Quantitative analysis of BCL2 mRNA expression in nasopharyngeal carcinoma: an unfavorable and independent prognostic factor

Abstract

Programmed cell death plays a vital role in a wide variety of physiological processes. Defects in apoptotic cell death contribute to neoplastic diseases by preventing or delaying normal cell death. BCL2 (Bcl-2) is an anti-apoptotic gene with marked up-regulation in various malignancies, such as breast cancer, in which expression of the BCL2 protein has been proposed as a prognostic tumor biomarker. The purpose of the current study was to investigate mRNA expression of the BCL2 gene in nasopharyngeal carcinoma (NPC) biopsies and assess its prognostic value. For this purpose, total RNA was isolated from 89 malignant and hyperplastic nasopharyngeal biopsies from Tunisian patients. After testing the quality of the extracted RNA, cDNA was prepared by reverse transcription. A highly sensitive real-time PCR methodology for BCL2 mRNA quantification was developed using SYBR® Green chemistry. GAPDH served as an endogenous control gene. Relative quantification analysis was performed using the comparative C (T) (2(-∆∆CT)) method. High BCL2 mRNA levels were detected in advanced-stage nasopharyngeal tumors (p = 0.030). Furthermore, BCL2 mRNA expression was strongly associated with lymph node involvement (p = 0.009) and presence of distal metastases (p = 0.013). Survival analysis demonstrated that patients with BCL2-positive nasopharyngeal tumors have significantly shorter disease-free and overall survival (p = 0.011 and p = 0.028, respectively). The major contribution of the current study is the quantification and evaluation, for the first time, of the prognostic significance of the BCL2 mRNA expression in nasopharyngeal carcinoma (NPC) patients. Our results suggest that mRNA expression levels of BCL2 may represent a novel unfavorable and independent tumor biomarker for nasopharyngeal carcinoma.