Analysis of HSP27 and the Autophagy Marker LC3B+ Puncta Following Preoperative Chemotherapy Identifies High-Risk Osteosarcoma Patients.

Abstract

Chemotherapy-induced autophagy is a proposed mechanism of chemoresistance and potential therapeutic target in osteosarcoma. We evaluated heat shock protein 27 (HSP27) and autophagy-related proteins as predictors of pathologic treatment response and prognostic markers among osteosarcoma patients who received standard chemotherapy. We analyzed 394 tumor specimens (pre-treatment, post-treatment, and metastases) from 260 osteosarcoma patients by immunohistochemistry for cytoplasmic light chain 3B (LC3B)-positive puncta, sequestosome 1 (SQSTM1), high mobility group box 1 (HMGB1), and HSP27 expression. The staining percentage and intensity for each marker were scored and the extent to which marker expression was correlated with pathologic response, relapse-free survival (RFS), and overall survival (OS) was assessed. LCB3+ puncta in post-treatment primary tumors (50%) and metastases (67%) was significantly higher than in pre-treatment biopsy specimens (30%; P = 0.023 and <0.001). Among 215 patients with localized osteosarcoma, both pre-treatment [multivariate hazard ratio (HR), 26.7; 95% confidence interval (CI), 1.47-484; P = 0.026] and post-treatment HSP27 expression (multivariate HR, 1.85; 95% CI, 1.03-3.33; P = 0.039) were associated with worse OS. Lack of LC3B+ puncta at resection was an independent poor prognostic marker in both univariate (HR, 1.78; 95% CI, 1.05-3.03; P = 0.034) and multivariate models (HR, 1.75; 95% CI, 1.01-3.04; P = 0.045). Patients with LC3B+/HSP27- tumors at resection had the best 10-year OS (75%) whereas patients with LC3B-/HSP27+ tumors had the worst 10-year survival (25%). Neither HSP27 expression nor the presence of LCB3+ puncta was correlated with pathologic treatment response. Our findings establish HSP27 expression and LC3B+ puncta as independent prognostic markers in osteosarcoma patients receiving standard chemotherapy and support further investigation into strategies targeting HSP27 or modulating autophagy in osteosarcoma treatment. Mol Cancer Ther; 17(6); 1315-23. ©2018 AACR.