stilbenes and Leukemia--Myelogenous--Chronic--BCR-ABL-Positive

The phosphorylation of histone H2AX, a novel tumor suppressor protein, is involved in regulation of cancer cell apoptosis. The aim of this study was to examine whether H2AX phosphorylation was required for resveratrol-induced apoptosis of human chronic myelogenous leukemia (CML) cells in vitro.. K562 cells were tested. Cell apoptosis was analyzed using flow cytometry, and the phosphorylation of H2AX and other signaling proteins was examined with Western blotting. To analyze the signaling pathways, the cells were transfected with lentiviral vectors encoding H2AX-wt or specific siRNAs.. Treatment of K562 cells with resveratrol (20-100 μmol/L) induced apoptosis and phosphorylation of H2AX at Ser139 in time- and dose-dependent manners, but reduced phosphorylation of histone H3 at Ser10. Resveratrol treatment activated two MAPK family members p38 and JNK, and blocked the activation of another MAPK family member ERK. Pretreatment with the p38 inhibitor SB202190 or the JNK inhibitor SP600125 dose-dependently reduced resveratrol-induced phosphorylation of H2AX, which were also observed when the cells were transfected with p38- or JNK-specific siRNAs. Overexpression of H2AX in K562 cells markedly increased resveratrol-induced apoptosis, whereas overexpression of H2AX-139m (Ser139 was mutated to block phosphorylation) inhibited resveratrol-induced apoptosis. K562 cells transfected with H2AX-specific siRNAs were resistant to resveratrol-induced apoptosis.. H2AX phosphorylation at Ser139 in human CML cells, which is regulated by p38 and JNK, is essential for resveratrol-induced apoptosis.

Topics: Antineoplastic Agents; Apoptosis; Dose-Response Relationship, Drug; Histones; Humans; JNK Mitogen-Activated Protein Kinases; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Kinase Inhibitors; Resveratrol; RNA Interference; Signal Transduction; Stilbenes; Time Factors; Transfection

To investigate the effect of treatment with resveratrol combined with imatinib mesylate on human chronic myelogenous leukemia K562 cell growth inhibition and apoptosis, in vitro cultured human chronic myelogenous leukemia K562 cells were incubated with different concentrations of resveratrol and imatinib mesylate when the cells were in the logarithmic phase. Next, the cell growth inhibition was evaluated using the MTT assay and cellular morphology observation. Apoptosis was determined using Annexin V fluorescein isothiocyanate/propidium iodide double staining. The results demonstrated that treatment with resveratrol (concentration-dependent) and imatinib mesylate showed significantly greater inhibition of K562 cell growth and a higher apoptosis rate of K562 cells than imatinib mesylate medication alone and the control group (P < 0.01). The imatinib mesylate medication alone group showed significant inhibition of K562 cell growth and apoptosis rate of K562 cells compared to the control group (P < 0.01). Our findings indicate that imatinib mesylate and resveratrol are potent drug treatments for human chronic myelogenous leukemia, offering a promising means of inhibiting cell growth and apoptosis.

Topics: Apoptosis; Cell Cycle; Cell Proliferation; Drug Resistance, Neoplasm; Humans; Imatinib Mesylate; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Resveratrol; Stilbenes

Efforts to enhance the antileukemic properties of arsenic trioxide are clinically relevant and may lead to the development of new therapeutic approaches for the management of certain hematological malignancies. We provide evidence that concomitant treatment of acute myeloid leukemia (AML) cells or chronic myeloid leukemia (CML) cells with resveratrol potentiates arsenic trioxide-dependent induction of apoptosis. Importantly, clonogenic assays in methylcellulose demonstrate potent suppressive effects of the combination of these agents on primitive leukemic progenitors derived from patients with AML or CML. Taken together, these findings suggest that combinations of arsenic trioxide with resveratrol may provide an approach for targeting of early leukemic precursors and, possibly, leukemia initiating stem cells.

