• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.427-436
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• 2012

Targeted therapy has been a very promising strategy of drug development research. Many molecular mechanims of diseases have been known to be regulated by abundance of proteins, such as receptors and hormones. Chemoprevention for treatment and prevention of diseases are continuously developed. Pre-clinical and clinical studies in chemoprevention field yielded many valuable data in preventing the onset of disease and suppressing the progress of their growth, making chemoprevention a challenging and a very rational strategy in future researches. Natural products being rich of flavonoids are those fruits belong to the genus citrus. Ethanolic extract of Citrus reticulata and Citrus aurantiifolia peels showed anticarcinogenic, antiproliferative, co-chemotherapeutic and estrogenic effects. Several examples of citrus flavonoids that are potential as chemotherapeutic agents are tangeretin, nobiletin, hesperetin, hesperidin, naringenin, and naringin. Those flavonoids have been shown to possess inhibition activity on certain cancer cells' growth through various mechanisms. Moreover, citrus flavonoids also perform promising effect in combination with several chemotherapeutic agents against the growth of cancer cells. Some mechanisms involved in those activities are through cell cycle modulation, antiangiogenic effect, and apoptosis induction.Previous studies showed that tangeretin suppressed the growth of T47D breast cancer cells by inhibiting ERK phosphorylation. While in combination with tamoxifen, doxorubicin, and 5-FU, respectively, it was proven to be synergist on several cancer cells. Hesperidin and naringenin increased cytotoxicitity of doxorubicin on MCF-7 cells and HeLa cells. Besides, citrus flavonoids also performed estrogenic effect in vivo. One example is hesperidin having the ability to decrease the concentration of serum and hepatic lipid and reduce osteoporosis of ovariectomized rats. Those studies showed the great potential of citrus fruits as natural product to be developed as not only the source of co-chemotherapeutic agents, but also phyto-estrogens. Therefore, further study needs to be conducted to explore the potential of citrus fruits in overcoming cancer.

• Tuberculosis and Respiratory Diseases
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• v.69 no.1
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• pp.1-15
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• 2010

Lung cancer remains the most common cause of cancer death in the United States and worldwide. About 80~90% of cases are smoking-related and smoking cessation programs are of great importance in reducing lung cancer risk. However, the lifetime risk for lung cancer remains elevated even in ex-smokers. Chemoprevention holds the promise to further reduce this risk and thus to decrease lung cancer incidence and mortality. Over the last decades, most chemoprevention trials for lung cancer have yielded negative outcomes. Population-based studies suggest that high intake of certain foods such as soy, red wine or green vegetables may be associated with decreased cancer risk. Because of these observations and their general safety, a plethora of natural compounds is currently being studied for the chemoprevention of cancer. In this review we discuss promising in vitro and in vivo data of novel natural compounds, their interference with molecular mechanisms responsible for lung cancer development and potential implications for their further preclinical and clinical investigation.

• Archives of Pharmacal Research
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• v.28 no.1
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• pp.1-15
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• 2005

Cancer is still a major global health concern even after an everlasting strive in conquering this dread disease. Emphasis is now given to chemoprevention to reduce the risk of cancer and also to improve the quality of life among cancer afflicted individuals. Recent progress in molecular biology of cancer has identified key components of the cellular signaling network, whose functional abnormality results in undesired alterations in cellular homeostasis, creating a cellular microenvironment that favors premalignant and malignant transformation. Multiple lines of evidence suggest an elevated expression of cyclooxygenase-2 (COX-2) is causally linked to cancer. In response to oxidative/pro-inflammatory stimuli, turning on unusual signaling arrays mediated through diverse classes of kinases and transcription factors results in aberrant expression of COX-2. Population-based as well as laboratory studies have explored a broad spectrum of chemopreventive agents including selective COX-2 inhibitors and a wide variety of anti-inflammatory phytochemicals, which have been shown to target cellular signaling molecules as underlying mechanisms of chemoprevention. Thus, unraveling signaling pathways regulating aberrant COX-2 expression and targeted blocking of one or more components of those signal cascades may be exploited in searching chemopreventive agents in the future.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.179-184
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• 2014

Chemoresistance of breast cancer to doxorubicin is mediated mainly through activation of NF-kB and over expression of HER2. Curcumin and its analogues (PGV-0 and PGV-1) exert cytotoxic effects on T47D breast cancer cells. Suppression of NF-kB activation is suggested to contribute to this activity. The present study aimed to explore the effects of curcumin, PGV-0, and PGV-1 singly and in combination with doxorubicin on MCF-7/Dox cells featuring over-expression of HER2. In MTT assays, curcumin, PGV-0, and PGV-1 showed cytotoxicity effects against MCF-7/Dox with IC50 values of $80{\mu}M$, $21{\mu}M$, and $82{\mu}M$ respectively. These compounds increased MCF-7/Dox sensitivity to doxorubicin. Cell cycle distribution analysis exhibited that the combination of curcumin and its analogues with Dox increased sub G-1 cell populations. Curcumin and PGV-1 but not PGV-0 decreased localization of p65 into the nucleus induced by Dox, indicating that activation of NF-kB was inhibited. Molecular docking of curcumin, PGV-0, and PGV-1 demonstrated high affinity to HER2 at ATP binding site. This interaction were directly comparable with those of ATP and lapatinib. These findings suggested that curcumin, PGV-0 and PGV-1 enhance the Dox cytotoxicity to MCF-7 cells through inhibition of HER2 activity and NF-kB activation.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.5
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• pp.2683-2688
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• 2016

