title: Sorafenib and Mek inhibition is synergistic in medullary thyroid carcinoma in vitro.
abstract: Clinical trials using kinase inhibitors have demonstrated transient partial responses and disease control in patients with progressive medullary thyroid cancer (MTC). The goal of this study was to identify potential combinatorial strategies to improve on these results using sorafenib, a multikinase inhibitor with activity in MTC, as a base compound to explore signaling that might predict synergystic interactions. Two human MTC cell lines, TT and MZ-CRC-1, which harbor endogenous C634W or M918T RET mutations, respectively, were exposed to sorafenib, everolimus, and AZD6244 alone and in combination. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide (MTT) and poly (ADP-ribose) polymerase (PARP) cleavage assays were performed to measure cell survival and apoptosis. Western blots were performed to confirm activity of the compounds and to determine possible mechanisms of resistance and predictors of synergy. As a solitary agent, sorafenib was the most active compound on MTT assay. Western blots confirmed that sorafenib, everolimus, and AZD6244 inhibited their anticipated targets. At concentrations below its IC(50), sorafenib-treated TT and MZ-CRC-1 cells demonstrated transient inhibition and then re-activation of Erk over 6 h. In concordance, synergistic effects were only identified using sorafenib in combination with the Mek inhibitor AZD6244 (P<0.001 for each cell line). Cells treated with everolimus demonstrated activation of Akt and Ret via TORC2 complex-dependent and TORC2 complex-independent mechanisms respectively. Everolimus was neither additive nor syngergistic in combination with sorafenib or AZD6244. In conclusion, sorafenib combined with a Mek inhibitor demonstrated synergy in MTC cells in vitro. Mechanisms of resistance to everolimus in MTC cells likely involved TORC2-dependent and TORC2-independent pathways.
authors: Division of Endocrinology, Diabetes and Metabolism, The Ohio State University and The Arthur G. James Cancer Hospital, Columbus, Ohio 43210, USA.
authors: Yoon Woo
authors: YW
authors: Koh
authors: Manisha H
authors: MH
authors: Shah
authors: Kitty
authors: K
authors: Agarwal
authors: Samantha K
authors: SK
authors: McCarty
authors: Bon Seok
authors: BS
authors: Koo
authors: Victoria J
authors: VJ
authors: Brendel
authors: Chaojie
authors: C
authors: Wang
authors: Kyle
authors: K
authors: Porter
authors: David
authors: D
authors: Jarjoura
authors: Motoyasu
authors: M
authors: Saji
authors: Matthew D
authors: MD
authors: Ringel
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001557:Benzenesulfonates / Q000008:administration & dosage; D001562:Benzimidazoles / Q000008:administration & dosage; D002277:Carcinoma / Q000188:drug therapy* / Q000378:metabolism; D018278:Carcinoma, Neuroendocrine; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D000068338:Everolimus; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D051096:Proto-Oncogene Proteins c-ret / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000008:administration & dosage; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives; D000077157:Sorafenib; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000378:metabolism
chemical_list: C517975:AZD 6244; D000970:Antineoplastic Agents; D001557:Benzenesulfonates; D001562:Benzimidazoles; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D009536:Niacinamide; D000068338:Everolimus; D000077157:Sorafenib; C546842:MTOR protein, human; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020123:Sirolimus