Prediction of antitumor activity of chemotherapeutic agent by measurement of telomerase activity and expression of human telomerase reverse transcriptase gene.

为了建立一种预测抗癌药物敏感性的方法，我们以人胃癌细胞和乳腺癌细胞株为研究对象，分别加入阿霉素(DOX)、5-氟尿嘧啶(5-FU)、顺铂(CDDP)和伊立替康(CPT-11；SN-38)培养，检测细胞数量、细胞周期、端粒酶活性和hTERT基因表达。在DOX、5-FU和CDDP处理组中，端粒酶活性和hTERT mRNA的表达随着抗肿瘤作用的增强而逐渐降低。而CPT-11治疗组在药物治疗24小时后，端粒酶活性和hTERT表达出现一过性升高。细胞周期变化与端粒酶活性及hTERT基因表达均无相关性。抗肿瘤活性与人端粒酶RNA亚单位和人端粒酶蛋白p80的表达无关。将人胃癌细胞株MKN-28移植到裸鼠体内进行了体内实验。与体外实验结果相似，经DOX、5-FU和CDDP处理后，端粒酶活性和hTERT mRNA表达逐渐降低。反之，CPT-11处理后端粒酶活性和hTERT基因表达也出现一过性升高，hTERT可能是调节端粒酶活性的最重要因素。在大多数抗癌药物中，端粒酶活性和hTERT mRNA的表达随抗肿瘤作用的增强而降低。然而，在某些抗癌药物中也观察到一过性增加。因此，我们必须谨慎地将该检测系统应用于临床试验。

In order to develop an assay for predicting sensitivity to anticancer drugs, we evaluated the telomerase activity and expression of human telomerase reverse transcriprase (hTERT) gene using human gastric and breast cancer cell lines.Doxorubicin (DOX), 5-fluorouracil (5-FU), cis-platinum (CDDP) and irinotecane (CPT-11; SN-38) were added to the culture of human gastric and breast cancer cell lines (3 types each), and then cell number, cell cycle, telomerase activity and expression of hTERT mRNA were serially measured. In DOX, 5-FU and CDDP treated group, telomerase activity and expression of hTERT mRNA gradually decreased in accordance with antitumor effect. However, transient increase in telomerase activity and hTERT expression were observed 24 hr after drug treatment in CPT-11 treated group. There was no correlation between the changes in cell cycle and telomerase activity nor hTERT mRNA expression. There also was no relationship between antitumor activity and expression of human telomerase RNA subunit nor human telomerase protein p80.Human gastric cancer cell line MKN-28 was transplanted to nude mouse and in vivo experiment was also carried out. Similar to the results obtained from in vitro experiment, gradual decrease in telomerase activity and hTERT mRNA expression were obtained after treatment by DOX, 5-FU and CDDP. On the contrary, transient increase in telomerase activity and hTERT mRNA expression were also observed by CPT-11 treatment.From these results, hTERT is supposed to be the most important factor which regulate the telomerase activity. In most of anticancer drugs, telomerase activity and hTERT mRNA expression decreased in accordance with antitumor effect. However, transient increase was also observed in certain kind of anticancer drug. Therefore, we have to be careful to apply this assay system for clinical test.