Construction of the POT1 promoter report gene vector, and the effect and underlying mechanism of the POT1 promoter in regulating telomerase and telomere length

By using human genomic DNA as a template to clone protection of telomere 1 (POT1) promoter gene segments and construct the POT1 promoter luciferase report gene vector (pGL3-Control-POT1-promoter), the association between POT1, and the regulation of telomerase and telomere length was investigated. In the present study, two recombinant luciferase report gene vectors were constructed, which included different regions of the POT1 promoter. The plasmids were transformed into DH5α and the positive clones were obtained. The two plasmids termed as pGL3-Control-POT1-promoter-1 and pGL3-Control-POT1-promoter-2, were confirmed using restriction enzyme analysis and sequencing. They were separately and transiently transfected into four types of human tumor cells (A549, H460, HepG2 and HeLa). The transcriptional activities of the POT1 promoter were verified using the dual-luciferase assay. The relative expression of POT1 and human telomerase reverse transcriptase (hTERT), and telomere length were analyzed using quantitative polymerase chain reaction in the four types of non-transfected tumor cells. Using SPSS software, correlations between POT1 promoter activity, and POT1 expression, hTERT expression and telomere length were analyzed. Two POT1 promoter fragments (POT1-promoter-1 and -2) were successfully constructed into the pGL3-Control luciferase report gene vector. POT1-promoter-1 exhibited significantly stronger transcription activity compared with POT1-promoter-2. The results of the partial correlation and linear regression analyses were similar: POT1 promoter activity was identified to be significantly and positively correlated with POT1 expression and telomere length (partial correlation coefficients, both P<0.05; linear regression, both P<0.01). However, POT1 promoter activity and hTERT expression were significantly negatively correlated (both P<0.05). The results obtained in the present study suggest that the POT1 promoter influences telomere length. Furthermore, these data indicated that POT1 promoter activity and POT1, as well as telomere length, may be a useful biomarker for tumor detection and future patient prognosis.