Resveratrol, a natural product derived from grapes, is a new inducer of differentiation in human myeloid leukemias

Resveratrol, EGCG and Vitamins Modulate Activated T Lymphocytes

Vitamins and bioactives, which are constituents of the food chain, modulate T lymphocyte proliferation and differentiation, antibody production, and prevent inflammation and autoimmunity. We investigated the effects of vitamins (vitamin A (VA), D (VD), E (VE)) and bioactives (i.e., resveratrol (Res), epigallocatechin-3-gallate (EGCG)) on the adaptive immune response, as well as their synergistic or antagonistic interactions. Freshly isolated T lymphocytes from healthy individuals were activated with anti-CD3/CD28 antibodies for 4–5 days in the presence of bioactives and were analyzed by cytofluorometry. Interleukins, cytokines, and chemokines were measured by multiple ELISA. Gene expression was measured by quantitative RT-PCR. Res and EGCG increased CD4 surface intensity. EGCG led to an increased proportion of CD8⁺ lymphocytes. Anti-CD3/CD28 activation induced exuberant secretion of interleukins and cytokines by T lymphocyte subsets. VD strongly enhanced T_h2 cytokines (e.g., IL-5, IL-13), whereas Res and EGCG favored secretion of T_h1 cytokines (e.g., IL-2, INF-γ). Res and VD mutually influenced cytokine production, but VD dominated the cytokine secretion pattern. The substances changed gene expression of interleukins and cytokines in a similar way as they did secretion. Collectively, VD strongly modulated cytokine and interleukin production and favored T_h2 functions. Resveratrol and EGCG promoted the T_h1 response. VA and VE had only a marginal effect, but they altered both T_h1 and T_h2 response. In vivo, bioactives might therefore interact with vitamins and support the outcome and extent of the adaptive immune response.

Resveratrol Inhibits the Tumorigenesis of Follicular Thyroid Cancer via ST6GAL2-Regulated Activation of the Hippo Signaling Pathway

Follicular thyroid carcinoma (FTC) is a common endocrine malignancy with highly aggressive features. In this study, next-generation sequencing technology was used to identify aberrant expression of sialyltransferase (ST) family members in FTC. Aberrant high expression of alpha-2,6-sialyltransferase 2 (ST6GAL2) was demonstrated to promote tumorigenesis of FTC in vitro and in vivo. Furthermore, ST6GAL2 promoted tumorigenesis by inactivating the Hippo signaling pathway. Resveratrol is a native compound extracted from Vitis species, and many studies have confirmed its protective cardiovascular and antineoplastic effects. Here we found that resveratrol can inhibit the tumorigenesis of FTC by suppressing the expression of ST6GAL2, further activating the Hippo pathway. In summary, this study revealed the role of the ST6GAL2-Hippo signaling pathway in FTC tumorigenesis and indicated that resveratrol, a commonly found antineoplastic compound, could inhibit tumorigenesis of FTC by regulating the abovementioned pathways.

Effects of nutraceuticals on anaplastic thyroid cancer cells

PURPOSE

The anaplastic thyroid carcinoma (ATC) is the most aggressive thyroid cancer with a high mortality rate. Since nutraceuticals may exert beneficial effects on tumor biology, here, effects of four of these compounds [resveratrol, genistein, curcumin and epigallocatechin-3-gallate (EGCG)] on ATC cell lines were investigated.

METHODS

Two ATC-derived cell lines were used: SW1736 and 8505C. Cell viability and in vitro aggressiveness was tested by MTT and soft agar assays. Apoptosis was investigated by Western Blot, using an anti-cleaved-PARP antibody. mRNA and miRNA levels were quantified by real-time PCR.

