Resveratrol modulates roscovitine-mediated cell cycle arrest of human MCF-7 breast cancer cells

Factors Influencing the Maturation and Developmental Competence of Yak (Bos grunniens) Oocytes In Vitro

The yak (Bos grunniens) is a unique breed living on the Qinghai-Tibet Plateau and its surrounding areas, providing locals with a variety of vital means of living and production. However, the yak has poor sexual maturity and low fertility. High-quality mature oocytes are the basis of animal breeding technology. Recently, in vitro culturing of oocytes and embryo engineering technology have been applied to yak breeding. However, compared to those observed in vivo, the maturation rate and developmental capacity of in vitro oocytes are still low, which severely limits the application of in vitro fertilization and embryo production in yaks. This review summarizes the endogenous and exogenous factors affecting the in vitro maturation (IVM) and developmental ability of yak oocytes reported in recent years and provides a theoretical basis for obtaining high-quality oocytes for in vitro fertilization and embryo production in yaks.

Biochemical profiling of lead-intoxicated impaired lipid metabolism and its amelioration using plant-based bioactive compound

The aim of this study was to investigate the lead (Pb)-induced lipid metabolism impairment and its amelioration using plant-based therapeutic interventions. Pb-induced hepatotoxicity can disturb the normal levels of natural antioxidant enzymes including glutathione (GSH) and superoxide dismutase (SOD) exerting a crucial impact on membrane unsaturated fatty acids (FA), hence leading to lipid peroxidation. Furthermore, Pb toxicity can also alter the regulation of various hormones involved in the synthesis of 3-hydroxy-methyl glutaryl CoA (HMG-CoA reductase), leading to an impairment in normal levels of serum cholesterol and other associated conjugated lipid molecules such HDL-cholesterol, LDL-cholesterol and VLDL-cholesterol. In this study, the lipoprotein fractions, cholesterol, triglyceride (TGs) and biomarkers of liver functions were estimated by employing respective assay kits. The levels of antioxidant enzymes, FFAs and HMG-CoA reductase were determined by employing sandwich ELISA method. The administration of PbAc in experimental rats induced a significant disturbance in lipid profile (P < 0.05) accompanying a significant reduction in natural antioxidant defence system (P < 0.05). The significant alteration in the levels of serum antioxidant enzymes can lead to membrane lipid peroxidation that is reflected by a significantly (P < 0.05) high level of serum MDA in PbAc-induced experimental rats. However, the administration of resveratrol proved therapeutically effective in the treatment of Pb toxicity. Overall, the results of this study accompanying histopathological examination had proved the ameliorating effect of resveratrol in Pb-induced lipid metabolism impairment by adopting vitamin C as a standard therapeutic intervention.

Kolaviron Ameliorates 7, 12-Dimethylbenzanthracene - Induced Mammary Damage in Female Wistar Rats

BACKGROUND

Kolaviron (KV) is a flavonoid rich portion obtained from Garcinia kola seeds with a number of reported pharmacological effects. However, its ameliorative effects on 7,12-Dimethylbenzanthracene (DMBA)-induced mammary damage has not been fully investigated, despite the reported use of the seeds in the treatment of inflammatory related disorders.

OBJECTIVE

To evaluate the ameliorative effects of KV on DMBA-induced mammary damage in female Wistar rats.

METHODS

Forty-nine (49) female Wistar rats were randomly assigned into seven groups of seven rats each. DMBA was administered orally to rats in five of the groups as a single dose of 80 mg/kg body wt while the remaining two groups received the vehicle. The rats were palpated weekly for 3 months to monitor tumor formation. After 3 months of DMBA administration, 1 ml of blood was collected to assay for estrogen receptor- α (ER-α) level. Thereafter, the vehicle (dimethyl sulfoxide) was daily administered to the negative control and positive control groups for the 14 days duration of the experiment while three groups were each given a daily oral dose of 50, 100 and 200 mg/kg body wt of KV for the duration of the experiment. The last DMBA-induced group received 10 mg/kg body wt of the standard drug tamoxifen twice in a week and the remaining DMBA-free group received 200 mg/kg body wt KV. Subsequently, the animals were humanly sacrificed and ER-α, sialic acids, sialidase, sialyltransferase levels were assay for in blood and mammary tissues followed by histopathological examinations.

