PROTECTIVE EFFECTS OF CYANIDIN-3-O-GLUCOSIDE-RICH HASKAP (LONICERA CAERULEA L.) BERRY AGAINST NITROSAMINE-INDUCED LUNG CARCINOGENESIS

Abstract

Despite pre-screening programs and novel therapeutics, lung cancer is the most common and foremost cause of cancer death among men and the second diagnosed cancer among women. Primarily, cigarette smoke constituents alter the cellular and molecular functions of lung epithelial cells, resulting in carcinogenesis. Haskap berry (HB, Lonicera caerulea) is rich in anthocyanins, particularly cyanidin-3-O-glucoside (C3G), and its antioxidant capacity is greater than many commonly consumed fruits. HB could attenuate the nicotine-derived nitrosamine ketone (NNK)-induced oxidative stress and DNA instability in vitro. The current research was designed to investigate the efficacy and mode of action of HB against NNK-induced lung carcinogenesis and to develop a pulmonary delivery method to avoid first-pass metabolism and increase the tissue distribution of HB. First, the effect of HB against NNK-induced lung tumorigenesis was determined in A/J mice. Then the effect of HB against NNK-modulated oxidative stress, cell proliferation, DNA damage, inflammation, and metabolism was examined in vitro and in vivo, along with formulating HB extract-encapsulated nanoparticles as a pulmonary anthocyanin carrier. HB diet significantly reduced the lung tumour multiplicity (20 - 40%) and tumour area (60%). Further, HB suppressed mitogen-activated protein kinase, activated antioxidant enzymes, attenuated proinflammatory cytokines in the lungs, and downregulated liver cytochrome P450 enzymes (cyp2a4 and cyp2a5) in A/J mice. Pre-incubation of BEAS-2B cells with HB extract (50 µg/mL) decreased NNK-induced oxidative adducts, cell proliferation, and DNA damage and upregulated the ataxia-telangiectasia mutated-dependent DNA damage repair cascade compared to non-treated human normal lung epithelial (BEAS-2B) cells. Pulmonary delivery of a low dose (28 μg C3G/mouse/day) of encapsulated HB anthocyanins extended the lung retention of C3G and delayed its metabolism. As a dietary supplement, HB suppressed lung tumorigenesis by inhibiting cell proliferation, oxidative stress, DNA damage, and metabolic activation of carcinogenic NNK. Pulmonary delivery of HB-incorporated nanoparticles enhances the retention and delays C3G metabolism. Therefore, HB could be a potential nutraceutical in preventing or reducing lung carcinogenesis among high-risk populations.