Leukemia inhibitory factor protects cholangiocarcinoma cells from drug-induced apoptosis via a PI3K/AKT-dependent Mcl-1 activation

// Stuart Duncan Morton 1, * , Massimiliano Cadamuro 1, 2, * , Simone Brivio 2 , Marta Vismara 1, 2 , Tommaso Stecca 3 , Marco Massani 3 , Nicolo Bassi 3, 4 , Alberto Furlanetto 5 , Ruth Elizabeth Joplin 6 , Annarosa Floreani 4 , Luca Fabris 1, 7 , Mario Strazzabosco 2, 7 1 Department of Molecular Medicine, University of Padua, Padua, Italy 2 Department of Surgery & Translational Medicine, University of Milan-Bicocca, Milan, Italy 3 Fourth Surgery Division, Treviso Regional Hospital, Treviso, Italy 4 Department of Surgical, Oncological and Gastroenterological Sciences, University of Padua, Padua, Italy 5 Pathology Unit, Treviso Regional Hospital, Treviso, Italy 6 School of Immunity and Infection, University of Birmingham, Birmingham, UK 7 Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT, USA * These authors have contributed equally to this work Correspondence to: Luca Fabris, e-mail: luca.fabris@unipd.it , luca.fabris@yale.edu Keywords: cholangiocarcinoma, leukemia inhibitory factor, chemoresistance, Mcl-1, phosphatidylinositol-3 kinase Received: February 04, 2015      Accepted: July 08, 2015      Published: July 20, 2015 ABSTRACT 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.