Serine protease HtrA1 modulates chemotherapy-induced cytotoxicity
Jeremy Chien, … , Scott H. Kaufmann, Viji Shridhar
Jeremy Chien, … , Scott H. Kaufmann, Viji Shridhar
Published July 3, 2006
Citation Information: J Clin Invest. 2006;116(7):1994-2004. https://doi.org/10.1172/JCI27698.
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Research Article Oncology

Serine protease HtrA1 modulates chemotherapy-induced cytotoxicity

Abstract

Resistance to chemotherapy presents a serious challenge in the successful treatment of various cancers and is mainly responsible for mortality associated with disseminated cancers. Here we show that expression of HtrA1, which is frequently downregulated in ovarian cancer, influences tumor response to chemotherapy by modulating chemotherapy-induced cytotoxicity. Downregulation of HtrA1 attenuated cisplatin- and paclitaxel-induced cytotoxicity, while forced expression of HtrA1 enhanced cisplatin- and paclitaxel-induced cytotoxicity. HtrA1 expression was upregulated by both cisplatin and paclitaxel treatment. This upregulation resulted in limited autoproteolysis and activation of HtrA1. Active HtrA1 induces cell death in a serine protease–dependent manner. The potential role of HtrA1 as a predictive factor of clinical response to chemotherapy was assessed in both ovarian and gastric cancer patients receiving cisplatin-based regimens. Patients with ovarian or gastric tumors expressing higher levels of HtrA1 showed a higher response rate compared with those with lower levels of HtrA1 expression. These findings uncover what we believe to be a novel pathway by which serine protease HtrA1 mediates paclitaxel- and cisplatin-induced cytotoxicity and suggest that loss of HtrA1 in ovarian and gastric cancers may contribute to in vivo chemoresistance.

Authors

Jeremy Chien, Giovanni Aletti, Alfonso Baldi, Vincenzo Catalano, Pietro Muretto, Gary L. Keeney, Kimberly R. Kalli, Julie Staub, Michael Ehrmann, William A. Cliby, Yean Kit Lee, Keith C. Bible, Lynn C. Hartmann, Scott H. Kaufmann, Viji Shridhar

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Figure 1

Suppression of HtrA1 by siRNA attenuates cisplatin cytotoxicity.

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Suppression of HtrA1 by siRNA attenuates cisplatin cytotoxicity. Sensiti...
Sensitivity to drugs was assessed by apoptosis and clonogenic survival assay in SKOV3 cells transfected with siRNAs or antisense RNA. (A) Immunoblot analysis of HtrA1 expression in ovarian cell lines. (B) SKOV3 cells were transiently transfected with siRNAs for 48 hours and subsequently treated with 20 μM cisplatin, and apoptotic cells were visualized by Hoechst staining and counted. Apoptotic cells showing chromatin condensation and fragmentation are indicated by arrowheads. (C) Analysis of apoptosis by Hoechst staining showed a significant attenuation of apoptosis in cells transfected with HtrA1 siRNA (1900si) compared with those transfected with scrambled siRNA (1900scr). Immunoblot analysis of siRNA-transfected cells indicated efficient downregulation of HtrA1 in 1900si-transfected cells (inset). (D) SKOV3 clonal lines stably expressing antisense RNA or empty vector were treated with various concentrations of cisplatin for 24 hours, washed and grown in fresh drug-free medium for 2 weeks, stained, and counted. Stable suppression of HtrA1 promoted clonogenic survival of antisense-expressing clones (asHtrA1 no. 5 and no. 7) compared with vector-expressing clones (Vector no. 3 and 9). Data are expressed as mean ± SEM and represent 3 independent trials performed at least in triplicate. *P < 0.05, **P < 0.01, #P < 0.001 or as indicated; α = 0.05, unpaired 2-tailed Student’s t test for 2 groups, and ANOVA followed by Newman-Keuls test for multiple comparison.