Abstract

The authors studied EBV genome expression in 40 conventionally processed samples of nasopharyngeal carcinomas (NPC), using in situ hybridization for EBERs and immunohistochemistry for LMP, Bcl-2 and p53 proteins. The NPCs consisted of 6 keratinizing squamous cell carcinomas (KSCs), 13 nonkeratinizing carcinomas (NKCs) and 21 undifferentiated carcinomas (UCs). The results were summarized as follows: 1) EBERs were expressed in 80.0% of all the NPCs (32/40). As for the subtypes, they were detected in 92.3% of NKCs (12/13), in 90.5% of the UCs (19/21), and in 16.7% of the KSCs (1/6). In positive cases, the nuclei of tumor cells displayed uniformly strong staining. 2) LMP was expressed in 10.0% of all the NPCs (4/40), all of which were UC. The LMP expression in the UCs was not correlated to the expression of EBERs, Bcl-2 and p53 proteins. 3) Bcl-2 protein was detected in 85.0% of all the NPCs (34/40). As for the subtypes, they were detected in 92.3% of the NKCs (12/13), in 90.5% of the UCs (19/21), and in 50.0% of the KSCs (3/6). 4) p53 protein was detected in 75.0% of all the NPCs (30/40). As for the subtypes, they were detected in 81.0% of the UCs (17/21), in 69.2% of the NKCs (9/13), and in 66.7% of the KSCs (4/6). 5) In the NPCs the expression of EBER showed a significantly positive correlation with that of p53 or Bcl-2 protein. The above results indicate that the association of EBV with NPC is chiefly with poorly differentiated and undifferentiated carcinomas. Additionally, carcinomas commonly display widespread, strong immunoreactivity of Bcl-2 and p53 proteins over tumor cells. In conclusion, these observations indicate that the EBV-association in NPC appears to contribute to the overexpression of tumor-related genes during carcinogenesis.

• Keywords: Nasopharyngeal carcinoma;EBERs, LMP;p53 protein;Bcl-2 protein;