Vitamin D3 potentiates the antitumorigenic effects of arsenic trioxide in human leukemia (HL-60) cells

Emerging perspectives: unraveling the anticancer potential of vitamin D3

Vitamin D3, a fat-soluble vitamin known for its critical function in calcium homeostasis and bone health, is gaining interest for its anticancer properties. Observational studies have suggested a negative relationship between vitamin D levels and the incidence of some malignancies throughout the years, prompting substantial investigation to find its anticancer effects. The purpose of this comprehensive review is to investigate the diverse function of vitamin D3 in cancer prevention and therapy. We explored the molecular mechanism underlying its effects on cancer cells, which range from cell cycle control and death to angiogenesis and immune response modulation. Insights from in vitro and in vivo studies provide valuable evidence supporting its anticancer potential. Furthermore, we look at epidemiological and clinical studies that investigate the relationship between vitamin D3 levels and cancer risk or treatment results. Vitamin D3 supplementation's safety profile and cost-effectiveness increase its attractiveness as an adjuvant therapy in conjunction with traditional treatment regimens. Our critical review of the current literature provides an in-depth understanding of vitamin D3's anticancer effect, covering the obstacles and possibilities in realizing its promise for cancer prevention and therapy. The findings of this study might pave the way for the development of innovative treatment techniques that take use of the advantages of vitamin D3 to fight cancer and improve patient care. As research progresses, a better understanding of vitamin D3's anticancer processes will surely simplify its incorporation into personalized cancer care techniques, hence enhancing patient outcomes in the battle against cancer.

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.

Catechin, epicatechin, curcumin, garlic, pomegranate peel and neem extracts of Indian origin showed enhanced anti-inflammatory potential in human primary acute and chronic wound derived fibroblasts by decreasing TGF-β and TNF-α expression

BACKGROUND

Although chronic wounds are devastating and can cause burden at multiple levels, chronic wound research is still far behind. Chronic wound treatment is often less efficient due to delay in diagnosis and treatment, non-specific treatment mainly due to lack of knowledge of wound healing or healing resistance genes. It's known that chronic wounds do not progress towards healing, because it gets stalled in inflammatory phase of wound healing.

OBJECTIVE

We aimed to use phytoextracts possessing excellent anti-inflammatory properties to regulate the unbalanced levels of cytokines responsible for increased inflammation.

METHODS

Evaluation of anti-inflammatory activity of selected phytoextracts namely, Camellia sinensis (L.) Kuntze, Acacia catechu (L.f) Willd., Curcuma longa (L.), Allium sativum (L.), Punica granatum (L.) and Azadirachta indica A. hereafter, called as catechin, epicatechin, curcumin, garlic, pomegranate and neem extracts, respectively in Acute wound fibroblasts (AWFs) and Chronic wound fibroblasts (CWFs) using flow cytometry.

RESULTS

The phytoextracts exhibited no cytotoxicity below 100 μg/ml on normal Human Dermal fibroblasts (HDFs), while garlic extract showed highest cell viability followed by catechin, epicatechin, curcumin, pomegranate peel and neem based on IC₅₀ value. Garlic, catechin and epicatechin extracts showed highest anti-inflammatory activities for both TGF-β and TNF-α in both AWFs and CWFs treated cells. After treatment of AWFs with catechin, epicatechin and garlic extracts, TGF-β and TNF-α expression was significantly reduced compared to untreated AWFs and reached to almost normal HDFs level. Also, after treatment of CWFs with catechin, epicatechin and garlic extracts, TGF-β and TNF-α expression was significantly reduced compared to untreated CWFs and was lesser than untreated AWFs.

CONCLUSION

The present findings reveal the potential of catechin, epicatechin and garlic extracts for the treatment of acute and chronic wounds with excellent anti-inflammatory properties.

