were positively associated with multiple myeloma. Furthermore, there was a suggestion that carbohydrate intake may be positively associated, whereas vitamin D and calcium intake may be inversely associated, with multiple myeloma risk. Despite very limited data on dietary factors in relation to multiple myeloma, the findings from this study concur with previously published studies, suggesting an inverse association for consumption of fish, cruciferous vegetables and green vegetables, and a positive association for some dairy products.

Dietary red palm oil reduces ischaemia-reperfusion injury in rats fed a hypercholesterolaemic diet

We have previously shown that dietary red palm oil (RPO) supplementation improves functional recovery in hearts subjected to ischaemia-reperfusion. However, little knowledge exists concerning the effects of RPO supplementation of a high-cholesterol diet on ischaemia-reperfusion injury. The signalling mechanisms responsible for RPO's effects in the presence of cholesterol also remain to be elucidated. Therefore, the aim of the present study was to examine the effects of RPO, given with a high-cholesterol diet, on mitogen-activated protein kinase (MAPK) phosphorylation and apoptosis. Long-Evans rats were fed a control diet, a control diet containing 2% cholesterol, or a control diet containing 2% cholesterol and 7 g RPO per kg (CRPO) for 5 weeks. Hearts were excised and mounted on an isolated working heart perfusion apparatus. Cardiac function was measured after which hearts were freeze-clamped and used to assess MAPK phosphorylation and to evaluate apoptosis. Cholesterol supplementation caused a poor aortic output (AO) recovery compared with the control group (35.5 (sem 6.2) v. 55.4 (sem 2.5) %), but when RPO was added, the percentage AO increased significantly. The cholesterol group's poor AO was associated with a significant increase in p38-MAPK phosphorylation, whereas the CRPO-supplemented group showed as significant reduction in p38-MAPK phosphorylation when compared with the cholesterol-supplemented group. This significant reduction in p38-MAPK was also associated with reduced apoptosis as indicated by significant reductions in caspase-3 and poly(ADP-ribose) polymerase cleavage.

A phase II trial of dexamethasone, vitamin D, and carboplatin in patients with hormone-refractory prostate cancer

BACKGROUND

A Phase II prospective trial was performed to study the efficacy of combination therapy with dexamethasone, calcitriol (1,25-dihydroxyvitamin D3), and carboplatin in patients with hormone-refractory prostate cancer (HRPC). Preclinical data from prostate cancer cell lines suggested a synergistic effect of these therapies.

METHODS

All patients had pathologically confirmed prostate cancer with at least 2 consecutive increases in prostate-specific antigen (PSA). Treatment started with 1 mg of oral dexamethasone given daily with 0.5 mcg of daily calcitriol added at the start of Week 5. Carboplatin (area under the concentration time curve = 2) was started at the beginning of Week 7. Initially, carboplatin was given weekly; however, the protocol was changed later to give carboplatin for the first 4 weeks of a 6-week cycle. Of 40 patients who consented to participate, 6 patients were ineligible or declined to start therapy, leaving 34 treated patients. The median follow-up was 80.7 weeks (range, 11.5-260 weeks).

RESULTS

A formal PSA response was seen in 13 of 34 treated patients (38.2%; 95% confidence interval [95% CI], 22.2-56.4%). The median overall survival was 97.7 weeks (95% CI, 61-114 weeks). Significant adverse events that were observed during the trial period included 2 deaths (myocardial infarction and cardiogenic shock), 4 patients with Grade 3 neutropenia (according to the National Cancer Institute Common Toxicity Criteria, version 2.0), 2 patients with thrombosis, 2 patients with inflammatory bowel symptoms, and 2 patients with new-onset diabetes mellitus.

CONCLUSIONS

The novel combination of dexamethasone, calcitriol, and carboplatin for patients with HRPC produced a PSA response in 13 of 34 patients and had an acceptable side-effect profile.