RESULTS

All tested nutraceuticals caused in both cell lines decrease of cell viability and increase of apoptosis. In contrast, only curcumin reduced in vitro aggressiveness in both SW1736 and 8505C cell lines, while genistein and EGCG determined a reduction of colony formation only in 8505C cells. Effects on genes related to the thyroid-differentiated phenotype were also tested: resveratrol and genistein administration determined the increment of almost all tested mRNAs in both cell lines. Instead curcumin and EGCG treatments had opposite effects in the two cell lines, causing the increment of almost all the mRNAs in 8505C cells and their reduction in SW1736. Finally, effects of nutraceuticals on levels of several miRNAs, known as important in thyroid cancer progression (hsa-miR-221, hsa-miR-222, hsa-miR-21, hsa-miR-146b, hsa-miR-204), were tested. Curcumin induced a strong and significant reduction of all miR analyzed, except for has-miR-204, in both cell lines.

CONCLUSIONS

Altogether, our results clearly indicate the anti-cancer proprieties of curcumin, suggesting the promising use of this nutraceutical in ATC treatment. Resveratrol, genistein and EGCG have heterogeneous effects on molecular features of ATC cells.

Resveratrol strongly enhances the retinoic acid-induced superoxide generating activity via up-regulation of gp91-phox gene expression in U937 cells

The membrane bound cytochrome b₅₅₈ composed of gp91-phox and p22-phox proteins, and cytosolic proteins p40-, p47-and p67-phox are important components of superoxide (O₂^-)-generating system in phagocytes. Here, we describe that resveratrol, a pleiotropic phytochemical belonging to the stilbenoids, dramatically activates the O₂^--generating system during retinoic acid (RA)-induced differentiation of human monoblastic leukemia U937 cells to macrophage-like cells. When U937 cells were cultured in the presence of RA and resveratrol, the O₂^--generating activity increased more than 5-fold compared with that in the absence of the latter. Semiquantitative RT-PCR showed that co-treatment with RA and resveratrol strongly enhanced transcription of the gp91-phox compared with those of the RA-treatment only. On the other hand, immunoblot analysis revealed that co-treatment with RA and resveratrol caused remarkable accumulation of protein levels of gp91-phox (to 4-fold), p22-phox (to 5-fold) and p47-phox (to 4-fold) compared with those of the RA-treatment alone. In addition, ChIP assay suggested that resveratrol participates in enhancing the gene expression of gp91-phox via promoting acetylation of Lys-9 residues and Lys-14 residues of histone H3 within chromatin around the promoter regions of the gene. These results suggested that resveratrol strongly enhances the RA-induced O₂^--generating activity via up-regulation of gp91-phox gene expression in U937 cells.

Diptoindonesin G promotes ERK-mediated nuclear translocation of p-STAT1 (Ser727) and cell differentiation in AML cells

Exploration of a new differentiation therapy that extends the range of differentiation for treating acute myeloid leukemia (AML) is attractive to researchers and clinicians. Here we report that diptoindonesin G (Dip G), a natural resveratrol aneuploid, exerts antiproliferative activity by inducing G2/M phase arrest and cell differentiation in AML cell lines and primary AML cells. Gene-profiling experiments showed that treating human leukemia HL-60 cells with Dip G was associated with a remarkable upregulation of STAT1 target gene expression, including IFIT3 and CXCL10. Mechanistically, Dip G activated ERK, which caused phosphorylation of STAT1 at Ser727 and selectively enhanced the interaction of p-STAT1 (Ser727) and p-ERK, further promoting their nuclear translocation. The nuclear translocation of p-STAT1 and p-ERK enhanced the transactivation of STAT1-targeted genes in AML cells. Furthermore, in vivo treatment of HL-60 xenografts demonstrated that Dip G significantly inhibited tumor growth and reduced tumor weight by inducing cell differentiation. Taken together, these results shed light on an essential role for ERK-mediated nuclear translocation of p-STAT1 (Ser727) and its full transcriptional activity in Dip G-induced differentiation of AML cells. Furthermore, these results demonstrate that Dip G could be used as a differentiation-inducing agent for AML therapy, particularly for non-acute promyelocytic leukemia therapy.

Resveratrol loaded gelatin nanoparticles synergistically inhibits cell cycle progression and constitutive NF-kappaB activation, and induces apoptosis in non-small cell lung cancer cells

PURPOSE

Previously, we reported that the prepared resveratrol (RSV) loaded gelatin nanoparticles (GNPs) possessed enhanced anticancer effect than free RSV in non-small cell lung carcinoma cells and Swiss albino mice. The present study aims to explore the relevant mechanism of cell death induced by the combination of RSV-GNPs in NCI-H460 cells.

