T. Fujiwara et al., THERAPEUTIC EFFECT OF A RETROVIRAL WILD-TYPE P53 EXPRESSION VECTOR INAN ORTHOTOPIC LUNG-CANCER MODEL, Journal of the National Cancer Institute, 86(19), 1994, pp. 1458-1462
Background: Mutations in the p53 tumor suppressor gene (also known as
TP53) are common in human lung cancers. The wild-type form of p53 is d
ominant over the mutant; thus, restoration of wild-type p53 function i
n lung cancer cells may suppress their growth as tumors. Purpose: We i
nvestigated the therapeutic efficacy of direct administration of a ret
roviral wild-type p53 (wt-p53) expression vector (LNp53B) in an orthot
opic human lung cancer model in nu/nu mice. Methods: Proliferation of
H226Br cells was determined by cell counting after infection with LNp5
3B in vitro. Irradiated (350 cGy) female BALB/c nu/nu mice were inocul
ated intratracheally with 2 x 10(6) H226Br cells (whose p53 gene has a
homozygous mutation at codon 254) and treated beginning 3 days later
with an intratracheal instillation of LNp53B retroviral supernatant fo
r 3 days. Results: Infection with LNp53B inhibited proliferation of H2
26Br cells in vitro. Thirty days after tumor cell inoculation, 62%-80%
of the control mice showed macroscopic tumors of the right main stem
bronchus. LNp53B suppressed H226Br tumor formation in 62%-100% of mice
, and the effect was abrogated by dilution of the retroviral supernata
nt with inactive vector. Conclusions: Direct administration of a retro
viral vector expressing wt-p53 may inhibit local growth in vivo of hum
an lung cancer cells with abnormal p53 expression. Implications: Devel
opment of gene-replacement treatment strategies based on the type of m
utations found in target cancers is warranted and may lead to the deve
lopment of new adjunctive therapies and gene-specific prevention strat
egies for lung cancer.