Leukemia inhibitory factor protects cholangiocarcinoma cells from drug-induced apoptosis via a PI3K/AKT-dependent Mcl-1 activation
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Stuart Duncan Morton1,*, Massimiliano Cadamuro1,2,*, Simone Brivio2, Marta Vismara1,2, Tommaso Stecca3, Marco Massani3, Nicolò Bassi3,4, Alberto Furlanetto5, Ruth Elizabeth Joplin6, Annarosa Floreani4, Luca Fabris1,7, Mario Strazzabosco2,7
1Department of Molecular Medicine, University of Padua, Padua, Italy
2Department of Surgery & Translational Medicine, University of Milan-Bicocca, Milan, Italy
3Fourth Surgery Division, Treviso Regional Hospital, Treviso, Italy
4Department of Surgical, Oncological and Gastroenterological Sciences, University of Padua, Padua, Italy
5Pathology Unit, Treviso Regional Hospital, Treviso, Italy
6School of Immunity and Infection, University of Birmingham, Birmingham, UK
7Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT, USA
*These authors have contributed equally to this work
Keywords: cholangiocarcinoma, leukemia inhibitory factor, chemoresistance, Mcl-1, phosphatidylinositol-3 kinase
Received: February 04, 2015 Accepted: July 08, 2015 Published: July 20, 2015
Cholangiocarcinoma is an aggressive, strongly chemoresistant liver malignancy. Leukemia inhibitory factor (LIF), an IL-6 family cytokine, promotes progression of various carcinomas. To investigate the role of LIF in cholangiocarcinoma, we evaluated the expression of LIF and its receptor (LIFR) in human samples. LIF secretion and LIFR expression were assessed in established and primary human cholangiocarcinoma cell lines. In cholangiocarcinoma cells, we tested LIF effects on proliferation, invasion, stem cell-like phenotype, chemotherapy-induced apoptosis (gemcitabine+cisplatin), expression levels of pro-apoptotic (Bax) and anti-apoptotic (Mcl-1) proteins, with/without PI3K inhibition, and of pSTAT3, pERK1/2, pAKT. LIF effect on chemotherapy-induced apoptosis was evaluated after LIFR silencing and Mcl-1 inactivation.
Results show that LIF and LIFR expression were higher in neoplastic than in control cholangiocytes; LIF was also expressed by tumor stromal cells. LIF had no effects on cholangiocarcinoma cell proliferation, invasion, and stemness signatures, whilst it counteracted drug-induced apoptosis. Upon LIF stimulation, decreased apoptosis was associated with Mcl-1 and pAKT up-regulation and abolished by PI3K inhibition. LIFR silencing and Mcl-1 blockade restored drug-induced apoptosis.
In conclusion, autocrine and paracrine LIF signaling promote chemoresistance in cholangiocarcinoma by up-regulating Mcl-1 via a novel STAT3- and MAPK-independent, PI3K/AKT-dependent pathway. Targeting LIF signaling may increase CCA responsiveness to chemotherapy.
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