RESULTS

Significantly higher levels of estrogen receptor-α (ER-α), formation of lobular neoplastic cells, epithelial hyperplasia, lymphocyte infiltration and increased sialylation were detected in DMBA-induced rats. Treatment with KV at 50, 100 and 200 mg/kg body weight resulted in a significant (p<0.05) decrease in ER-α level, significantly (p<0.05) lower free serum sialic acid (21.1%), total sialic acid level of the mammary tissue (21.57%), sialyltransferase activity (30.83%) as well as mRNA level of the sialyltransferase gene (ST3Gal1) were observed after KV interventions.

CONCLUSION

The findings suggest that KV could be further explored in targeting DMBA-induced mammary damage implicated in mammary carcinogenesis.

Anticancer effects of olive oil polyphenols and their combinations with anticancer drugs

Cancer presents one of the leading causes of death in the world. Current treatment includes the administration of one or more anticancer drugs, commonly known as chemotherapy. The biggest issue concerning the chemotherapeutics is their toxicity on normal cells and persisting side effects. One approach to the issue is chemoprevention and the other one is the discovery of more effective drugs or drug combinations, including combinations with polyphenols. Olive oil polyphenols (OOPs), especially hydroxytyrosol (HTyr), tyrosol (Tyr) and their derivatives oleuropein (Ole), oleacein and oleocanthal (Oc) express anticancer activity on different cancer models. Recent studies report that phenolic extract of virgin olive oil may be more effective than the individual phenolic compounds. Also, there is a growing body of evidence about the combined treatment of OOPs with various anticancer drugs, such as cisplatin, tamoxifen, doxorubicin and others. These novel approaches may present an advanced strategy in the prevention and treatment of cancer.

Resveratrol for breast cancer prevention and therapy: Preclinical evidence and molecular mechanisms

Globally, breast cancer is the most frequently diagnosed cancer among women. The major unresolved problems with metastatic breast cancer is recurrence after receiving objective response to chemotherapy, drug-induced side effects of first line chemotherapy and delayed response to second line of treatment. Unfortunately, very few options are available as third line treatment. It is clear that under such circumstances there is an urgent need for new and effective drugs. Phytochemicals are among the most promising chemopreventive treatment options for the management of cancer. Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a non-flavonoid polyphenol present in several dietary sources, including grapes, berries, soy beans, pomegranate and peanuts, has been shown to possess a wide range of health benefits through its effect on a plethora of molecular targets.The present review encompasses the role of resveratrol and its natural/synthetic analogue in the light of their efficacy against tumor cell proliferation, metastasis, epigenetic alterations and for induction of apoptosis as well as sensitization toward chemotherapeutic drugs in various in vitro and in vivo models of breast cancer. The roles of resveratrol as a phytoestrogen, an aromatase inhibitor and in stem cell therapy as well as adjuvent treatment are also discussed. This review explores the full potential of resveratrol in breast cancer prevention and treatment with current limitations, challenges and future directions of research.

Cytotoxic effect of natural trans-resveratrol obtained from elicited Vitis vinifera cell cultures on three cancer cell lines

