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 4

HtrA1-induced cell death is dependent on serine protease activity.

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HtrA1 is upregulated and activated during chemotherapeutic drug treatmen...
OV202 cells were transiently transfected with various plasmids, and cell death was analyzed by morphologic examination, MTT reduction, and LDH release assays. (A) WTΔMac-transfected cells showed extensive cell death, which could be prevented by pretreatment with 50 μg/ml serine protease inhibitor AEBSF but not by cotransfection with dnCasp9. Vector- and SAΔMac-transfected cells did not show extensive cell death. 20 μM UCN-01–treated cells were used as positive controls. (B) OV202 cells transfected with various HtrA1 constructs for 8 hours were assayed for caspase activities using specific caspase substrates provided in Promega’s Caspase-Glo assay kits. In some groups, cells were cotransfected with the caspase inhibitor CrmA (cytokine response modifier A) or dnCasp9 or were preincubated with AEBSF (50 μg/ml). No significant increase in caspase-8 or -9 activity (relative to vector control) was observed following WTΔMac transfection. However, a significant increase in caspase-3/7 activity was observed with WTΔMac transfection. Caspase-3/7 activation was not blocked by CrmA or dnCasp9 but was blocked by AEBSF. 20 μM UCN-01 treatment was used as a positive control for the caspase-3/7 activity assay. Data are from experiments performed in triplicate, and error bars represent SEM.