The study of innate drug resistance of human hepatocellular
carcinoma Bel
7402
cell line
Min Huang, GengTao Liu
*
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union of Medical College,
Beijing 100050, People's Republic of China
Received 17 June 1998; received in revised form 27 August 1998; accepted 31 August 1998
Abstract
The innate drug resistance of human hepatocellular carcinoma (HCC) Bel
7402
cell line was studied in vitro. MTT assay
showed that Bel
7402
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-¯uorouracil (5-FU) toxicity between these two cell lines is much less and the resistance of Bel
7402
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 Bel
7402
cells
was elevated compared with the sensitive KB cells. The accumulation of Dox in innate resistant Bel
7402
cells was 50.7% lower
than that in sensitive KB cells by using spectro¯uometric analyses, and the accumulation of Dox increased 1.6 fold in Bel
7402
cells in the presence of Ver. The susceptibility of Dox-induced apoptosis was also increased in the presence of Ver by using ¯ow
cytometric assay and DNA fragmentation quantitative assay as well as by Hoechst 33258 staining. It appears that the innate
Bel
7402
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. q 1999 Elsevier Science Ireland Ltd. All rights reserved.
Keywords: Human hepatocellular carcinoma; Innate resistance; Doxorubicin; 5-Fluorouracil; Verapamil
1. Introduction
It is well known that hepatocellular carcinoma
(HCC) is one of the malignant tumours with poor
chemosensitivity to anticancer agents. Besides factors
such as lower ¯ow capacity of blood in the solid
tumour and lower permeability to drugs, both intrinsic
drug resistance and acquired drug resistance are
obstacles in HCC chemotherapy. During our study
on the establishment of a drug resistant model of
human HCC, it was found, unexpectedly, that the
human HCC Bel
7402
cell line established from patho-
logically proven human hepatocellular carcinoma by
Cheng et al. [1] possesses innate resistance to Dox, the
®rst choice drug for therapy of HCC. Thus, we have
studied the characteristics of intrinsic resistance of the
Bel
7402
cell line.
2. Materials and methods
2.1. Drugs and chemicals
5-Fluororacil (5-FU) (Shanghai Pudong Haipu
Cancer Letters 135 (1999) 97±105
0304-3835/99/$ - see front matter q 1999 Elsevier Science Ireland Ltd. All rights reserved.
PII: S0304-3835(98)00280-8
* Corresponding author. Tel.: 1 86-10-63165178; fax: 1 86-
10-63017757; e-mail: liugtwur@public.bta.net.cn.