[Reversal of multidrug resistance of human hepatocellular carcinoma cells by wild-type p53 gene and related mechanisms].
OBJECTIVE
The mechanism of cell apoptosis plays an important role in tumor multidrug resistance (MDR). Wild-type p53 (wt-p53) gene is an activator of cell apoptosis, and is closely related to tumor MDR. This study was to explore the effect of p53 gene on the reversal of MDR of human hepatocellular carcinoma (HCC) and related mechanisms.


METHODS
The eukaryotic expression plasmid pCR 3.1-p53 was constructed and transfected into human HCC cell line Bel-7402. Proliferation and chemosensitivity of Bel-7402 cells to vincristine (VCR) were measured by MTT assay. The morphology of transfected Bel-7402 cells was observed. The expression of P-glycoprotein (P-gp) was detected by immunochemistry. The expression of multidrug resistance gene 1 (mdr1), multidrug resistance related protein (MRP), glutathione S-transferase pi (GST pi), and topoisomerase II alpha (Topo II alpha) were detected by reverse transcription-polymerase chain reaction (RT-PCR).


RESULTS
The growth of wt-p53-transfected Bel-7402 cells was obviously slower than that of untransfected cells. After transfection with wt-p53, the chemosensivity of Bel-7402 cells to VCR was enhanced at the concentration of 0.01, 0.1, 1.0, 10, and 25 microg/ml. The optimal concentration was 1.0 microg/ml. After wt-p53 transfection and VCR treatment, the number of Bel-7402 cells was decreased; the cells were swollen severely with irregular projections; pyknosis, karyorrhexis and karyolysis were observed. After wt-p53 transfection, the expression of mdr1 and P-gp in Bel-7402 cells was down-regulated remarkably, and the expression of Topo II alpha was up-regulated.


CONCLUSIONS
Wild-type p53 gene raises chemosensitivity of Bel-7402 cells to VCR, which may be partly related to the down-regulation of mdr1 and up-regulation of Topo II alpha.
Gai
Xiao-Dong
XD
Department of Pathologic Anatomy, Medical College, Beihua University, Jilin, Jilin, 132013, P. R. China. gaixiaodong@yahoo.com.cn
Li
Guo-Li
GL
Huang
Jing-Zi
JZ
Xue
Hong-Jie
HJ
Wang
Dan
D
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004250:DNA Topoisomerases, Type II / Q000096:biosynthesis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D016158:Genes, p53; D051549:Glutathione S-Transferase pi / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D014750:Vincristine / Q000494:pharmacology*
C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000951:Antigens, Neoplasm; D000972:Antineoplastic Agents, Phytogenic; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D014750:Vincristine; D051549:Glutathione S-Transferase pi; D004250:DNA Topoisomerases, Type II