A feasibility study of chemosensitivity testing in primary cultures from malignant gliomas, and analysis of drug resistance mechanisms

Abstract

Malignant gliomas are the commonest primary malignant tumours of the brain and carry a poor prognosis with current treatment modalities. Chemotherapy is an increasingly important treatment option for these turnouts; however response is limited by the development of drug resistance. A study was undertaken to investigate the feasibility of providing information about tumour chemosensitivity in vitro by culturing glioma tumour cells in a hospital setting and performing chemnosensitivity assays on them using five common chemotherapeutic agents i.e. Cisplatin, Carmustine, Paclitaxel, Temozolomide and Etoposide. It was found that a successful culture was obtained in roughly half the patients (21/47) where culture was attempted, and in those successful cultures information about drug sensitivity could be provided within 3 weeks. The
colorimnetric MTS assay and the luminescent ATP assay were compared for chemosensitivity results and it was found that the ATP assay was more sensitive in that it could detect cell death at lower cell numbers. A wide variation was found in the range of chemosensitivities between known glial cell lines and primary cultures and also between the various primary cultures. De Novo drug resistance was also shown to develop in subsequent subcultures derived from the primary culture. Every tumour is unique phenotypically and genotypically and several factors induding clinical characteristics, radiological features and conventional histology might act as pointers to this uniqueness. Proteins ktown to be associated with drug resistance in other tumours might be contributory to the development of drug resistance in gliomas. Profiles of successfully
assayed tumours (nr19) were prepared induding clinical and radiological data, histology, culture characteristics, chemosensitivity data and immunohistochemistry for pglycoprotein (PGP), multiple drug resistance associated protein 1(MRP1), p53, Ki-67 and MGMT proteins. These profiles did not show any correlation between the factors analyzed and chemosensitivity to the five chemotherapeutic agents used. Functional studies of drug efflux pumps PGP and MRPI, performed on 5 cultures using drug efflux assays and confocal microscopy demonstrated no correlation between presence of the proteins on immunostaining and their functional activity.