The cytomegalovirus protein UL138 induces apoptosis of gastric cancer cells by binding to heat shock protein 70
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Wenjing Chen1,*, Kezhi Lin2,*, Liang Zhang1, Gangqiang Guo3, Xiangwei Sun1, Jing Chen4, Lulu Ye3, Sisi Ye3, Chenchen Mao1, Jianfeng Xu1, Lifang Zhang4, Lubin Jiang3,5, Xian Shen1, Xiangyang Xue3
1Department of General Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
2Experimental Center, Wenzhou Medical University, Wenzhou, China
3Department of Microbiology and Immunology, Institute of Molecular Virology and Immunology, Institute of Tropical Medicine, Wenzhou Medical University, Wenzhou, China
4Department of Rheumatology, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
5Key Laboratory of Molecular Virology and Immunology, Unit of Pathogen-Host Interaction and Epigenetics, Institut Pasteur of Shanghai, Shanghai, China
*These authors contributed equally to this work
Xiangyang Xue, e-mail: firstname.lastname@example.org
Xian Shen, e-mail: email@example.com
Lubin Jiang, e-mail: firstname.lastname@example.org
Keywords: gastric cancer, cytomegalovirus, UL138, apoptosis, HSP70
Received: July 21, 2015 Accepted: December 05, 2015 Published: December 30, 2015
It has been hypothesized that human cytomegalovirus (HCMV) could act as a tumor promoter and play an “oncomodulatory” role in the neoplastic process of several human malignancies. However, we demonstrate for the first time that UL138, a HCMV latency-associated gene, could act as a tumor inhibitor in gastric cancer (GC). The expression of UL138 is down-regulated in HCMV positive gastric adenocarcinoma tissues, especially in poorly or none differentiated tumors. Overexpression of UL138 in several human GC cell lines inhibits cell viability and induces apoptosis, in association with the reduction of an anti-apoptotic Bcl-2 protein and the induction of cleaved caspase-3 and caspase-9. Moreover, protein array analysis reveals that UL138 interacts with a chaperone protein, heat shock protein 70 (HSP70). This interaction is confirmed by immunoprecipitation and immunostaining in situ in GC cell lines. In addition, this UL138-mediated cancer cell death could efficiently lead to suppression of human tumor growth in a xenograft animal model of GC. In conclusion, these results uncover a previously unknown role of the cytomegalovirus protein UL138 in inducing GC cells apoptosis, which might imply a general mechanism that viral proteins inhibit cancer growth in interactions with both chaperones and apoptosis-related proteins. Our findings might provide a potential target for new therapeutic strategies of GC treatment.
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