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

为了建立一种预测胃癌和乳腺癌细胞对抗癌药物敏感性的方法，我们用阿霉素（DOX）、5-氟尿嘧啶（5-FU）、顺铂（CDDP）和伊立替康（irinotecane）检测了胃癌和乳腺癌细胞株的端粒酶活性和端粒酶逆转录酶（hTERT）基因的表达将CPT-11; SN-38添加到人胃癌和乳腺癌细胞系（各3种）的培养物中，然后连续测量细胞数量、细胞周期、端粒酶活性和hTERT mRNA表达。DOX、5-FU和CDDP治疗组端粒酶活性和hTERTmRNA表达随抗肿瘤作用的增强而逐渐降低。而CPT-11治疗组在药物治疗后24小时观察到端粒酶活性和hTERT表达的短暂增加。细胞周期变化与端粒酶活性及hTERTmRNA表达无相关性。人端粒酶RNA亚单位和人端粒酶蛋白p80的表达与其抗肿瘤活性无关。人胃癌细胞株MKN-28裸鼠移植瘤体内实验。与体外实验结果相似，DOX、5-FU和CDDP处理后端粒酶活性和hTERTmRNA表达逐渐降低。CPT-11处理后，端粒酶活性和hTERTmRNA表达均呈一过性升高，提示hTERTmRNA可能是调节端粒酶活性的重要因素。大多数抗肿瘤药物的抗肿瘤作用与端粒酶活性和hTERTmRNA表达的降低一致。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测定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.