BACKGROUND:Adult T-cell leukemia (ATL) is an acute malignancy of activated T-cells caused by the human T-cell lymphotrophic virus type-1 (HTLV-1).

MATERIALS AND METHODS:The effects of non-cytotoxic concentrations of ascorbic acid (AA) were evaluated against HTLV-1 positive and negative cells. The effect of AA on apoptosis and proliferation was evaluated by cell cycle analysis. The role of p53, p21 Bax and Bcl-2a on cell cycle modulation and apoptosis was also assessed. The anti-proliferative effects were tested by determining the changes in the expression of transforming growth factors (TGF-alpha, TGF-beta1 and TGF-beta2).

RESULTS:Ascorbic acid was found to reduce the proliferation of cells and induce apoptosis by the modulation of p53, p21, Bcl-2 and Bax.

CONCLUSION:The results of this study show the anti-proliferative effects of AA against leukemic cells.

Sulindac has anti-neoplastic properties against colorectal cancers; however, its use as a chemopreventive agent has been limited due to toxicity and efficacy concerns. Combinatorial treatment of colorectal cancers has been attempted to maximize anti-cancer efficacy with minimal side effects by administrating NSAIDs in combination with other inhibitory compounds or drugs such as L-ascorbic acid (vitamin C), which is known to exhibit cytotoxicity towards various cancer cells at high concentrations. In this study, we evaluated a combinatorial strategy utilizing sulindac and vitamin C. The death of HCT116 cells upon combination therapy occurred via a p53-mediated mechanism. The combination therapeutic resistance developed in isogenic p53 null HCT116 cells and siRNA-mediated p53 knockdown HCT116 cells, but the exogenous expression of p53 in p53 null isogenic cells resulted in the induction of cell death. In addition, we investigated an increased level of intracellular ROS (reactive oxygen species), which was preceded by p53 activation. The expression level of PUMA (p53-upregulated modulator of apoptosis), but not Bim, was significantly increased in HCT116 cells in response to the combination treatment. Taken together, our results demonstrate that combination therapy with sulindac and vitamin C could be a novel anti-cancer therapeutic strategy for p53 wild type colon cancers.

Resveratrol, a polyphenol found in red wine, peanuts, soy beans, and pomegranates, possesses a wide range of biological effects. Since resveratrol's properties seem ideal for treating neurodegenerative diseases, its ability to diminish amyloid plaques was tested. Mice were fed clinically feasible dosages of resveratrol for forty-five days. Neither resveratrol nor its conjugated metabolites were detectable in brain. Nevertheless, resveratrol diminished plaque formation in a region specific manner. The largest reductions in the percent area occupied by plaques were observed in medial cortex (-48%), striatum (-89%) and hypothalamus (-90%). The changes occurred without detectable activation of SIRT-1 or alterations in APP processing. However, brain glutathione declined 21% and brain cysteine increased 54%. The increased cysteine and decreased glutathione may be linked to the diminished plaque formation. This study supports the concept that onset of neurodegenerative disease may be delayed or mitigated with use of dietary chemo-preventive agents that protect against beta-amyloid plaque formation and oxidative stress.

The present study was undertaken to examine whether blue LED irradiation induces cellular apoptosis in B16-F10 cells and whether it blocks the early growth of melanoma cells in mice. Irradiation with blue LED was observed to reduce cell viability and to induce apoptotic cell death, as accompanied by exposure of phosphatidylserine on the plasma outside membrane and an accumulation of a sub-G1 population. Furthermore, the mitochondrial membrane potential increased, and mitochondria-related apoptotic proteins (cytochrome c, caspase 3, and PARP) were observed. In addition, the level of intracellular superoxide anion (O2(-)) gradually increased. Interestingly the phosphorylation of p53 increased at earlier times under blue LED irradiation, but reduced after exposure for a longer time. Additionally, the thickness of the mice footpad injected with B16-F10 cells decreased significantly until the 9th day of blue LED irradiation, indicating the inhibition of the early growth rate of the melanoma cells. Our data demonstrate that blue LED irradiation induces apoptotic cell death by activating the mitochondria-mediated pathway and reduces the early growth rate of melanoma cells. Further studies are needed to elucidate the precise mechanism of blue LED in melanoma cells.

OBJECTIVE:To observe the proliferation inhibition, apoptosis, and cell proliferation cycle of human lung carcinoma cell line A549 treated with Inotodiol extracts from Inonotus obliquus and explore the possibility of Inotodiol extracts from Inonotus obliquus as a new tumor chemopreventive drug.