trans-Resveratrol (trans-R) has been reported to be a potential cancer chemopreventive agent. Although its cytotoxic activity against different cancer cell lines has been tested, its effect on human acute leukemia cell lines has scarcely been investigated, and only a few in vitro studies were performed using human breast epithelial cell lines. Due to its potential value for human health, demand for trans-R has rapidly increased, and new biotechnological strategies to obtain it from natural edible sources have been developed. Thus, grapevine cell cultures represent a reliable system of trans-R production since they biosynthesize trans-R constitutively or in response to elicitation. In addition, there are no studies deepen on the inhibitory effect of trans-R, produced by elicited grapevine cell cultures, on growth of human tumor cell lines. In this work, the effect of trans-R extracted from the culture medium, after elicitation of grapevine cell cultures, was tested on two human acute lymphocytic and monocytic leukemia cell lines, and one human breast cancer cell line. The effect of trans-R on cell proliferation was not only dose- and time-dependent but also cell type-dependent, as seen from the different degrees of susceptibility of cancer cell lines tested. As regards the effect of trans-R on cell cycle distribution, low trans-R concentrations increased cells in the S phase whereas a high trans-R concentration increased G₀/G₁ phase in all cell lines. Perturbation of the cell cycle at low trans-R concentrations did not correlate with the induction of cell death, whereas a high trans-R concentration, cell proliferation decreased as a result of increasing apoptosis in the three cell lines. In leukemia cells, trans-R up-regulated the expression of caspase-3 while trans-R-induced apoptosis in breast cells occur through a caspase-3-independent mechanism mediated by a down-regulation of Bcl-2.

Silencing of the polyamine catabolic key enzyme SSAT prevents CDK inhibitor-induced apoptosis in Caco-2 colon cancer cells

Roscovitine and purvalanol are purine derivative cyclin-dependent kinase (CDK) inhibitors that induce apoptosis in various types of cancer cells. However, their impact on the apoptotic cell death mechanism requires further elucidation. Natural polyamines putrescine, spermidine and spermine play essential roles in the regulation of cell growth and proliferation. Increased levels of polyamines in cells are considered to be involved in cancer progression. Intracellular polyamine levels are under the control of several catabolic enzymes, such as spermidine/spermine-N-acetyl transferase (SSAT), acetylpolyamine oxidase (APAO) and spermine oxidase (SMO), which could be altered by several therapeutic drugs. However, the possible role of polyamines in drug-induced apoptosis has yet to be clarified. In the present study, our aim was to determine the modulation of the polyamine catabolic pathway related to CDK inhibitor-induced apoptosis in Caco-2 cells. We found that roscovitine and purvalanol (each 20 μM) induced apoptosis by activating caspase-9 and -3, and inhibiting the mitochondrial membrane potential in Caco-2 cells. CDK inhibitors decreased the intracellular putrescine and spermine levels without affecting spermidine levels. Although both roscovitine and purvalanol induced SSAT expression, they did not exert a significant effect on the APAO expression profile. SSAT transient silencing prevented roscovitine-induced apoptosis compared to parental cells. Thus, we concluded that roscovitine and purvalanol significantly induce apoptosis in Caco-2 cells by modulating the polyamine catabolism, and that SSAT could be an important target in evaluating the potential role of polyamines in apoptotic cell death.

Roscovitine confers tumor suppressive effect on therapy-resistant breast tumor cells

Introduction

Current clinical strategies for treating hormonal breast cancer involve the use of anti-estrogens that block estrogen receptor (ER)α functions and aromatase inhibitors that decrease local and systemic estrogen production. Both of these strategies improve outcomes for ERα-positive breast cancer patients, however, development of therapy resistance remains a major clinical problem. Divergent molecular pathways have been described for this resistant phenotype and interestingly, the majority of downstream events in these resistance pathways converge upon the modulation of cell cycle regulatory proteins including aberrant activation of cyclin dependent kinase 2 (CDK2). In this study, we examined whether the CDK inhibitor roscovitine confers a tumor suppressive effect on therapy-resistant breast epithelial cells.

Methods

Using various in vitro and in vivo assays, we tested the effect of roscovitine on three hormonal therapy-resistant model cells: (a) MCF-7-TamR (acquired tamoxifen resistance model); (b) MCF-7-LTLTca (acquired letrozole resistance model); and (c) MCF-7-HER2 that exhibit tamoxifen resistance (ER-growth factor signaling cross talk model).

