Dietary resveratrol does not delay engraftment, sensitize to vincristine or inhibit growth of high-risk acute lymphoblastic leukemia cells in NOD/SCID mice

Pterostilbene downregulates BCR/ABL and induces apoptosis of T315I-mutated BCR/ABL-positive leukemic cells

In this study, we examined the antileukemic effects of pterostilbene, a natural methylated polyphenol analog of resveratrol that is predominantly found in berries and nuts, using various human and murine leukemic cells, as well as bone marrow samples obtained from patients with leukemia. Pterostilbene administration significantly induced apoptosis of leukemic cells, but not of non-malignant hematopoietic stem/progenitor cells. Interestingly, pterostilbene was highly effective in inducing apoptosis of leukemic cells harboring the BCR/ABL fusion gene, including ABL tyrosine kinase inhibitor (TKI)-resistant cells with the T315I mutation. In BCR/ABL⁺ leukemic cells, pterostilbene decreased the BCR/ABL fusion protein levels and suppressed AKT and NF-κB activation. We further demonstrated that pterostilbene along with U0126, an inhibitor of the MEK/ERK signaling pathway, synergistically induced apoptosis of BCR/ABL⁺ cells. Our results further suggest that pterostilbene-promoted downregulation of BCR/ABL involves caspase activation triggered by proteasome inhibition-induced endoplasmic reticulum stress. Moreover, oral administration of pterostilbene significantly suppressed tumor growth in mice transplanted with BCR/ABL⁺ leukemic cells. Taken together, these results suggest that pterostilbene may hold potential for the treatment of BCR/ABL⁺ leukemia, in particular for those showing ABL-dependent TKI resistance.

Resveratrol ameliorates toxic effects of cadmium on placental development in mouse placenta and human trophoblast cells

BACKGROUND

Cadmium (Cd) is a common heavy metal pollutant. Prenatal exposure to Cd results in adverse effects on fetal development. Placental apoptosis, inflammation, and epigenetic disruption have been implicated in Cd-induced placental toxicity. Resveratrol (Res) is a naturally occurring polyphenol with anti-apoptotic, anti-inflammatory, and epigenetic regulatory activities. In present study, the effects of Res on placental toxicity induced by Cd were evaluated.

METHODS

Pregnant CD-1 mice were fed with base diet containing 0.2% Res started on gestational day 0 (GD0), and intraperitoneally injected with 4.5 mg/kg CdCl₂ or saline once on GD9. JEG-3 cells were treated with 20 μM Res for 24 hr in the absence or presence of 20 μM CdCl₂ for the second 12 hr. The fetal outcomes, the apoptosis in placenta and JEG-3 cells, the expression of inflammatory cytokines and chemokines including tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein-2 (MIP-2) and chemokine (C-X-C motif) ligand 1 (KC), and expression of endoplasmic reticulum (ER) stress markers were evaluated. The expression and activities of DNA methyltransferase (DNMT), and the activation of Akt signaling pathway were detected.

RESULTS

Cd exposure resulted in decreased fetal weight and crown-rump length while Res ameliorated these outcomes. Res suppressed Cd-induced apoptosis in placenta and JEG-3 cells, and decreased Cd-induced expression of TNF-α, IFN-γ, MCP-1, MIP-2, and KC in placenta. Cd greatly increased ER stress in placenta in mice, which was partially ameliorated by Res treatment. Res decreased Cd-induced upregulation of DNMT activity and suppressed Cd-induced expression of DNMT3B. Res restored estradiol secretion, enhances activity and protein levels of SIRT1 and inhibited Cd-induced activation of Akt signaling pathway.

CONCLUSION

Res ameliorated Cd-induced placental toxicity and regulated DNMT3 expression and PI3K/Akt pathway activation.

Resveratrol as an Adjuvant for Normal Tissues Protection and Tumor Sensitization

Cancer is one of the most complicated diseases in present-day medical science. Yearly, several studies suggest various strategies for preventing carcinogenesis. Furthermore, experiments for the treatment of cancer with low side effects are ongoing. Chemotherapy, targeted therapy, radiotherapy and immunotherapy are the most common non-invasive strategies for cancer treatment. One of the most challenging issues encountered with these modalities is low effectiveness, as well as normal tissue toxicity for chemo-radiation therapy. The use of some agents as adjuvants has been suggested to improve tumor responses and also alleviate normal tissue toxicity. Resveratrol, a natural flavonoid, has attracted a lot of attention for the management of both tumor and normal tissue responses to various modalities of cancer therapy. As an antioxidant and anti-inflammatory agent, in vitro and in vivo studies show that it is able to mitigate chemo-radiation toxicity in normal tissues. However, clinical studies to confirm the usage of resveratrol as a chemo-radioprotector are lacking. In addition, it can sensitize various types of cancer cells to both chemotherapy drugs and radiation. In recent years, some clinical studies suggested that resveratrol may have an effect on inducing cancer cell killing. Yet, clinical translation of resveratrol has not yielded desirable results for the combination of resveratrol with radiotherapy, targeted therapy or immunotherapy. In this paper, we review the potential role of resveratrol for preserving normal tissues and sensitization of cancer cells in combination with different cancer treatment modalities.

