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ヒト正常上皮細胞系でのテロメレース活性の局在と細胞周期依存性：安本茂¹,国村忠司²,菊地慶司¹,清水昭男³,森村茂¹（¹神奈川がんセ・研・分子腫瘍,²ニッショー・総研,³神奈川がんセ・研・病理）

Cell cycle- dependence of telomerase activity in normal human regenerating epithelial cells: Shigeru YASUMOTO¹, Chuji KUNIMURA², Keiji KIKUCHI², Akio SHIMIZU³, Shigeru MORIMURA¹ (¹Lab. Mol.. Cell Biol., Kanagawa Cancer Ctr. Res. Inst, ²Nissho Co. Res. Ctr., ³Dept. Pathology, Kanagawa Cancer Ctr. Res. Inst)

Telomerase activity is correlated with the immortality of various cultured cells and cancer cells. The activity, however, is also demonstrated in various normal regenerating cells which normally have a finite life span in vivo and in vitro, though its biological implication remains unclear. Using cultured normal human epithelial cells, we show that telomerase activity is associated with epithelial cell subsets which actively proliferate in vitro. Unlike in most cancer cell lines, telomerase activity was evidently up-regulated when the cells entered into S phase in primary human epithelial cells. To characterize the cells which have telomerase activity, the primary human epithelial cell population of uterine cervix was dissociated into several distinctive cellular subsets by means of immunocytochemical cell fractionation. Telomerase activity was found to be closely associated with the subset which expressed predominantly integrin b1 and epidermal growth factor receptor. We further identified the telomerase-negative subpopulation which contained a small subset that strongly coexpresses p75NGFR low affinity nerve growth factor receptor, integrin beta4 and bcl-2 protein. The location of the p75NGFR expressing cells contrasts to that of the Ki-67 positive cells in vivo and is distinctive of telomerase positive cycling cells, indicating that these cells remain at the G0 phase. The present study supports the notion that telomerase activity is linked to cell cycle regulation, implying that telomerase is activated upon cell proliferation in regenerating normal human epithelial cells.