Apoptosis Induction by Rafflesia kerrii Meijer Flower Extract via Caspase-Dependent and Down-Regulation of ERK Signaling Pathway in Epidermoid Carcinoma Cells

Abstract

Plant extracts have been shown to be important sources of anti-cancer agents. Rafflesia kerrii Meijer (RM) is found in the rainforest of southern part of Thailand and its local name is Bua Phut. The single biggest flower has awful smell to attract flies for pollination. This study aims to investigate the activity of RM flower extract on apoptosis induction in skin cancer cells. The results showed that the RM flower extract showed the anti-proliferative activity in A431 skin cancer cells in a time- and dose-dependent manner. The morphological changes and nuclear staining with Hoechst 33342 showed evidence of apoptosis including nuclear condensation and fragmentation. RM flower extract also activated caspase-3 expression. Furthermore, phosphorylated-ERK was decreased but phosphorylated-JNK and phosphorylated-p38 were increased in A431 cells treated with RM flower extract. RM flower extract also decreased phosphorylated Akt. These results suggest that RM flower extract induced apoptosis in skin cancer cells through down-regulation of ERK and Akt signaling pathway. RM flower extract may represent an important source of novel potential antitumor agents due to its cytotoxic activity towards malignant cells. Keywords: Rafflesia kerrii Meijer, cytotoxicity, apoptosis, skin cancer, A431 cells. Read more →