• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.5
• /
• pp.1827-1831
• /
• 2015

Background: We generated a mouse model of prostate cancer based on the adult-prostate-specific inactivation of phosphatase and tensin homolog (PTEN) using the Cre-loxP system. The potential of our mice as a useful animal model was examined by evaluating the chemopreventive efficacy of the anti-androgen, chlormadinone acetate (CMA). Materials and Methods: Six-week-old mice were treated subcutaneously with $50{\mu}g/g$ of CMA three times a week for 9 or 14 weeks and sacrificed at weeks 15 and 20. Macroscopic change of the entire genitourinary tract (GUT) and histologically evident prostate gland tumor development were evaluated. Proliferation and apoptosis status in the prostate were examined by immunohistochemistry. Results: CMA triggered significant shrinkage of not only the GUT but also prostate glands at 15 weeks compared to the control (p=0.017 and p=0.010, respectively), and the trend became more marked after a further five-weeks of treatment. The onset of prostate adenocarcinoma was not prevented but the proliferation of cancer cells was inhibited by CMA, which suggested the androgen axis is critical for cancer growth in these mice. Conclusions: Conditional PTEN-deficient mice are useful as a preclinical model for chemoprevention studies and serve as a valuable tool for the future screening of potential chemopreventive agents.

• Preventive Nutrition and Food Science
• /
• v.20 no.1
• /
• pp.73-77
• /
• 2015

As an approach to search for chemopreventive agents, we tested p-coumaric acid, 3-methoxy-p-coumaric acid (ferulic acid), and 3,5-dimethoxy-p-coumaric acid (sinapic acid) in B16/F10 melanoma cells. Intracellular melanin contents were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and cytotoxicity of the compounds were examined by lactate dehydrogenase (LDH) release. p-Coumaric acid showed inhibitory effect on melanogenesis, but ferulic acid increased melanin content, and sinapic acid had almost no effect on melanogenesis. Treatment with ferulic acid resulted in a 2 to 3 fold elevation in the production of melanin. Correlatively, cell viability decreased in a dose-dependent manner when treated with ferulic acid. However, ferulic acid did not affect the LDH release from the cells. Treatment with sinapic acid resulted in a 50~60% elevation in the release of LDH when treated with a $200{\mu}g/mL$ concentration and showed neither cytostasis nor increase of melanin synthesis in a dose-dependent manner. Taken together, p-coumaric acid inhibits melanogenesis, ferulic acid induces melanogenesis, and sinapic acid exerts cytotoxic effects in B16/F10 murine melanoma cells. The results indicate that the addition of methoxy groups to p-coumaric acid shows the melanogenic or cytotoxic effects in melanoma cells compared to the original compound. Therefore, this study suggests the possibility that methoxylated p-coumaric acid, ferulic acid can be used as a chemopreventive agent.

• Toxicological Research
• /
• v.21 no.4
• /
• pp.355-360
• /
• 2005

Epidemiological and laboratory studies provide insight into the anti-carcinogenic potential of garlic and its constituent compounds. Garlic is appealing as an anti-carcinogenic agent due to its ability to induce apoptosis in vitro. Diallyl disulfide (DADS) is one of the major components of garlic that used to determine inhibition of cell proliferation and induced apoptosis in human colon cell lines. In this study, human colorectal cancer cell lines (LOVO, HCT-116, SW-480) were exposed to DADS. The inhibitory effects of DADS dose level more than $50\;{\mu}M$ in the cell viability of all cell lines. Cell growth activity inhibits of human colon cancer cell lines. The inhibitory effects of DADS dose level more than $25\~50\;{\mu}M$ in the cell growth using MTT assay. We found that DADS may have the apoptosis action (chromatin condensation, DNA fragmentation) using DAPI staining and increased the expression of caspase-3 at the dose level more than $100\;{\mu}M$, decreased the expression level of $\beta-catenin$ at dose dependent in the western blotting. We suggest that DADS may have a potential candidate as cancer chemopreventive agents.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.10
• /
• pp.5855-5860
• /
• 2013