MAP kinases p38 and JNK are activated by the steroid hormone 1alpha,25(OH)2-vitamin D3 in the C2C12 muscle cell line

In chick skeletal muscle cell primary cultures, we previously demonstrated that 1alpha,25(OH)2-vitamin D3 [1alpha,25(OH)2D3], the hormonally active form of vitamin D, increases the phosphorylation and activity of the extracellular signal-regulated mitogen-activated protein (MAP) kinase isoforms ERK1 and ERK2, their subsequent translocation to the nucleus and involvement in DNA synthesis stimulation. In this study, we show that other members of the MAP kinase superfamily are also activated by the hormone. Using the muscle cell line C2C12 we found that 1alpha,25(OH)2D3 within 1 min phosphorylates and increases the activity of p38 MAPK. The immediately upstream mitogen-activated protein kinase kinases 3/6 (MKK3/MKK6) were also phosphorylated by the hormone suggesting their participation in p38 activation. 1Alpha,25(OH)2D3 was able to dephosphorylate/activate the ubiquitous cytosolic tyrosine kinase c-Src in C2C12 cells and studies with specific inhibitors imply that Src participates in hormone induced-p38 activation. Of relevance, 1alpha,25(OH)2D3 induced in the C2C12 line the stimulation of mitogen-activated protein kinase activating protein kinase 2 (MAPKAP-kinase 2) and subsequent phosphorylation of heat shock protein 27 (HSP27) in a p38 kinase activation-dependent manner. Treatment with the p38 inhibitor, SB203580, blocked p38 phosphorylation caused by the hormone and inhibited the phosphorylation of its downstrean substrates. 1Alpha,25(OH)2D3 also promotes the phosphorylation of c-jun N-terminal protein kinases (JNK 1/2), the response is fast (0.5-1 min) and maximal phosphorylation of the enzyme is observed at physiological doses of 1alpha,25(OH)2D3 (1 nM). The relative contribution of ERK-1/2, p38, and JNK-1/2 and their interrelationships in hormonal regulation of muscle cell proliferation and differentiation remain to be established.

Complementary and alternative medicine for advanced prostate cancer

Complimentary and alternative medicines (CAM) have increased drastically in popularity in the past decade. These are largely in the form of nutritional supplements. Despite a wealth of information sources on the subject, the fundamental problem with CAM therapies is a dearth of evidence-based medicine. Advanced prostate cancer has significant long-term morbidity, and there is a growing interest in alternative and complimentary forms of therapy that will improve the outcomes of patients who have recurrent or advanced prostate cancer while obviating the need for more toxic forms of therapy. In this article we summarize the use of some of the more common CAM nutritional supplements and review the scientific data that are available to support their use.

p38-MAPK and PKB/Akt, possible role players in red palm oil-induced protection of the isolated perfused rat heart?

It has been shown that dietary red palm oil (RPO) supplementation improves reperfusion function. However, no exact protective cellular mechanisms have been established. To determine a potential mechanism for functional improvement, we examined the regulation of both mitogen-activated protein kinases (MAPKs) and PKB/Akt in the presence and absence of dietary RPO supplementation in ischemia/reperfusion-induced injury. Wistar rats were fed a control diet or control diet plus 7 g RPO/kg diet for 6 weeks. Hearts were excised and mounted on an isolated working heart perfusion apparatus. Cardiac function was measured before and after hearts were subjected to 25 min of total global ischemia. Hearts subjected to the same conditions were freeze clamped and used to characterize the degree of phosphorylation of extracellular signal-regulated kinase, p38, c-Jun NH(2)-terminal protein kinase (JNK) and PKB/Akt. Dietary RPO supplementation significantly improved aortic output recovery (72.1 +/- 3.2% vs. 54.0 +/- 3.2%, P < .05). This improved aortic output recovery was associated with significant increases in p38 and PKB/Akt phosphorylation during reperfusion when compared with control hearts. Furthermore, a significant decrease in JNK phosphorylation and attenuation of poly(ADP-ribose) polymerase cleavage occurred in the RPO-supplemented group during reperfusion. Our results suggest that dietary RPO supplementation caused differential phosphorylation of the MAPKs and PKB/Akt during ischemia/reperfusion-induced injury. These changes in phosphorylation were associated with improved functional recovery and reduced cleavage of an apoptotic marker, arguing that dietary RPO supplementation may confer protection via the MAPK and PKB/Akt signaling pathways during ischemia/reperfusion-induced injury.

