DETECTION OF C-MYC GENE-EXPRESSION IN NASOPHARYNGEAL CARCINOMA BY NONRADIOACTIVE IN-SITU HYBRIDIZATION AND IMMUNOHISTOCHEMISTRY

Objectives To investigate the c-myc gene expression in nasopharyngeal carcinoma (NPC) at mRNA and protein levels, and to evaluate the relati onship between the degree of expression and the clinicopathological da ta. Methods The expression of c-myc specific mRNA and protein was dete cted using in situ hybridization with digoxigenin-labeled probe and im munohistochemistry in 12 cases of normal nasopharyngeal epithelium (NE ) and 18 cases of NPC. The intensity of staining for each sample was a ssessed as negative, weak, moderate and intense. Statistical analyses were performed using the Chi square test and the rank sum rest. Result s For normal NE, 41.7% (5/12) had weak (4/12) or moderate (1/12) stain ing for c-myc protein and 41.7% (5/12) had weak staining for c-myc mRN A. In contrast, 89.6% (43/48) of NPC showed some degree of c-myc prote in positive and 87.5% (42/48) showed some degree of c-myc mRNA positiv e. In most samples, the expression of c-myc protein was consistent wit h that of c-myc mRNA. C-myc protein and mRNA expression levels in NPC were significantly higher than those in normal NE, and correlated with early recurrence, but they were nor significantly related ro patient' s age, sex, EBVCA-lgA titre, disease stage, lymph node status and meta stasis. Conclusions C-myc gene over-expression may be involved in the pathogenesis and early recurrence of NPC. Further studies are needed t o substantiate the preliminary findings.