Influence of resveratrol on oxidative damage in genomic DNA and apoptosis induced by cisplatin

Cisplatin is a potent chemotherapeutic agent that has gained widespread use against various malignant tumours in a variety of human malignancies. Like other chemotherapeutic agents, cisplatin is genotoxic and apoptogenic in non-tumour cells and the formation of reactive oxygen species appears to be responsible for these toxicities. The anti-genotoxic and anti-apoptotic effects of resveratrol, a polyphenol found in numerous plant species, against cisplatin-induced genotoxicity and apoptosis in vivo were evaluated by use of standard techniques in somatic and germinal cells of mice. Pre-treatment of mice with resveratrol significantly reduced cisplatin-induced genotoxicity and apoptosis and effectively suppressed the apoptotic signalling triggered by cisplatin. The protective effect of resveratrol was found to be stronger at the higher dose, indicating the dose-dependent effect of resveratrol. Cisplatin induced marked biochemical alterations characteristic of oxidative DNA stress. Prior administration of resveratrol before the cisplatin challenge ameliorated these biochemical markers. In conclusion, this study provides evidence for the first time that resveratrol has a protective role in the abatement of cisplatin-induced genotoxicity and apoptosis in somatic and germinal cells of mice. This activity resides, at least in part, in its radical scavenger activity. Therefore, resveratrol can be a promising chemoprotective agent to avert secondary malignancies and abnormal reproductive outcomes in cured cancer patients exposed to cisplatin, without diminishing its anti-neoplastic activity.     

The apoptotic effect of intercalating agents on HPV-negative cervical cancer C-33A cells

Summary. Cervical cancer is one of the leading causes of female cancer death worldwide with about 500,000 deaths per year. Both mitomycin C and cisplatin are alkylating agents, which bind and intercalate DNA, and thus used as anti-cancer drugs. In these studies, we focused on investigating the apoptotic effects of intercalating agents on HPV-negative cervical cancer C-33A cells. Accordingly, C-33A cells were treated with carboplatin, mitomycin C or cisplatin. Cell cycle analysis revealed that treatment with mitomycin C and cisplatin but not with carboplatin resulted in apoptosis. Both mitomycin C and cisplatin induced apoptosis in C-33A cells via caspase-8 and -3 processing in a Fas/FasL-dependent manner and also suppressed IL-18 expression, while they down-regulated IκB expression and up-regulated p65 expression. These results suggest that both mitomycin C and cisplatin induce apoptosis, not only via the caspase-8 and -3 dependent Fas/FasL pathway, but also via the regulation of NF-κB activity and IL-18 expression in HPV-negative cervical cancer C-33A cells.     

The cytoprotective effect of the phytoestrogen genistein on tumor cells

In order to determine the cytotoxic or cytoprotective effect of the synthetic isoflavonoid genistein, we studied its effect on HeLa tumor cells, which contain estrogen alpha receptors and do not contain estrogen beta receptors. It was shown that the genistein concentration (IC ₅₀ = 0.2 mM) at which the half maximal inhibition of the HeLa cell viability is achieved is ten times higher than the concentrations of tamoxifen and cisplatin, which are reference agents with a cytotoxic effect. At micromolar concentrations (0.1–10 µM) genistein decreased the cytotoxic effects of cisplatin and tamoxifen. We found the reduced Bax mRNA expression and increased Bcl-2 mRNA expression during incubation of the cells with genistein, which also indicates its cytoprotective anti-apoptotic effect. Genistein, even in high concentrations, had no effect on the membrane potential and calcium capacity of isolated mitochondria and did not activate the opening of the Ca²⁺-induced mitochondrial pore. Thus, the data show a protective effect of the isoflavonoid genistein on tumor cells.     

Novel titanocene anti-cancer drugs and their effect on apoptosis and the apoptotic pathway in prostate cancer cells

Advanced prostate cancer is not curable by current treatment strategies indicating a significant need for new chemotherapeutic options. Highly substituted ansa-titanocene compounds have shown promising cytotoxic activity in a range of cancers. The objectives of this study are to examine the effects of these titanocene compounds on prostate cancer cells. Prostate cell lines were treated with three novel titanocene compounds and compared to titanocene dichloride and cisplatin. Percent apoptosis, viability and cell cycle were assessed using propidium iodide DNA incorporation with flow cytometry. Cytochrome C was assessed by western blotting of mitochondrial and cytoplasmic fractions. Apoptosis Inducing Factor was assessed by confocal microscopy. These novel compounds induced more apoptosis compared to cisplatin in a dose dependent manner. Compound Y had the most significant effect on cell cycle and apoptosis. Despite the release of cytochrome C from the mitochondrial fraction there was no inhibition of apoptosis with the pan caspase inhibitor, ZVAD-FMK. AIF was shown to translocate from the cytosol to the nucleus mediating a caspase independent cell death. Bcl-2 over expressing PC-3 cells, which were resistant to cisplatin induced apoptosis, underwent apoptosis following treatment with all the titanocene compounds. This study demonstrates possible mechanisms by which these novel titanocene compounds can mediate their apoptotic effect in vitro. The fact that they can induce more apoptosis than cisplatin in advanced cancer cell lines would confer an advantage over cisplatin. They represent exciting new agents with future potential for the treatment of advanced prostate cancer.     