Mechanism by Which Mammalian Target of Rapamycin Inhibitors Sensitize Multiple Myeloma Cells to Dexamethasone-Induced Apoptosis

Mammalian target of rapamycin (mTOR) inhibitors curtail cap-dependent translation. However, they can also induce post-translational modifications of proteins. We assessed both effects to understand the mechanism by which mTOR inhibitors like rapamycin sensitize multiple myeloma cells to dexamethasone-induced apoptosis. Sensitization was achieved in multiple myeloma cells irrespective of their PTEN or p53 status, enhanced by activation of AKT, and associated with stimulation of both intrinsic and extrinsic pathways of apoptosis. The sensitizing effect was not due to post-translational modifications of the RAFTK kinase, Jun kinase, p38 mitogen-activated protein kinase, or BAD. Sensitization was also not associated with a rapamycin-mediated increase in glucocorticoid receptor reporter expression. However, when cap-dependent translation was prevented by transfection with a mutant 4E-BP1 construct, which is resistant to mTOR-induced phosphorylation, cells responded to dexamethasone with enhanced apoptosis, mirroring the effect of coexposure to rapamycin. Thus, sensitization is mediated by inhibition of cap-dependent translation. A high-throughput screening for translational efficiency identified several antiapoptotic proteins whose translation was inhibited by rapamycin. Immunoblot assay confirmed rapamycin-induced down-regulated expressions of XIAP, CIAP1, HSP-27, and BAG-3, which may play a role in the sensitization to apoptosis. Studies in a xenograft model showed synergistic in vivo antimyeloma effects when dexamethasone was combined with the mTOR inhibitor CCI-779. Synergistic effects were associated with an enhanced multiple myeloma cell apoptosis in vivo. This study supports the strategy of combining dexamethasone with mTOR inhibitors in multiple myeloma and identifies a mechanism by which the synergistic effect is achieved.

Modulation of tyrosine phosphorylation signalling pathways by 1alpha,25(OH)2-vitamin D3

Hormonally active vitamin D(3), 1alpha,25(OH)(2)D(3), interacts with the classic vitamin D nuclear receptor that regulates gene transcription and with a putative cell membrane receptor that mediates rapid biological responses. 1alpha,25(OH)(2)D(3) actions on target tissues regulate: mineral metabolism and intracellular Ca(2+); protein kinase cascades leading to cell proliferation, differentiation and apoptosis; muscle growth and contractility; and the immune system. There is evidence for underlying 1alpha,25(OH)(2)D(3)-mediated protein tyrosine phosphorylation signalling in bone, intestine, muscle, epidermal and cancer cells. Extracellular-signal-regulated kinases-1/2, p38 and/or c-jun N-terminal kinase pathways play important roles in mediating 1alpha,25(OH)(2)D(3) actions. Studies to elucidate key regulatory metabolic steps and crosstalk sites in these pathways would enhance our understanding of the significance of tyrosine phosphorylation cascades in normal 1alpha,25(OH)(2)D(3) physiology, pathophysiology and pharmacology.

High-dose calcitriol and carboplatin in metastatic androgen-independent prostate cancer

Calcitriol acts synergistically with carboplatin in preclinical models of adenocarcinoma of the prostate. The authors sought to test high-dose oral calcitriol in combination with carboplatin in patients with metastatic androgen-independent prostate cancer. Seventeen patients received oral calcitriol (0.5 microg/kg) on day 1 and intravenous carboplatin (AUC 7 or AUC 6 in patients with prior radiation) on day 2, repeated every 4 weeks. PSA response was the primary end point and was defined as a 50% reduction confirmed 4 weeks later. Palliative response (2-point reduction or normalization of pain on the present pain intensity [PPI] scale without increased analgesic consumption) was also examined. One of 17 patients (6%, 95% CI, 0-28) achieved a confirmed PSA response. Four patients (24%, 95% CI, 7-49) had PSA reductions ranging from 24 to 38%. Of the 15 patients with a PPI > or = 1 point on entry, 3 (18%, 95% CI, 4-48) met criteria for palliative response. Treatment-related toxicity was mild and generally similar to that expected with single-agent carboplatin. Despite encouraging preclinical evidence, the addition of oral calcitriol to carboplatin in this study was not associated with an increase in the response rate when compared with the reported activity of carboplatin alone.