NLS-RARα contributes to differentiation block and increased leukemogenic potential in vivo

The fusion oncogene, promyelocytic leukemia (PML)-retinoic acid receptor-α (RARα), is crucial for acute promyelocytic leukemia (APL) pathogenesis. Previous studies have reported that PML-RARα is cleaved by neutrophil elastase (NE), an early myeloid-specific serine protease, leading to translocation of the nuclear localization signal (NLS) of the PML protein to the N-terminal of RARα. This study was designed to evaluate the value of NLS-RARα in the early diagnosis of APL. To investigate the potential functional role of NLS-RARα in leukemogenesis, HL-60 and U937 cell lines were transfected with NLS-RARα lentivirus and negative control (LVNC). The results showed that the induced expression of NLS-RARα down-regulated expressions of CD11b, CD11c, and CD14 compared to the LVNC group induced by 1α, 25-dihydroxyvitamin D₃(1,25(OH)₂D₃). This suggested that NLS-RARα overexpression inhibited granulocytic and monocytic differentiation of myeloid leukemia cells. In addition, Wright-Giemsa staining, flow cytometry, respiratory burst assay, and NBT reduction assay all confirmed the importance of NLS-RARα in differentiation. The mechanistic investigations revealed that induced NLS-RARα expression inhibited 1,25(OH)₂D₃-induced granulocytic differentiation by regulating the cell cycle regulators p19^INK4D, p21^WAF1/CIP1, cyclinD1, cyclin E1, and pRB. Furthermore, the cleaved protein NLS-RARα enhanced the oncogenicity of U937 cells in NOD/SCID mice. These findings collectively demonstrated that NLS-RARα blocked granulocytic and monocytic differentiation of myeloid leukemia cells by inhibiting the downstream targets of the RARα signal pathway and the cell cycle. This may provide a promising new target and method for diagnosing and treating APL.

Arsenic Trioxide and Icariin Show Synergistic Anti-leukemic Activity

Although As2O3 (ATO) has been recommended as the front-line agent for treatment of acute promyelocytic leukemia (APL), particularly for relapsed or refractory APL, it has been associated with profound toxicity. Icariin is a natural compound with activity against a variety of cancers. This study was designed to investigate the effect of Icariin on APL cells and to determine whether Icariin can potentiate the antitumor activity of ATO in APL cells. Cell proliferation and apoptosis were measured using MTT assay and flow cytometry, respectively. The expression of apoptosis and proliferation-related molecules was detected by Western blotting. Reactive oxygen species (ROS) and mitochondrial membrane potential were determined with florescence staining. Icariin inhibited proliferation in a dose-dependent manner and induced apoptosis in both of the tested APL cell lines. Icariin enhanced the in vitro antitumor activity of ATO against APL. The antitumor activity of Icariin and its enhancement of the antitumor activity of ATO correlated with the increase in accumulation of intracellular ROS. Our results showed that Icariin, by increasing intracellular ROS, exhibited antitumor activity and potentiated the antitumor activity of ATO against APL. Therefore, combination treatment with Icariin and ATO might offer a novel therapeutic option for patients with APL, although further studies are needed.

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.

Melatonin enhances arsenic trioxide-induced cell death via sustained upregulation of Redd1 expression in breast cancer cells

Melatonin is implicated in various physiological functions, including anticancer activity. However, the mechanism(s) of its anticancer activity is not well understood. In the present study, we investigated the combined effects of melatonin and arsenic trioxide (ATO) on cell death in human breast cancer cells. Melatonin enhanced the ATO-induced apoptotic cell death via changes in the protein levels of Survivin, Bcl-2, and Bax, thus affecting cytochrome c release from the mitochondria to the cytosol. Interestingly, we found that the cell death induced by co-treatment with melatonin and ATO was mediated by sustained upregulation of Redd1, which was associated with increased production of reactive oxygen species (ROS). Combined treatment with melatonin and ATO induced the phosphorylation of JNK and p38 MAP kinase downstream from Redd1 expression. Rapamycin and S6K1 siRNA enhanced, while activation of mTORC1 by transfection with TSC2 siRNA suppressed the cell death induced by melatonin and ATO treatment. Taken together, our findings suggest that melatonin enhances ATO-induced apoptotic cell death via sustained upregulation of Redd1 expression and inhibition of mTORC1 upstream of the activation of the p38/JNK pathways in human breast cancer cells.

