Effect of hyperthermia in combination with TRAIL on the JNK‐Bim signal transduction pathway and growth of xenograft tumors

Approximately 25% of patients with colorectal cancer develop metastases to the liver, and surgery is currently the best treatment available. But there are several patients who are unresectable, and isolated hepatic perfusion (IHP) offers a different approach in helping to treat these patients. IHP is a method used for isolating the liver and delivering high doses of chemotherapeutic agents. The efficacy of IHP has been improved by combining hyperthermia not only with chemotherapeutics but with other deliverable agents such as tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL). In this study, we used human colorectal cancer CX‐1 cells and treated them with hyperthermia and TRAIL, causing cytotoxicity. We were able to demonstrate that the numbers of live cells were significantly reduced with hyperthermia and 10 ng/ml of TRAIL combined. We also showed that the effect of hyperthermia on TRAIL in our studies was enhancement of the apoptotic pathway by the promotion of JNK and Bim_EL activity as well as PARP cleavage. We have also used our CX‐1 cells to generate tumors in Balb/c nude mice. With intratumoral injections of TRAIL combined with hyperthermia at 42°C, we were able to show a delayed onset of tumor growth in our xenograft model. J. Cell. Biochem. 110: 1073–1081, 2010. Published 2010 Wiley‐Liss, Inc.