Effects of dexamethasone, all-trans retinoic acid, vitamin D(3) and interferon-alpha on FO myeloma cells

BACKGROUND

Since multiple myeloma responds poorly to conventional chemotherapy or radiotherapy, new therapeutic approaches are needed. This study investigated the effects of dexamethasone, all-trans retinoic acid (ATRA), the active metabolite of vitamin D(3) [1,25(OH)(2)D(3)] and interferon-alpha on FO mouse myeloma cells (non-immunoglobulin-secreting myeloma cell line) in single drug or drug combination groups in vitro.

METHODS

Apoptosis ratio and change in cell counts in 4 single drug groups (dexamethasone, ATRA, vitamin D(3) and interferon-alpha) and 6 combination drug groups (dexamethasone + vitamin D(3,) dexamethasone + ATRA, dexamethasone + interferon-alpha, vitamin D(3) + ATRA, vitamin D(3) + interferon-alpha, interferon-alpha + ATRA) were compared with the control group.

RESULTS

When treatment groups were compared with the control group, there was a significant increase in apoptosis in all, but this was most prominent in the group treated with dexamethasone alone. The apoptosis ratios were 0.10 and 6.82% in the control and dexamethasone-only groups, respectively. We also found that there was a significant decrease in cell count, particularly in the dexamethasone-only, ATRA-only, and ATRA-vitamin D(3) combination groups.

CONCLUSION

ATRA, interferon-alpha, vitaminD(3) and particularly dexamethasone have significant effects on FO mouse myeloma cells resulting in a decreased cell count and an increased apoptosis ratio. This study should be repeated with human myeloma cell lines for further information.

Update on hormone-refractory prostate cancer

PURPOSE OF REVIEW

Androgen deprivation therapy is the cornerstone treatment for men with de novo or recurrent metastatic prostate cancer. Unfortunately, androgen deprivation therapy is primarily palliative, with nearly all men progressing to an androgen-independent state. Hormone-refractory prostate cancer presents significant management challenges and is the focus of this review.

RECENT FINDINGS

Investigations into the pathophysiology of hormone-refractory prostate cancer, the exploration of chemotherapeutic combinations, novel biological targets, skeletal protectants, and radiopharmaceuticals, as well as new prognostic tools are expanding the clinician's armamentarium and improving patient outcomes.

SUMMARY

Bisphosphonates and chemotherapy are providing effective palliative approaches. Phase II trials of taxane-based regimens show higher response rates and longer survival than has typically been achieved with existing standards. Two completed randomized phase III studies to be reported in mid-2004 will more definitively answer the question of whether currently available chemotherapy can improve survival.

Calcitriol in cancer treatment: From the lab to the clinic

1,25-Dihydroxyvitamin D (calcitriol), the most active metabolite of vitamin D, has significant antineoplastic activity in preclinical models. Several mechanisms of activity have been proposed. These include inhibition of proliferation associated with cell cycle arrest and, in some models, differentiation, reduction in invasiveness and angiogenesis, and induction of apoptosis. Proposed mechanisms differ between tumor models and experimental conditions, and no unifying hypothesis about the mechanism of antineoplastic activity has emerged. Synergistic and/or additive effects with cytotoxic chemotherapy, radiation, and other cancer drugs have been reported. Significantly supraphysiological concentrations of calcitriol are required for antineoplastic effects. Such concentrations are not achievable in patients when calcitriol is dosed daily due to predictable hypercalcemia and hypercalcuria; however, phase I trials have demonstrated that intermittent dosing allows substantial dose escalation and has produced potentially therapeutic peak calcitriol concentrations. Recently, a phase II study reported encouraging levels of activity for the combination of high-dose calcitriol and docetaxel administered on a weekly schedule in patients with androgen-independent prostate cancer. This regimen is now under study in a placebo-controlled randomized trial in androgen-independent prostate cancer and in phase II studies in several other tumor types. Further work is needed to elucidate the molecular mechanisms of antineoplastic activity and optimal clinical applications of calcitriol in cancer.