Results

Hormonal therapy-resistant cells exhibited aberrant activation of the CDK2 pathway. Roscovitine at a dose of 20 μM significantly inhibited the cell proliferation rate and foci formation potential of all three therapy-resistant cells. The drug treatment substantially increased the proportion of cells in G2/M cell cycle phase with decreased CDK2 activity and promoted low cyclin D1 levels. Interestingly, roscovitine also preferentially down regulated the ERα isoform and ER-coregulators including AIB1 and PELP1. Results from xenograft studies further showed that roscovitine can attenuate growth of therapy-resistant tumors in vivo.

Conclusions

Roscovitine can reduce cell proliferation and survival of hormone therapy-resistant breast cancer cells. Our results support the emerging concept that inhibition of CDK2 activity has the potential to abrogate growth of hormonal therapy-resistant cells.

Polyamine depletion enhances the roscovitine-induced apoptosis through the activation of mitochondria in HCT116 colon carcinoma cells

Small molecule inhibitors of cyclin-dependent kinases (CDKs) show high therapeutic potential in various cancer types which are characterized by the accumulation of transformed cells due to impaired apoptotic machinery. Roscovitine, a CDK inhibitor showed to be a potent apoptotic inducer in several cancer cells. Polyamines, putrescine, spermidine and spermine, are biogenic amines involved in many cellular processes, including apoptosis. In this study, we explored the potential role of polyamines in roscovitine-induced apoptosis in HCT116 colon cancer cells. Roscovitine induced apoptosis by activating mitochondrial pathway caspases and modulating the expression of Bcl-2 family members. Depletion of polyamines by treatment with difluoromethylornithine (DFMO) increased roscovitine-induced apoptosis. Transient silencing of ornithine decarboxylase, polyamine biosynthesis enzyme and special target of DFMO also increased roscovitine-induced apoptosis in HCT116 cells. Interestingly, additional putrescine treatment was found pro-apoptotic due to the presence of non-functional ornithine decarboxylase (ODC). Finally, roscovitine altered polyamine catabolic pathway and led to decrease in putrescine and spermidine levels. Therefore, the metabolic regulation of polyamines may dictate the power of roscovitine induced apoptotic responses in HCT116 colon cancer cells.

Autophagic and apoptotic mechanisms of curcumin-induced death in K562 cells

Curcumin (1), a natural polyphenolic compound, has shown strong antioxidant and anticancer activities. Several molecular mechanisms have been attributed to its inhibitory effects on a wide range of tumor cells. In this study, the response of the chronic myeloid leukemia cell line K562 cells to 1 is investigated. Curcumin inhibited the viability of K562 cells in a dose- and time-dependent manner. Furthermore, curcumin-induced cell death was associated with the formation of the apoptosome complex, the collapse of the mitochondrial membrane potential, and caspase-3 activation. Curcumin treatment also induced Bid cleavage and downregulated the expression of Bcl-2 protein. Surprisingly, even with these molecular features of apoptosis, we showed that 1 stimulated autophagy, which was evidenced by microtubule-associated protein light chain 3 (LC3) immunoreactivty. Curcumin also increased the protein levels of beclin 1 and membrane form LC3 (LC3-II). Autophagy inhibitor bafilomycin A1 and the pan-caspase inhibitor Z-VAD-fmk suppressed curcumin-induced K562 cell death. Overall, these results suggest that curcumin induces autophagic and apoptotic death of K562 cells. These findings suggest that both apoptotic and autophagic mechanisms contribute to the curcumin-induced K562 cell death.

Evaluation of anti-leukemia effect of resveratrol by modulating STAT3 signaling

Resveratrol is a natural occurring phytoalexin present in grapes and berries, that has been shown to have chemopreventive/therapeutic activity. But the precise mechanism of resveratrol involved in leukemia is not well understood. In this study, we examine its anti-leukemia effect both in vitro and in vivo. Our data indicate that resveratrol contributes to inhibiting growth, inducing apoptosis and cell cycle arrest in the three leukemia cell lines (Jurkat, SUP-B15, and Kasumi-1), and reducing the phosphorylation of STAT3, meanwhile modulating the expression of Bcl-2 and Bax. In vivo, resveratrol could prolong the life span of Kasumi-1-bearing mice, and attenuate the activity of STAT3. Taken altogether, this investigation focuses on signaling pathways involved in STAT3 by resveratrol and to delineate its molecular mechanisms underlying anti-leukemia effect.

