Development of novel radioresistant oral squamous cell carcinoma cell lines.

Abstract

Objectives. Oral cancer is the most common head and neck cancer with an estimated 2 75 000 new cases in 2002.1 Currently radiotherapy plays an important role in the management of oral cancer. Rates of radioresistance reported in the literature range from 19–53%.2 This wide range of reported rates of radioresistance stems from variation in the definition of a radioresistant tumour. As all tumours in vivo posses a heterogeneous cell population, samples of tumour tissue taken for analysis cannot be guaranteed to have originated from a radioresistant subpopulation. These, and other factors, cause the discrepancy in resistance rates. This study aimed to address these issues by creating novel radioresistant cell lines. Method. Two oral cancer cell lines were studied. They were divided into two samples and cultured in identical conditions. Initial dose response curves and survival fractions were calculated for each at the outset of the study. One sample was then exposed to a course of fractionated radiotherapy at 4 Gy increments on a fortnightly basis whilst the other was cultured without exposure. Dose response curves were then constructed for the two daughter samples. Results. Each daughter cell line was found to survive doses of radiotherapy in excess of their parental counterpart. The LD50 (lethal dose killing 50% of cells) was 5.85 Gy for the daughter cell line and 0.91Gy for the parental cells. Conclusions. We have created two radioresistant oral squamous cell carcinoma cell lines to allow further analysis to be performed on readily available proven radioresistant oral cancer cell lines. References 1 Parkin D.M., Bray F., Ferlay J. et al. (2005) Global Cancer Statistics, 2002. CA Cancer J Clin, 55, 74–108 2 Eckardt A., Barth E.L., Kokemueller H. et al. (2004) Recurrent carcinoma of the head and neck: treatment stratergies and survival analysis in a 20-year period. Oral Oncology, 40, 427–32