Development of weekly high-dose calcitriol based therapy for prostate cancer

Calcitriol, the principal biologically active ligand of the Vitamin D receptor (VDR), has been shown to inhibit cancer cell proliferation in in vitro and in vivo models of prostate cancer and a wide range of other neoplasms. In addition, calcitriol's activity appears to be additive, and in some experimental systems, synergistic with dexamethasone and several cytotoxic chemotherapy agents. While effects on progression through the cell cycle, induction of apoptosis, inhibition of angiogenesis, and reduction in tumor invasiveness have been demonstrated, the exact mechanisms of VDR-mediated antineoplastic activity remain incompletely understood. Antineoplastic activity of calcitriol requires substantially supraphysiologic concentrations of this compound. Dose escalation of calcitriol administered daily was severely limited by predictable hypercalcemia and/or hypercalcuria. This limitation has been overcome with intermittent dosing of calcitriol. At Oregon Health & Science University, weekly oral administration of calcitriol allowed the attainment of peak serum calcitriol concentrations well above 1 nM, a concentration that inhibits prostate cancer proliferation by more than 50% in vitro. Weekly high-dose calcitriol was then combined with weekly docetaxel in a Phase II clinical trial carried out in men with metastatic androgen-independent prostate cancer. Treatment resulted in PSA response (defined as a confirmed 50% reduction) in 81% of patients. This level of activity, as well as the median time to progression of 11.4 months and median survival of 19.5 months, compared favorably to results with docetaxel alone and led to the development of a recently initiated randomized trial of docetaxel with calcitriol or placebo in the same patient population.

Vitamin D enhances caspase-dependent and -independent TNFalpha-induced breast cancer cell death: The role of reactive oxygen species and mitochondria

Calcitriol, the hormonal form of vitamin D, potentiates the activity of some common anticancer drugs and agents of the anticancer immune system, including tumor necrosis factor alpha (TNFalpha). TNFalpha-induced cytotoxicity is due to both caspase-dependent and -independent pathways. Cotreatment with calcitriol enhanced both modes of TNFalpha-induced death in MCF-7 breast cancer cells. It increased caspase-3-like activity as assayed by the cleavage of poly-(ADP-ribose)polymerase and of the fluorogenic substrate ac-DEVD-AMC. It also enhanced TNFalpha-induced caspase-independent cytotoxicity in the presence of the pan-caspase inhibitor zD-2,6-dichlorobenzoyloxymethylketone. The antioxidants N-acetylcysteine, reduced glutathione, lipoic acid and ascorbic acid markedly reduced the enhancing effect of the hormone on TNFalpha-induced caspase activation. N-acetylcysteine and reduced glutathione also decreased caspase-independent cytotoxicity in the presence or absence of calcitriol, indicating that reactive oxygen species (ROS) have a key role in the cross talk between TNFalpha and calcitriol. Mitochondrial damage is common to both TNFalpha-induced caspase-dependent and -independent pathways and may underlie excessive production of ROS. Mitochondrial membrane potential (DeltaPsi) was assessed by the specific potential-sensitive fluorescent probe JC-1. The hormone augmented the drop in DeltaPsi and release of cytochrome c from mitochondria, induced by TNFalpha. The effect of calcitriol on DeltaPsi was mimicked by rotenone, which increased both the drop in DeltaPsi and caspase activation induced by TNFalpha. It is possible that the interaction of TNFalpha and calcitriol on the level of the mitochondria is the underlying mechanism responsible for the enhancement of TNFalpha-induced, ROS-mediated caspase-dependent and -independent cell death.

Antiapoptotic action of 1alpha,25-dihydroxyvitamin D3 in primary human melanocytes

