19-Nor-1,25(OH)2D2(a Novel, Noncalcemic Vitamin D Analogue), Combined with Arsenic Trioxide, Has Potent Antitumor Activity against Myeloid Leukemia

Positive Association of Urinary Dimethylarsinic Acid (DMAV) with Serum 25(OH)D in Adults Living in an Area of Water-Borne Arsenicosis in Shanxi, China

Limited studies have demonstrated that inorganic arsenic exposure is positively associated with serum vitamin D levels, although the correlation between urinary arsenic species and serum vitamin D has not been investigated in areas of water-borne arsenicosis. A cross-sectional study of 762 participants was conducted in Wenshui Country, Shanxi Province, a water-borne arsenicosis area. The results showed a positive relationship between urinary arsenic species (inorganic arsenic (iAs), methylarsonic acid (MMAV), dimethylarsinic acid (DMAV) and serum 25(OH)D. Log-binomial regression analysis indicated a 0.4% increase in the risk of vitamin D excess for every 1-unit increment in the Box-Cox transformed urinary DMAV after adjustment for covariates. After stratifying populations by inorganic arsenic methylation metabolic capacity, serum 25(OH)D levels in the populations with iAs% above the median and primary methylation index (PMI) below the median increased by 0.064 ng/mL (95% CI: 0.032 to 0.096) for every one-unit increase in the Box-Cox transformed total arsenic (tAs) levels. Serum 25(OH)D levels increased by 0.592 ng/mL (95% CI: 0.041 to 1.143) for every one-unit rise in the Box-Cox transformed iAs levels in people with skin hyperkeratosis. Overall, our findings support a positive relationship between urinary arsenic species and serum 25(OH)D. It was recommended that those residing in regions with water-borne arsenicosis should take moderate vitamin D supplements to avoid vitamin D poisoning.

Arsenic trioxide induces ferroptosis in neuroblastoma by mediating GPX4 transcriptional inhibition

Neuroblastoma (NB), the most common extracranial solid tumor in childhood, significantly contributes to cancer-related mortality, presenting a dearth of efficacious treatment strategies. Previously, our studies have substantiated the potent cytotoxicity of arsenic trioxide (ATO) against NB cells, however, the specific underlying mechanism remains elusive. Here, we first identified ATO as a novel GPX4 inhibitor, which could trigger the ferroptosis in NB cells. In vitro, ATO significantly inhibited the proliferation and migration ability of NB cells SK-N-AS and SH-SY5Y, and induced ferroptosis. Furthermore, the iron chelator deferoxamine reversed ATO-mediated intracellular reactive oxygen species accumulation and hindered the generation of the lipid peroxidation product malondialdehyde. Conversely, ferric ammonium citrate notably intensified its cytotoxic effects, especially on retinoic acid (RA)-resistant SK-N-AS cells. Subsequently, the quantitative real-time polymerase chain reaction results showed ATO significantly inhibited the transcription of GPX4 in NB cells. Remarkably, immunoblotting analysis revealed that MG132 exhibited a notable effect on elevating GPX4 levels in NB cells. Nevertheless, pretreatment with MG132 failed to reverse the ATO-mediated decrease in GPX4 levels. These findings suggested that ATO reduced the GPX4 expression level in NB cells by mediating GPX4 transcriptional repression rather than facilitating ubiquitinated degradation. In conclusion, our research has successfully indicated that ATO could induce ferroptosis and initiate lipid peroxidation by regulating the transcriptional repression of GPX4, and ATO holds promise as a potential anti-tumor agent in NB, specifically for patients with RA-resistant HR-NB.

