Elevated expression of thyroid hormone receptor alpha 2 (c-erb A-alpha 2) in nasopharyngeal carcinoma

Differential display was used to identify genes differentially expressed be tween cultured normal nasal epithelial cells and nasopharyngeal carcinoma ( NPC) cell lines. A 130 bp cDNA fragment showing homology with thyroid hormo ne receptor alpha2 (TR-alpha2 or c-erb A-alpha2) was identified in NPC cell lines. Northern blot analysis using the 130 bp cDNA fragment and a TR-alph a2 specific cDNA containing part of the coding region as probes, we were ab le to detect a 2.7 kb transcript corresponding to that of TR-alpha2 in NPC cell lines but not in normal nasal epithelial cells. RNA in situ hybridizat ion was used to detect TR-alpha2 expression in clinical biopsies obtained f rom NPC patients and non-tumour controls. TR-alpha2 mRNA was detected in 1 out of 24 (4.2%) normal nasopharynx epithelium biopsies, in 5 out of 27 (18 .5%) primary and 15 out of 24 (62.5%) recurrent tumours. The positive rate of TR-alpha2 expression in recurrent NPC biopsies was significantly higher than that in normal nasopharynx epithelium (P<0.00001). The relevance of th e elevated expression of TR-<alpha>2 in the pathogenesis process of NPC was discussed. (C) 2000 Cancer Research Campaign.