Proteolytic activation of pro-macrophage-stimulating protein by hepsin.

Article Details


Ganesan R, Kolumam GA, Lin SJ, Xie MH, Santell L, Wu TD, Lazarus RA, Chaudhuri A, Kirchhofer D

Proteolytic activation of pro-macrophage-stimulating protein by hepsin.

Mol Cancer Res. 2011 Sep;9(9):1175-86. doi: 10.1158/1541-7786.MCR-11-0004. Epub 2011 Aug 29.

PubMed ID
21875933 [ View in PubMed

Macrophage-stimulating protein (MSP) is a plasminogen-related growth factor and ligand for the receptor tyrosine kinase RON. The MSP/RON system promotes wound healing and invasive tumor growth and suppresses proinflammatory immune response. MSP binding to RON requires proteolytic conversion of the inactive single-chain form (pro-MSP) into the disulfide-linked alpha/beta heterodimer. The pro-MSP cleavage sequence (Ser-Lys-Leu-Arg(483) downward arrowVal(484)) closely matches the substrate recognition sequences of hepsin, a type II transmembrane serine protease, that is overexpressed in several cancers. Here, we show that recombinant hepsin cleaves pro-MSP at the consensus site Arg(483)-Val(484) with superior efficiency compared with the known activators MT-SP1 and hepatocyte growth factor activator (HGFA). At least 50% of pro-MSP was processed within 1 hour at a hepsin concentration of 2.4 nmol/L and at a molar enzyme to substrate ratio of 1:500. An uncleavable single-chain variant of MSP weakly bound to a RON-Fc fusion protein, whereas hepsin-cleaved MSP bound with a K(D) of 10.3 nmol/L, suggesting that the high-affinity binding site in MSP beta-chain was properly formed. LNCaP prostate cancer cells overexpressing hepsin on the cell surface efficiently activated pro-MSP, which was blocked by a specific anti-hepsin antibody. Incubation of pro-MSP with hepsin led to robust RON-mediated phosphorylation of mitogen-activated protein kinase, ribosomal S6 protein, and Akt in human A2780 ovarian carcinoma cells stably expressing RON protein. In macrophages, pro-MSP with hepsin induced chemotaxis and attenuated lipopolysaccharide-dependent production of nitric oxide. These findings suggest that the MSP/RON signaling pathway may be regulated by hepsin in tissue homeostasis and in disease pathologies, such as in cancer and immune disorders.

DrugBank Data that Cites this Article

NameUniProt ID
Serine protease hepsinP05981Details