Mechanistic update of Trisenox in blood cancer

Acute promyelocytic leukemia (APL)/blood cancer is M3 type of acute myeloid leukemia (AML) formed inside bone marrow through chromosomal translocation mutation usually between chromosome 15 & 17. It accounts around 10% cases of AML worldwide. Trisenox (TX/ATO) is used in chemotherapy for treatment of all age group of APL patients with highest efficacy and survival rate for longer period. High concentration of TX inhibits growth of APL cells by diverse mechanism however, it cures only PML-RARα fusion gene/oncogene containing APL patients. TX resistant APL patients (different oncogenic make up) have been reported from worldwide. This review summarizes updated mechanism of TX action via PML nuclear bodies formation, proteasomal degradation, autophagy, p53 activation, telomerase activity, heteromerization of pRb & E2F, and regulation of signaling mechanism in APL cells. We have also provided important information of combination therapy of TX with other molecules mechanism of action in acute leukemia cells. It provides updated information of TX action for researcher which may help finding new target for further research in APL pathophysiology or new TX resistant APL patients drug designing.

An overview of arsenic trioxide-involved combined treatment algorithms for leukemia: basic concepts and clinical implications

Arsenic trioxide is a first-line treatment drug for acute promyelocytic leukemia, which is also effective for other kinds of leukemia. Its side effects, however, limit its clinical application, especially for patients with complex leukemia symptoms. Combination therapy can effectively alleviate these problems. This review summarizes the research progress on the combination of arsenic trioxide with anticancer drugs, vitamin and vitamin analogs, plant products, and other kinds of drugs in the treatment of leukemia. Additionally, the new progress in arsenic trioxide-induced cardiotoxicity was summarized. This review aims to provide new insights for the rational clinical application of arsenic trioxide.

Combined Vitamin D, Omega-3 Fatty Acids, and a Simple Home Exercise Program May Reduce Cancer Risk Among Active Adults Aged 70 and Older: A Randomized Clinical Trial

Objective: The aim of this study was to test the individual and combined benefit of vitamin D, omega-3, and a simple home strength exercise program on the risk of any invasive cancer. Design: The DO-HEALTH trial is a three-year, multicenter, 2 × 2 × 2 factorial design double-blind, randomized-controlled trial to test the individual and combined benefit of three public health interventions. Setting: The trial was conducted between December 2012 and December 2017 in five European countries. Participants: Generally healthy community-dwelling adults ≥70 years were recruited. Interventions: Supplemental 2000 IU/day of vitamin D3, and/or 1 g/day of marine omega-3s, and/or a simple home strength exercise (SHEP) programme compared to placebo and control exercise. Main outcome: In this pre-defined exploratory analysis, time-to-development of any verified invasive cancer was the primary outcome in an adjusted, intent-to-treat analysis. Results: In total, 2,157 participants (mean age 74.9 years; 61.7% women; 40.7% with 25-OH vitamin D below 20 /ml, 83% at least moderately physically active) were randomized. Over a median follow-up of 2.99 years, 81 invasive cancer cases were diagnosed and verified. For the three individual treatments, the adjusted hazard ratios (HRs, 95% CI, cases intervention versus control) were 0.76 (0.49-1.18; 36 vs. 45) for vitamin D3, 0.70 (0.44-1.09, 32 vs. 49) for omega-3s, and 0.74 (0.48-1.15, 35 vs. 46) for SHEP. For combinations of two treatments, adjusted HRs were 0.53 (0.28-1.00; 15 vs. 28 cases) for omega-3s plus vitamin D3; 0.56 (0.30-1.04; 11 vs. 21) for vitamin D3 plus SHEP; and 0.52 (0.28-0.97; 12 vs. 26 cases) for omega-3s plus SHEP. For all three treatments combined, the adjusted HR was 0.39 (0.18-0.85; 4 vs. 12 cases). Conclusion: Supplementation with daily high-dose vitamin D3 plus omega-3s, combined with SHEP, showed cumulative reduction in the cancer risk in generally healthy and active and largely vitamin D-replete adults ≥70 years. Clinical Trial Registration: ClinicalTrials.gov, Identifier: NCT01745263.

Effect of Vitamin D on Graft-versus-Host Disease

The different cell subsets of the immune system express the vitamin D receptor (VDR). Through the VDR, vitamin D exerts different functions that influence immune responses, as previously shown in different preclinical models. Based on this background, retrospective studies explored the impacts of vitamin D levels on the outcomes of patients undergoing allogeneic hematopoietic stem-cell transplantation, showing that vitamin D deficiency is related to an increased risk of complications, especially graft-versus-host disease. These results were confirmed in a prospective cohort trial, although further studies are required to confirm this data. In addition, the role of vitamin D on the treatment of hematologic malignancies was also explored. Considering this dual effect on both the immune systems and tumor cells of patients with hematologic malignancies, vitamin D might be useful in this setting to decrease both graft-versus-host disease and relapse rates.

Vitamin D: Bolus Is Bogus-A Narrative Review

In this review we summarize the impact of bolus versus daily dosing of vitamin D on 25(OH)D and 1,25(OH)2D levels, as well as on key countervailing factors that block vitamin D functions at the cellular level. Further, we discuss the role of bolus versus daily dosing of vitamin D for several health outcomes, including respiratory infections and coronavirus disease 2019 (COVID-19), rickets, falls and fractures, any cancer, and cancer-related mortality. This discussion appears timely because bolus doses continue to be tested for various disease outcomes despite a growing amount of evidence suggesting lack of efficacy or even detrimental effects of bolus dosing of vitamin D for outcomes where daily dosing at modest levels was effective in the vitamin D deficient. As a result, these discordant results may bias health recommendations for vitamin D if the recommendations are based on meta-analyses combining both daily and bolus dosing trials. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

SUV39H1 is a New Client Protein of Hsp90 Degradated by Chaetocin as a Novel C-Terminal Inhibitor of Hsp90

Hsp90 is often overexpressed with activated form in cancer cells, and many key cellular proteins are dependent upon the Hsp90 machinery (these proteins are called “client protein”). Nowadays, more client proteins and more inhibitors of Hsp90 are being discovered. Chaetocin has been identified as an inhibitor of histone methyl transferase SUV39H1. Herein, we find that Chaetocin is an inhibitor of Hsp90 which binds to the C-terminal of Hsp90α. Chaetocin inhibited a variety of Hsp90 client proteins including AMl1-ETO and BCL-ABL, the mutant fusion-protein in the K562 and HL-60 cells. SUV39H1 mediates epigenetic events in the pathophysiology of hematopoietic disorders. We found that inhibition of Hsp90 by Chaetocin and 17-AAG had ability to induce degradation of SUV39H1 through proteasome pathway. In addition, SUV39H1 interacted with Hsp90 through co-chaperone HOP. These results suggest that SUV39H1 belongs to a client protein of Hsp90. Moreover, Chaetocin was able to induce cell differentiation in the two cells in the concentration range of Hsp90 inhibition. Altogether, our results demonstrate that SUV39H1 is a new client protein of Hsp90 degradated by Chaetocin as a novel C-terminal inhibitor of Hsp90. The study establishes a new relationship of Chaetocin and SUV39H1, and paves an avenue for exploring a new strategy to target SUV39H1 by inhibition of Hsp90 in leukemia.

Novel Combination of Arsenic Trioxide (As2O3) Plus Resveratrol in Inducing Programmed Cell Death of Human Neuroblastoma SK-N-SH Cells

AIM

Arsenic trioxide (As₂O₃), known as pi-shuang and the most toxic compound in traditional Chinese medicine, has been used as an antitumor agent for thousands of years. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a natural phenol that has significant anti-bacterial, anti-fungaI and antiaging activities. Our study aimed to examine the combined anticancer effects of As₂O₃ and resveratrol against human neuroblastoma SK-N-SH cells, and elucidate the underlying intracellular signaling.

MATERIALS AND METHODS

SK-N-SH cells were treated with an extremely low-dose (2-4 μM) of As₂O₃ alone or combined with 75 μg/ml resveratrol for further comparisons. Cell viability, apoptotic signaling as well as synergistic cytotoxic effects were estimated using the MTT assay, microscopy observation, flow cytometric analysis for loss of mitochondrial membrane potential (MMP) and reactive oxygen species (ROS), and typical quantitative western blotting analysis. Student's t-test, and one- and two-way analysis of variance (ANOVA) were used for examination of significant differences.

RESULTS

The combined treatment was more effective than single treatment of As₂O₃ or resveratrol alone in suppressing cell viability, which correlated with the elevation of ROS levels. The intracellular mechanisms of cytotoxicity of As₂O₃ plus resveratrol were revealed as ROS accumulation and relative decrease of MMP, leading to activation of caspase-3 and -9, but not of caspase-1, -7 and-8. Combination treatment reduced the expression of B-cell lymphoma 2 (BCL2), BH3 interacting domain death agonist (BID), and BCL-x/L.

CONCLUSION

Combined treatment at extremely low concentration of two agents from natural products, As₂O₃ and resveratrol, has high potential as a cocktail of anticancer drugs for neuroblastoma.

Oncogenomic disruptions in arsenic-induced carcinogenesis

Chronic exposure to arsenic affects more than 200 million people worldwide, and has been associated with many adverse health effects, including cancer in several organs. There is accumulating evidence that arsenic biotransformation, a step in the elimination of arsenic from the human body, can induce changes at a genetic and epigenetic level, leading to carcinogenesis. At the genetic level, arsenic interferes with key cellular processes such as DNA damage-repair and chromosomal structure, leading to genomic instability. At the epigenetic level, arsenic places a high demand on the cellular methyl pool, leading to global hypomethylation and hypermethylation of specific gene promoters. These arsenic-associated DNA alterations result in the deregulation of both oncogenic and tumour-suppressive genes. Furthermore, recent reports have implicated aberrant expression of non-coding RNAs and the consequential disruption of signaling pathways in the context of arsenic-induced carcinogenesis. This article provides an overview of the oncogenomic anomalies associated with arsenic exposure and conveys the importance of non-coding RNAs in the arsenic-induced carcinogenic process.

Vitamin D Control of Hematopoietic Cell Differentiation and Leukemia

It is now well known that in the mammalian body vitamin D is converted by successive hydroxylations to 1,25-dihydroxyvitamin D (1,25D), a steroid-like hormone with pleiotropic properties. These include important contributions to the control of cell proliferation, survival and differentiation, as well as the regulation of immune responses in disease. Here, we present recent advances in current understanding of the role of 1,25D in myelopoiesis and lymphopoiesis, and the potential of 1,25D and analogs (vitamin D derivatives; VDDs) for the control of hematopoietic malignancies. The reasons for the unimpressive results of most clinical studies of the therapeutic effects of VDDs in leukemia and related diseases may include the lack of a precise rationale for the conduct of these studies. Further, clinical trials to date have generally used extremely heterogeneous patient populations and, in many cases, small numbers of patients, generally without controls. Although low calcemic VDDs have been used and combined with agents that can increase the leukemia cell killing or differentiation effects in acute leukemias, the sequencing of agents used for combination therapy should to be more clearly delineated. Most importantly, it is recommended that in future clinical trials the rationale for the basis of the enhancing action of drug combinations should be clearly articulated and the effects on anticancer immunity should also be evaluated.

Evaluation of Arsenic Trioxide Potential for Lung Cancer Treatment: Assessment of Apoptotic Mechanisms and Oxidative Damage

Background

Lung cancer is one of the most lethal and common cancers in the world, causing up to 3 million deaths annually. The chemotherapeutic drugs that have been used in treating lung cancer include cisplatin-pemetrexed, cisplastin-gencitabinoe, carboplatin-paclitaxel and crizotinib. Arsenic trioxide (ATO) has been used in the treatment of acute promyelocytic leukemia. However, its effects on lung cancer are not known. We hypothesize that ATO may also have a bioactivity against lung cancer, and its mechanisms of action may involve apoptosis, DNA damage and changes in stress-related proteins in lung cancer cells.

Methods

To test the above stated hypothesis, lung carcinoma (A549) cells were used as the test model. The effects of ATO were examined by performing 6-diamidine-2 phenylindole (DAPI) nuclear staining for morphological characterization of apoptosis, flow cytometry analysis for early apoptosis, and western blot analysis for stress-related proteins (Hsp70 and cfos) and apoptotic protein expressions. Also, the single cell gel electrophoresis (Comet) assay was used to evaluate the genotoxic effect.

Results

ATO-induced apoptosis was evidenced by chromatin condensation and formation of apoptotic bodies as revealed by DAPI nuclear staining. Cell shrinkage and membrane blebbing were observed at 4 and 6 µg/ml of ATO. Data from the western blot analysis revealed a significant dose-dependent increase (p < 0.05) in the Hsp 70, caspase 3 and p53 protein expression, and a significant (p < 0.05) decrease in the cfos, and bcl-2 protein expression at 4 and 6 µg/ml of ATO. There was a slight decrease in cytochrome c protein expression at 4 and 6 µg/ ml of ATO. Comet assay data revealed significant dose-dependent increases in the percentages of DNA damage, Comet tail lengths, and Comet tail moment.

Conclusion

Taken together our results indicate that ATO is cytotoxic to lung cancer cells and its bioactivity is associated with oxidative damage, changes in cellular morphology, and apoptosis.

Vitamin D in cancer chemoprevention

CONTEXT

There is increasing evidence that Vitamin D (Vit D) and its metabolites, besides their well-known calcium-related functions, may also exert antiproliferative, pro-differentiating, and immune modulatory effects on tumor cells in vitro and may also delay tumor growth in vivo.

OBJECTIVE

The aim of this review is to provide fresh insight into the most recent advances on the role of Vit D and its analogues as chemopreventive drugs in cancer therapy.

METHODS

A systematic review of experimental and clinical studies on Vit D and cancer was undertaken by using the major electronic health database including ISI Web of Science, Medline, PubMed, Scopus and Google Scholar.

RESULTS AND CONCLUSION

Experimental and clinical observations suggest that Vit D and its analogues may be effective in preventing the malignant transformation and/or the progression of various types of human tumors including breast cancer, prostate cancer, colorectal cancer, and some hematological malignances. These findings suggest the possibility of the clinical use of these molecules as novel potential chemopreventive and anticancer agents.

Monocytic differentiation induced by side-chain modified analogs of vitamin D in ex vivo cells from patients with acute myeloid leukemia

The differentiation-inducing potential of side-chain modified analogs of vitamins D, compared to the reference compound, 1,25-dihydroxyvitamin D3, was studied in blast cells from patients with acute myeloid leukemia and in cell lines. Analogs PRI-1906 and PRI-1907 showed increased cell-differentiation activities, PRI-1907 even at a very low concentration. Our study revealed a high variability of individual patients' blasts in their susceptibility to vitamin D analogs. The blasts of the patients with normal karyotype and with mutated NPM1 reacted to analogs with stronger differentiation than the blasts of the remaining patients, while the blasts with mutated FLT3 receptor reacted with weaker differentiation than the remaining blasts.

Vitamin D nutritional policy needs a vision for the future

Historically vitamin D is known to be essential for normal bone growth and quality, and thus appropriate dietary vitamin D supplementation can eliminate vitamin D deficiency childhood rickets and adult osteomalacia. In spite of many government and medical associations' worldwide guidelines for the reference daily intake (RDI) of vitamin D, scientists and nutritionists from many countries agree that at present about half of elderly North Americans and Western Europeans and probably also of the rest of the world are not receiving enough vitamin D to maintain healthy bone. In addition, over the past decade there has been a dramatic increase in our understanding of the many biological actions that result from vitamin D acting through its daughter steroid hormone, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] in collaboration with its cognate vitamin D receptor (VDR). Consequently, evidence has accumulated that beside intestine and bone, there are five additional physiological systems where the VDR with 1alpha,25(OH)(2)D generates biological responses. These include the immune system (both the innate and adaptive), pancreas and metabolic homeostasis, heart-cardiovascular, muscle and brain systems as well as the control of the cell cycle, and thus of the disease process of cancer. Acting through the VDR, 1alpha,25(OH)(2)D(3) can produce a wide array of favorable biological effects that collectively are projected to contribute to the improvement of human health. Responsible medicine demands that worldwide vitamin D nutritional guidelines reflect current scientific knowledge about vitamin D's spectrum of activities. Thus, worldwide vitamin D nutritional policy is now at a crossroads. This paper presents several proposed policy changes with regard to the amount of vitamin D daily intake that if implemented will maximize vitamin D's contribution to reducing the frequency of many diseases, which would then increase the quality and longevity of life and significantly reduce the cost of medical care worldwide.

Different susceptibilities to 1,25-dihydroxyvitamin D3-induced differentiation of AML cells carrying various mutations

This study was designed to compare the differentiation-inducing potential of 1,25-dihydroxyvitamin D(3) (1,25D) with some analogs (VDAs) in a panel of acute myeloid leukemia (AML) cell lines and in blast cells isolated from patients with AML. Of the cell lines studied, HL60 proved to be the most sensitive to each of the differentiation-inducing agents when compared to THP-1, NB-4 and U-937 cell lines. Three of the VDAs tested (PRI-1906, PRI-2191 and PRI-2201) were similarly effective as 1,25D in all the cell lines tested. However, blast cells from AML showed a varying sensitivity towards 1,25D. For example, blast cells isolated from patients in which the whole or part of chromosome 7 was deleted were extremely sensitive to 1,25D and its analogs. In contrast, 1,25D failed to increase the expression of differentiation markers in blast cells isolated from patients carrying activating mutations in Flt3 gene. Since, the expression of vitamin D receptor (VDR) in cells with Flt3 mutations was increased to the same extent as in other AML cells this suggests that failure of these cells to differentiate lies downstream of the receptor. That blast cells with different cytogenetic abnormalities have dissimilar responses to 1,25D and its analogs, may have implications in the use of 1,25D as a 'differentiation therapy' for myeloid leukemias. The analog PRI-2191 (tacalcitol) was found to be the most potent in inducing patient's cells differentiation.

Vitamin D3-driven signals for myeloid cell differentiation--implications for differentiation therapy

Primitive myeloid leukemic cell lines can be driven to differentiate to monocyte-like cells by 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), and, therefore, 1,25(OH)(2)D(3) may be useful in differentiation therapy of myeloid leukemia and myelodysplastic syndromes (MDS). Recent studies have provided important insights into the mechanism of 1,25(OH)(2)D(3)-stimulated differentiation. For myeloid progenitors to complete monocytic differentiation a complex network of intracellular signals has to be activated and/or inactivated in a precise temporal and spatial pattern. 1,25(OH)(2)D(3) achieves this change to the 'signaling landscape' by (i) direct genomic modulation of the level of expression of key regulators of cell signaling and differentiation pathways, and (ii) activation of intracellular signaling pathways. An improved understanding of the mode of action of 1,25(OH)(2)D(3) is facilitating the development of new therapeutic regimens.

RRR-alpha-vitamin E succinate potentiates the antitumor effect of calcitriol in prostate cancer without overt side effects

PURPOSE

To determine the antitumor efficacy of using calcitriol combined with RRR-alpha-vitamin E succinate (VES) on prostate cancer.

EXPERIMENTAL DESIGN

The effects of VES or VES in combination with calcitriol on the calcitriol target genes were evaluated by Western blot and real-time PCR. The antiproliferation effect of the combination in prostate cancer cells was evaluated by the combination index method. The role of the vitamin D(3) receptor (VDR) in the enhanced antitumor effects of the combination was confirmed by small interfering RNA knockdown strategy. Xenograft-bearing mice were used to reaffirm the antitumor efficacy of this combination. Pathohistology analyses and expressions of VDR and its target genes were analyzed in untreated and treated tumors.

RESULTS

VES selectively increased VDR protein in different prostate cancer cells. Low doses of calcitriol combined with VES were significantly superior to the additive effect of individual treatments against prostate cancer cell proliferation. The expression of VDR target genes involved in antiproliferation were further sensitized in the presence of VES. Knockdown of VDR expression abolished the combination benefits in LNCaP and PC3 cells. Consistently, in prostate cancer xenograft models, VES enhanced the therapeutic efficacy of a tolerated dose of calcitriol yet without overt evidence of systemic toxicity and hypercalcemia. This notable in vivo effect was also accompanied by up-regulation of VDR target genes.

CONCLUSIONS

Low-dose calcitriol combined with vitamin E analogue could be a solution to the calcemic side effect. The demonstration of superior antitumor activity of low-dose calcitriol plus VES provides the preclinical basis for developing a useful therapeutic strategy for prostate cancer.

Synergistic antileukemic activity of carnosic acid-rich rosemary extract and the 19-nor Gemini vitamin D analogue in a mouse model of systemic acute myeloid leukemia

OBJECTIVE

Differentiation therapy with the hormonal form of vitamin D, 1alpha,25-dihydroxyvitamin D(3) (1,25D(3)), is a promising approach to treatment of acute myeloid leukemia (AML); however, 1,25D(3) induces hypercalcemia at pharmacologically active doses. We investigated the in vitro and in vivoantileukemic efficacy of combined treatment with non-toxic doses of a low-calcemic 1,25D(3) analogue, 1,25-dihydroxy-21(3-hydroxy-3-methyl-butyl)-19-nor-cholecalciferol (19-nor-Gemini; Ro27-5646), and rosemary plant agents in a mouse model of AML.

METHODS

Proliferation and differentiation of WEHI-3B D- (WEHI) murine myelomonocytic leukemia cellsin vitro were determined by standard assays. Reactive oxygen species, glutathione and protein expression levels were measured by flow cytometry, enzymatic assay and Western blotting, respectively. Systemic AML was developed by intravenous injection of WEHI cells in syngeneic Balb/c mice.

RESULTS

19-nor-Gemini had a higher potency than its parent compounds, Gemini (Ro27-2310) and 1,25D(3), in the induction of differentiation (EC(50) = 0.059 +/- 0.011, 0.275 +/- 0.093 and 0.652 +/- 0.085 nM, respectively) and growth arrest (IC(50) = 0.072 +/- 0.018, 0.165 +/- 0.061 and 0.895 +/- 0.144 nM, respectively) in WEHI cells in vitro, and lower in vivo toxicity. Combined treatment of leukemia-bearing mice with 19-nor-Gemini (injected intraperitoneally) and standardized rosemary extract (mixed with food) resulted in a synergistic increase in survival (from 42.2 +/- 2.5 days in untreated mice to 66.5 +/- 4.2 days, n = 3) and normalization of white blood cell and differential counts. This was consistent with strong cooperative antiproliferative and differentiation effects of low concentrations of 19-nor-Gemini or 1,25D(3) combined with rosemary extract or its major polyphenolic component, carnosic acid, as well as with the antioxidant action of rosemary agents and vitamin D derivatives in WEHI cell cultures.

CONCLUSION

Combined effectiveness of 1,25D(3) analogues and rosemary agents against mouse AML warrants further exploration of this therapeutic approach in translational models of human leukemia.

Phase II study of doxercalciferol for the treatment of myelodysplastic syndrome

We conducted a phase II trial of doxercalciferol, a vitamin D2 analogue, in 15 patients with MDS. Each received doxercalciferol 12.5 microg orally daily for 12 weeks. Nine of 15 patients completed the prescribed course and of these, six had stable disease. No patient had a response (IWG criteria) and overall eight patients experienced progressive disease while on therapy. Two patients with chronic myelomonocytic leukemia (CMML) had a marked rise in monocytes on study. Overall the treatment was well tolerated. One patient was removed from study due to hypercalcemia. We conclude that short-term treatment with doxercalciferol has limited activity in patients with MDS.

Enhancement of Arsenic Trioxide (As(2)O(3))- Mediated Apoptosis Using Berberine in Human Neuroblastoma SH-SY5Y Cells

OBJECTIVE

Arsenic trioxide (As(2)O(3)) has been used as an anticancer agent in traditional Chinese medicine for thousand years and berberine is an isoquinoline alkaloid present that has indicated significant antimicrobial activity. We have examined the combined anticancer effects of As(2)O(3) and berberine against the human neuroblastoma (HNB) SH-SY5Y cells in vitro, and to elucidate underlying molecular mechanism.

METHODS

HNB SH-SY5Y cells were treated with 2 microM As(2)O(3) and 75 microg/ml berberine, and their survival, cell death mechanism as well as synergistic cytotoxic effects were estimated by using MTT assay, DAPI staining, agarose gel electrophoresis, flow cytometric analysis, and western blot analysis.

RESULTS

The combined treatment of two drugs also markedly decreased cell viability. The cytotoxic effects of two drugs were revealed as apoptosis characterized by chromatin condensation, DNA fragmentation, and the loss of mitochondrial membrane potential. The apoptotic cytotoxicity was accompanied by activation of caspase-3 protease as well as decreased the expression of Bcl-2, Bid, and Bcl-x/L. In addition, the cells treated with combination of two drugs also showed significantly increased intracellular reactive oxygen species levels and lipid peroxidation compared to cells As(2)O(3) or berberine only.

CONCLUSION

Combined treatment of As(2)O(3) with berberine induced activation of apoptotic signaling pathways in HNB SH-SY5Y cells. These results suggest that the possibility of the combined treatment of two chemotherapeutic agents with low concentration improving cytotoxic effect for cancer cells with minimal side effects.

Identification of a molecular signature predictive of sensitivity to differentiation induction in acute myeloid leukemia

Acute myeloid leukemia (AML) blasts are immature committed myeloid cells unable to spontaneously undergo terminal maturation, and characterized by heterogeneous sensitivity to natural differentiation inducers. Here, we show a molecular signature predicting the resistance or sensitivity of six myeloid cell lines to differentiation induced in vitro with retinoic acid or vitamin D. The identified signature was further validated by TaqMan assay for the prediction of response to an in vitro differentiation assay performed on 28 freshly isolated AML blast populations. The TaqMan assay successfully predicts the in vitro resistance or responsiveness of AML blasts to differentiation inducers. Furthermore, performing a meta-analysis of publicly available microarray data sets, we also show the accuracy of our prediction on known phenotypes and suggest that our signature could become useful for the identification of patients eligible for new therapeutic strategies.

Opposing effects of arsenic trioxide on hepatocellular carcinomas in mice

Arsenic trioxide (As2O3) is a potent antitumor agent used to treat acute promyelocytic leukemia (APL) and, more recently, solid tumors. However, the dose of As2O3 required to suppress human xenographs in mice is markedly higher than that used to treat APL in humans. Paradoxically, low doses of As2O3 stimulate angiogenesis, which might be expected to promote tumor growth. Clearly, appropriate dosages of As2O3 are required to treat human patients to avoid toxicity and undesirable side effects. In the present study, we investigated As2O3 with respect to its toxicity and effects on tumor growth, angiogenesis and cell apoptosis using H22 hepatocellular carcinoma (HCC) cells in a mouse model of HCC. As2O3 inhibited tumor growth and angiogenesis, and enhanced tumor cell apoptosis at doses greater than 1 mg/kg, but mice lost weight and failed to thrive at doses of 4 mg/kg and greater. In contrast, low doses (<1 mg/kg) of As2O3 promoted tumor growth, upregulated the expression of vascular endothelial growth factor and tumor angiogenesis, and had no effect on tumor cell apoptosis. In vitro studies demonstrated that As2O3 inhibited the proliferation of H22 tumor cells and bovine aortic endothelial cells, and induced their apoptosis in a dose- and time-dependent fashion, suggesting that the mechanism of As2O3-mediated inhibition of tumor growth is due to direct effects of the drug on both tumor cells and endothelia. In summary, different doses of As2O3 have opposing effects on tumor growth and angiogenesis. The results demonstrate that As2O3 has a narrow window of therapeutic opportunity with respect to dosage, and that low doses of the drug as used in metronomic therapy should be used with extreme caution.