Fanyin Meng1, Yoko Yamagiwa, Yoshiyuki Ueno, Tushar Patel. 1. Division of Gastroenterology, Scott and White Clinic, Texas A&M University System Health Science Center College of Medicine, 2401 South 31st Street, Temple, TX 76508, USA.
Abstract
BACKGROUND/AIMS: Over-expression of IL-6 has been implicated in cholangiocarcinoma growth but the cellular mechanisms involved are unknown. Our aims were to assess the mechanisms by which over-expression of IL-6 promotes transformed cell growth in malignant cholangiocytes. METHODS: Stably transfected cell lines over-expressing IL-6 were derived from malignant human cholangiocytes. Transformed cell growth was assessed by anchorage independent growth in vitro and by xenograft growth in nude mice. Expression of the anti-apoptotic protein Mcl-1 was quantitated by immunoblot analysis and by real-time PCR. Gene silencing was performed using siRNA. Dominant negative upstream kinase activators and isoform-specific constructs were used to evaluate the involvement of p38 MAP kinase signaling pathways. RESULTS: Over-expression of IL-6 increased xenograft growth, anchorage independent growth and cell survival but did not significantly alter cell proliferation. The basal expression of Mcl-1 was increased in IL-6 over-expressing cells. Selective knockdown of Mcl-1 by siRNA increased gemcitabine-induced cytotoxicity. Moreover, IL-6 increased Mcl-1 mRNA and protein expression via a p38 MAPK dependent mechanism. CONCLUSIONS: These data demonstrate a major role of survival signaling pathways in mediating the effects of IL-6 over-expression in cholangiocarcinoma growth. Mcl-1 is identified as a mediator of IL-6-induced tumor cell survival and shown to be transcriptionally regulated by IL-6 via a p38 MAPK dependent pathway. We conclude that modulation of IL-6 mediated survival signaling pathways involving the p38 MAPK or downstream targets such as Mcl-1 may prove useful therapeutic strategies for human cholangiocarcinoma.
BACKGROUND/AIMS: Over-expression of IL-6 has been implicated in cholangiocarcinoma growth but the cellular mechanisms involved are unknown. Our aims were to assess the mechanisms by which over-expression of IL-6 promotes transformed cell growth in malignant cholangiocytes. METHODS: Stably transfected cell lines over-expressing IL-6 were derived from malignant human cholangiocytes. Transformed cell growth was assessed by anchorage independent growth in vitro and by xenograft growth in nude mice. Expression of the anti-apoptotic protein Mcl-1 was quantitated by immunoblot analysis and by real-time PCR. Gene silencing was performed using siRNA. Dominant negative upstream kinase activators and isoform-specific constructs were used to evaluate the involvement of p38 MAP kinase signaling pathways. RESULTS: Over-expression of IL-6 increased xenograft growth, anchorage independent growth and cell survival but did not significantly alter cell proliferation. The basal expression of Mcl-1 was increased in IL-6 over-expressing cells. Selective knockdown of Mcl-1 by siRNA increased gemcitabine-induced cytotoxicity. Moreover, IL-6 increased Mcl-1 mRNA and protein expression via a p38 MAPK dependent mechanism. CONCLUSIONS: These data demonstrate a major role of survival signaling pathways in mediating the effects of IL-6 over-expression in cholangiocarcinoma growth. Mcl-1 is identified as a mediator of IL-6-induced tumor cell survival and shown to be transcriptionally regulated by IL-6 via a p38 MAPK dependent pathway. We conclude that modulation of IL-6 mediated survival signaling pathways involving the p38 MAPK or downstream targets such as Mcl-1 may prove useful therapeutic strategies for humancholangiocarcinoma.
Authors: F Kimura; M Miyazaki; T Suwa; T Sugiura; T Shinoda; H Itoh; S Ambiru; H Shimizu; K Nakagawa Journal: Hepatogastroenterology Date: 1999 May-Jun
Authors: Shogo Kobayashi; Nathan W Werneburg; Steven F Bronk; Scott H Kaufmann; Gregory J Gores Journal: Gastroenterology Date: 2005-06 Impact factor: 22.682
Authors: Tanios Bekaii-Saab; Mitch A Phelps; Xiaobai Li; Motoyasu Saji; Laura Goff; John Sae Wook Kauh; Bert H O'Neil; Stephanie Balsom; Catherine Balint; Ryan Liersemann; Vasily V Vasko; Mark Bloomston; William Marsh; L Austin Doyle; Gilian Ellison; Michael Grever; Matthew D Ringel; Miguel A Villalona-Calero Journal: J Clin Oncol Date: 2011-04-25 Impact factor: 44.544