Structure specific monoclonal antibody against autoactivation loop of PRSS14 inhibits protease activation and suppresses cancer cell migration

초록

PRSS14, also known as matriptase and epithin, is a type II transmembrane serine protease and overexpressed in various epithelial cancer types. Previously, we showed that it is involved in angiogenesis, TGFβ induced EMT, transendothelial migration, and metastasis of epithelial cancers. Bioinformatics analysis of The Cancer Genome Atlas (TCGA) revealed that its expression was strongly correlated with poor prognosis of basal type breast cancer and better prognosis marker than Her2, especially for ER negative patients. PRSS14 is intracellularly cleaved (aa149) and localized on the membrane. Upon triggering, it undergoes ectodomain shedding (aa189, aa 205) and autoactivation (aa615). In order to control the protease activation by preventing autoactivation cleavage of PRSS14 with monoclonal antibodies (mAbs), we designed antigenic peptide of human PRSS14 sequences containing the autoactivation site. Peptide sequences were optimized to maintain the native structural conformation by forming loop structure. Using this loop peptide conjugated with carrier as an antigen, it can abolish the metastasis of 4T1 breast cancer in balb/c mouse. We applied hybridoma technique with the same antigen and screened the structure specific monoclonal antibody. One clone showed strong specificity to native form of antigen and interfere induced autoactivation of protein. It also showed cross reactivity to ortholog mouse sequence. This mAb reduced motility of 4T1 breast cancer cell in wound healing and transwell migration assays. Therefore, this mAb is a strong candidate for further application as a new diagnostic and therapeutic antibody for the metastatic cancers.