METHODS AND RESULTS

To increase its bioavailability and anticancer efficacy, we have encapsulated RSV-GNPs by Coacervation method. The detailed methods of preparation and characterization of RSV-GNPs were reported in our earlier publication. RSV-GNPs treated cells showed a further increased level of lipid peroxidative markers, i.e. TBARS and LHP in NCI-H460 cells. Activities of antioxidant enzymes SOD, CAT, GPx and GSH levels were decreased upon the treatment with RSV-GNPs in NCI-H460 cells. The nuclear fragmentation was evaluated by DAPI staining and data showed condensed apoptotic bodies upon treatment with the combination of RSV-GNPs compared to RSV alone treatment group. In addition, cell death induced by RSV-GNPs was mainly due to apoptosis which was characterized by a nuclear DNA fragmentation in a ladder-pattern was obtained from the genomic DNA analysis. Moreover, Western blotting analysis showed that apoptosis induced by RSV-GNPs is associated with the increased Bax, p53, p21, caspase-3 protein levels, and decreased Bcl-2 and NF-κB proteins expression, which indicates the involvement of mitochondria-dependent apoptosis in the anticancer efficacy of RSV-GNPs in NCI-H460 cells. It was also found that this enhanced anticancer efficacy of RSV-GNPs induced cell arrest in the G0/G1 phase of cell cycle.

CONCLUSIONS

Taken together, the results of our study clearly suggested that the cell death induced by the combination of RSV-GNPs would involve alteration in expression of p53, p21, caspase-3, Bax, Bcl-2 and NF-κB, indicating oxidative mechanism in NCI-H460 cells. Based on these results, it is concluded that GNPs is an ideal way to deliver RSV because of its high loading efficiency and superior efficacy in NCI-H460 cells.

Resveratrol: from basic studies to bedside

Plants produce a remarkable amount of low molecular mass natural products endowed with a large array of pivotal biological activities. Among these molecules, resveratrol (3,5,4'-trihydroxystilbene) has been identified as an important modulator of cell phenotype with a complex and pleiotropic mode of action. Extensive literature regarding its activity, mainly employing cellular models, suggests that this polyphenol controls cell proliferation, induces differentiation, and activates apoptosis and autophagy. The compound also modulates angiogenesis and inflammation. Similarly, studies on implanted cancers and chemical-induced tumors confirm the potential chemotherapeutical interest of the compound. Likewise, several reports clearly demonstrated, in animal models, that the compound might positively affect the development and evolution of chronic diseases including type 2 diabetes, obesity, coronary heart disease, metabolic syndrome, and neurogenerative pathologies. Finally, a number of investigations stated that the toxicity of the molecule is scarce. Despite these promising observations, few clinical trials have yet been performed to evaluate the effectiveness of the molecule both in prevention and treatment of human chronic disease. Preliminary findings therefore suggest the need for more extensive clinical investigations.

SIRT1 activation enhances HDAC inhibition-mediated upregulation of GADD45G by repressing the binding of NF-κB/STAT3 complex to its promoter in malignant lymphoid cells

We explored the activity of SIRT1 activators (SRT501 and SRT2183) alone and in combination with panobinostat in a panel of malignant lymphoid cell lines in terms of biological and gene expression responses. SRT501 and SRT2183 induced growth arrest and apoptosis, concomitant with deacetylation of STAT3 and NF-κB, and reduction of c-Myc protein levels. PCR arrays revealed that SRT2183 leads to increased mRNA levels of pro-apoptosis and DNA-damage-response genes, accompanied by accumulation of phospho-H2A.X levels. Next, ChIP assays revealed that SRT2183 reduces the DNA-binding activity of both NF-κB and STAT3 to the promoter of GADD45G, which is one of the most upregulated genes following SRT2183 treatment. Combination of SRT2183 with panobinostat enhanced the anti-growth and anti-survival effects mediated by either compound alone. Quantitative-PCR confirmed that the panobinostat in combination with SRT2183, SRT501 or resveratrol leads to greater upregulation of GADD45G than any of the single agents. Panobinostat plus SRT2183 in combination showed greater inhibition of c-Myc protein levels and phosphorylation of H2A.X, and increased acetylation of p53. Furthermore, EMSA revealed that NF-κB binds directly to the GADD45G promoter, while STAT3 binds indirectly in complexes with NF-κB. In addition, the binding of NF-κB/STAT3 complexes to the GADD45G promoter is inhibited following panobinostat, SRT501 or resveratrol treatment. Moreover, the combination of panobinostat with SRT2183, SRT501 or resveratrol induces a greater binding repression than either agent alone. These data suggest that STAT3 is a corepressor with NF-κB of the GADD45G gene and provides in vitro proof-of-concept for the combination of HDACi with SIRT1 activators as a potential new therapeutic strategy in lymphoid malignancies.

