ABSTRACT
Quassinoids often exhibit antioxidant and antiproliferative activity. Emerging evidence suggests that these natural metabolites also display chemopreventive actions. In this study, we investigated the potential for the quassinoid glaucarubulone glucoside (Gg), isolated from the endemic Jamaican plant Castela macrophylla (Simaroubaceae), to display potent cytotoxicity and inhibit human cytochrome P450s (CYPs), particularly CYP1A enzymes, known to convert polyaromatic hydrocarbons into carcinogenic metabolites. Gg reduced the viability of MCF-7 breast adenocarcinoma cells (IC50 = 121 nm) to a greater extent than standard of care anticancer agents 5-fluorouracil, tamoxifen (IC50 >10 µm) and the tamoxifen metabolite 4-hydroxytamoxifen (IC50 = 2.6 µm), yet was not cytotoxic to non-tumorigenic MCF-10A breast epithelial cells. Additionally, Gg induced MCF-7 breast cancer cell death. Gg blocked increases in reactive oxygen species in MCF-10A cells mediated by the polyaromatic hydrocarbon benzo[a]pyrene (B[a]P) metabolite B[a]P 1,6-quinone, yet downregulated the expression of genes that promote antioxidant activity in MCF-7 cells. This implies that Gg exhibits antioxidant and cytoprotective actions in non-tumorigenic breast epithelial cells and pro-oxidant, cytotoxic actions in breast cancer cells. Furthermore, Gg inhibited the activities of human CYP1A according to non-competitive kinetics and attenuated the ability of B[a]P to induce CYP1A gene expression in MCF-7 cells. These data indicate that Gg selectively suppresses MCF-7 breast cancer cell growth without impacting non-tumorigenic breast epithelial cells and blocks B[a]P-mediated CYP1A induction. Taken together, our data provide a rationale for further investigations of Gg and similar plant isolates as potential agents to treat and prevent breast cancer. Copyright © 2017 John Wiley & Sons, Ltd.
Subject(s)
Antineoplastic Agents, Phytogenic/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/genetics , Cytotoxins/therapeutic use , Glaucarubin/analogs & derivatives , Plant Extracts/therapeutic use , Simaroubaceae/chemistry , Antioxidants/therapeutic use , Cell Line, Tumor/drug effects , Cell Proliferation/drug effects , Cytochrome P-450 Enzyme System/drug effects , Female , Gene Expression/drug effects , Glaucarubin/therapeutic use , Humans , Jamaica , MCF-7 Cells/drug effects , Quassins/therapeutic useABSTRACT
BACKGROUND: Renal cell carcinoma (RCC) accounts for 2% of all adult malignancies and is associated with a case fatality rate as high as 40%. RCC has been on the rise for the last 6 decades at a steady increase of 2% per annum. Much work has been done to uncover the pathogenesis of the disease and the role of angiogenesis has been a recurrent denominator connected to vascular endothelial growth factor (VEGF) and its downstream effectors along with the mammalian target of rapamycin (mTOR) mediated signal transduction pathway. OBJECTIVE: This review will discuss relevant inhibitors of key biomarkers to the disease in hopes of paving the way for novel treatments geared towards improving RCC morbidity and mortality rates. RESULTS AND CONCLUSION: Currently, treatment of advanced RCC includes one or more of the following: partial or radical nephrectomy, systemic therapy, immunotherapy and targeted therapy. Still drug resistance continues to be a challenge to many of the approved drugs and those undergoing clinical trials. However, the inclusion of targeted therapies has improved advanced RCC treatment success rates over that of surgery alone, and over that of the use of traditional chemotherapy for this relatively chemo-resistant disease. In an era of personalized medicine, research utilizing a polypharmacology approach could enhance efficacy of drug leads to treating RCC.