Additive effects of antitumor drugs and lymphokine-activated killer cell cytotoxic activity in tumor cell killing determined by lactate-dehydrogenase-release assay

Summary The effect of pretreatment with antitumor drugs on lymphokine-activated killer (LAK) cell cytotoxic activity, determined by lactate-dehydrogenase(LDH)-release assay, was investigated. LAK cells were induced by incubating peripheral blood lymphocytes of healthy donors in medium containing interleukin-2 (IL-2) and monoclonal anti-CD3 antibody for 6–7 days. A human lung squamous carcinoma cell line, SQ-5, was used as an adherent target. After 24 h exposure of the target cells to cisplatin, doxorubicin, or mitomycin C, the drugs were washed off and LAK cells were added at an E/T ratio of 5. During further incubation for 48 h, LDH release from cisplatin- or doxorubicin-pretreated target cells was markedly higher than that from non-pretreated target cells. The combination of cisplatin and LAK cells has an additive cytotoxic effect and that of mitomycin C and LAK cells does not; there may also be an additive effect late in the toxicity mechanism between doxorubicin and LAK cells.     

Protection of human colon epithelial cells against deoxycholate by rottlerin

The bile salt, deoxycholate (DOC), can harm cells and cause disease. Hence, there is interest in identifying compounds capable of protecting cells against DOC. In HCT-116 colon epithelial cells, DOC increased generation of reactive oxygen species and caused DNA damage and apoptosis. These effects of DOC were inhibited by rottlerin, which is a phenolic compound of plant origin. In elucidating its mechansim, rottlerin prevented the release of cytochrome c from mitochondria into cytosol, and also prevented the cleavage of caspase-3. Yet, rottlerin by itself markedly decreased mitochondrial membrane potential and increased mitochondrial superoxide production, but this did not result in cytochrome c release or in caspase-3 cleavage. At a higher test concentration, two other phenolic phytochemicals, namely, quercetin and resveratrol, were each able to largely prevent the occurrence of apoptosis in cells exposed to DOC. In contrast, epigallocatechin gallate, curcumin, and genistein were ineffective.     

Cytokines as suppressors of apoptosis

Many cytokines have been isolated by their ability to induce growth and have been called growth factors. But these cytokines are also essential to induce cell viability, and cell viability and growth can be separately regulated. Using as examples myeloid hematopoietic cells, lymphocytes and neuronal cells, in vitro and in vivo studies have shown the role of cytokines in inducing viability of different cell types during development to mature cells. Some cytokines can act on more than one cell type. Cytokines induce viability of normal and cancer cells by suppressing the apoptotic machinery activated by wild-type p53, or by cytotoxic agents including irradiation and compounds used in cancer chemotherapy. Cytokines can be used to decrease apoptosis in normal cells and inhibition of cytokine activity may improve cancer therapy by enhancing apoptosis in cancer cells. The apoptosis suppressing function of cytokines is mediated by changing the balance in the activity of apoptosis inducing and suppressing genes. Apoptosis suppression is upstream of caspase activation in the apoptotic process. Cytokines can suppress multiple pathways leading to apoptosis, only some of which were suppressed by other agents such as some antioxidants, Ca²⁺-mobilizing compounds and protease inhibitors.     

p53-dependent and p53-independent activation of apoptosis in mammary epithelial cells reveals a survival function of EGF and insulin

