Identifying molecular candidates associated with acquired temozolomide resistance in human malignant glioma: a proteomics approach

Abstract

Temozolomide (TMZ) provides significant benefits in the treatment of malignant glioma but many patients continue to suffer from progressive or recurrent diseases due to their tumours’ intrinsic or acquired resistance to TMZ. Understanding the molecular mechanism underlying TMZ-resistance is important for the development of novel treatment strategies. OBJECTIVES: To employ proteomic profiling to study the global protein expression changes in TMZ-resistant malignant glioma cell-lines, and to investigate the potential role of one of the identified protein candidates, prolyl 4-hydroxylase, beta polypeptide (P4HB). MATERIALS AND METHOD: Human malignant glioma cell-lines (D54 and U87) with acquired TMZ-resistance were developed, and protein profiling analysis was performed using two dimensional gel electrophoresis (2DE). Potential protein spot candidates were identified by MALDI-TOF/TOF. Transient transfection with small interfering RNAs was used to knock down potential candidates to study their biological roles. RESULTS: Fifteen spots were identified as the most dysregulated proteins in TMZ-resistant glioma cells. Amongst these, the protein P4HB was found to be consistently dysregulated in D54 and U87. Transient knock-down was found to significantly down-regulate P4HB expression and increase TMZ-induced apoptosis. CONCLUSION: P4HB plays an important role in hypoxia-induced cell death. The present study describes its role in the regulation of apoptosis in TMZ-treated malignant glioma cells. P4HB is a potential candidate for future studies in TMZ-induced cytotoxicity and novel therapeutic strategies for the treatment of TMZ-resistant malignant glioma.