1alpha,25-Dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] has been shown to induce cell growth arrest and to possess differentiation-inducing behaviour in both primary melanocytes and melanoma cell lines. Moreover, in several melanoma cell lines it has been demonstrated that the antiproliferative action is accompanied by an increase in apoptosis. In contrast, here we show that physiological concentrations of 1,25-(OH)(2)D(3) did not induce apoptosis in primary melanocytes despite a cell growth inhibitory effect. Furthermore, treatment with 1,25-(OH)(2)D(3) made melanocytes resistant to several inductors of programmed cell death, including tumour necrosis factor-alpha and ultraviolet radiation. The antiapoptotic effect of 1,25-(OH)(2)D(3) was completely abolished by the addition of N,N-dimethylsphingosine, which blocks the formation of the sphingolipid degradation product sphingosine 1-phosphate (S1P), suggesting a crucial role for this sphingolipid in 1,25-(OH)(2)D(3)-mediated cytoprotection. Indeed, stimulation of melanocytes with S1P also resulted in an antiapoptotic action. In addition, S1P induced cell growth arrest of human melanocytes. This was an unexpected finding, as S1P is generally known as a potent mitogenic molecule in a variety of cells, including fibroblasts. As both 1,25-(OH)(2)D(3) and S1P have been identified to modify the Bcl-2/Bax ratio in epithelial cells, we also measured the expressions of these proteins; however, treatment of melanocytes with either 1,25-(OH)(2)D(3) or S1P did not alter the Bcl-2/Bax ratio. In conclusion, 1,25-(OH)(2)D(3) was shown to protect human melanocytes from apoptosis by formation of S1P, which is opposite to its apoptotic action in diverse melanoma cell lines.

1,25-Dihydroxyvitamin D3 inhibits ultraviolet B-induced apoptosis, Jun kinase activation, and interleukin-6 production in primary human keratinocytes

We investigated the capacity of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] to protect human keratinocytes against the hazardous effects of ultraviolet B (UVB)-irradiation, recognized as the most important etiological factor in the development of skin cancer. Cytoprotective effects of 1,25(OH)(2)D(3) on UVB-irradiated keratinocytes were seen morphologically and quantified using a colorimetric survival assay. Moreover, 1,25(OH)(2)D(3) suppressed UVB-induced apoptotic cell death. An ELISA, detecting DNA-fragmentation, demonstrated that pretreatment of keratinocytes with 1,25(OH)(2)D(3) 1 microM for 24 h reduced UVB-stimulated apoptosis by 55-70%. This suppression required pharmacological concentrations 1,25(OH)(2)D(3) and a preincubation period of several hours. In addition, 1,25(OH)(2)D(3) also inhibited mitochondrial cytochrome c release (90%), a hallmark event of UVB-induced apoptosis. Furthermore, we demonstrated that 1,25(OH)(2)D(3) reduced two important mediators of the UV-response, namely, c-Jun-NH(2)-terminal kinase (JNK) activation and interleukin-6 (IL-6) production. As shown by Western blotting, pretreatment of keratinocytes with 1,25(OH)(2)D(3) 1 microM diminished UVB-stimulated JNK activation with more than 30%. 1,25(OH)(2)D(3) treatment (1 microM) reduced UVB-induced IL-6 mRNA expression and secretion with 75-90%. Taken together, these findings suggest the existence of a photoprotective effect of active vitamin D(3) and create new perspectives for the pharmacological use of active vitamin D compounds in the prevention of UVB-induced skin damage and carcinogenesis.

Vitamin D2 analog 19-nor-1,25-dihydroxyvitamin D2: antitumor activity against leukemia, myeloma, and colon cancer cells

BACKGROUND

1,25-Dihydroxyvitamin D(3) inhibits growth of several types of human cancer cells in vitro, but its therapeutic use is hampered because it causes hypercalcemia. 19-nor-1,25-Dihydroxyvitamin D(2) (paricalcitol) is a noncalcemic vitamin D analog that is approved by the Food and Drug Administration for the treatment of secondary hyperparathyroidism. We investigated the antitumor activity and mechanism of action of paricalcitol in vitro and in vivo.

METHODS

Effects of paricalcitol on proliferation, the cell cycle, differentiation, and apoptosis were examined in cancer cell lines. Effects on tumor growth were examined with colon cancer cell xenografts in nude mice (five in the experimental group and five in the control group). The interaction of paricalcitol with the vitamin D receptor (VDR) in mononuclear spleen cells and myeloid stem cells from wild-type and VDR knockout mice was examined. All statistical tests were two-sided.

