Breast cancer is the leading cause of death among women worldwide.Chemoprevention and chemotherapy play beneficial roles in reducing the incidence and mortality of cancer.Epidemiological and experimental studies showed that naturally-occurring antioxidants present in the diet may act as anticancer agents.Identifying the abnormalities of cellular energy metabolism facilitates early detection and management of breast cancer.The present study evaluated the effect of tangeretin on cellular metabolic energy fluxes in 7,12-dimethylbenz(a)anthracene(DMBA)-induced proliferative breast cancer.The results showed that the activities of glycolytic enzymes significantly increased in mammary tissues of DMBA-induced breast cancer bearing rats.The gluconeogenic tricarboxylic acid(TCA) cycle and respiratory chain enzyme activities significantly decreased in breast cancer-bearing rats.In addition,proliferating cell nuclear antigen(PCNA) was highly expressed in breast cancer tissues.However,the activities of glycolytic enzymes were significantly normalized in the tangeretin pre- and post-treated rats and the TCA cycle and respiratory chain enzyme activities were significantly increased in tangeretin treated rats.Furthermore,tangeretin down-regulated PCNA expression on breast cancerbearing rats.Our study demonstrates that tangeretin specifically regulates cellular metabolic energy fluxes in DMBA-induced breast cancer-bearing rats. Breast cancer is the leading cause of death among women worldwide. Chemoprevention and chemotherapy play beneficial roles in reducing the incidence and mortality of cancer. Epidemiological and experimental studies showed that naturally-occurring antioxidants present in the diet may act as anticancer agents. Identifying the abnormalities of cellular energy metabolism facilitates early detection and management of breast cancer. The present study evaluating the effect of tangeretin on cellular metabolic energy fluxes in 7,12-dimethylbenz (a) anthracene (DMBA) -induced proliferative breast cancer. The results showed that the activities of glycolytic enzymes significantly increased in mammary tissues of DMBA-induced breast cancer bearing rats. The gluconeogenic tricarboxylic acid (TCA) cycle and respiratory chain enzyme activities were significantly decreased in breast cancer-bearing rats. In addition, proliferating cell nuclear antigen (PCNA) was highly expressed in breast cancer tissues. Host, the activitie s of glycolytic enzymes were significantly normalized in the tangeretin pre- and post-treated rats and the TCA cycle and respiratory chain enzyme activities were significantly increased in tangeretin treated rats. Future thermo, tangeretin down-regulated PCNA expression on breast cancer bearing rats. Our study demonstrates that tangeretin specifically regulates cellular metabolic energy fluxes in DMBA-induced breast cancer-bearing rats.