Diets, Phytochemicals, and Chemoprevention of Tumorigenesis

β-Elemene inhibits 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate-induced skin tumorigenesis through suppression of NF-κB-associated signaling events in the mouse skin model

β-Elemene (1-methyl-1-vinyl-2,4-diisopropenyl-cyclohexane), a natural sesquiterpene-derived curcumae radix, exhibits a variety of pharmacologic properties including anticancer. However, the molecular action of β-elemene in chemical-induced skin carcinogenesis remains unclear. Therefore, the present study executes to investigate a possible effect of β-elemene in the 7,12-dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor model. The experimental mice were subjected to execute two-stage skin carcinogenesis and it has been initiated by the addition of DMBA on the dorsal portion of the mouse skin. One week after, for chemical carcinogen of mice, topical exposure of DMBA has been induced following with TPA (5 nmol) in acetone (200 μL) given weekly twice for 20 weeks respectively. After completion of the experimental period, we noticed that 100% of tumor incidence, histopathological changes, decreased lipid peroxidation (LPO), and decreased antioxidant levels in DMBA/TPA-promoted skin carcinogenesis. Furthermore, enhanced activity of inflammatory protein markers (nuclear factor [NF]-κB, tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nitric oxide synthase) and cell-proliferative messenger RNA markers (PCNA, cyclin D1), and increased antiapoptotic protein Bcl-2; decreased proapoptotic protein marker events Bax and caspase 3 and 9 expressions were noticed in DMBA/TPA promoted skin tissue. In this study, we noticed that β-elemene noticeably reversed the histopathological changes and antioxidant levels in tumor-bearing mice. Conversely, β-elemene effectively inhibits inflammation, cell proliferation events, and enhances proapoptotic factors, by suppression of NF-κB transcriptional activation in DMBA/TPA animals. Thus, we concluded that β-elemene prevents DMBA/TPA promoted skin carcinogenesis through its antioxidant and abate inflammation markers and cell-proliferative markers also activating proapoptotic molecules.

Molecular effects of hesperetin, a citrus flavanone on7,12-dimethylbenz(a)anthracene induced buccal pouch squamous cell carcinoma in golden Syrian hamsters

In recent years, researchers have been focused on citrus flavanone, a naturally occurring bioactive substance of hesperetin. To investigate the molecular mechanism based chemopreventive efficacy of hesperetin on 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch (HBP) squamous cell carcinoma (SCC). The oral tumour was provoked by painted with 0.5% DMBA on left buccal pouch thrice a week for 10 consecutive weeks developed well-differentiated SCC and tumour formation was 100% in DMBA alone. We evaluated the chemopreventive potential of hesperetin by assessing the lipid peroxidation (LPO) by-products, status of enzymatic, non-enzymatic antioxidants, detoxifying agents etc. Moreover, modulating expression of apoptotic and cell proliferation markers were observed in HBP SCC experimental hamsters. Oral administration of hesperetin (20 mg/kg b.w.) to DMBA painted hamsters significantly reversed the stages of oral SCC. Our findings indicate that hesperetin possesses a chemopreventive effect in DMBA-induced oral SCC by exerting anti-carcinogenic property.

[6]-Shogaol, a Novel Chemopreventor in 7,12-Dimethylbenz[a]anthracene-induced Hamster Buccal Pouch Carcinogenesis

Oral cancer is a major cause of morbidity and mortality in developing countries. Despite advances in chemotherapy for the cancer management, the survival rate has not yet been improved. Dietary nutrient has been receiving a lot of attention and interest in the chemotherapeutic development. [6]-Shogaol is a major bioactive compound identified in ginger that possesses many pharmacological properties. The aim of the present study is to investigate the effect of [6]-shogaol on 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch (HBP) carcinogenesis. Oral squamous cell carcinoma induced in HBP by painting with 0.5% 7,12-dimethylbenz(a)anthracene (DMBA), thrice in a week for 16 weeks. We observed 100% tumour incidence, decreased levels of lipid peroxidation, antioxidant, and phase II detoxification enzymes (GST, GR and GSH) in DMBA-induced hamsters. Further, enhanced activity of phase I enzymes (cytochrome p450 and b5) and over-expression of mutant p53, Bcl-2 and decreased expression of wild type p53 and Bax were noticed in DMBA-induced hamsters. Our results indicated that [6]-shogaol (10, 20 and 40 mg/kg body weight) treated with DMBA-painted hamsters, considerably reversed tumour incidence, improved antioxidant status, phase II detoxification enzymes, and also inhibit lipid peroxidation and phase I enzymes. Moreover, [6]-shogaol inhibits mutant p53 and Bcl-2 expression and significantly restored normal p53, Bax levels. Thus, we concluded that [6]-shogaol prevents DMBA-induced HBP carcinogenesis through its antioxidant as well as modulating apoptotic signals.