Abstract 875: Acquisition of chemoresistance in tumor cells requires crosstalk between dying and remnant live tumor cells via HMGB1 Free

Chemoresistance often develops during drug treatment in cancer patients but its mechanism remains unclear. To understand acquisition of drug resistance, we investigated whether tumor cells dying during drug treatment might signal to neighboring live cells to program themselves for survival in the drug-containing environment. The experimental design was to identify a factor in the supernatants of docetaxel (DTX)-treated human DU145 and PC3 prostate tumor cells that could cause live tumor cells to resist apoptosis and cell death under docetaxel. We discovered that dying cells release HMGB1 which can bind TLR4 or RAGE on live tumor cells causing the induction of cytoplasmic Clusterin (CLU). We demonstrated that CLU is a potent prosurvival protein that can trap Bax from translocating to the mitochondria to cause caspade 3 activation and subsequent apoptosis. Proof of this pathway came from the ability of anti-HMGB1to prevent supernatants from dying cells to induce CLU in newly-plated tumor cells. The receptors for HMGB1 were identified by use of anti-TLR4 and anti-RAGE, which prevented recombinant HMGB1 or dying cell supernatants from inducing CLU in newly-plated tumor cells, causing them to subsequently succumb to DTX toxicity. Moreover, overexpression of anti-sense CLU in tumor cells abrogated their ability to respond to recombinant HMGB1 or dying cell supernatants to induce drug resistance. Most importantly, standard chemotherapeutic agents including gemcitabine, taxol, Ara-C, doxorubicin, cisplatin, etoposide and carboplatin, can cause the release of HMGB1 from dying tumor cells, implicating this crosstalk between dying and live tumor cells as a common pathway towards multi-drug resistance.

Citation Format: Junmin Zhou, Xianghong Chen, Danielle L. Gilvary, Melba Marie Tejera, Erika A. Eksioglu, Thu Le Trinh, Sheng Wei, Julie Djeu. Acquisition of chemoresistance in tumor cells requires crosstalk between dying and remnant live tumor cells via HMGB1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 875.