Monitoring of long-term effects of resveratrol on cell cycle progression of human HeLa cells after administration of a single dose

Expression of the human papillomavirus-encoded oncoproteins E6 and E7 in human HeLa cervical carcinoma cells results in their escape from the proper control of the cell cycle progression. Therefore, their susceptibility to agents modulating cell cycle differs from that in cells in which the control of cell cycle regulation is intact. Recently, a number of experimental studies revealed that polyphenols, especially resveratrol, could exert a strong antiproliferative effect. Polyphenols (e.g., resveratrol or epicatechins), potent antioxidant agents, are abundant components of our diet and, therefore, may not only affect the proliferation of healthy cells in the organism but also modulate the action of distinct anticancer drugs. Indeed, it has been shown that resveratrol enhances the antimitotic effect exerted by roscovitine (ROSC), a potent cyclin-dependent kinase inhibitor, on human MCF-7 breast cancer cells. In the present contribution the action of resveratrol alone and in combination with ROSC on human HeLa cells was determined. Resveratrol inhibited proliferation of exponentially growing HeLa cells. Exposure of HeLa cells to 50 micromol/L resveratrol blocked cells in the S phase in a time-dependent manner. After 12 h the population of G(2)/M-phase cells completely disappeared, and during a further 12 h the frequency of S-phase cells markedly increased and reached approximately 90%. Thus, resveratrol synchronized HeLa cells in the S phase. After removal of resveratrol, synchronized HeLa cells rapidly progressed through the cell cycle. Four hours after medium change, more than 70% of cells moved into the G(2)/M phase. Moreover, resveratrol combined with ROSC enhanced the antiproliferative action of resveratrol.

The prosurvival role of autophagy in Resveratrol-induced cytotoxicity in human U251 glioma cells

Background

Previous study reported that resveratrol has anti-tumor activity. In this study, we investigated the involvement of autophagy in the resveratrol-induced apoptotic death of human U251 glioma cells.

Methods

The growth inhibition of U251 cells induced by resveratrol was assessed with methyl thiazolyl tetrazolium (MTT). The activation of autophagy and proapoptotic effect were characterized by monodansylcadaverine labeling and Hoechst stain, respectively. Mitochondrialtransmembrane potential (ΔΨm) was measured as a function of drug treatment using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1). The role of autophagy and apoptosis in the resveratrol-induced death of U251 cells was assessed using autophagic and caspase inhibitors. Immunofluorescence, flow cytometry, and Western blot analysis were used to study the apoptotic and autophagic mechanisms.

Results

Methyl thiazolyl tetrazolium (MTT) assays indicated that resveratrol decreased the viability of U251 cells in a dose- and time-dependent manner. Flow cytometry analysis indicated that resveratrol increased cell population at sub-G1 phase, an index of apoptosis. Furthermore, resveratrol-induced cell death was associated with a collapse of the mitochondrial membrane potential. The pan-caspase inhibitor Z-VAD-fmk suppressed resveratrol-induced U251 cell death. Resveratrol stimulated autophagy was evidenced by punctuate monodansylcadaverine(MDC) staining and microtubule-associated protein light chain 3 (LC3) immunoreactivty. Resveratrol also increased protein levels of beclin 1 and membrane form LC3 (LC3-II). Autophagy inhibitors 3-methylademine (3-MA) and bafilomycin A1 sensitized the cytotoxicity of resveratrol.

Conclusion

Together, these findings indicate that resveratrol induces autophagy in human U251 glioma cells and autophagy suppressed resveratrol-induced apoptosis. This study thus suggests that autophagy inhibitors can increase the cytotoxicity of resveratrol to glioma cells.