DOI: 10.14457/tu.the.2017.1738
title: Composition and molecular mechanisms of royal jelly’s active ingredients: protective effects on human lymphocytes, cytotoxic effects on MCF-7 breast cancer cell line

description: Royal jelly (RJ), a nutritious natural product from bees, is used as a traditional medicine for health promotion and longevity. 10-hydroxy-2-decenoic acid (10-H2DA), the unique fatty acid in RJ, also has anti-angiogenic and anti-tumor activities. However, molecular mechanisms on their cancer prevention and anti-cancer properties are still inconclusive. The study aimed to elucidate the cytogenetic effects and molecular mechanisms of RJ and its ingredients as chemopreventive and chemotherapeutic agents. Genotoxic and antigenotoxic effects against doxorubicin (DXR) of RJ, ethereal extract (EE), defatted material (DM), and 10-H2DA were investigated by the in vitro sister chromatid exchange (SCE) assay. Cytotoxic and antiproliferative effects of 10-H2DA alone and 10-H2DA co-treatments with DXR against MCF-7 breast cancer cells were evaluated by the MTS tetrazolium assay.Gene expression modulations were detected by Western blot analysis. Cell cycle distribution, cell apoptosis were determined by flow cytometry. Morphological changes were detected by Hoechst 33258/propidium iodide double staining. We revealed that RJ treatments (0.0005-0.5 mg/mL) were not genotoxic nor cytotoxic on human lymphocytes by the in vitro SCE assay. The lowest dose of RJ maximally enhanced cell proliferation, cell survival, longevity, and antioxidative response through induction of c-MYC/BAX, BCL2/BAX, h-TERT/BAX and NRF2/BAX. It activated G1/S, G2/M progression through increased cyclin E1 and cyclin B1.On the contrary, the highest dose at 5 mg/mL RJ significantly increased SCE level. Nevertheless, pretreatment of 5 mg/mL RJ significantly decreased DXR-induced SCE levels. RJ (5 mg/mL) co-treatment with DXR protected human cells through reduction of cell apoptosis, increased antioxidative response and enhanced longevity. It delayed G2/M cell cycle through decreased cyclin B1, possibly allowing cells to repair.Moreover, 125 μg/mL 10-H2DA significantly inhibited MCF-7 cell proliferation through induction of cell cycle arrest (decreased cyclin D1 and CDK4), cell apoptosis (decreased BCL2/BAX), shortened lifespan (decreased hTERT), and inhibited oncoprotein c-MYC. The co-treatment of DXR with 125 μg/ml 10-H2DA potentiated DXR-induced antiproliferative effects against MCF-7 cells. It enhanced cell apoptosis, cell cycle arrest and inhibited cell proliferation (decreased c-MYC). Unpredictably, all above treatments increased NRF2, the antioxidative response.Therefore, RJ is a promising candidate as a chemopreventive agent by stimulating human cell growth, longevity and antioxidative response; with correct doses, it protects cells from genotoxic damage. Also, 10-H2DA is a promising candidate for chemotherapy by inhibiting breast cancer cells through enhancing cell apoptosis, inducing cell cycle arrest, shortening lifespan and inhibiting cell proliferation; adding DXR enhanced antiproliferative properties. Further in vitro and in vivo studies are needed to confirm the evidence.