The p53 tumor suppressor protein has been implicated as a mediator of programmed cell death (PCD). A series of nontransformed mammary epithelial cell (MEC) lines were used to correlate p53 function with activation of PCD. Treatment of MECs expressing mutant, inactive, or no p53 with DNA-damaging agents did not induce apoptosis. Upon introduction of temperature-sensitive p53 into HC11 cells, which lack wild-type (wt) p53, PCD was observed after mitomycin treatment at 32 degrees, when the ts p53 protein is in wt conformation. Thus, wt p53 mediates activation of PCD in response to mitomycin in HC11 cells. Treatment of the MCF10-A cells, which express wt p53, with various DNA- damaging agents led to nuclear accumulation of p53. Only mitomycin treatment led to an increase in the number of apoptotic nuclei. ErbB-2- transformed MCF10-A cells responded to mitomycin, cisplatin, and 5-Fl- uracil, suggesting that signaling from activated ErbB-2 enhances the cells ability to respond to DNA damage. A combination of high cell density and serum-free medium induces apoptosis in all MECs tested, irrespective of their p53 status. Under these conditions, EGF or insulin act as survival factors in preventing PCD. These data might elucidate some aspects of breast involution and tumorigenesis.     

Synthesis of genistein derivatives and determination of their protective effects against vascular endothelial cell damages caused by hydrogen peroxide

A series of genistein derivatives, prepared by alkylation and difluoromethylation, were tested for their inhibitory effects on the hydrogen peroxide induced impairment in human umbilical vein endothelial (HUVE-12) cells in vitro. The HUVE-12 cells were pretreated with either the vehicle solvent (DMSO), genistein, or different amounts of the genistein derivatives for 30 min before exposed to 1 mM hydrogen peroxide for 24 h. Cell apoptosis was determined by flow cytometry with propidium iodide (PI) staining. Cellular injury was estimated by measuring the lactate dehydrogenase (LDH) release. Data suggested that the genistein derivatives possessed a protective effect on HUVE-12 cells from hydrogen peroxide induced apoptosis and reduced LDH release. Among these derivatives, 7-difluoromethyl-5,4'-dimethoxygenistein exhibited the strongest activity against hydrogen peroxide induced apoptosis of HUVE-12 cells.     

Pro-apoptotic versus anti-apoptotic properties of dietary resveratrol on tumoral and normal cardiac cells

Resveratrol is a natural dietary polyphenol found in grape skin, red wine, and various other food products. Resveratrol has proved to be an effective chemopreventive agent for different malignant tumors. It has also been shown to prevent vascular alterations such as atherosclerosis and inflammatory-associated events. In view of these observations, we investigated the anti-proliferative and pro-apoptotic activities of resveratrol on a tumoral cardiac cell line (HL-1 NB) derived from mouse tumoral atrial cardiac myocytes. These effects were compared with those found on normal neonatal mouse cardiomyocytes. HL-1 NB cells and neonatal cardiomyocytes were treated with resveratrol (5, 30, and/or 100 μM) for different times of culture (24, 48, and/or 72 h). Resveratrol effects were determined by various microscopical and flow cytometric methods. After resveratrol treatment, a strong inhibition of tumoral cardiac HL1-NB cell growth associated with a loss of cell adhesion was observed. This cell proliferation arrest was associated with an apoptotic process revealed by an increased percentage of cells with fragmented and/or condensed nuclei (characteristic of apoptotic cells) identified after staining with Hoechst 33342 and by the presence of cells in subG1. At the opposite, on normal cardiomyocytes, no cytotoxic effects of resveratrol were observed, and a protective effect of resveratrol against norepinephrine-induced apoptosis was found on normal cardiomyocytes. Altogether, the present data demonstrate that resveratrol (1) induces apoptosis of tumoral cardiac HL1-NB cells, (2) does not induce cell death on normal cardiomyocytes, and (3) prevents norepinephrine-induced apoptosis on normal cardiomyocytes.     

Protective effect of DCTN (trans-dehydrocrotonin) against induction of micronuclei and apoptosis by different mutagenic agents in vitro

The use of medicinal plants to combat diseases has increased in the last years despite the little information available with regard to the possible health risks they represent. The aim of the present study was to determine in vitro the possible clastogenic, apoptotic and cytotoxic effects of the active principle of Croton cajucara, trans-dehydrocrotonin (DCTN), and determine its protective effect against three mutagenic agents using the micronucleus test (MN) and apoptosis index in CHO-K1 cells. Three DNA damage inducing agents were utilized in the clastogenicity and anticlastogenicity tests (methylmethane sulfonate (MMS), mitomycin C (MMC) and doxorubicin (DXR); a negative control (PBS) and solvent control were also included. DCTN at concentrations of 400, 320, 240, 160 and 80microM did not show clastogenic activity in cultured CHO-K1 cells in the micronucleus test, did not induce apoptosis and showed negligible cytotoxicity in all cases. DCTN at concentrations of 240 and 400microM was tested for protective activity using three treatment protocols in relation to positive controls: pre-treatment, simultaneous treatment and post-treatment. The micronucleus test showed a protective effect for DCTN which varied among the different treatment protocols and with regard to the different DNA damage inducing agents. In the apoptosis test, DCTN was seen to have a protective effect under the following conditions: (I) at both concentrations in relation to MMS, in all three treatment protocols; (II) at both concentrations against damage caused by MMC with pre-treatment and at the higher concentration with simultaneous treatment; (III) at both concentrations against DXR with simultaneous treatment. Therefore, DCTN itself is not a clastogenic or cytotoxic substance, and does not induce apoptosis the in vitro system used. These results together with findings reported for DCTN in vivo, support the indication of this active principle at these concentrations for therapeutic use.     

