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Bufalin extracts are a part of traditional Chinese medicine, Chansu. In the current study, we investigated the effect of bufalin on the proliferation of the human hepatocellular carcinoma (HCC) cell lines, Huh-7 and HepG-2, and explored the therapeutic potential of the drug. Our results demonstrated that bufalin markedly inhibited cell proliferation and promoted apoptosis in the Huh-7 and HepG-2 cells in vitro. The underlying mechanism of the bufalin-induced apoptosis was the induction of endoplasmic reticulum (ER) stress via the IRE1-JNK pathway. In addition, during the ER stress response, the autophagy pathway, characterized by the conversion of LC3-I to LC3-II, was activated, resulting in increased Beclin-1 protein levels, decreased p62 expression and stimulation of autophagic flux. Our data supported the pro-survival role of bufalin-induced autophagy when the autophagy pathway was blocked with specific chemical inhibitors; the involvement of the IRE1 pathway in the ER stress-induced autophagy was also demonstrated when the expression of IRE1 and CHOP was silenced using siRNA. These data indicate that combining bufalin with a specific autophagy inhibitor could be a promising therapeutic approach for the treatment of HCC.

In recent years, substantial research interests have arisen to decipher miRNA function in cell death modules such as apoptosis and autophagy. Despite enormous success, it is increasingly evident that systems biology approaches that analyze the intra- and inter-modular connectivity are essential to uncover the generic organizing principles of the miRNA-mediated cell death network. We therefore constructed the miRDeathDB database to archive experimentally confirmed programmed cell death (PCD)-associated miRNAs together with their target proteins. Based on global analysis of the miRNA-mediated cell death network, we find there are two classes of miRNAs important to the cell death output. One class tends to have more regulatory links to proteins within death modules, whereas the other one lies on the boundary between modules, and tends to connect with more protein pairs across the modules. These findings indicate that miRNAs provide a novel communication mechanism between PCD-related proteins involved in both intra- and inter-cell death modules. Furthermore, miRDeathDB can also facilitate researcher access to a variety of resources centered on PCD-associated miRNAs.