Topics: Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; Autophagy; Cell Line, Tumor; Drug Synergism; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Neoplastic Stem Cells; Oxides; Resveratrol; Stilbenes

A series of 22 stilbene derivatives based on resveratrol were synthesized incorporating acetoxy-, benzyloxy-, carboxy-, chloro-, hydroxy- and methoxy functional groups. We examined the cytotoxicity of these 22 stilbenes in human K562 chronic myelogenous leukemia cells. Only four compounds were cytotoxic namely 4'-hydroxy-3-methoxystilbene (15), 3'-acetoxy-4-chlorostilbene (19), 4'-hydroxy-3,5-dimethoxystilbene or pterostilbene (3) and 3,5-dibenzyloxy-4'-hydroxystilbene (28) with IC(50)s of 78 µM, 38 µM, 67 µM and 19.5 µM respectively. Further apoptosis assessment on the most potent compound, 28, confirmed that the cells underwent apoptosis based on phosphatidylserine externalization and loss of mitochondrial membrane potential. Importantly, we observed a concentration-dependent activation of caspase-9 as early as 2 hr with resultant caspase-3 cleavage in 28-induced apoptosis. Additionally, a structure-activity relationship (SAR) study proposed a possible mechanism of action for compound 28. Taken together, our data suggests that the pro-apoptotic effects of 28 involve the intrinsic mitochondrial pathway characterized by an early activation of caspase-9.

Topics: Apoptosis; Caspase 9; Cell Survival; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Membrane Potential, Mitochondrial; Stilbenes; Structure-Activity Relationship

Bcr-Abl fusion protein activates tyrosine kinase, resulting in the proliferation of leukemia cells, especially chronic myeloid leukemia (CML) cells. Imatinib (IM) effectively targets Bcr-Abl tyrosine kinase, but development of resistance to IM occurs with varying frequency.. Elucidation of the common regulatory pathway upstream of Bcr-Abl in IM-sensitive and IM-resistant CML cells is important for developing novel therapeutics against CML.. This study demonstrated that IM preferentially inhibited the viability and Bcr-Abl expression in IM-sensitive K562 (K562) cells, but not in Bcr-Abl overexpressing IM-resistant K562 (K562R) cells. Both K562 and K562R cells expressed Shh preproprotein, cleaved Shh C-terminal and N-terminal peptides, as well as mRNA level of major Shh signaling molecules, including sonic hedgehog (Shh), patched (PTCH), smoothened (Smo) and Gli-1. Moreover, Gli-1 translocation into nucleus was evident in these two cell lines, suggesting that both K562 and K562R cells possess activated and major components of the Shh signaling pathway. Silencing of Gli-1 by interference RNA was accompanied by inhibition of Bcr-Abl protein expression. Pharmacological suppression of Bcr-Abl expression was restored by the Smo agonist purmorpharmine. Treatment of Shh peptide in both K562 and K562R cells not only increased Shh and Gli-1 expression, but also up-regulated Bcr-Abl expression. Resveratrol, a known Bcr-Abl inhibitor, reduced Gli-1 activation and inhibited the viability of CML cells.. Shh signaling may regulate Bcr-Abl expression in human chronic myeloid leukemia cells. Novel compounds inhibiting both Shh signaling and Bcr-Abl expression, such as resveratrol, may have potential to be effective agents against CML independent of IM resistance.

