OBJECTIVETo investigate the expression of murine double minute 2 (mdm2), p53, p21 and latent membrane protein 1 (LMP-1) in nasal NK/T-cell lymphoma (NKTL) and analyze their relationship with the clinical stage and prognosis.

METHODSThe clinicopathological and follow-up data of 62 patients with NKTL proven by pathology were collected. Paraffin-embedded tissue sections were examined for mdm2, p53, p21 and LMP-1 proteins by tissue microarray technique and immunohistochemistry. In situ hybridization was used to detect EBER1/2.

RESULTSThe positive expression rates of mdm2, p53, p21 and LMP-1 proteins in NKTL were 61.3%, 79.0%, 58.1% and 48.4%, respectively, and EBER1/2 was 90.3%. The positive expression rates of mdm2 in Ann Arbor stage I, II, III and IV NKTL were 43.5%, 62.5%, 73.3% and 87.5%, respectively; p53 were 69.6%, 75.0%, 86.7% and 100.0%; p21 were 47.8%, 56.3%, 60.0% and 87.5%; while those of LMP-1 were 60.9%, 50.0%, 26.7% and 50.0%, respectively. With the progression of tumor, the positive expression rates of mdm2, p53 and p21 proteins gradually increased. There were statistically significant differences between them (P<0.05). There were statistically positive correlations among those three genes (P<0.05). The prognosis of the positive expression group of these three genes was worse than that of negative expression group (P<0.05). No statistically significant difference was observed between the expression of LMP-1 protein and the clinical stage or prognosis (P>0.05). The expression of p53 protein was an independent prognostic factor.

CONCLUSIONThe expression of mdm2, p53 and p21 proteins is closely related with the pathogenesis and progression of NKTL. They are good markers for judgement of the biological behavior of NKTL. The expression of p53 protein is an independent prognostic factor. Though no significant relationship was found between the expression of LMP-1 protein and the clinical stage or prognosis, it may play some role in tumor progression.