Antiproliferation and redifferentiation in thyroid cancer cell lines by polyphenol phytochemicals

Thyroid carcinogenesis is accompanied by loss of thyroid-specific functions and refractory to radioiodine and thyroid stimulating hormone (TSH) suppression therapy. Redifferentiating agents have been shown to inhibit tumor growth and improve the response to conventional therapy. Polyphenol phytochemicals (PPs) in fruits and vegetables have been reported to inhibit cancer initiation, promotion, progression and induce redifferentiation in selected types. In this study we examined PPs induce redifferentiation in thyroid cancer cell lines. We investigated the effects of genistein, resveratrol, quercetin, kaempferol, and resorcinol on the F9 embryonal carcinoma cell differentiation model. The thyroid cancer cell lines, TPC-1, FTC-133, NPA, FRO, and ARO, displayed growth inhibition in response to genistein, resveratrol, quercetin. We further demonstrated that genistein decreased the dedifferention marker CD97 in NPA cells and resveratrol decreased CD97 in FTC-133, NPA, FRO cells and quercetin decreased CD97 in all cell lines. We observed increased expression of differentiation marker NIS in FTC-133 cells in response to genistein, and resveratrol but no change in NPA, FRO, ARO cells. Quercetin increased or induced NIS in FTC-133, NPA, FRO cells. These findings suggest that PPs may provide a useful therapeutic intervention in thyroid cancer redifferentiation therapy.

Resveratrol ameliorates DNA damage, prooxidant and antioxidant imbalance in 1,2-dimethylhydrazine induced rat colon carcinogenesis

Colorectal cancer is one of the most common internal malignancies in Western society. Currently oxidative stress has been increasingly postulated as a major contributor to carcinogenesis. The assessment of damage in various biological matrices, such as tissues and cells, is vital to understand the development of carcinogenesis and subsequently devising intervention strategies. Thus, the major objective of the present study was to examine the effect of resveratrol (Res) on DNA damage in a short-term study of 16 days and circulatory lipid peroxidation, enzymic/non-enzymic antioxidants status in a long-term study of 30 weeks in 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis. Wistar male rats were divided into 6 groups, group 1 were control rats, group 2 rats received Res (8mg/kg body weight, orally, everyday), rats in groups 3-6 were administered (DMH, 20mg/kg body weight, s.c.) as four injections in order to induce DNA damage in the short-term or once a week for the first 15 weeks in the long-term study. In addition to DMH, group 4 (initiation), 5 (post-initiation) and 6 (entire-period) received Res (8mg/kg body weight, p.o., everyday). The results revealed that, supplementation with Res (entire-period) treatment regimen significantly reduced the DMH-induced leukocytic DNA damage (tail length, tail moment, % DNA in the comet tail and olive tail moment) as compared to DMH-alone treated rats. In addition, entire-period Res supplementation increased the enzymic (superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glutathione S-transferase) and non-enzymic (reduced glutathione, vitamin C, vitamin E and beta-carotene) antioxidant status with a corresponding decrease in the extent of lipid peroxidation markers (thiobarbituric acid reactive substances, diene conjugates and lipid hydroperoxides). Conversely, Res supplementation during initiation and post-initiation regimen did not produce greater modulatory effects. Our results indicate that DMH-induced DNA damage and oxidative stress were suppressed/prevented effectively by chronic Res supplementation.

