Abstract
There are characteristic G-rich repeats, i. e. telomeric repeats, at every chromosome end in eukaryotes. The telomeric repeats are considered to be lost in proportion to cell divisions in somatic cells and cultured cells. We analyzed the length of telomeric repeats in natural occurring human tumors, neuroblastomas and lung cancers, to investigate whether the length of telomeric repeats simply reflects the number of cell divisions the tumor cell has passed. In neuroblastoma, reduction of telomeric repeats demonstrated a significant correlation with stage at diagnosis, poor prognosis, and percentage of tumor cells in S-phase. In lung cancer, the occurrence of reduction or elongation of telomeric repeats was observed only in late stage, in metastatic lesions, or in cancer tissues with a high percentage of cells in S-phase, except for adenocarcinoma. According to the telomere hypothesis, the length of telomeric repeats is stably maintained by re-activation of telomerase in immortalized transformed cells. Such re-activation of telomerase, elongation or convergence of telomeric repeats, was suspected only in 7.3% and 6.5% cases in neuroblastoma and lung cancer, respectively.
