Protective effect of green algae against 7,12-dimethylbenzanthracene (DMBA)-induced breast cancer in rats

The present study investigated the chemopreventive effects of the water extract of chlorella on the development and growth of DMBA-induced mammary tumors. Female rats were daily administered vehicle control or chlorella either at 0.5 g or at 1.0 g kg^-1 body weight starting at age of 35 days and continued to the end of the experiment. At age of 50 days breast tumor was induced by administering DMBA at 25 mg kg^-1 body weight. Similar DMBA dose was administered to DMBA-alone group at age of 50 days. As a control for chlorella treatment one group (chlorella-alone) was administered chlorella at 1.0 g kg^-1 body weight starting at age of 35 days and continued to the end of the experiment. Animals were then followed for 15 weeks. Effects of chlorella on the expression of proliferating cell nuclear antigen (PCNA), p53 and estrogen receptor (ER) were investigated in mammary tissues of control and experimental groups using immunohistochemistry. Present data demonstrated that chlorella treatment restored the normal expression levels of PCNA and ER. Chlorella also significantly increased cell death as assessed by the terminal deoxynucleotidyl transferase-mediated triphoshate nick-end labeling (TUNEL) analysis. In conclusion, the protective role of chlorella's water extract against carcinogen-induced breast cancer seems to be mediated through its anti-proliferative and pro-apoptotic properties.