Huang M, Liu G
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union of Medical College, Beijing, People's Republic of China.
Cancer Lett. 1999 Jan 8;135(1):97-105. doi: 10.1016/s0304-3835(98)00280-8.
The innate drug resistance of human hepatocellular carcinoma (HCC) Bel7402 cell line was studied in vitro. MTT assay showed that Bel7402 cells were innately resistant to doxorubicin (Dox), and even more resistant to vincristine (VCR). This resistance could be effectively reversed by verapamil (Ver), one of the classical multidrug resistance (MDR) modulating agents. However, the differences in 5-fluorouracil (5-FU) toxicity between these two cell lines is much less and the resistance of Bel7402 cells could only be slightly reversed by Ver, which may be experimental noise. Immunocytochemical staining using anti-p-glycoprotein monoclonal antibody JSB-1 indicated that the expression of the P-glycoprotein (P-gp) in the innate Bel7402 cells was elevated compared with the sensitive KB cells. The accumulation of Dox in innate resistant Bel7402 cells was 50.7% lower than that in sensitive KB cells by using spectrofluometric analyses, and the accumulation of Dox increased 1.6 fold in Bel7402 cells in the presence of Ver. The susceptibility of Dox-induced apoptosis was also increased in the presence of Ver by using flow cytometric assay and DNA fragmentation quantitative assay as well as by Hoechst 33258 staining. It appears that the innate Bel7402 cells might be useful in screening new antitumour drugs or new chemosensitisers which could overcome the innate or acquired resistant mechanism, and the toxicity and reversal effects with 5-FU are different from those known to be P-gp substrates such as VCR, Dox, and taxol.
对人肝癌Bel7402细胞系的天然耐药性进行了体外研究。MTT法显示，Bel7402细胞对阿霉素（Dox）天然耐药，对长春新碱（VCR）的耐药性更强。维拉帕米（Ver）作为经典的多药耐药（MDR）调节剂之一，可有效逆转这种耐药性。然而，这两种细胞系对5-氟尿嘧啶（5-FU）的毒性差异要小得多，Ver只能轻微逆转Bel7402细胞的耐药性，这可能是实验误差。使用抗P-糖蛋白单克隆抗体JSB-1进行免疫细胞化学染色表明，与敏感的KB细胞相比，天然Bel7402细胞中P-糖蛋白（P-gp）的表达升高。通过荧光光谱分析，天然耐药的Bel7402细胞中阿霉素的蓄积量比敏感的KB细胞低50.7%，在Ver存在的情况下，Bel7402细胞中阿霉素的蓄积量增加了1.6倍。通过流式细胞术、DNA片段定量分析以及Hoechst 33258染色，在Ver存在的情况下，阿霉素诱导的细胞凋亡敏感性也增加。看来，天然Bel7402细胞可能有助于筛选能够克服天然或获得性耐药机制的新型抗肿瘤药物或新型化学增敏剂，并且其对5-FU的毒性和逆转作用与已知的P-gp底物如VCR、Dox和紫杉醇不同。
