title: Paclitaxel resistance and multicellular spheroid formation are induced by kallikrein-related peptidase 4 in serous ovarian cancer cells in an ascites mimicking microenvironment.
abstract: High tumor kallikrein-related-peptidase 4 (KLK4) levels are associated with a poor outcome for women with serous epithelial ovarian cancer (EOC), for which peritoneal dissemination and chemoresistance are key events. To determine the role of KLK4 in these events, we examined KLK4-transfected SKOV-3 and endogenous KLK4 expressing OVCA432 cells in 3-dimensional (3D) suspension culture to mimic the ascites microenvironment. KLK4-SKOV-3 cells formed multicellular aggregates (MCAs) as seen in ascites, as did SKOV-3 cells treated with active KLK4. MCA formation was reduced by treatment with a KLK4 blocking antibody or the selective active site KLK4 sunflower trypsin inhibitor (SFTI-FCQR). KLK4-MCAs formed larger cancer cell foci in mesothelial cell monolayers than those formed by vector and native SKOV-3 cells, suggesting KLK4-MCAs are highly invasive in the peritoneal microenvironment. A high level of KLK4 is expressed by ascitic EOC cells compared to matched primary tumor cells, further supporting its role in the ascitic microenvironment. Interestingly, KLK4 transfected SKOV-3 cells expressed high levels of the KLK4 substrate, urokinase plasminogen activator (uPA), particularly in 3D-suspension, and high levels of both KLK4 and uPA were observed in patient cells taken from ascites. Importantly, the KLK4-MCAs were paclitaxel resistant which was reversed by SFTI-FCQR and to a lesser degree by the general serine protease inhibitor, Aprotinin, suggesting that in addition to uPA, other as yet unidentified substrates of KLK4 must be involved. Nonetheless, these data suggest that KLK4 inhibition, in conjunction with paclitaxel, may improve the outcome for women with serous epithelial ovarian cancer and high KLK4 levels in their tumors.
authors: Cancer Program, Institute of Health and Biomedical Innovation and Faculty of Sciences and Technology, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
authors: Ying
authors: Y
authors: Dong
authors: Carson
authors: C
authors: Stephens
authors: Carina
authors: C
authors: Walpole
authors: Joakim E
authors: JE
authors: Swedberg
authors: Glen M
authors: GM
authors: Boyle
authors: Peter G
authors: PG
authors: Parsons
authors: Michael A
authors: MA
authors: McGuckin
authors: Jonathan M
authors: JM
authors: Harris
authors: Judith A
authors: JA
authors: Clements
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001201:Ascites / Q000201:enzymology / Q000473:pathology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007610:Kallikreins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D017239:Paclitaxel / Q000494:pharmacology* / Q000627:therapeutic use; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018874:Spheroids, Cellular; D059016:Tumor Microenvironment
chemical_list: D000970:Antineoplastic Agents; D017931:DNA Primers; D007610:Kallikreins; C120801:kallikrein 4; D017239:Paclitaxel