Biological Mechanisms by Which Antiproliferative Actions of Resveratrol Are Minimized

Preclinical and clinical studies have offered evidence for protective effects of various polyphenol-rich foods against cardiovascular diseases, neurodegenerative diseases, and cancers. Resveratrol is among the most widely studied polyphenols. However, the preventive and treatment effectiveness of resveratrol in cancer remain controversial because of certain limitations in existing studies. For example, studies of the activity of resveratrol against cancer cell lines in vitro have often been conducted at concentrations in the low μM to mM range, whereas dietary resveratrol or resveratrol-containing wine rarely achieve nM concentrations in the clinic. While the mechanisms underlying the failure of resveratrol to inhibit cancer growth in the intact organism are not fully understood, the interference by thyroid hormones with the anticancer activity of resveratrol have been well documented in both in vitro and xenograft studies. Thus, endogenous thyroid hormones may explain the failure of anticancer actions of resveratrol in intact animals, or in the clinic. In this review, mechanisms involved in resveratrol-induced antiproliferation and effects of thyroid hormones on these mechanisms are discussed.

Modulatory potential of resveratrol during lung inflammatory disease

Neutrophils are the first cells to achieve the sites of infection or inflammation in the lungs. The massive accumulation of these cells is associated with acute and chronic lung injury. Therefore, they have been implicated in the pathogenesis of many lung diseases through the release of reactive oxygen intermediates, proteolytic enzymes and Neutrophil Extracellular Traps (NETs). The excessive and continuous release of NETs, fibers composed by decondensed chromatin coated with neutrophil proteins, are associated to the impairment of lung function in different pathological settings. Flavonoids inhibit the respiratory burst of neutrophils in mammals. However, one of these flavonoids, resveratrol has a particular chemical property. It reduce Cu(II) to Cu(I) form with concomitant formation of reactive oxygen species, which can produce DNA breakage as reported in several in vitro models. We hypothesize that direct resveratrol administration in lungs can cleave DNA in NETs, improving lung function during acute airway infections or chronic inflammatory lung diseases. If the hypothesis is correct, the control of NET formation can be used to reduce the inflammatory environment in lung after neutrophil stimuli. Additionally, the production of proinflammatory cytokines by neutrophils could be also diminished by resveratrol administration. In this sense, this flavonoid provides a multifaceted opportunity for treatment of lung diseases with strong or chronic neutrophil activation.

Curcumin Affects Phase II Disposition of Resveratrol Through Inhibiting Efflux Transporters MRP2 and BCRP

PURPOSE

To evaluate the impact of curcumin on the disposition of resveratrol phase II metabolites in vivo, and explain the observations by performing in vitro studies in transporter-overexpressed cells.

METHODS

Pharmacokinetic studies of resveratrol with and without the co-administration of curcumin were performed in both FVB wild-type and Bcrp1 (-/-) mice. Human UGT1A9-overexpressing HeLa cells and human MRP2-overexpressing MDCK II-UGT1A1 cells were used as in vitro tools to further determine the impact of curcumin as a transporter inhibitor on resveratrol metabolites.

RESULTS

We observed higher exposure of resveratrol conjugates in Bcrp1 (-/-) mice compared to wild-type mice. In wild-type mice, curcumin increased the AUC of resveratrol glucuronide by 4-fold compared to the mice treated without curcumin. The plasma levels of resveratrol and its sulfate conjugate also increased moderately. In Bcrp1 (-/-) mice, there was a further increase (6-fold increase) in AUC of resveratrol glucuronide observed when curcumin was co-administered compared to AUC values obtained in wild-type mice without curcumin treatment. In the presence of 50 nM curcumin, the clearance of resveratrol-3-O-glucuronide and resveratrol-3-O-sulfate reduced in both MRP2-overexpressing MDCKII-UGT1A1 cells and Human UGT1A9-overexpressing HeLa cells.

CONCLUSIONS

These results suggest that curcumin alters the phase II distribution of resveratrol through inhibiting efflux transporters including MRP2 and BCRP.

