Establishment of novel human esophageal cancer cell line in relation to telomere dynamics and telomerase activity.

The telomere and the telomerase in human esophageal cancer are not yet completely understood. The regulatory mechanism of telomerase activity and telomere dynamics has drawn considerable attention. It is generally assumed that when telomerase has been activated, no further telomere shortening should ensue; however, a much more complex pattern of telomere dynamics may exist in telomerase-positive cancer cells. A novel human esophageal cancer cell line (KAN-ES) was established and characterized. Using KAN-ES and its serially passaged subclones up to the 55th generation, we determined the alteration of telomere length (TRF), telomerase activity (TA), telomerase RNA expression (hTR), population doubling time, karyotype, and cytokeratin 14 expression during the process of establishing a cancer cell line. We found that the TRF was maintained between 4.0 and 5.0 kb during the serial passages, despite sustained high TA (assessed by an in vitro TRAP assay). No close relationships were found among TRF, TA, and hTR expression. TA and telomere dynamics were not associated with cellular growth ability and differentiation. However, the number of population doublings showed significant correlations with both the TA and doubling times. In conclusion, these dissociations between telomere dynamics and TA support the existence of additional controls on TRF in cancer cells. KAN-ES and its restored subclones should prove a valuable resource for esophageal cancer research.