Lü Xinquan, Deng Qing, Li Huixiang, Suo Zhenhe
Department of Pathology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, P.R. China ;
Exp Ther Med. 2011 Sep;2(5):821-826. doi: 10.3892/etm.2011.279. Epub 2011 Jun 2.
Drug resistance of cancer stem/initiating cells has been considered to be one of the main reasons for tumor relapse. However, knowledge concerning the changes in stem/ initiating cells during chemotherapy is limited. In the present study, the breast cancer cell line MDA-MB-468 was cultured with 5-fluorouracil and serially passaged. Six cell generations were collected. Semi-quantitative RT-PCR and flow cytometric techniques were used to evaluate the protein and mRNA expression of stem/initiating factors (CD44(+)/CD24(-), Oct 3/4, SOX2 and β-catenin), drug-resistance genes (BCRP and MRP1) and an anti-apoptosis gene (survivin). The clone formation rate was also examined in every generation of cells. The results showed that, under conditions of persistent chemotherapy, the factors representing the quantity of stem/initiating cells (β-catenin, Oct 3/4 and SOX2) followed a fluctuating trend of decrease-increase-further increase-decrease-increase-decrease, and factors representing the proportion of stem/initiating cells (proportion of CD44(+)/CD24(-) and the clone formation rate) demonstrated a fluctuating trend of increase-further increase-further increase-decrease. The drug-resistance genes (BCRP and MRP1) and the anti-apoptosis gene (survivin) demonstrated a wave of increase-further increase-further increase-decrease-increase (MRP1 decrease)-decrease. β-catenin, Oct 3/4 and SOX2 showed a positive correlation (r=1, p<0.01). Our study confirmed that the drug resistance of cancer cells is mainly due to tumor stem/initiating cells, and that under conditions of persistent chemotherapy, the quantity or function of breast cancer stem/initiating cells increases and decreases alternately.
癌症干细胞/起始细胞的耐药性被认为是肿瘤复发的主要原因之一。然而，关于化疗期间干细胞/起始细胞变化的知识有限。在本研究中，乳腺癌细胞系MDA-MB-468用5-氟尿嘧啶培养并连续传代。收集了六个细胞代次。采用半定量RT-PCR和流式细胞术技术评估干细胞/起始因子（CD44(+)/CD24(-)、Oct 3/4、SOX2和β-连环蛋白）、耐药基因（BCRP和MRP1）和抗凋亡基因（存活素）的蛋白质和mRNA表达。还检测了每代细胞的克隆形成率。结果表明，在持续化疗条件下，代表干细胞/起始细胞数量的因子（β-连环蛋白、Oct 3/4和SOX2）呈现出下降-上升-进一步上升-下降-上升-下降的波动趋势，代表干细胞/起始细胞比例的因子（CD44(+)/CD24(-)比例和克隆形成率）呈现出上升-进一步上升-进一步上升-下降的波动趋势。耐药基因（BCRP和MRP1）和抗凋亡基因（存活素）呈现出上升-进一步上升-进一步上升-下降-上升（MRP1下降）-下降的波动。β-连环蛋白、Oct 3/4和SOX2呈正相关（r=1，p<0.01）。我们的研究证实癌细胞的耐药性主要归因于肿瘤干细胞/起始细胞，并且在持续化疗条件下，乳腺癌干细胞/起始细胞的数量或功能交替增加和减少。