RESULTS

Paricalcitol inhibited the proliferation of myeloid leukemia cell lines HL-60, NB-4, and THP-1 cells at an effective dose that inhibited growth 50% (ED(50)) of 2.4-5.8 x 10(-9) M by inducing cell cycle arrest and differentiation. Paricalcitol inhibited the proliferation of NCI-H929 myeloma cells at an ED(50) of 2.0 x 10(-10) M by inducing cell cycle arrest and apoptosis. Paricalcitol also inhibited the proliferation of colon cancer cell lines HT-29 (ED(50) = 1.7 x 10(-8) M) and SW837 (ED(50) = 3.2 x 10(-8) M). HT-29 colon cancer xenografts in paricalcitol-treated nude mice were smaller (1044 mm(3) and 1752 mm(3), difference = 708 mm(3), 95% confidence interval = 311 to 1104 mm(3); P =.03) and weighed less (1487 mg and 4162 mg, difference = 2675 mg, 95% confidence interval = 2103 to 3248 mg; P<.001) than those in vehicle-treated mice. Paricalcitol induced committed myeloid hematopoietic stem cells from wild-type but not from VDR knockout mice to differentiate as macrophages.

CONCLUSION

Paricalcitol has anticancer activity against myeloid leukemia, myeloma, and colon cancer cells that may be mediated through the VDR. Because it has been approved by the Food and Drug Administration, clinical trials of this agent in certain cancers are reasonable.

LIGHT sensitizes IFNgamma-mediated apoptosis of MDA-MB-231 breast cancer cells leading to down-regulation of anti-apoptosis Bcl-2 family members

LIGHT is a new member of the tumor necrosis factor superfamily, which binds to lymphotoxin beta receptor, herpes virus entry mediator, or TR6. This work was carried out to elucidate the molecular mechanism of LIGHT-sensitized, interferon gamma (IFNgamma)-mediated apoptosis of MDA-MB-231 cells. It was revealed that LIGHT treatment resulted in down-regulation of anti-apoptosis Bcl-2 family member: Bcl-2, Bcl-X(L), Bag-1, and Mcl-1; up-regulation of pro-apoptosis Bcl-2 family member: Bak and Ser (112)-phosphor-Bad; down-regulation of pro-apoptosis Bcl-2 member Bax; the other pro-apoptosis member Bid remains unaltered. LIGHT treatment also resulted in activation of caspase-3, caspase-6, caspase-7, caspase-8, caspase-9, DFF45, and PARP. However, caspase activation and caspase activity, especially caspase-3 activity, is not required for LIGHT-induced apoptosis of MDA-MB-231 cells, since caspase-3 inhibitor, benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone, and a broad range caspase inhibitor, benzyloxycarbonyl-val-ala-asp-fluoromethylketone failed to block the apoptosis induced by LIGHT and IFNgamma in MDA-MB-231 cells. In summary, LIGHT-sensitized IFNgamma-mediated apoptosis of MDA-MB-231 cells is probably through down-regulation of anti-apoptosis Bcl-2 family members; it could be caspase (especially caspase-3)-independent, even though extensive caspase activation was observed.

The vitamin D3 analog EB1089 induces apoptosis via a p53-independent mechanism involving p38 MAP kinase activation and suppression of ERK activity in B-cell chronic lymphocytic leukemia cells in vitro

EB1089, a novel vitamin D3 analog, has been shown to have cytotoxic and antiproliferative properties in a variety of malignant cells. However, its potential as a treatment for B-cell chronic lymphocytic leukemia (B-CLL) has not been evaluated. EB1089 induced apoptosis in all of the 102 B-CLL samples tested with a mean LD(50) (the concentration of EB1089 required to kill 50% of cells) value (+/- SD) of 2.1 x 10(-8) M (+/- 1.4 x 10(-8) M). Furthermore, no significant difference was found in the cytotoxicity of EB1089 in B-CLL samples from previously treated and untreated patients (P =.1637). Induction of apoptosis was associated with a reduction in Bcl-2 and Mcl-1 protein expression, but this was evident only in the apoptotic cells. In contrast, the expression of Bax, p21, and p53 was not altered in the viable or apoptotic cells from either B- or T-lymphocyte lineages. EB1089-induced apoptosis was preceded by activation of p38 mitogen-activated protein (MAP) kinase and suppression of extracellular signal-regulated kinase (ERK) activity, and this was associated with downstream activation of caspase-3. The pancaspase inhibitor (Z-VAD-FMK) and the caspase-9 inhibitor (Z-LEHD-FMK) were able to partially abrogate the apoptotic effects of EB1089 but did not affect the phosphorylation of p38 MAP kinase or the suppression of ERK. The B-CLL cells in the study were shown to highly express vitamin D receptor, but an additional receptor-independent mechanism of cell killing cannot be ruled out at this stage. These findings show that EB1089 is a potent apoptosis-inducing agent in B-CLL cells and may be useful in the treatment of B-CLL patients, particularly those with p53 mutations or drug-resistant disease.