METHODS:Human lung cancer cell line A549 was treated with different concentrations of Inotodiol, the effects of Inotodiol on cell apoptosis, the expression of Ki-67, Bcl-2, Bax, and p53 and cell cycle were detected by TUNEL assay, immunohistochemistry, and flow cytometry assay respectively.

RESULTS:Inotodiol extracts had antiproliferation effect on human lung carcinoma cell line A549. The expression of Ki-67 decreased with the increase of Inotodiol concentration and exposure time (P<0.05), in a dose-dependent and time-dependent manner. The typical characteristics of the apoptosis of A549 cells treated with Inotodiol were observed, and the apoptotic rate of A549 cell at 48 h was the highest by TUNEL assay. Inotodiol arrested A549 cells in the S phase, and apoptotic peak was observed by flow cytometry. Immunocytochemistry indicated that the expression of Bcl-2 protein decreased, while the expression of p53 and Bax proteins increased in A549 cells treated with Inotodiol, compared with the control cells (P<0.05).

CONCLUSION:Inotodiol can inhibit proliferation and induce the apoptosis of A549 cells, and its molecular mechanism may be associated with the up-regulating expression of p53 and bax proteins and down-regulating expression of Bcl-2 protein, which arrested A549 cells in S phase.

Epidemiological studies report that regular physical activity can reduce the risk for prostate cancer, the most common solid-tumor cancer in US men. Regular exercise alters the serum IGF axis in vivo and reduces cell proliferation while increasing apoptosis in serum-stimulated LNCaP prostate cancer cells in vitro. The present study tests the hypothesis that these effects on tumor cell lines are mediated by enhancement of the function of the p53 gene known to arrest cell growth and induce apoptosis. When LNCaP cells were cultured in exercise serum and compared with control serum, cell growth was reduced by 27%, and there was a similar 33% decrease in proliferating cell nuclear antigen protein, a marker for cell cycling. Apoptosis was increased by 371% with the exercise serum, and there was a 100% increase in p53 protein (75.2 +/- 2.0 vs. 38.2 +/- 2.0 pg/microg protein). When serum was used to stimulate LN-56 cells, a cell line with nonfunctional p53 derived from LNCaP, no significant reduction in cell growth or increase in apoptosis with the exercise serum was observed. These results indicate that exercise training alters serum factors in vivo that increase cellular p53 protein content and is associated with reduced growth and induced apoptosis in LNCaP prostate cancer cells in vitro.

In this study, in order to investigate the anticancer mechanism of Calvatia gigantea extract, edible mushroom species, which belong to Lycoperdaceae family, changes of CCND1, CCND2, CDK4, p21, Akt, Bax, Bcl-2, p53, caspase-3 and caspase-9 were evaluated in A549 lung cancer cells. Cytotoxic effect of C. gigantea extract was evaluated by using XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5 carboxanilide). The C. gigantea extract was treated in a time and dose dependent manner within the range 25 μg/ml-2 mg/ml to determine the IC50 dose. IC50 dose for C. gigantea extract was detected as 500 μg/ml for 72 h. According to expression results, while CCND1, CCND2, CDK4, Akt and Bcl-2 expression clearly decreased, Bax, p53, caspase-3 and caspase-9 expression clearly increased in the dose group cells (A549 cells treated with 500 μg/ml dose of C. gigantea extract for 72 h). However, there was no change in p21 expression. C. gigantea extract induced cell cycle arrest and apoptosis by decreasing the CCND1, CCND2, CDK4, Akt and Bcl-2 expression and by increasing Bax, p53, caspase-3 andcaspase-9 expression in A549 cells. Mushrooms are eukaryotic organisms heavily used because of their supposedly anticancer effect. Many mushroom species have been used for medical purposes, as a result of also having many effects such as antibiotic, antiviral and anticancer effects. It is thought that the C. gigantea extract may be a significant agent for treatment of lung cancer as a single agent or in combination with other drugs.

GFG-3a is a novel glycoprotein previously purified from the fermented mycelia of Grifola frondosa with novel sugar compositions and protein sequencing. The present study aims to investigate its effects on the cell cycle, differential proteins expression, and apoptosis of human gastric cancer SGC-7901 cells. Our findings revealed that GFG-3a induced the cell apoptosis and arrested cell cycle at S phase. GFG-3a treatment resulted in the differential expression of 21 proteins in SGC-7901 cells by upregulating 10 proteins including RBBP4 associated with cell cycle arrest and downregulating 11 proteins including RUVBL1, NPM, HSP90AB1, and GRP78 involved in apoptosis and stress response. qRT-PCR and Western blot analysis also suggested that GFG-3a could increase the expressions of Caspase-8/-3, p53, Bax, and Bad while decrease the expressions of Bcl2, Bcl-xl, PI3K, and Akt1. These results indicated that the stress response, p53-dependent mitochondrial-mediated, Caspase-8/-3-dependent, and PI3k/Akt pathways were involved in the GFG-3a-induced apoptosis process in SGC-7901 cells. These findings might provide a basis to prevent or treat human gastric cancer with GFG-3a and understand the tumor-inhibitory molecular mechanisms of mushroom glycoproteins.

Because of irregular dietary habits and lifestyle in Taiwan, the incidence and mortality rate of colorectal cancer have been increasing rapidly these years. This study investigated the inhibitory activity against the proliferation of human colorectal cancer HCT-116 cells by Inonotus obliquus extracts obtained from submerged fermentation. Cell viability was measured by the reduction of MTT and cell membrane integrity was determined by lactic dehydrogenase (LDH) release. The mRNA expression of proapoptosis and antiapoptosis mediators was assayed by real-time PCR, and the levels of p53 and NF-κB p65 were assessed using Western blot analysis. Furthermore, the influences of I. obliquus extracts to HCT-116 cells were evaluated by caspase-3 activity. The results can be summarized as, for the mitochondrial apoptotic pathway, quantitative RT-PCR data showed up-regulation of proapoptotic genes(Bax, bad, and caspase-3) and increased Bax/bcl-2 ratio by I. obliquus extracts. Moreover, treating with 20 mg/mL I. obliquus extracts augmented caspase-3 activity in HCT-116 cells. Induction of cell cycle G0/G1 phase arrest: I. obliquus extracts up-regulated the mRNA expression of proapoptotic genes (p53, p21WAF1/CIP1) and down-regulated antiapoptotic gene (CyclinD1), while extracts of I. obliquus mycelia increased the expressions of p53 protein in HCT-116 cells. I. obliquus extracts decreased the expression of NF-κB p65 protein and COX-2 gene in HCT-116 cells. Taking together, I. obliquus extracts may be used as a potentially novel food material for health care to improve the treatment of colorectal cancer.

In spite of the global consumption of mushrooms, only two epidemiological studies demonstrated an inverse correlation between mushroom intake and the risk of cancer. Therefore, in the present study we evaluated whether extracts from edible mushrooms Agaricus bisporus (portabella), Flammulina velutipes (enoki), Lentinula edodes (shiitake) and Pleurotus ostreatus (oyster) affect the growth of breast and colon cancer cells. Here, we identified as the most potent, P. ostreatus (oyster mushroom) which suppressed proliferation of breast cancer (MCF-7, MDA-MB-231) and colon cancer (HT-29, HCT-116) cells, without affecting proliferation of epithelial mammary MCF-10A and normal colon FHC cells. Flow cytometry revealed that the inhibition of cell proliferation by P. ostreatus was associated with the cell cycle arrest at G0/G1 phase in MCF-7 and HT-29 cells. Moreover, P. ostreatus induced the expression of the tumor suppressor p53 and cyclin-dependent kinase inhibitor p21(CIP1/WAF1), whereas inhibited the phosphorylation of retinoblastoma Rb protein in MCF-7 cells. In addition, P. ostreatus also up-regulated expression of p21 and inhibited Rb phosphorylation in HT-29 cells, suggesting that that P. ostreatus suppresses the proliferation of breast and colon cancer cells via p53-dependent as well as p53-independent pathway. In conclusion, our results indicated that the edible oyster mushroom has potential therapeutic/preventive effects on breast and colon cancer.

Ganoderma lucidum polysaccharides (GLPs), isolated from spores, mycelia and fruiting bodies of Ganoderma lucidum, have been suggested to possess anticancer activities in a large number of basic studies. A recent survey revealed that GLP-induced inhibition of cancer cell growth was dependent on the existence of functional p53. However, the actual role of p53-mediated tumor-suppressing pathways in facilitating the anticancer effect of GLPs is still unclear. In the present study, we investigated the interaction between GLPs and mutant p53 that exists in more than half of the known types of cancers. Ourresults showed that GLPs reactivated mutant p53 in colorectal cancer HT29 (p53R273H) and SW480 (p53R273H&P309S) cells while applied alone or together with 5-fluorouracil (5-FU). This reactivation further induced cell growth inhibition and apoptosis. In addition, western blot assay and in vitro cell-free apoptosis assay suggested that the activation of mutant p53 was effective in both a transcriptional-dependent and -independent pathway. Altogether, our data demonstrated for the first time that GLPs show prominent anticancer activities by reactivating several types of mutant p53. Therefore, targeting mutant p53 by GLPs alongside other chemotherapeutics may be considered as a novel treatment strategy for cancer.