Action of resveratrol alone or in combination with roscovitine, a CDK inhibitor, on cell cycle progression in human HL-60 leukemia cells

Results of a number of epidemiological and experimental studies indicate that polyphenols (e.g. resveratrol (RES), epicatechins etc.), antioxidant agents and abundant micronutrients in our food could have strong anti-mitotic as well as pro-apoptotic effects. In this study we raised the question whether roscovitine (ROSC), an inhibitor of cyclin-dependent kinases (CDKs) with increased selectivity towards CDK2, could be able to affect human leukemia HL-60 cells in which the p53 gene is inactivated and whether ROSC-induced effects could be additionally modulated by compounds of natural origin, especially by polyphenols e.g. RES. Exposure of HL-60 cells to ROSC for 24 h inhibited their proliferation. Flow cytometric analyses revealed that unlike MCF-7 cells, HL-60 cells were arrested in G(1) upon ROSC treatment. Furthermore, ROSC also induced apoptosis in HL-60 cells. After treatment with 40 microM ROSC for 24 h the frequency of hypoploid cells representing cells undergoing apoptosis reached approximately 50%. In the next step the action of RES alone or in combination with ROSC was examined. Interestingly, synergistic effects were observed after combined treatment for 24 h and sequential post-incubation for 48 h in the presence of RES. Such combined treatment resulted in a marked reduction of the frequency of the S- and G(2)/M-phase cells and simultaneously increased the G(1) cell population up to 80% at a fourfold lower ROSC dose. Further analyses revealed that the combined treatment strongly activated caspase-3. These results clearly evidence that RES strongly potentiates ROSC-induced apoptosis.

Identification of a terphenyl derivative that blocks the cell cycle in the G0-G1 phase and induces differentiation in leukemia cells

To further explore the SAR of resveratrol-related trans-stilbene derivatives, here we describe the synthesis of (a) a series of 3,5-dimethoxy analogues in which a variety of substituents were introduced at positions 2', 3', 4', and 5' of the stilbene scaffold and (b) a second group of derivatives (2-phenylnaphthalenes and terphenyls) that incorporate a phenyl ring as a bioisosteric replacement of the stilbene alkenyl bridge. We thoroughly characterized all of the new compounds with respect to their apoptosis-inducing activity and their effects on the cell cycle. One of the new derivatives, 13g, behaved differently from the others, as it was able to block the cell cycle in the G(0)-G(1) phase and also to induce differentiation in acute myelogenous leukemia HL60 cells. Compared to resveratrol, the synthetic terphenyl 13g showed a more potent apoptotic and differentiating activity. Moreover, it was active on both multidrug resistance and Bcr-Abl-expressing cells that were resistant to resveratrol.

Resveratrol inhibits phorbol ester-induced expression of COX-2 and activation of NF-kappaB in mouse skin by blocking IkappaB kinase activity

Aberrant expression of cyclooxygenase-2 (COX-2) has been implicated in tumor promotion. Resveratrol, a phytoalexin present in grapes, was reported to inhibit multistage mouse skin carcinogenesis. In the present study, we found that topically applied resveratrol significantly inhibited COX-2 expression induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Resveratrol-suppressed phosphorylation and subsequent degradation of IkappaBalpha, thereby inhibiting activation of nuclear factor-kappaB (NF-kappaB) in TPA-stimulated mouse skin. Pretreatment with resveratrol also suppressed TPA-induced phosphorylation of extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein (MAP) kinase. Resveratrol blunted TPA-induced phosphorylation of p65 and its interaction with CBP/p300, rendering NF-kappaB transcriptionally inactive. To get further insights into the molecular basis of NF-kappaB inactivation by resveratrol, we examined the role of IkappaB kinase (IKK) in mediating TPA-induced activation of NF-kappaB and COX-2 expression. TPA treatment led to rapid induction of IKK activity in mouse skin, which was abolished either by resveratrol or an IKK inhibitor Bay 11-7082. Topical application of Bay 11-7082 also abrogated TPA-induced NF-kappaB activation and COX-2 expression, supporting the involvement of IKK in TPA-induced COX-2 expression. Taken together, the above findings suggest that resveratrol targets IKK in blocking TPA-induced NF-kappaB activation and COX-2 expression in mouse skin in vivo.

