Correlation of dyskerin expression with active proliferation independent of telomerase.

Abstract

Dyskerin, which is an important component of the telomerase complex and is needed for normal telomerase activity, is frequently overexpressed in neoplasia. Dyskerin also plays an essential role in ribosome biogenesis. Because protein synthesis increases during tumorigenesis, this led us to hypothesize that dyskerin expression would be upregulated independently of the cell immortalization mechanism. Dyskerin and telomerase reverse transcriptase (TERT) expression were examined in oral squamous cell carcinomas (OSCC) and patient-matched controls, as well as in a panel of telomerase-positive and telomerase-negative cells. Antisense inhibition of TERT was used to test the effects of downregulation of telomerase on dyskerin expression. Dyskerin was frequently overexpressed in OSCC and in immortalized and transformed keratinocytes relative to primary cells, independently of TERT and telomerase activity. Instead, dyskerin expression strongly correlated with cell proliferation rates. The role of dyskerin in tumorigenesis does not correlate with its function within the telomerase complex.