Dual effect of oxidative stress on leukemia cancer induction and treatment

Oxidative stress (OS) has been characterized by an imbalance between the production of reactive oxygen species (ROS) and a biological system's ability to repair oxidative damage or to neutralize the reactive intermediates including peroxides and free radicals. High ROS production has been associated with significant decrease in antioxidant defense mechanisms leading to protein, lipid and DNA damage and subsequent disruption of cellular functions. In humans, OS has been reported to play a role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease, Huntington's disease, Lou Gehrig's disease, multiple sclerosis and Parkinson's disease, as well as atherosclerosis, autism, cancer, heart failure, and myocardial infarction. Although OS has been linked to the etiology and development of chronic diseases, many chemotherapeutic drugs have been shown to exert their biologic activity through induction of OS in affected cells. This review highlights the controversial role of OS in the development and progression of leukemia cancer and the therapeutic application of increased OS and antioxidant approaches to the treatment of leukemia patients.

Inhibition of long non-coding RNA NEAT1 impairs myeloid differentiation in acute promyelocytic leukemia cells

Background

Acute promyelocytic leukemia (APL) is characterized by the reciprocal translocation t(15;17), which fuses PML with retinoic acid receptor alpha (RARα). Although PML-RARα is crucially important for pathogenesis and responsiveness to treatment, the molecular and cellular mechanisms by which PML-RARα exerts its oncogenic potential have not been fully elucidated. Recent reports have suggested that long non-coding RNAs (lncRNAs) contribute to the precise control of gene expression and are involved in human diseases. Little is known about the role of lncRNA in APL.

Methods

We analyzed NEAT1 expression in APL samples and cell lines by real-time quantitative reverse transcription-PCR (qRT-PCR). The expression of PML-RARα was measured by Western blot. Cell differentiation was assessed by measuring the surface CD11b antigen expression by flow cytometry analysis.

Results

We found that nuclear enriched abundant transcript 1 (NEAT1), a lncRNA essential for the formation of nuclear body paraspeckles, is significantly repressed in de novo APL samples compared with those of healthy donors. We further provide evidence that NEAT1 expression was repressed by PML-RARα. Furthermore, significant NEAT1 upregulation was observed during all-trans retinoic acid (ATRA)-induced NB4 cell differentiation. Finally, we demonstrate the importance of NEAT1 in myeloid differentiation. We show that reduction of NEAT1 by small interfering RNA (siRNA) blocks ATRA-induced differentiation.

Conclusions

Our results indicate that reduced expression of the nuclear long noncoding RNA NEAT1 may play a role in the myeloid differentiation of APL cells.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-693) contains supplementary material, which is available to authorized users.

Proteomics-Based Identification of Differentially Abundant Proteins from Human Keratinocytes Exposed to Arsenic Trioxide

INTRODUCTION

Arsenic is a widely distributed environmental toxicant that can cause multi-tissue pathologies. Proteomic assays allow for the identification of biological processes modulated by arsenic in diverse tissue types.

METHOD

The altered abundance of proteins from HaCaT human keratinocyte cell line exposed to arsenic was quantified using a label-free LC-MS/MS mass spectrometry workflow. Selected proteomics results were validated using western blot and RT-PCR. A functional annotation analytics strategy that included visual analytical integration of heterogeneous data sets was developed to elucidate functional categories. The annotations integrated were mainly tissue localization, biological process and gene family.

RESULT

The abundance of 173 proteins was altered in keratinocytes exposed to arsenic; in which 96 proteins had increased abundance while 77 proteins had decreased abundance. These proteins were also classified into 69 Gene Ontology biological process terms. The increased abundance of transferrin receptor protein (TFRC) was validated and also annotated to participate in response to hypoxia. A total of 33 proteins (11 increased abundance and 22 decreased abundance) were associated with 18 metabolic process terms. The Glutamate--cysteine ligase catalytic subunit (GCLC), the only protein annotated with the term sulfur amino acid metabolism process, had increased abundance while succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial precursor (SDHB), a tumor suppressor, had decreased abundance.

CONCLUSION

A list of 173 differentially abundant proteins in response to arsenic trioxide was grouped using three major functional annotations covering tissue localization, biological process and protein families. A possible explanation for hyperpigmentation pathologies observed in arsenic toxicity is that arsenic exposure leads to increased iron uptake in the normally hypoxic human skin. The proteins mapped to metabolic process terms and differentially abundant are candidates for evaluating metabolic pathways perturbed by arsenicals.