Effects of cyclosporine on oxidant/antioxidant status in rat ovary tissues: Protective role of black grape extract

OBJECTIVES

It has been demonstrated that immunosuppressive drug cyclosporine A (CsA) increases the synthesis of reactive oxygen species (ROS) and lipid peroxidation products in vitro and in vivo studies, but its possible toxic effects in ovary tissue have not been defined yet. This study was designed to elucidate possible relation between CsA treatment and oxidant/antioxidant status in rat ovary tissue and, to determine if antioxidant supplementation is beneficial.

METHODS

CsA and black grape extracts were given to rats orally for 10 days. In each group (control, CsA, CsA plus black grape and black grape alone), there were 7 animals (28 rats in total). After the animals were sacrificed, their ovaries were removed to be used in the measurement of malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), catalase (CAT) and xanthine oxidase (XO) enzymes.

RESULTS

In the control, CsA plus black grape and black grape alone groups, MDA levels were significantly lower than CsA group. Xanthine oxidase activities were significantly higher in CsA and CsA plus black grape groups than control group. In addition, XO activity was significantly lower in black grape alone group than all the other groups including control group. There were no significant differences in the activities of SOD and CAT enzymes between the groups.

CONCLUSION

The results suggest that CsA leads to oxidant stress and peroxidation in rat ovary tissues mainly due to increased XO activity. It has been suggested that this oxidant stress and peroxidation reactions can be prevented by antioxidant food supplementation like black grape.

Inhibition of COX activity by NSAIDs or ascorbate increases cAMP levels and enhances differentiation in 1alpha,25-dihydroxyvitamin D3-induced HL-60 cells

Arachidonic acid metabolism is modulated during differentiation induced by 1alpha,25(OH)(2)D(3) in HL-60 cells. Antioxidants that affect arachidonic acid metabolism enhance this differentiation program. Ascorbate also enhances differentiation in 1alpha,25(OH)(2)D(3)-induced cells depending on the induction of cAMP. The aim of this work was to study if this cAMP rise depends on modulation of arachidonic acid metabolism by ascorbate. Cyclooxygenase inhibitors, indomethacin and aspirin, increased cAMP levels and also enhanced 1alpha,25(OH)(2)D(3)-induced differentiation in HL-60 cells. Ascorbate did not affect the release of arachidonic acid-derived metabolites but decreased the levels of TXB(2) and PGE(2), suggesting the inhibition of cyclooxygenase. On the other hand, free arachidonic acid increased both cAMP levels and differentiation in the absence or presence of 1alpha,25(OH)(2)D(3). Neither cyclooxygenase inhibitors nor ascorbate modified AA effect. Then, inhibition of cyclooxygenase activity by ascorbate could accumulate free arachidonic acid or other metabolites that increase cAMP levels and enhance differentiation in 1alpha,25(OH)(2)D(3)-induced HL-60 cells.

Synergistic action of resveratrol, an ingredient of wine, with Ara-C and tiazofurin in HL-60 human promyelocytic leukemia cells

OBJECTIVE

Resveratrol, a naturally occurring stilbene derivative, is a potent free-radical scavenger causing a number of biochemical and antineoplastic effects. It was shown to induce differentiation and apoptosis in leukemia cells. Resveratrol was also identified as an inhibitor of ribonucleotide reductase (RR), a key enzyme of DNA synthesis. We report about the biochemical effects of resveratrol on the concentration of deoxyribonucleoside triphosphates (dNTPs), the products of RR, and on the incorporation of 14C-labeled cytidine into the DNA of HL-60 human promyelocytic leukemia cells.

MATERIALS AND METHODS

Incorporation of 14C-labeled cytidine into the DNA of resveratrol-treated HL-60 cells was measured. Concentration of dNTPs was determined by a HPLC method. Cytotoxic effects of resveratrol, Ara-C, and tiazofurin were analyzed using growth inhibition and clonogenic assays. Induction of apoptosis was studied using a Hoechst/propidium iodide staining method.