High yield of endoreduplication induced by ICRF-193: a topoisomerase II catalytic inhibitor

Previous studies have demonstrated that phenolic compounds, including genistein (4',5,7-trihydroxyisoflavone) and resveratrol (3,4',5-trihydroxystilbene), are able to protect against carcinogenesis in animal models. This study was undertaken to examine the ability of genistein and resveratrol to inhibit reactive oxygen species (ROS)-mediated strand breaks in phi X-174 plasmid DNA. H(2)O(2)/Cu(II) and hydroquinone/Cu(II) were used to cause oxidative DNA strand breaks in the plasmid DNA. We demonstrated that the presence of genistein at micromolar concentrations resulted in a marked inhibition of DNA strand breaks induced by either H(2)O(2)/Cu(II) or hydroquinone/Cu(II). Genistein neither affected the Cu(II)/Cu(I) redox cycle nor reacted with H(2)O(2) suggest that genistein may directly scavenge the ROS that participate in the induction of DNA strand breaks. In contrast to the inhibitory effects of genistein, the presence of resveratrol at similar concentrations led to increased DNA strand breaks induced by H(2)O(2)/Cu(II). Further studies showed that in the presence of Cu(II), resveratrol, but not genistein was able to cause DNA strand breaks. Moreover, both Cu(II)/Cu(I) redox cycle and H(2)O(2) were shown to be critically involved in resveratrol/copper-mediated DNA strand breaks. The above results indicate that despite their similar in vivo anticarcinogenic effects, genistein and resveratrol appear to exert different effects on oxidative DNA damage in vitro.     

Effect of cisplatin upon expression of in vivo immune tumor resistance

The major intent of cancer treatment with cytotoxic drugs is direct tumor cell damage, but some of these drugs have been shown to be immunomodulatory. Cisplatin is a widely used cytotoxic drug that has been combined with biological response modifiers in recent clinical trials. To evaluate further whether cisplatin may independently alter the level of host resistance against tumor growth, the drug was tested in the Mc7 sarcoma rat tumor model. The expression of in vivo tumor resistance against Mc7 sarcoma in syngeneic Wistar rats is mediated by circulating non-cytotoxic T lymphocytes. These cells interact specifically with tumor cells to generate cytotoxic effectors locally at the site of a tumor challenge. Activities of these components of expression of tumor resistance were measured in vivo after administration of cisplatin and dose-dependent effects were found. Low-dose cisplatin (0.3 mg/kg) increased the activity of the circulating lymphocytes that mediate tumor resistance, and high-dose cisplatin (9 mg/kg) suppressed both mediator lymphocyte activity and the generation of antitumor effector mechanisms. These studies suggest that low-dose cisplatin may be immunomodulatory and combining it with biological response modifiers might be a useful strategy. However, high-dose cisplatin given with biological response modifiers may negate potential immunomodulatory activities of such agents.     

Synthesis of 26-hydroxy-22-oxocholestanic frameworks from diosgenin and hecogenin and their in vitro antiproliferative and apoptotic activity on human cervical cancer CaSki cells

Certain steroidal compounds have demonstrated an antiproliferative effect against several tumor cell lines; however, their complete role on cancer cells is not currently established. Herein, we report the synthesis and evaluation of two new 26-hydroxy-22-oxocholestanic steroids on cervical cancer CaSki cells. The title compounds were prepared from diosgenin and hecogenin in excellent yields. We determined their effect on cell proliferation, cell cycle, and cell death. The cytotoxic effect of the title compounds on CaSki and human lymphocytes was also evaluated, indicating that the main cell death process is not necrosis; the null effect on lymphocytes implies that they are not cytotoxic. The observation of apoptotic bodies as well as the increase in the expression of active caspase-3 along with the fragmentation of DNA confirmed that such new cholestanic frameworks induced apoptosis in tumor cells. Significantly, their antiproliferative activity on tumor cells did not affect the proliferative potential of normal fibroblasts from cervix and peripheral blood lymphocytes. The title compounds show selective antitumor activity and therefore serve as promising lead candidates for further optimization.     