Phytochemicals are among the natural chemopreventive agents with most potential for delaying, blocking or reversing the initiation and promotional events of carcinogenesis. They therefore offer cancer treatment strategies to reduce cancer related death. One such promising chemopreventive agent which has attracted considerable attention is sulforaphane (SFN), which exhibits anti-cancer, anti-diabetic, and anti-microbial properties. The present study was undertaken to assess effect of SFN alone and in combination with a chemotherapeutic agent, gemcitabine, on the proliferative potential of MCF-7 cells by cell viability assay and authenticated the results by nuclear morphological examination. Further we analyzed the modulation of expression of Bcl-2 and COX-2 on treatment of these cells with SFN by RT-PCR. SFN showed cytotoxic effects on MCF-7 cells in a dose- and time-dependent manner via an apoptotic mode of cell death. In addition, a combinational treatment of SFN and gemcitabine on MCF-7 cells resulted in growth inhibition in a synergistic manner with a combination index (CI)<1. Notably, SFN was found to significantly downregulate the expression of Bcl-2, an anti-apoptotic gene, and COX-2, a gene involved in inflammation, in a time-dependent manner. These results indicate that SFN induces apoptosis and anti-inflammatory effects on MCF-7 cells via downregulation of Bcl-2 and COX-2 respectively. The combination of SFN and gemcitabine may potentiate the efficacy of gemcitabine and minimize the toxicity to normal cells. Taken together, SFN may be a potent anti-cancer agent for breast cancer treatment.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.2
• /
• pp.951-957
• /
• 2013

Our aim was to investigate the chemopreventive potential of saffron in DMBA-induced hamster buccal pouch carcinogenesis. Assessment was by monitoring the percentage of tumor bearing hamsters, tumor size as well as the status of detoxification agents, lipid peroxidation and antioxidants. Oral squamous cell carcinomas were induced in the buccal pouch of Syrian golden hamsters by painting them with 0.5% DMBA in liquid paraffin three times a week for 14 weeks. We observed 100% oral tumor formation with severe histopathological abnormalities in all the hamsters treated with DMBA alone, activities of phase I and phase II detoxification enzymes, lipid peroxidation and antioxidants being significantly altered. Though oral administration of saffron completely prevented the formation of tumors, we noticed severe hyperplasia and dysplasia in hamsters treated with DMBA, suggesting that tumors might eventually develop. Oral administration of saffron return detoxification enzymes, lipid peroxidation and antioxidants to normal ranges. The chemopreventive potential of saffron thus is likely due to antioxidant properties and modulating effects on detoxification in favour of the excretion of carcinogenic metabolites during DMBA-induced hamster buccal pouch carcinogenesis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.26 no.2
• /
• pp.137-145
• /
• 2000

Carcinogenesis is a multi-stage process that generally consists of at least three steps; initiation, promotion, and progression. If one of these carcinogenic steps were suppressed or delayed, the cancer could be prevented. Cancer chemoprevention is defined to be inhibition or reversal of the carcinogenic process by the specific chemical agents and is a novel approach to cancer management alternative to conventional chemotherapy. Chlorophylln(CHL), a water-soluble derivative of chlorophyll, containing sodium and copper, has been known to be strong antimutagen in several test systems, but its mechanism of antimutagenic action is unknown. In the present experiment, the possibility of CHL as chemopreventive drugs on 7,12-dimethylbenz[a]anthracene(DMBA)-induced hamster buccal pouch carcinogenesis was investigated by mutagenicity test, carcinogenicity test, and frequency or spectrum of H-ras mutations in the both of DMBA-induced and chlorophylln-pretreated-DMBA induced tumor by polymerase chain reaction and non-isotopic restriction fragment length polymorphism. The treatment of CHL reduced the yields and multiplicity of the 0.5% DMBA-induced tumor, 86% to 62.5% and $3.7{\pm}0.6$ to $1.4{\pm}0.3$, respectively. The occurrence of histidine revertant by $20{\mu}mole$ DMBA was inhibited 25.6 to 81.7% by 1 to $5{\mu}M$ CHL in a dose-dependent manner. The mutation rates of H-ras gene in DMBA-induced and CHL-pretreated-DMBA induced tumor were 96%, 94% of which the most mutations were in codon 12/13. These results suggest that CHL inhibits the carcinogenic action of DMBA by the formation of complex between CHL and DMBA or the inhibition of the activation of DMBA in vivo. But CHL did not affect the mutation rates or its spectrum in already formed tumor.

