Disulfiram Eradicates Tumor-Initiating Hepatocellular Carcinoma Cells in ROS-p38 MAPK Pathway-Dependent and -Independent Manners

PLOS ONE, January 2014

24454751

Tetsuhiro Chiba, Eiichiro Suzuki, Kaori Yuki, Yoh Zen, Motohiko Oshima, Satoru Miyagi, Atsunori Saraya, Shuhei Koide, Tenyu Motoyama, Sadahisa Ogasawara, Yoshihiko Ooka, Akinobu Tawada, Tetsuya Nakatsura, Takehiro Hayashi, Taro Yamashita, Syuichi Kaneko, Masaru Miyazaki, Atsushi Iwama, Osamu Yokosuka

Tumor-initiating cells (TICs) play a central role in tumor development, metastasis, and recurrence. In the present study, we investigated the effect of disulfiram (DSF), an inhibitor of aldehyde dehydrogenase, toward tumor-initiating hepatocellular carcinoma (HCC) cells. DSF treatment suppressed the anchorage-independent sphere formation of both HCC cells. Flow cytometric analyses showed that DSF but not 5-fluorouracil (5-FU) drastically reduces the number of tumor-initiating HCC cells. The sphere formation assays of epithelial cell adhesion molecule (EpCAM)(+) HCC cells co-treated with p38-specific inhibitor revealed that DSF suppresses self-renewal capability mainly through the activation of reactive oxygen species (ROS)-p38 MAPK pathway. Microarray experiments also revealed the enrichment of the gene set involved in p38 MAPK signaling in EpCAM(+) cells treated with DSF but not 5-FU. In addition, DSF appeared to downregulate Glypican 3 (GPC3) in a manner independent of ROS-p38 MAPK pathway. GPC3 was co-expressed with EpCAM in HCC cell lines and primary HCC cells and GPC3-knockdown reduced the number of EpCAM(+) cells by compromising their self-renewal capability and inducing the apoptosis. These results indicate that DSF impaired the tumorigenicity of tumor-initiating HCC cells through activation of ROS-p38 pathway and in part through the downregulation of GPC3. DSF might be a promising therapeutic agent for the eradication of tumor-initiating HCC cells.