RESULTS

We found that resveratrol effectively inhibited incorporation of 14C-labeled cytidine into DNA. Furthermore, incubation of HL-60 cells with resveratrol significantly decreased intracellular dCTP, dTTP, dATP, and dGTP concentrations. Based on these results, we investigated the combination effects of resveratrol with Ara-C or tiazofurin, both antimetabolites, which are known to exhibit synergistic effects in combination with other inhibitors of RR. In growth inhibition, apoptosis, and clonogenic assays, resveratrol acted synergistically with both Ara-C and tiazofurin in HL-60 cells.

CONCLUSIONS

We conclude that resveratrol could become a viable candidate as one compound in the combination chemotherapy of leukemia and therefore deserves further testing.

Pterostilbene and 3'-hydroxypterostilbene are effective apoptosis-inducing agents in MDR and BCR-ABL-expressing leukemia cells

Pterostilbene and 3,5-hydroxypterostilbene are the natural 3,5-dimethoxy analogs of trans-resveratrol and piceatannol, two compounds which can induce apoptosis in tumor cells. In previous studies we demonstrated the importance of a 3,5-dimethoxy motif in conferring pro-apoptotic activity to stilbene based compounds so we now wanted to evaluate the ability of pterostilbene and 3,5-hydroxypterostilbene in inducing apoptosis in sensitive and resistant leukemia cells. When tested in sensitive cell lines, HL60 and HUT78, 3'-hydroxypterostilbene was 50-97 times more potent than trans-resveratrol in inducing apoptosis, while pterostilbene appeared barely active. However, both compounds, but not trans-resveratrol and piceatannol, were able to induce apoptosis in the two Fas-ligand resistant lymphoma cell lines, HUT78B1 and HUT78B3, and the multi drug-resistant leukemia cell lines HL60-R and K562-ADR (a Bcr-Abl-expressing cell line resistant to imatinib mesylate). Of note, pterostilbene-induced apoptosis was not inhibited by the pancaspase-inhibitor Z-VAD-fmk, suggesting that this compound acts through a caspase-independent pathway. On the contrary, 3'-hydroxypterostilbene seemed to trigger apoptosis through the intrinsic apoptotic pathway: indeed, it caused a marked disruption of the mitochondrial membrane potential delta psi and its apoptotic effects were inhibited by Z-VAD-fmk and the caspase-9-inhibitor Z-LEHD-fmk. Moreover, pterostilbene and 3'-hydroxypterostilbene, when used at concentrations that elicit significant apoptotic effects in tumor cell lines, did not show any cytotoxicity in normal hemopoietic stem cells. In conclusion, our data show that pterostilbene and particularly 3'-hydroxypterostilbene are interesting antitumor natural compounds that may be useful in the treatment of resistant hematological malignancies, including imatinib, non-responsive neoplasms.

Effects of black grape extract on activities of DNA turn-over enzymes in cancerous and non cancerous human colon tissues

Effects of extract of dried whole black grape including seed on adenosine deaminase (ADA), 5' nucleotidase (5'NT) and xanthine oxidase (XO) enzymes were investigated in cancerous and non-cancerous human colon tissues. Enzyme activities were measured in 20 colon tissues, 10 from cancerous region and 10 from non cancerous region with and without pre incubation with black grape extract. ADA and 5'NT activities were found increased and that of the XO decreased in the cancerous tissues relative to non cancerous ones. After incubation period with black grape extract for 12 h, ADA and 5'NT activities were found to be significantly lowered but that of XO unchanged in both cancerous and non cancerous tissues. Results suggest that ADA and 5'NT activities increase but XO activity decreases in cancerous human colon tissues, which may provide advantage to the cancerous tissues in obtaining new nucleotides for rapid DNA synthesis through accelerated salvage pathway activity. Black grape extract makes significant inhibition on the ADA and 5'NT activities of cancerous and non cancerous colon tissues, thereby eliminating this advantage of cancer cells, which might be the basis for the beneficial effect of black grape in some kinds of human cancers.

Effect of resveratrol on activation of nuclear factor kappa-B and inflammatory factors in rat model of acute pancreatitis

AIM: To observe the effect of resveratrol on nuclear factor Kappa-B (NF-κB) activation and the inflammatory response in sodium taurocholate-induced pancreatitis in rats.

METHODS: Seventy-two male SD rats were randomly divided into three groups: sham operation group (control), severe acute pancreatitis (SAP) group, and severe acute pancreatitis group treated with resveratrol (RES). A SAP model was established by injecting 4% sodium taurocholate 1 mL/kg through puncturing the pancreatic duct. In Res group, Res was given at 30 mg/kg b.m. intraperitoneally after the SAP model was successfully established. Eight animals from each group were sacrificed at 3, 6 and 12 h after modeling. The expression of NF-κB activation of pancreas was detected by immunohistochemical staining, whereas the levels of TNF-α and IL-8 in pancreatic tissues were estimated by radioimmunoassay. The pathological changes of pancreas and lungs were examined microscopically.

RESULTS: Much less hyperemia, edema, dust-colored necrotic focus and soaps were noticed in pancreas in RES group than in SAP group. In RES group, hemorrhage, exudates and infiltration of inflammatory cells in pancreas and interstitial edema, destruction of alveolar wall in lung were significantly less than in SAP group. In the SAP group, the activation of NF-κB in pancreatic tissues was enhanced significantly at any measure point compared with control group (64.23±10.72% vs 2.56±0.65%, 55.86±11.34% vs 2.32±0.42%, 36.23±2.30% vs 2.40±0.36%,P <0.01), TNF-α,IL-8 were also increased and reached their peak at 6 h and then declined. The activation of NF-κB and the levels of TNF-α and IL-8 in RES group were significantly lower than those in SAP group (P<0.01): activation (52.63±9.45% vs 64.23±10.72%, 40.52±8.40% vs 55.86±11.34%, 29.83±5.37% vs 36.23±2.30%), TNF-α (132.76±15.68 pg/mL vs 158.36±12.58 pg/mL, 220.32±23.57 pg/mL vs 247.67± 11.62 pg/mL, 175.68±18.43 pg/mL vs 197.35±12.57 pg/mL) and IL-8 (0.62±0.21 μg/L vs 0.83±0.10 μg/L, 1.10±0.124 μg/L vs 1.32±0.18 μg/L, 0.98±0.16 μg/L vs 1.27±0.23 μg/L).

CONCLUSION: The activation of NF-κB is involved in the inflammatory response of rats with SAP. Resveratrol could effectively inhibit the expression of NF-κB activation, alleviate the severity of SAP through its anti-inflammatory effects and regulate the inflammatory mediators.

Molecular basis of chemoprevention by resveratrol: NF-kappaB and AP-1 as potential targets

Recently, chemoprevention by the use of naturally occurring substances is considered as a priority to reduce the ever-increasing incidence of cancer. The intervention of multistage carcinogenesis by modulating intracellular signaling pathways may provide molecular basis of chemoprevention with a wide variety of dietary phytochemicals. Resveratrol, a red wine polyphenol, has been studied extensively for the chemopreventive activity in the context of its ability to interfere with the multistage carcinogenesis. Numerous intracellular signaling cascades converge with the activation of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), which act independently or coordinately to regulate expression of target genes. These ubiquitous eukaryotic transcription factors mediate pleiotropic effects on cellular transformation and tumor promotion. This review aims to update the molecular mechanisms underlying chemoprevention by resveratrol with special focus on its effect on cellular signaling cascades mediated by NF-kappaB and AP-1.

Redifferentiation therapy for thyroid cancer

Thyroid tumorigenesis and carcinogenesis accompany progressive loss of thyroid-specific differentiated functions. Some thyroid cancers are or become dedifferentiated, and they become refractory to efficacy-proven conventional therapies such as radioiodine ablation therapy and thyrotropin (TSH)-suppressive therapy. Redifferentiation therapy by either redifferentiating agents or gene transfer of differentiation-related genes may retard tumor growth and make tumors respond to conventional therapies.