Genistein Enhances the Cisplatin‐Induced Inhibition of Cell Growth and Apoptosis in Human Malignant Melanoma Cells

Genistein, a naturally occurring isoflavone found chiefly in soybeans, has been reported to be a potent antitumor agent. Genistein is presumed to exert multiple effects related to the inhibition of cancer growth. Metastatic melanoma is a chemotherapy‐refractory neoplasm. The present study was designed to explore the possible activity of genistein to inhibit the aberrant proliferation and to induce apoptosis of human malignant melanoma cells in cooperation with cisplatin treatment. Five human melanoma cell lines were utilized for these experiments. Genistein at physiologic concentrations (20 μM) did not induce apoptosis by itself but did enhance cisplatin‐induced apoptosis in all five human melanoma cell lines tested. The enhanced susceptibility among the cell lines was diverse. Changes in the expression of two anti‐apoptotic proteins, bcl‐2 and bcl‐xL, and one pro‐apoptotic protein, apoptotic protease activating factor‐1 (Apaf‐1), were examined. Genistein alone or cisplatin alone generally did not alter bcl‐2 expression or bcl‐xL expression, but slightly increased Apaf‐1 in some cell lines. The combined treatment with genistein and cisplatin significantly reduced bcl‐2 and bcl‐xL protein and increased Apaf‐1 protein expression. These data suggest that genistein therapy may enhance the chemosensitivity of melanoma patients.     

Genistein enhances the cisplatin-induced inhibition of cell growth and apoptosis in human malignant melanoma cells

Genistein, a naturally occurring isoflavone found chiefly in soybeans, has been reported to be a potent antitumor agent. Genistein is presumed to exert multiple effects related to the inhibition of cancer growth. Metastatic melanoma is a chemotherapy-refractory neoplasm. The present study was designed to explore the possible activity of genistein to inhibit the aberrant proliferation and to induce apoptosis of human malignant melanoma cells in cooperation with cisplatin treatment. Five human melanoma cell lines were utilized for these experiments. Genistein at physiologic concentrations (20 microM) did not induce apoptosis by itself but did enhance cisplatin-induced apoptosis in all five human melanoma cell lines tested. The enhanced susceptibility among the cell lines was diverse. Changes in the expression of two anti-apoptotic proteins, bcl-2 and bcl-xL, and one pro-apoptotic protein, apoptotic protease activating factor-1 (Apaf-1), were examined. Genistein alone or cisplatin alone generally did not alter bcl-2 expression or bcl-xL expression, but slightly increased Apaf-1 in some cell lines. The combined treatment with genistein and cisplatin significantly reduced bcl-2 and bcl-xL protein and increased Apaf-1 protein expression. These data suggest that genistein therapy may enhance the chemosensitivity of melanoma patients.     

Resveratrol Couples Apoptosis with Autophagy in UVB-Irradiated HaCaT Cells

UVB radiation causes about 90% of non-melanoma skin cancers by damaging DNA either directly or indirectly by increasing levels of reactive oxygen species (ROS). Skin, chronically exposed to both endogenous and environmental pro-oxidant agents, contains a well-organised system of chemical and enzymatic antioxidants. However, increased or prolonged free radical action can overwhelm ROS defence mechanisms, contributing to the development of cutaneous diseases. Thus, new strategies for skin protection comprise the use of food antioxidants to counteract oxidative stress. Resveratrol, a phytoalexin from grape, has gained a great interest for its ability to influence several biological mechanisms like redox balance, cell proliferation, signal transduction pathways, immune and inflammatory response. Therefore, the potential of resveratrol to modify skin cell response to UVB exposure could turn out to be a useful option to protect skin from sunlight-induced degenerative diseases. To investigate into this matter, HaCaT cells, a largely used model for human skin keratinocytes, were treated with 25 or 100 µM resveratrol for 2 and 24 hours prior to UVB irradiation (10 to 100 mJ/cm²). Cell viability and molecular markers of proliferation, oxidative stress, apoptosis, and autophagy were analyzed. In HaCaT cells resveratrol pretreatment: reduces UVB-induced ROS formation, enhances the detrimental effect of UVB on HaCaT cell vitality, increases UVB-induced caspase 8, PARP cleavage, and induces autophagy. These findings suggest that resveratrol could exert photochemopreventive effects by enhancing UVB-induced apoptosis and by inducing autophagy, thus reducing the odds that damaged cells could escape programmed cell death and initiate malignant transformation.