Inhibition of MSP-RON signaling pathway in cancer cells by a novel soluble form of RON comprising the entire sema sequence.
The RON receptor tyrosine kinase and its ligand macrophage stimulating protein (MSP) play a role in epithelial tumorigenesis. We report here a novel RON variant that antagonizes the RON-MSP pathway in various cancer cells. The variant is an 85 kDa soluble protein from an mRNA transcript with an insertion of 49 nucleotides between exons 5 and 6. The insertion created a stop codon leading to the formation of a RON variant consisting of the entire 35 kDa alpha-chain and a 45 kDa partial extracellular beta-chain. The protein was featured by a sema domain, a hinge motif and a portion of the first IPT unit (designated as RONDelta85). RONDelta85 binds directly to MSP, forms MSP-RONDelta85 complex, and inhibits RON phosphorylation. RONDelta85 disrupts RON or RONDelta160 dimerization, prevents their phosphorylation, and attenuates downstream signaling events. The action of RONDelta85 is specific to RON and has no effect on MET and EGFR. In colon and pancreatic cancer cells, RONDelta85 inhibits spontaneous or MSP-induced Erk1/2 and AKT phosphorylation, which results in impaired cell proliferation and colony formation. RONDelta85 also inhibits spontaneous and MSP-induced cell migration. We conclude that RONDelta85 is an antagonist to the MSP-RON pathway, which has potential for regulating RON/RON160-mediated tumorigenic activities.
Ma
Qi
Q
Center for Cancer Biology and Therapeutics, School of Pharmacy, Texas Tech University Health Sciences, Amarillo, TX 79106, USA.
Zhang
Kun
K
Yao
Hang-Ping
HP
Zhou
Yong-Qing
YQ
Padhye
Snehal
S
Wang
Ming-Hai
MH
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D014162:Transfection
D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; C082332:macrophage stimulating protein; D017228:Hepatocyte Growth Factor; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases