Chemopreventive efficacy of hesperetin (citrus flavonone) against 1,2-dimethylhydrazine-induced rat colon carcinogenesis

Background: Colorectal carcinogenesis is one of the most common cancers/lethal diseases. Chronic inflammation is considered a risk factor for colorectal cancer. Hesperetin, a flavonone found in citrus fruits and oranges is shown to possess potent growth inhibitory effects against various human cancer cells. It possesses anti-inflammatory and antioxidant properties. Aim of the scope: In the present study, we have evaluated the chemopreventive efficacy of hesperetin against rat colon carcinogenesis in male Wistar rats. Methods: Group 1 served as control, received modified pellet diet and group 2 rats received 20 mg/kg body weight of hesperetin p.o. every day. Groups 3-6 rats were given subcutaneous injections of 1,2-dimethylhydrazine (DMH, 20 mg/kg body weight) once a week for 15 consecutive weeks. In addition, rats in group 4 received hesperetin as in group 2 for the first 15 weeks (initiation), group 5 rats received hesperetin as in group 2 after the last injection of DMH and continued till the end of the experimental period (postinitiation). Group 6 rats received hesperetin as in group 2 throughout the entire experimental period of 32 weeks. Results: Detection of cell proliferation markers such as proliferating cell nuclear antigen (PCNA) (immunohistochemistry), argyrophilic nucleolar organizer regions (AgNORs) (silver staining); apoptosis (immunoblotting and immunohistochemistry); angiogenic growth factors (ELISA) indicated decreased cell proliferation and increased apoptotic markers in the colon. In addition, decreased angiogenic growth factors such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and downregulation of mRNA Cyclooxygenase-2 (COX-2) expressions were observed in mucosal and fecal samples of hesperetin-supplemented rats. Conclusions: Hesperetin supplementation showed an inhibition of cell proliferation markers, angiogenic growth factors, COX-2 mRNA expression and induction of apoptosis. Thus, hesperetin can be used as a potent chemopreventive agent against DMH-induced colon cancer.