α-Tocopheryl succinate and TRAIL selectively synergise in induction of apoptosis in human malignant mesothelioma cells

Malignant mesothelioma (MM) is a fatal type of neoplasia with poor therapeutic prognosis, largely due to resistance to apoptosis. We investigated the apoptotic effect of alpha-tocopheryl succinate (alpha-TOS), a strong proapoptotic agent, in combination with the immunological apoptogen TNF-related apoptosis-inducing ligand (TRAIL) on both MM and nonmalignant mesothelial cells, since MM cells show low susceptibility to the clinically intriguing TRAIL. All MM cell lines tested were sensitive to alpha-TOS-induced apoptosis, and exerted high sensitivity to TRAIL in the presence of subapoptotic doses of the vitamin E analogue. Neither TRAIL or alpha-TOS alone or in combination caused apoptosis in nonmalignant mesothelial cells. Isobologram analysis of the cytotoxicity assays revealed a synergistic interaction between the two agents in MM cells and their antagonistic effect in nonmalignant mesothelial cells. TRAIL-induced apoptosis and its augmentation by alpha-TOS were inhibited by the caspase-8 inhibitor Z-IETD-FMK and the pan-caspase inhibitor Z-VAD-FMK. Activation of caspase-8 was required to induce apoptosis, which was amplified by alpha-TOS via cytochrome c release following Bid cleavage, with ensuing activation of caspase-9. Enhancement of TRAIL-induced apoptosis in MM cells by alpha-TOS was also associated with upregulation of the TRAIL cognate death receptors DR4 and DR5. Our results show that alpha-TOS and TRAIL act in synergism to kill MM cells via mitochondrial pathway, and are nontoxic to nonmalignant mesothelial cells. These findings are indicative of a novel strategy for treatment of thus far fatal MM

Expression of Her-2/neu in extrahepatic cholangiocarcinoma

Rania Shamekh,1,* Marilin Rosa,2,* Zena Sayegh,2 Masoumeh Ghayouri,2 Richard Kim,3 Mokenge P Malafa,3 Domenico Coppola2 1Department of Pathology, University of South Florida, 2Department of Anatomic Pathology, 3Department of Gastrointestinal Oncology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA *These authors contributed equally to this work Background: Receptor tyrosine-protein kinase erbB-2, which is also frequently called human epidermal growth factor receptor-2 (Her-2) or Her-2/neu, has been found to be overexpressed in various human cancers.Hypothesis: The aim of this pilot study was to explore the frequency of Her-2/neu gene amplification and protein expression in extrahepatic cholangiocarcinoma (EHBC). We used the World Health Organization classification criteria for EHBC.Materials and methods: This was a retrospective study using 88 tissue samples, including 45 samples from non-neoplastic biliary tissue (NNB) and 43 samples of extrahepatic cholangiocarcinoma (EHBC). A tissue microarray including NNB and EHBC was constructed and analyzed by immunohistochemistry (IHC) and dual in situ hybridization for Her-2/neu protein expression and amplification, respectively. The Her-2/neu expression was scored following the guidelines used for the ToGA study.Results: All NNB samples and all but one EHBC samples showed no expression of Her-2/neu by IHC. The one EHBC case immunohistochemically positive for Her-2/neu had an IHC score of 3+. Her-2/neu gene amplification was present in two EHBC samples only and included the case found to be positive by IHC.Conclusion: Our findings are similar to those reported in the literature. Although Her-2/neu overexpression has been documented in many types of cancer, Her-2/neu protein overexpression tends to have no role in the development and/or progression of EHBC. Keywords: extrahepatic, cholangiocarcinoma, Her-2/neu, ToGA, immunohistochemistr

Vitamin E succinate inhibits survivin and induces apoptosis in pancreatic cancer cells

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States. Identifying novel chemotherapeutic and chemopreventive approaches is critical in the prevention and treatment of cancers such as pancreatic cancer. Vitamin E succinate (VES) is a redox-silent analog of the fat-soluble vitamin alpha-tocopherol. In the present study, we explored the antiproliferative action of VES and its effects on inhibitor of apoptosis proteins in pancreatic cancer cells. We show that VES inhibits cell proliferation and induces apoptosis in pancreatic cancer cells. Further, we demonstrate that VES downregulates the expression of survivin and X-linked inhibitor of apoptosis proteins. The apoptosis induced by VES was augmented by siRNA-mediated inhibition of survivin in PANC-1 cells. In summary, our results suggest that VES targets survivin signaling and induces apoptosis in pancreatic cancer cells