Weekly high-dose calcitriol and docetaxel in metastatic androgen-independent prostate cancer

PURPOSE

To determine the safety and efficacy of weekly high-dose oral calcitriol (Rocaltrol, Roche Pharmaceuticals, Basel, Switzerland) and docetaxel (Taxotere, Aventis Pharmaceuticals, Bridgewater, NJ) in patients with metastatic androgen-independent prostate cancer (AIPC).

PATIENTS AND METHODS

Thirty-seven patients were treated with oral calcitriol (0.5 micro g/kg) on day 1 followed by docetaxel (36 mg/m(2)) on day 2, repeated weekly for 6 weeks of an 8-week cycle. Patients maintained a reduced calcium diet and increased oral hydration. Prostate-specific antigen (PSA) response was the primary end point, which was defined as a 50% reduction in PSA level confirmed 4 weeks later.

RESULTS

Thirty of 37 patients (81%; 95% confidence interval [CI], 68% to 94%) achieved a PSA response. Twenty-two patients (59%; 95% CI, 43% to 75%) had a confirmed > 75% reduction in PSA. Eight of the 15 patients with measurable disease (53%; 95% CI, 27% to 79%) had a confirmed partial response. Median time to progression was 11.4 months (95% CI, 8.7 to 14 months), and median survival was 19.5 months (95% CI, 15.3 months to incalculable). Overall survival at 1 year was 89% (95% CI, 74% to 95%). Treatment-related toxicity was generally similar to that expected with single-agent docetaxel. Pharmacokinetics of either calcitriol or docetaxel were not affected by the presence of its companion drug in an exploratory substudy.

CONCLUSION

The combination of weekly oral high-dose calcitriol and weekly docetaxel is a well-tolerated regimen for AIPC. PSA and measurable disease response rates as well as time to progression and survival are promising when compared with contemporary phase II studies of single-agent docetaxel in AIPC. Further study of this regimen is warranted.

Des (1-3) IGF-I-stimulated growth of human stromal BPH cells is inhibited by a vitamin D3 analogue

Prostate growth and differentiation is under the control of androgens not only during fetal life and childhood but also in adulthood, and it has been proposed that increased prostatic concentration of androgens, or increased androgen responsiveness, causes benign prostatic hyperplasia (BPH). However, different androgen ablation strategies such as treatment with GnRH agonists and finasteride resulted in a modest decrease of the hyperplastic prostate volume. In the last few years it became evident that both androgen-dependent and androgen-independent growth factors promote prostate enlargement by inducing cell proliferation or reducing apoptosis. Therefore, new therapeutic strategies, aimed at reducing intraprostatic growth factor signaling, are under investigation. In this study, we report further evidence that a non hypercalcemic-analogue of vitamin D(3), analogue (V) decreases growth factor-induced human BPH cell proliferation and survival. We found that Des (1-3) insulin-like growth factor [Des (1-3) IGF-I], an IGF-I analogue, which does not bind to IGF-binding proteins, is a potent mitogen for BPH stromal cells via a dual mechanism: stimulation of cell growth and inhibition of apoptosis. Similar results were previously reported for another growth factor for BPH cells, keratinocyte growth factor (KGF). Accordingly, we speculate that both KGF and IGF might be involved in the pathogenesis of BPH. We also found analogue (V) not only inhibits the mitogenic activity of growth factors on BPH cells, but even decreased the basal expression of bcl-2, and induced apoptosis. Therefore, vitamin D(3) analogues might be considered for the medical treatment of BPH.