Topics: Antineoplastic Agents; Benzamides; Cell Survival; Drug Resistance, Neoplasm; Fusion Proteins, bcr-abl; Hedgehog Proteins; Humans; Imatinib Mesylate; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Piperazines; Pyrimidines; Resveratrol; RNA Interference; RNA, Messenger; RNA, Small Interfering; Signal Transduction; Stilbenes; Up-Regulation

To examine the antiproliferative and apoptotic effects of resveratrol on imatinib-sensitive and imatinib-resistant K562 chronic myeloid leukemia cells.. Antiproliferative effects of resveratrol were determined by the 3-Bis[2-methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5-carboxanilide inner salt (XTT) cell proliferation assay. Apoptotic effects of resveratrol on sensitive K562 and resistant K562/IMA-3 cells were determined through changes in caspase-3 activity, loss of mitochondrial membrane potential (MMP), and apoptosis by annexin V-(FITC).. The concentrations of resveratrol that inhibited cell growth by 50% (IC(50)) were calculated as 85 and 122 μM for K562 and K562/IMA-3 cells, respectively. There were 1.91-, 7.42- and 14.73-fold increases in loss of MMP in K562 cells treated with 10, 50, and 100 μM resveratrol, respectively. The same concentrations of resveratrol resulted in 2.21-, 3.30- and 7.65-fold increases in loss of MMP in K562/IMA-3 cells. Caspase-3 activity increased 1.04-, 2.77- and 4.8-fold in K562 and 1.02-, 1.41- and 3.46-fold in K562/IMA-3 cells in response to the same concentrations of resveratrol, respectively. Apoptosis was induced in 58.7%- and 43.3% of K562 and K562/IMA-3 cells, respectively, in response to 100 μM resveratrol.. Taken together these results may suggest potential use of resveratrol in CML, as well as in patients with primary and/or acquired resistance to imatinib.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Benzamides; Caspase 7; Cell Growth Processes; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Humans; Imatinib Mesylate; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Membrane Potential, Mitochondrial; Piperazines; Pyrimidines; Resveratrol; Stilbenes

Resveratrol, an important phytoalexin in many plants, has been reported to have cytotoxic effects on various types of cancer. Ceramide is a bioactive sphingolipid that regulates many signaling pathways, including cell growth and proliferation, senescence and quiescence, apoptosis, and cell cycle. Ceramides are generated by longevity assurance genes (LASS). Glucosylceramide synthase (GCS) and sphingosine kinase-1 (SK-1) enzymes can convert ceramides to antiapoptotic molecules, glucosylceramide, and sphingosine-1-phosphate, respectively. C8:ceramide, an important cell-permeable analogue of natural ceramides, increases intracellular ceramide levels significantly, while 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) and SK-1 inhibitor increase accumulation of ceramides by inhibiting GCS and SK-1, respectively. Chronic myelogenous leukemia (CML) is a hematological disorder resulting from generation of BCR/ABL oncogene. In this study, we examined the roles of ceramide metabolizing genes in resveratrol-induced apoptosis in K562 CML cells. There were synergistic cytotoxic and apoptotic effects of resveratrol with coadministration of C8:ceramide, PDMP, and SK-1 inhibitor. Interestingly, there were also significant increases in expression levels of LASS genes and decreases in expression levels of GCS and SK-1 in K562 cells in response to resveratrol. Our data, in total, showed for the first time that resveratrol might kill CML cells through increasing intracellular generation and accumulation of apoptotic ceramides.

Topics: Apoptosis; Ceramides; Down-Regulation; Glucosylceramides; Glucosyltransferases; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Lysophospholipids; Morpholines; Phosphotransferases (Alcohol Group Acceptor); Resveratrol; RNA, Neoplasm; Sphingosine; Stilbenes; Up-Regulation