• Biomolecules & Therapeutics
• /
• v.21 no.1
• /
• pp.49-53
• /
• 2013

A number of naturally-occurring or synthetic chemicals have been reported to exhibit prostate chemopreventive effects. Synthetic $5{\alpha}$-reductase (5-AR) inhibitors, e.g. finasteride and durasteride, gained special interests as possible prostate chemopreventive agents. Indeed, two large-scale epidemiological studies have demonstrated that finasteride or durasteride significantly reduced the incidence of prostate cancer formation in men. However, these studies have raised an unexpected concern; finasteride and durasteride increased the occurrence of aggressive prostate tumor formation. In the present study, we have observed that treatment of finasteride did not affect the growth of androgen-refractory PC-3 prostate cancer cells. Finasteride also failed to induce apoptosis or affect the expression of proto-oncogenes in PC-3 cells. Interestingly, we found that treatment of finasteride induced the expression of Nrf2 and HO-1 proteins in PC-3 cells. In particular, basal level of Nrf2 protein was higher in androgen-refractory prostate cancer cells, e.g. DU-145 and PC-3 cells, compared with androgen-responsive prostate cancer cells, e.g. LNCaP cells. Also, treatment of finasteride resulted in a selective induction of Nrf2 protein in DU-145 and PC-3 cells, but not in LNCaP cells. In view of the fact that upregulation of Nrf2-mediated phase II cytoprotective enzymes contribute to attenuating tumor promotion in normal cells, but, on the other hand, confers a selective advantage for cancer cells to proliferate and survive against chemical carcinogenesis and other forms of toxicity, we propose that finasteride-mediated induction of Nrf2 protein might be responsible, at least in part, for an increased risk of high-grade prostate tumor formation in men.

• Archives of Pharmacal Research
• /
• v.25 no.5
• /
• pp.561-571
• /
• 2002

The action mechanisms of several chemopreventive agents derived from herbal medicine and edible plants have become attractive issues in cancer research. Tea is the most widely consumed beverage worldwide. Recently, the cancer chemopreventive actions of tea have been intensively investigated. It have been demonstrated that the active principles of tea were attributed to their tea polyphenols. Recently, tremendous progress has been made in elucidating the molecular mechanisms of cancer chemoprevention by tea and tea polyphenols. The suppression of various tumor biomarkers including growth factor receptor tyrosine kinases, cytokine receptor kinases, P13K, phosphatases, ras, raf, MAPK cascades, NㆍFB, IㆍB kinase, PKA, PKB, PKC, c-jun, c-fos, c-myc, cdks, cyclins, and related transducing proteins by tea polyphenols has been studied in our laboratory and others. The IㆍB kinase (IKK) activity in LPS-activated murine macrophages (RAW 264.7 cells) was found to be inhibited by various tea polyphenols including (-) epigallocatechin-3-gallate (EGCG), theaflavin (TF-1), theaflavin-3-gal-late (TF-2) and theaflavin-3,3'-digallate (TF-3). TF-3 inhibited IKK activity in activated macrophages more strongly than did the other tea polyphenols. TF-3 inhibited both IKK1 and IKK2 activity and prevented the degradation of IㆍBㆍand IㆍBㆍin activated macrophage cells. The results suggested that the inhibition of IKK activity by TF-3 and other tea polyphenols could occur by a direct effect on IKKs or on upstream events in the signal transduction pathway. TF-3 and other tea polyphenols blocked phosphorylation of IB from the cytosolic fraction, inhibited NFB activity and inhibited increases in inducible nitric oxide synthase levels in activated macrophage. TF-3 and other tea polyphenols also inhibited strongly the activities of xanthine oxidase, cyclooxygenase, EGF-receptor tyrosine kinase and protein kinase C. These results suggest that TF-3 and other tea polyphenols may exert their cancer chemoprevention through suppressing tumor promotion and inflammation by blocking signal transduction. The mechanisms of this inhibition may be due to the blockade of the mitogenic and differentiating signals through modulating EGFR function, MAPK cascades, NFkB activation as wll as c-myc, c-jun and c-fos expression.

