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 2

Reexpression of HtrA1 promotes cisplatin toxicity.

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Reexpression of HtrA1 promotes cisplatin toxicity. (A) HtrA1-transfected...
(A) HtrA1-transfected OV167 cells showed a significant increase in cisplatin-induced cell death compared with cells transfected with vector. Immunoblot analyses indicated expression of HtrA1 in cells transfected with HtrA1. β-Actin immunoblots represent loading controls. (B) OV167 cells stably expressing HtrA1 also showed a significant decrease in clonogenic survival under cisplatin treatment compared with vector-transfected cells. (C) Increased cytotoxicity following cisplatin treatment observed in OV167 cells stably expressing HtrA1 was due to an increase in apoptosis, as these cells showed significantly higher apoptosis compared with vector-transfected or parental OV167 cell lines. (D) To test whether HtrA1 expression promotes cisplatin cytotoxicity in another HtrA1-deficient cell line, A2780 cells were transiently transfected with HtrA1 and treated with cisplatin for 24 hours. HtrA1-transfected A2780 cells showed a significant increase in cisplatin-induced cell death compared with cells transfected with vector. Immunoblot analyses indicated expression of HtrA1 in cells transfected with HtrA1. (E) A2780 clonal lines stably expressing HtrA1 (HtrA1 nos. 11, 20, and 21) showed a decrease in clonogenic survival compared to vector-transfected clones (Vector nos. 1 and 2) when treated with various concentrations of cisplatin for 24 hours. Immunoblot analyses of these stable clones indicated HtrA1 expression in A2780 clones transfected with HtrA1 (nos. 11, 20, and 21). Data are expressed as mean ± SEM and represent 3 independent trials performed at least in triplicate. *P < 0.05, **P < 0.001, #P < 0.0001, †P < 0.0005, ††P < 0.005; α = 0.05, unpaired 2-tailed Student’s t test for 2 groups, and ANOVA followed by Newman-Keuls test for multiple comparison.