3,4',5-trans-Trimethoxystilbene; a natural analogue of resveratrol with enhanced anticancer potency

Resveratrol is a phytoalexin produced by many plant species as a defence mechanism. Over the last decade, this polyphenol has been reported to be active against multiple targets associated with chronic disorders. However, its poor pharmacokinetic profile, as well as multiple discrepancies related to its in vitro and in vivo profile, has resulted not only on the study of suitable delivery systems, but the use of resveratrol derivatives. In this regard, the 3,4',5-trans-trimethoxystilbene (TMS), a natural analogue of resveratrol, has emerged as a strong candidate. TMS has an enhanced anticancer profile compared to resveratrol, exhibiting higher potency than resveratrol, as shown by multiple reports describing an improved cancer cell proliferation inhibition, induction of cell cycle arrest, decreased metastasis, reduced angiogenesis, and increased apoptosis. In this review, we provide a concise summary of results reported in the literature, related to the similarities and differences between resveratrol and TMS, and we submit to the scientific community that TMS is a promising and (still) understudied natural agent candidate, with potential applications in cancer research. Nevertheless, based on the available evidence, we also submit to the scientific community that TMS may also find a niche in any other research area in which resveratrol has been used.

Physiological levels of resveratrol metabolites are ineffective as anti-leukemia agents against Jurkat leukemia cells

Dietary resveratrol is metabolically transformed in vivo by the intestine and liver to produce resveratrol glucuronides and sulfates in humans. Little is known about the anticancer activities of these metabolic products. The majority of in vitro studies have investigated effects of resveratrol aglycone at supraphysiological levels. Physiological levels of resveratrol-3-O-glucuronide, resveratrol-4'-O-glucuronide, and resveratrol-3-O-sulfate, the major in vivo metabolites of dietary resveratrol, were evaluated as anticancer agents against Jurkat T leukemia cells. Propidium iodide was use to measure cell death and changes in cell cycle, and the mitochondrial membrane dye JC-1 was used to measure changes in mitochondrial membrane potential by flow cytometry. PKH67 was used to evaluate changes in proliferation of the cells by flow cytometry. Jurkat cells were exposed to 0, 2.5, 5, 10, 15, and 20 μM of each resveratrol metabolite, which are concentrations achievable in vivo. None of the resveratrol metabolites were able to kill Jurkat T leukemia cells or alter cell cycle or proliferation at these concentrations. Only resveratrol-3-O-sulfate induced depolarization of mitochondrial membranes but without induction of cell death. These results suggest that the in vivo transformation of resveratrol to these glucuronide and sulfate metabolites renders these agents ineffective against T leukemia cells.

The multiple mechanisms of cell death triggered by resveratrol in lymphoma and leukemia

Lymphoma and leukemia represent a serious threat to human health and life expectancy. Resveratrol is, among the natural-derived chemopreventive molecules, one of the most effective and better studied. In this paper the main mechanisms of cell death triggered by- or linked to- resveratrol are reviewed and discussed. The main focus is on lymphoma and leukemia experimental models where resveratrol has been tested and investigated at the cellular, molecular or physiological levels. The most relevant in vivo challenges involving resveratrol are also reported and analyzed in order to define the key features of this polyphenol and the potential for the treatment of hematologic tumors.

Oral or parenteral administration of curcumin does not prevent the growth of high-risk t(4;11) acute lymphoblastic leukemia cells engrafted into a NOD/SCID mouse model

In this study, the efficacy of orally and parenter-ally administered curcumin was evaluated in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice (NOD.CB17-Prkdc^scid/J mice) engrafted with the human t(4;11) acute lymphoblastic leukemia line, SEM. SEM cells were injected into the tail vein and engraftment was monitored by flow cytometry. Once engraftment was observed, the chemotherapeutic potential was examined by injecting mice intraperitoneally with curcumin (5 mg/kg body weight) dissolved in dimethylsulfoxide (DMSO) or DMSO alone (control) every other day, or vincristine (0.5 mg/kg body weight) 3 times per week for 4 weeks (n=16 per group). The intraperitoneal administration of curcumin did not inhibit the growth of the leukemia cells. To determine the efficacy of oral curcumin, mice were fed a control diet or a diet containing 0.5% w/w curcumin 3 weeks prior to the injection of the leukemia cells and throughout the experimental period (n=16 per group). To determine whether dietary curcumin can enhance the efficacy of a conventional chemotherapeutic agent, vincristine was injected intraperitoneally into leukemic mice fed the different diets. Dietary curcumin did not delay the engraftment or growth of leukemia cells, or sensitize the cells to vincristine. Liquid chromatography-tandem mass spectrometry analyses of mouse sera showed that curcumin rapidly metabolized to glucuronidated and sulfated forms within 1 h post-injection and these were the major curcumin metabolites found in the sera of the mice fed the curcumin diet. In contrast to the findings in previous in vitro models, the current data indicate that orally or parenterally administered curcumin is not a potent preventive agent against high-risk t(4;11) acute lymphoblastic leukemia.