• Biomolecules & Therapeutics
• /
• v.10 no.4
• /
• pp.240-245
• /
• 2002

Cancer metastasis represents the most important cause of cancer death and antitumor agents that may inhibit this process have been extensively pursued. Invasion and metastasis of malignantly transformed cells involve degradation of the extracellular matrix (ECM) components by matrix metalloproteinases (MMP), especially MMP-2 and -9. We previously showed that H-ras-induced invasive phenotype may involve MMP-2, rather than MMP-9, in MCF10A cells. In the present study, we investigated the chemopreventive effect of Aster, a widely used culinary vegetable in Korea. We screened twelve extracts from three Aster species (Aster scaber, Aster oharai and Aster glehni) for the inhibitory effect on MMP activities of H-ras MCF10A human breast epithelial cells. All of the extracts tested in this study efficiently inhibited the gelatinolytic activities of MMP-2 and MMP-9. A more prominent inhibition was observed in MMP-2 activity compared to MMP-9. Out of twelve extracts, eight extracts showed>90％ inhibition of MMP-2 activity in H-ras MCF10A cells while only one extract showed>90％ inhibition of MMP-9 activity. We selected three extracts (AO-3, AG-3 and AS-EA) for further studies since they exerted a marked inhibition in the ratio of MMP-2 to MMP-9. Treatment with AO-3, AG-3 and AS-EA in H-ras MCF10A cells caused a significant inhibition of invasive phenotype and migration, proving a chemopreventive potential of these extracts. Taken together, our results demonstrate that extracts of Aster effectively inhibit invasion and migration of highly malignant human breast cells, possibly via downregulation of MMP-2 and MMP-9.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.7
• /
• pp.2939-2946
• /
• 2015

Many of the anti-cancer agents currently used have an origin in natural sources including plants. Aloe vera is one such plant being studied extensively for its diverse health benefits, including cancer prevention. In this study, the cytotoxic potential of Aloe vera crude extract (ACE) alone or in combination with cisplatin in human breast (MCF-7) and cervical (HeLa) cancer cells was studied by cell viability assay, nuclear morphological examination and cell cycle analysis. Effects were correlated with modulation of expression of genes involved in cell cycle regulation, apoptosis and drug metabolism by RT-PCR. Exposure of cells to ACE resulted in considerable loss of cell viability in a dose- and time-dependent fashion, which was found to be mediated by through the apoptotic pathway as evidenced by changes in the nuclear morphology and the distribution of cells in the different phases of the cell cycle. Interestingly, ACE did not have any significant cytotoxicity towards normal cells, thus placing it in the category of safe chemopreventive agent. Further, the effects were correlated with the downregulation of cyclin D1, CYP 1A1, CYP 1A2 and increased expression of bax and p21 in MCF-7 and HeLa cells. In addition, low dose combination of ACE and cisplatin showed a combination index less than 1, indicating synergistic growth inhibition compared to the agents applied individually. In conclusion, these results signify that Aloe vera may be an effective anti-neoplastic agent to inhibit cancer cell growth and increase the therapeutic efficacy of conventional drugs like cispolatin. Thus promoting the development of plant-derived therapeutic agents appears warranted for novel cancer treatment strategies.