Resveratrol is known to downregulate the high endogenous level of Heat shock protein 70 (Hsp70) in Chronic Myelogenous Leukemia (CML) K562 cells and induce apoptosis. Since Heat Shock Factor 1 (HSF1) controls transcription of Hsp70, we wanted to probe the signaling pathways responsible for transcriptional activation of HSF1.. Cells exposed to 40microM Resveratrol rapidly abolished serine473 phosphorylation of Akt and significantly reduced its kinase activity. Inactivation of Akt pathway by Resveratrol subsequently blocked serine9 phosphorylation of Gsk3beta. Active non-phosphorylated Gsk3beta rendered HSF1 transcriptionally inactive and reduced Hsp70 production. Blocking PI3K/Akt activity also demonstrated similar effects on Hsp70 comparable to Resveratrol. Inactivation of Gsk3beta activity by inhibitors SB261763 or LiCl upregulated Hsp70. Resveratrol significantly modulated ERK1/2 activity as evident from hyper phosphorylation at T302/Y304 residues and simultaneous upregulation in kinase activity. Blocking ERK1/2 activation resulted in induction of Hsp70. Therefore, increase in ERK1/2 activity by Resveratrol provided another negative influence on Hsp70 levels through negative regulation of HSF1 activity. 17-allylamino-17-demethoxygeldanamycin (17AAG), a drug that inhibits Hsp90 chaperone and degrades its client protein Akt concomitantly elevated Hsp70 levels by promoting nuclear translocation of HSF1 from the cytosol. This effect is predominantly due to inhibition of both Akt and ERK1/2 activation by 17AAG. Simultaneously treating K562 with Resveratrol and 17AAG maintained phosho-ERK1/2 levels close to untreated controls demonstrating their opposite effects on ERK1/2 pathway. Resveratrol was found not to interfere with Bcr-Abl activation in K562 cells.. Thus our study comprehensively illustrates that Resveratrol acts downstream of Bcr-Abl and inhibits Akt activity but stimulates ERK1/2 activity. This brings down the transcriptional activity of HSF1 and Hsp70 production in K562 cells. Additionally, Resveratrol can be used in combination with chemotherapeutic agents such as 17AAG, an Hsp90 inhibitor reported to induce Hsp70 and hence compromise its chemotherapeutic potential.

Topics: Blotting, Western; Cell Line, Tumor; Down-Regulation; Extracellular Signal-Regulated MAP Kinases; HSP70 Heat-Shock Proteins; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Microscopy, Fluorescence; Phosphorylation; Proto-Oncogene Proteins c-akt; Resveratrol; Stilbenes

Autophagy that is induced by starvation or cellular stress can enable cancer cell survival by sustaining energy homeostasis and eliminating damaged organelles and proteins. In response to stress, cancer cells have been reported to accumulate the protein p62/SQSTM1 (p62), but its role in the regulation of autophagy is controversial. Here, we report that the plant phytoalexin resveratrol (RSV) triggers autophagy in imatinib-sensitive and imatinib-resistant chronic myelogenous leukemia (CML) cells via JNK-dependent accumulation of p62. JNK inhibition or p62 knockdown prevented RSV-mediated autophagy and antileukemic effects. RSV also stimulated AMPK, thereby inhibiting the mTOR pathway. AMPK knockdown or mTOR overexpression impaired RSV-induced autophagy but not JNK activation. Lastly, p62 expression and autophagy in CD34+ progenitors from patients with CML was induced by RSV, and disrupting autophagy protected CD34+ CML cells from RSV-mediated cell death. We concluded that RSV triggered autophagic cell death in CML cells via both JNK-mediated p62 overexpression and AMPK activation. Our findings show that the JNK and AMPK pathways can cooperate to eliminate CML cells via autophagy.

Topics: Adaptor Proteins, Signal Transducing; Amino Acid Chloromethyl Ketones; AMP-Activated Protein Kinases; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Autophagy; Benzamides; Blotting, Western; Caspase Inhibitors; Caspases; Cell Survival; Drug Resistance, Neoplasm; Humans; Imatinib Mesylate; JNK Mitogen-Activated Protein Kinases; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Macrolides; Microscopy, Confocal; Microscopy, Electron; Piperazines; Pyrimidines; Resveratrol; RNA Interference; Sequestosome-1 Protein; Stilbenes; Tumor Cells, Cultured; Vacuolar Proton-Translocating ATPases

