title: Quantitative proteomics discloses MET expression in mitochondria as a direct target of MET kinase inhibitor in cancer cells.
abstract: Cancer cells with MET overexpression are paradoxically more sensitive to MET inhibition than cells with baseline MET expression. The underlying molecular mechanisms are incompletely understood. Here, we have traced early responses of SNU5, a MET-overexpressing gastric cancer cell line, exposed to sublethal concentration of PHA-665752, a selective MET inhibitor, using iTRAQ-based quantitative proteomics. More than 1900 proteins were quantified, of which >800 proteins were quantified with at least five peptides. Proteins whose expression was perturbed by PHA-665752 included oxidoreductases, transfer/carrier proteins, and signaling proteins. Strikingly, 38% of proteins whose expression was confidently assessed to be perturbed by MET inhibition were mitochondrial proteins. Upon MET inhibition by a sublethal concentration of PHA-665752, mitochondrial membrane potential increased and mitochondrial permeability transition pore was inhibited concomitant with widespread changes in mitochondrial protein expression. We also showed the presence of highly activated MET in mitochondria, and striking suppression of MET activation by 50 nm PHA-665752. Taken together, our data indicate that mitochondria are a direct target of MET kinase inhibition, in addition to plasma membrane MET. Effects on activated MET in the mitochondria of cancer cells that are sensitive to MET inhibition might constitute a novel and critical noncanonical mechanism for the efficacy of MET-targeted therapeutics.
authors: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
authors: Tiannan
authors: T
authors: Guo
authors: Yi
authors: Y
authors: Zhu
authors: Chee Sian
authors: CS
authors: Gan
authors: Sze Sing
authors: SS
authors: Lee
authors: Jiang
authors: J
authors: Zhu
authors: Haixia
authors: H
authors: Wang
authors: Xin
authors: X
authors: Li
authors: James
authors: J
authors: Christensen
authors: Shiang
authors: S
authors: Huang
authors: Oi Lian
authors: OL
authors: Kon
authors: Siu Kwan
authors: SK
authors: Sze
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D020869:Gene Expression Profiling; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D040901:Proteomics; D019859:Proto-Oncogene Proteins c-met / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053719:Tandem Mass Spectrometry
chemical_list: D019859:Proto-Oncogene Proteins c-met