Abstract 3796: Substrate specificity of human kallikrein-related peptidase 2 (KLK2) towards beta chain of interleukin-10 receptor

Abstract

Abstract The kallikrein-related peptidases (KLKs) comprise a family of 15 homologous secreted trypsin- or chymotrypsin-like serine proteases. KLK2 and KLK3 have the most organ restricted expression profile of all KLKs; specifically, they are abundantly expressed in the luminal epithelium of the prostate. The expression of KLK2 gene is regulated by the androgens and androgen receptor (AR) signaling and like human PSA, serum KLK2 can also function as a biomarker for prostate cancer (PCa). The present work provides biochemical data related to the hydrolytic activities of KLK2 on libraries of fluorescence resonance energy transfer (FRET) peptides in the presence of sodium citrate, a kosmotropic salt that is present in normal prostate tissue and seminal fluid in high concentration. The peptide SYR↓IF (cleaved at↓) was the highly hydrolyzed and best substrate so far reported for KLK2. The sequence YRIF is present in the N-terminal segment (59YRIF62) in the β chain of interleukin-10 receptor. In order to verify the effect of KLK2 in the IL10RB surface expression in the bone marrow-derived macrophages (BMDM) cells, they were incubated with KLK2 at 37ºC for 2 hours. BMDM treated with KLK2 showed a significant reduction in the IL10RB surface expression compared with control group, indicating that KLK2 acts directly on this receptor, decreasing its expression. The effect of this reduction was evaluated trough BMDM activation assay. After incubation of BMDM cells with KLK2, they were washed and incubated with or without LPS, IFN-γ and recombinant IL10. When incubated with recombinant IL10, control macrophage showed a significant reduction of NO, TNF-α and IL-12p40 levels indicating the IL10RB functionality and according to IL10 immunosuppressive effect. However, KLK2 pretreated macrophage maintained NO, TNF-α and IL-12p40 levels, even in the presence of recombinant IL10, leading a proinflammatory status in BMDM culture, while KLK3 doesn't show the same effect. Taken together, the data indicates that KLK2 decreases the surface expression of IL10RB on macrophage cells and contributes to a proinflammatory environment. Citation Format: Luiz J. Neto, Maria A. Juliano, Juliana R. Oliveira. Substrate specificity of human kallikrein-related peptidase 2 (KLK2) towards beta chain of interleukin-10 receptor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3796.