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder caused by the oncogenic activity of the Bcr-Abl protein, a deregulated tyrosine kinase. Calcium may act directly on cellular enzymes and in conjunction with other cellular metabolites, such as cyclic nucleotides, to regulate cell functions. Alteration in the ionized calcium concentration in the cytosol has been implicated in the initiation of secretion, contraction, and cell proliferation as well as the production of reactive oxygen species (ROS) has been correlates with normal cell proliferation through activation of growth-related signaling pathways. In this study we evaluated in peripheral blood leukocytes from CML patients the role of the balance between intracellular calcium and oxidative stress in CML disease in order to identify possible therapeutic targets in patients affected by this pathology. Our results demonstrated that peripheral blood mononuclear cells derived from CML patients displayed decreased intracellular calcium [Ca(2+)](i) fluxes both after InsP(3) as well as ATP and ionomycin (IONO) administration. CML cells showed lower levels of superoxide dismutase (SOD) activity and significantly higher malondialdehyde levels (MDA) than peripheral blood mononuclear cells derived from control patients. Finally we showed that resveratrol is able to down-regulate InsP3 and ATP effects on intracellular calcium [Ca(2+)](i) fluxes as well as the effects of ATP and IONO on oxidative stress in CML cells.

Topics: Adenosine Triphosphate; Adult; Calcium; Female; Homeostasis; Humans; Intracellular Space; Ionomycin; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Male; Malondialdehyde; Middle Aged; Nitric Oxide; Oxidative Stress; Resveratrol; Stilbenes; Superoxide Dismutase

Resveratrol (RSV) is an attractive candidate for cancer therapy via its ability to intervene at different levels in the AMPK/mTOR pathway. Indeed, RSV is unique in its capacity to inhibit both mTOR and S6 kinase and to activate AMPK. Our recent data reveals that RSV triggered autophagic cell death (ACD) in Chronic Myelogenous Leukemia (CML) cells, via both AMPK activation and JNK-mediated p62/SQSTM1 expression. Here we discuss how Resveratrol can mediate ACD in CML cells and the possibility of utilizing the AMPK/mTOR and JNK/p62 pathways via Resveratrol to combat CML and other hematopoietic malignancies.

Topics: Adaptor Proteins, Signal Transducing; AMP-Activated Protein Kinases; Animals; Apoptosis; Autophagy; Cell Line, Tumor; Humans; JNK Mitogen-Activated Protein Kinases; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Models, Biological; Resveratrol; Stilbenes

Imatinib is successfully used in the treatment of chronic myelogenous leukemia (CML), and the main mechanisms of resistance in refractory patients are now partially understood. In the present study, we investigated the mechanism of action of resveratrol in imatinib-sensitive (IM-S) and -resistant (IM-R) CML cell lines. Resveratrol induced loss of viability and apoptosis in IM-S and IM-R in a time- and dose-dependent fashion. Inhibition of cell viability was detected for concentrations of resveratrol as low as 5 microM, and the IC(50) values for viability, clonogenic assays, apoptosis, and erythroid differentiation were in the 10-25 microM range. The effect of imatinib and resveratrol was additive in IM-S but not in IM-R clones in which the resveratrol effect was already maximal. The effect of resveratrol on apoptosis was partially rescued by zVAD-fmk, suggesting a caspase-independent contribution. Resveratrol action was independent of BCR-ABL expression and phosphorylation, and in agreement was additive to BCR-ABL silencing. Finally, phytoalexin inhibited the growth of BaF3 cells expressing mutant BCR-ABL proteins found in resistant patients, including the multiresistant T315I mutation. Our findings show that resveratrol induces apoptosis, caspase-independent death, and differentiation that collectively contribute to the specific elimination of CML cells. Resveratrol should provide therapeutic benefits in IM-R patients and in other hematopoietic malignancies.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Benzamides; Caspases; Cell Differentiation; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Humans; Imatinib Mesylate; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Piperazines; Pyrimidines; Resveratrol; Stilbenes