Cannabis is the most commonly used illegal drug of abuse in Western society. Delta(9)-tetrahydrocannabinol, the psychoactive ingredient of marijuana, regulates a variety of neuronal processes including neurotransmitter release and synaptic transmission. An increasing body of evidence suggests that cannabinoids play a key role in the regulation of neuronal viability. In cortical neurons tetrahydrocannabinol has a neurodegenerative effect, the mechanisms of which are poorly understood, but involve the cannabinoid receptor subtype, CB(1). In this study we report that tetrahydrocannabinol (5 muM) evokes a rapid phosphorylation, and thus activation, of the tumour suppressor protein, p53, in a manner involving the cannabinoid CB(1) receptor, and the stress-activated protein kinase, c-jun N-terminal kinase, in cultured cortical neurons. Tetrahydrocannabinol increased expression of the p53-transcriptional target, Bax and promoted Bcl phosphorylation. These events were abolished by the p53 inhibitor, pifithrin-alpha (100 nM). The tetrahydrocannabinol-induced activation of the pro-apoptotic cysteine protease, caspase-3, and DNA fragmentation was also blocked by pifithrin-alpha. A siRNA knockdown of p53 further verified the role of p53 in tetrahydrocannabinol-induced apoptosis. This study demonstrates a novel cannabinoid signalling pathway involving p53 that culminates in neuronal apoptosis.

Human Papilloma Virus (HPV) is associated in most instances with cervical cancer. The HPV oncoproteins target P53 protein for degradation, leading to deregulation of cell cycle. We investigated whether stabilization of P53 in cervical cancer cells, by downregulating HPV transcription would restore the apoptotic ability of these cells. Our findings show that vitamin C downregulates the redox sensitive transcription factor AP-1 and decreases one of its transcription targets HPV E6, and stabilizes P53. This was associated with an increase in Bax and decrease in Bcl-2 and telomerase activity. Accumulation of P53 and its target gene bax then sensitized HeLa cells to cell-cycle arrest, cell death/apoptosis induced by cisplatin, and etoposide. Increasing drug sensitivity of cervical carcinoma cells by stabilizing P53 using vitamin C is a novel approach and has potential clinical relevance.

PURPOSE:Cervical cancer is the second most prevalent cancer in women worldwide. Survival of patients has been improved by cisplatin-based chemotherapy, but its effectiveness is limited due to its adverse effects on many tissues, especially nephrotoxicity. To optimize the efficacy of CDDP, we propose a combination therapy using natural products with minimal side effects. Vitamin C being a natural antioxidant is capable of selectively targeting cancer cells at pharmacological concentrations. Vitamin C synergistically enhances the activity of chemotherapeutic agents without increasing toxicity to normal cells. Therefore, we exploited co-therapy with cisplatin and vitamin C to kill cervical cancer cells.

METHODS:We elucidated the role of CDDP and VC on cervical cancer cell line (SiHa) by using cell growth assays, DNA fragmentation analysis, comet assay, in vitro morphological assessment of apoptosis (AO/EB and DAPI staining), ROS analysis by DCFDA, flow cytometry, biochemical assays (GST, GSH, NO, catalase, TPA) and Western blotting.

RESULTS:Our results clearly demonstrated that CDDP and VC treatment exhibited ameliorative effect on induction of cell death by p53 overexpression and generation of hydrogen peroxide in SiHa cells, thereby reducing the dosage of CDDP required to induce cell death in cancer cells.

CONCLUSIONS:These studies provide novel approaches to combat cisplatin resistance in cervical cancer.

Vitamin C (VC) is an important antioxidant and enzyme co-factor that works by stimulating the immune system and protecting against infections. It is well known that melanoma cells are more susceptible to VC than any other tumor cells. However, the role of VC in the treatment of colon cancer has not been studied. Cisplatin (CDDP) is a DNA damaging agent and is widely used for treating cancer, while the role of p53 in CDDP-induced cell death has been stressed. Using cell growth assays, morphological methods, Western blotting, flow cytometry, and DNA fragmentation analysis, we measured the expression of p53 level involved in the effect of VC on CDDP-induced apoptosis of HCT116, a human colon cancer cell line. CDDP plus VC treatment resulted in significantly increased apoptosis along with upregulation of p53 compared to untreated cells and/or CDDP-treated cells. These results suggest that VC enhanced CDDP sensitivity and apoptosis via upregulation of p53.