5-fluorouracil and hydroxyurea enhance adenovirus-mediated transgene expression in colon and hepatocellular carcinoma cells.
OBJECTIVE
To investigate the efficient transduction of tumor cells which remains a major limitation of cancer gene therapy.


METHODS
In this study, we tested whether treatment with antimetabolic drugs 5-FU and hydroxyurea (HU) could improve adenovirus-mediated gene expression in tumor cells.


RESULTS
We found that 5-FU and HU treatment significantly increased beta-gal activity in adenovirus (Ad.CMVBG)-infected human colon carcinoma (LoVo) and hepatocellular carcinoma (SMMC7721) cells in a dose- and time-dependent manner. These increases were maximized at 5.01+/-0.42-fold and 3.32+/-0.32-fold for 5-FU (50 microM), and at 6.60+/-0.50-fold and 4.82+/-0.43-fold for HU (5 mM) treatment, respectively, after 48 h infection. Transient increases in viral uptake, determined by real-time PCR for viral DNA content and by confocal microscopy for viral particles, were observed in 5-FU or HU-treated cells that partially contribute to the overall increases of beta-gal expression. Moreover, mRNA levels for the beta-gal gene in infected cells were significantly increased in both LoVo and SMMC7721 cells by 5-FU and HU treatment in contrast to the inhibition of viral DNA replication and the unchanged mRNA levels for alpha-actin gene. The induction appeared to be the result of enhanced transcription since beta-gal mRNA half-life was not affected by drug treatment. However, similar induction was not detected in CMV-beta-gal-expressing stable cells, suggesting that an adenovirus-associated mechanism might be involved in this induction.


CONCLUSIONS
Our findings suggest that it may be possible to improve tumor cell transduction by adenovirus using chemotherapy.
Huang
Xiao W
XW
Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109-0582, USA.
Tang
Zhao Y
ZY
Lawrence
Theodore S
TS
Zhang
Ming
M
D000256:Adenoviridae; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000378:metabolism*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D004279:DNA, Viral; D004305:Dose-Response Relationship, Drug; D005472:Fluorouracil / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005822:Genetic Vectors; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D018613:Microscopy, Confocal; D016133:Polymerase Chain Reaction; D013997:Time Factors; D019076:Transgenes / Q000187:drug effects*; D001616:beta-Galactosidase / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D004279:DNA, Viral; D001616:beta-Galactosidase; D005472:Fluorouracil; D006918:Hydroxyurea