Overexpression of resistance-related proteins (metallothioneins, glutathione-S-transferase ?, heat shock protein 27, and lung resistance-related protein) in osteosarcoma

Open Access
Publisher Website
Google Scholar
Abstract
BACKGROUND The prognosis for patients with osteosarcoma has improved over the past 20 years, mainly due to developments in chemotherapy. Some proteins have been reported to show drug resistance. Theoretically, overexpression of some of these proteins makes treatment difficult, leading to poorer outcome. METHODS Specimens taken from conventional osteosarcomas of the extremity bones from 60 patients younger than 30 years were used. In all cases, preoperative oncostatic chemotherapy was undertaken after biopsy. If available, biopsy specimens were also used for sequential comparison. Among resistance‐related proteins, expression of metallothioneins (MTs), glutathione‐S‐transferase π (GST π), heat shock protein 27 (Hsp27), and lung resistance‐related protein (LRP) was evaluated immunohistochemically in paraffin sections. The log rank test was used for univariate analysis and the Cox regression model for multivariate analysis. RESULTS At biopsy, only overexpression of Hsp27 was associated with poor prognosis. At surgery, a relationship was observed between poor prognosis and overexpression of GST π, Hsp27, and LRP. Groups overexpressing one protein tended to overexpress another. Overexpression of these proteins in surgical specimens also correlated with histologic response to preoperative chemotherapy and clinical stage. In multivariate analysis, Hsp27 overexpression at biopsy was an independent prognostic factor. CONCLUSIONS Inherent overexpression of Hsp27 is independently related to poor outcome in osteosarcoma patients. Overexpression of GST π, Hsp27, and LRP at surgery might be associated with failure of preoperative chemotherapy. Control of the expression of these proteins may improve the outcome for patients with osteosarcoma. Cancer 1997; 79:2336‐44. © 1997 American Cancer Society.