Plagiochin E is a new macrocyclic bisbibenzyl compound isolated from Marchantia polymorpha. In the previous studies, we reported that when combined with fluconazole, plagiochin E had synergetic effects against the resistant strain of Candida albicans. Herein, we examined the reversal effect of plagiochin E on multidrug resistance in adriamycin-induced resistant K562/A02 cells and the parental K562 cells. Its cytotoxicity and reversal effects on multidrug resistance were assessed by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide) assay. Apoptosis percentage of cells was obtained from Annexin V/fluorescein isothiocyanate (FITC) and propridium iodide (PI) double-staining. The effects of plagiochin E on P-glycoprotein activity were evaluated by measuring rhodamine 123 (Rh123)-associated mean fluorescence intensity and P-glycoprotein expression on the basis of the flow cytometric technology, respectively. The results showed that plagiochin E ranging from 2 to 12 mug/ml had little cytotoxicity against K562/A02 cells. When combined with adriamycin, it significantly promoted the sensitivity of K562/A02 cells toward adriamycin through increasing intracellular accumulation of adriamycin in a dose-dependent manner. Further study demonstrated that the inhibitory effect of plagiochin E on P-glycoprotein activity was the major cause of increased stagnation of adriamycin inside K562/A02 cells, indicating that plagiochin E, as a new class of mutidrug resistance inhibitor, may effectively reverse the multidrug resistance in K562/A02 cells via inhibiting expression and drug-transport function of P-glycoprotein.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents, Phytogenic; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; Bridged-Ring Compounds; Cell Proliferation; Cell Separation; Cell Survival; Dose-Response Relationship, Drug; Down-Regulation; Doxorubicin; Drug Interactions; Drug Resistance, Neoplasm; Flow Cytometry; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Rhodamine 123; Stilbenes; Time Factors

Chronic myelogenous leukemia (CML) is a myeloproliferative disease associated with a characteristic chromosomal translocation called the Philadelphia chromosome. This results in the expression of the Bcr-Abl fusion protein, a constitutively active protein tyrosine kinase. Although there are a few treatment options with Bcr-Abl kinase inhibitors, drug resistance is often encountered. One of the major obstacles in overcoming drug resistance in CML is the high endogenous levels of heat shock protein 70 (Hsp70). Resveratrol is a phytoalexin produced by several plants. We studied the chemotherapeutic effects and mode of action of resveratrol on K562 (CML) cells. Resveratrol induced apoptosis in K562 cells in a time-dependent manner. This was established by increased annexin V binding, corroborated with an enhanced caspase-3 activity and a rise in the sub-G(0)/G(1) population. Resveratrol treatment also caused suppression of Hsp70 both in mRNA and protein levels. The downregulation of Hsp70 by resveratrol exposure was correlated with a diminished presence of heat shock factor 1 (HSF1) in the nucleus, and the downregulation of transcriptional activity of HSF1. High endogenous levels of Hsp70 have been found to be a deterrent for sensitivity to chemotherapy. We show here that resveratrol could considerably enhance the apoptosis induction in K562 cells by 17-allylamino-17-demethoxygeldanamycin, an anticancer agent that inhibits Hsp90 but augments Hsp70 levels. We conclude that resveratrol significantly downregulated Hsp70 levels through inhibition of HSF1 transcriptional activity and appreciably augmented the pro-apoptotic effects of 17-allylamino-17-demethoxygeldanamycin.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Benzoquinones; Blotting, Western; Caspase 3; Cell Nucleus; DNA-Binding Proteins; Electrophoretic Mobility Shift Assay; Flow Cytometry; G1 Phase; Gene Expression Regulation, Neoplastic; Heat Shock Transcription Factors; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Humans; K562 Cells; Lactams, Macrocyclic; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Promoter Regions, Genetic; Resting Phase, Cell Cycle; Resveratrol; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleotide Reductases; RNA, Messenger; Stilbenes; Transcription Factors