A salt compound of a curcumin analogue, potassium pentagamavunon-0 (K PGV-0) has been synthesized to improve solubility of pentagamavunon-0 which has been proven to have anti-proliferative effects on several cancer cells. The purpose of this study was to investigate cytotoxic activity and metastasis inhibition by K PGV-0 alone and in combination with achemotherapeutic agent, doxorubicin (dox), in breast cancer cells. Based on MTT assay analysis, K PGV-0 showed cytotoxic activity in T47D and 4T1 cell lines with $IC_{50}$ values of $94.9{\mu}M$ and $49.0{\pm}0.2{\mu}M$, respectively. In general, K PGV-0+dox demonstrated synergistic effects and decreased cell viability up to 84.7% in T47D cells and 62.6% in 4T1 cells. Cell cycle modulation and apoptosis induction were examined by flow cytometry. K PGV-0 and K PGV-0+dox caused cell accumulation in G2/M phase and apoptosis induction. Regarding cancer metastasis, while K PGV-0 alone did not show any inhibition of 4T1 cell migration, K PGV-0+dox exerted inhibition. K PGV-0 and its combination with dox inhibited the activity of MMP-9 which has a pivotal role in extracellular matrix degradation. These results show that a combination of K PGV-0 and doxorubicin inhibits cancer cell growth through cell cycling, apoptosis induction, and inhibition of cell migration and MMP-9 activity. Therefore, K PGV-0 may have potential for development as a co-chemotherapeutic agent.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.501-508
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• 2007

Proanthocyanidins (PACs), also named condensed tannins, are polymers of flavan-3-ols such as (+ )-(gallo)catechin and (-)-epi(gallo)catechin. A proper analysis of the PACs, with difficult challenges due to their complex structures, is crucial in studies of cancer chemoprevention. Cancer is a leading cause of mortality around the world. Many experimental studies have shown that dietary PACs are potential chemopreventive agents that block or suppress against multistage carcinogenesis in both in vitro and in vivo models. Cancer chemoprevention by dietary PACs has been shown effective through different mechanisms of action such as antioxidant, apoptosis-inducing, and enzyme inhibitory activities. Good sources of dietary PACs are nuts, fruits, beans, chocolate, fruit juice, red wine, and green tea. The chemopreventive potential of dietary PACs should be considered together with their bioavailability in humans. The safety issues regarding carcinogenesis and gastrointestinal disorder are also reviewed.

• Journal of Digestive Cancer Reports
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• v.8 no.2
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• pp.97-101
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• 2020

Metformin is a widely used first-line anti-diabetic drug worldwide. Epidemiologic studies using the large population-based cohort database have shown the association between metformin uses and reduced risk of various type cancers including gastric cancer. In the gastric cancer prevention, metformin use was associated with the significant reduction of gastric cancer risk, especially for long-term metformin users. However, there is no well-designed randomized controlled clinical trial investigating the effect of metformin as a chemopreventive drug for gastric cancer. Therefore, further well-designed clinical trials will be needed to implement metformin for chemoprevention of gastric cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3343-3352
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• 2014

Chemoprevention is an attempt to use nontoxic natural and synthetic substances or their mixtures to intervene the relatively early stages of carcinogenesis, before invasive characteristics are manifested. The consumption of fruits is well known to reduce the risk of human cancers. Although most fruits are available only on a seasonal basis, recent advances in food processing technologies have made it possible to extend the shelf life of fruits and fruit-products. Fruits can be preserved by applying different drying processes to reduce the moisture content. Different varieties of dried fruits are now sold in supermarkets, thereby making them readily accessible to consumers. Since oxidative stress and chronic inflammation play important roles in cancer development, dried fruits with antioxidative and anti-inflammatory properties hold promise for cancer chemoprevention. The antioxidant, anti-inflammatory and chemopreventive activities of dried fruits are largely attributed to their polyphenols and vitamins. Dried fruits contain adequate amounts of bioactive principles, such as anthocyanins, acetogenins, catechins, coumarins, phenolic acids, terpenes, xanthones, and others. Since numerous health beneficial phytochemicals in fruits are conserved even after processing, regular intake of dried fruits can help prevent cancer. This review addresses the chemopreventive potential of representative dried fruits and their active constituents.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.2425-2427
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• 2012

Ornithine decarboxylase (ODC), the first enzyme in the polyamine biosynthesis, plays an important role in tumor progression, cell proliferation and differentiation. In recent years, ODC has been the subject of intense study among researchers, as a target for anti-cancer therapy and specific inhibitory agents, have the potential to suppress carcinogenesis and find applications in clinical therapy. In particular, it is suggested that ODC is a promising candidate target for natural products in cancer chemoprevention. Future exploration of ornithine decarboxyalse inhitors present in nature may offer great hope for finding new cancer chemporeventive agents.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4393-4402
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• 2012

Colon cancer is the third most common malignant neoplasm in the world and it remains an important cause of death, especially in western countries. The toxic environmental pollutant, 1, 2-dimethylhydrazine (DMH), is also a colon-specific carcinogen. Tannic acid (TA) is reported to be effective against various types of chemically induced toxicity and also carcinogenesis. In the present study, we evaluated the chemopreventive efficacy of TA against DMH induced colon toxicity in a rat model. Efficacy of TA against the colon toxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, lipid peroxidation, histopathological changes and expression of early molecular markers of inflammation and tumor promotion. DMH treatment induced oxidative stress enzymes (p<0.001) and an early inflammatory and tumor promotion response in the colons of Wistar rats. TA treatment prevented deteriorative effects induced by DMH through a protective mechanism that involved reduction of oxidative stress as well as COX-2, i-NOS, PCNA protein expression levels and TNF-${\alpha}$ (p<0.001) release. It could be concluded from our results that TA markedly protects against chemically induced colon toxicity and acts plausibly by virtue of its antioxidant, anti-inflammatory and antiproliferative activities.