Tissue-specific growth suppression and chemosensitivity promotion in human hepatocellular carcinoma cells by retroviral-mediated transfer of the wild-type p53 gene

✍ Scribed by G W Xu; Z T Sun; K Forrester; X W Wang; J Coursen; C C Harris

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 646 KB
• Volume: 24
• Category: Article
• ISSN: 0270-9139
• DOI: 10.1002/hep.510240546

✦ Synopsis

HCC patients are generally resistant to chemotherapy, Selective expression of cytotoxic gene products in tuwhich, in some cases, may be the result of a loss of function mor cells is one of the goals of gene therapy for treating mutation in the p53 gene. cancer. We are developing such a strategy for the treat-Gene therapy is one developing approach for the treatment ment of human hepatocellular carcinoma (HCC) by linkof human cancer. 10 The association of p53 with human HCC ing the wild-type p53 (WT-p53) gene with HCC-associin these high-risk geographic areas offers a unique opportuated transcriptional control elements (TCE) to achieve nity for the treatment of this disease. One strategy would selective growth inhibition of retrovirally transduced involve the introduction of the WT-p53 gene into HCC cells HCC cells. Replication-defective, amphotrophic retrovivia a replication-defective retrovirus. Restoration of WT-p53 ruses were constructed containing a WT-p53 complefunction may result in a reversal of the cancer phenotype and mentary DNA (cDNA) that is transcriptionally regulated increase sensitivity to chemotherapeutic drugs. Huber et al. by the HCC-associated a-fetoprotein (AFP) gene TCE. and Macri and Gordon used a strategy to selectively target Expression of exogenous WT-p53 from this retroviral tumor cells by creating a chimeric gene composed of tissuevector was limited to AFP-producing cells. Introduction specific transcriptional control elements (TCE) lined to the of WT-p53 into AFP-positive HCC cells by retroviral ingene of interest. 11,12 The 5-flanking region of the human afection markedly inhibited their clonal growth in monofetoprotein (AFP) gene contains cell-specific transcriptional layer and soft agar cultures, and increased the sensitivelements (AFP TCE), which function in AFP-producing HCC ity of these cells to the chemotherapeutic drug, cisplatin.

cells but not in normal adult hepatocytes to cause tissue-Therefore, restoration of WT-p53 expression in HCC specific expression. 12 Therefore, linkage of the WT-p53 gene cells, in combination with chemotherapeutic drugs, can to the AFP TCE would result in tumor-specific expression be considered as a strategy for the therapy of human of the exogenous p53, and consequently, tumor cell-specific liver cancer. (HEPATOLOGY 1996;24:1264-1268.)

growth inhibition, as well as increase the sensitivity of these cells to cancer therapeutic drugs.

Mutations of the p53 tumor suppressor gene are frequently

We have designed a strategy to transduce the WT-p53 gene found in human hepatocellular carcinomas (HCC), especially into human liver cancer cells for the treatment of this maligin tumors from geographic areas where hepatitis B virus and nancy. A retroviral vector containing AFP TCE/WT-p53 chidietary aflatoxin B 1 exposure are risk factors. In these areas, mera was created to generate tissue-specific expression of most of the p53 mutations are located at the third nucleotide WT-p53 in HCC cells. Infection of AFP-producing HCC cells position of codon 249. 1-4 A dose-dependent relationship begrown in culture with this retrovirus resulted in tumor celltween dietary aflatoxin B 1 intake and codon 249 ser mutation specific expression of WT-p53 and growth inhibition, and inof p53 is observed in HCC from Asia, Africa, and North creased sensitivity to the chemotherapeutic drug, cisplatin. America. 5 In addition, the mutation load of 249 ser mutant cells in nontumorous liver tissue is positively correlated with

Methods

dietary aflatoxin B 1 exposure. 6 Exposure of human liver cells Materials. Plasmid pC53-SN 13 containing a 1.8-kilobase (kb) huto aflatoxin B 1 in vitro produces 249 ser (AGG to AGT) p53 man WT-p53 complementary DNA (cDNA) and plasmid PG 13 -CAT 14 mutations. 7 These results indicate that expression of the were obtained from B. Vogelstein (Johns Hopkins University). pXT1 249 ser mutant p53 protein provides a specific growth and/or was obtained from Stratagene (La Jolla, CA). Human AFP TCE se- survival advantage to human liver cells and are consistent quences were isolated from plasmid pAF5.1-CAT 12 and were provided with the hypothesis that p53 mutations can occur early in by T. Tamaoki (