The tumorigenicity of the transduced H460a cells was studied in 
an orthotopic lung cancer model. Intratracheal inoculation of 
' H460a cells in irradiated (350cGy) nu/nu mice resulted in the 
I growth of endobronchial tumors with mediastinal extension in 
>80% of mice after 4 weeks. The H460a-AS-LNSX, H460a-LNSX, 
and H460a cells (10 5 /mouse) were injected endotracheally in 0.1 
ml of medium and the mediastinal block was harvested after 4 
weeks. Mice were assessed for tumor growth without knowledge 
of the treatment group. Seven of 9 mice inoculated with H460a- 
LNSX (mean volume 12.5 ± 2.2 SE mm 3 ) and 12 of 14 mice 
inoculated with H460a parental cells (mean volume 39.9 ± 4.25 
SE mm 3 ) had tumors. Only 3 of 17 mice receiving H460a-AS- 
LNSX cells had tumors (mean volume 2.95 ± 1.25 mm 3 ). We 
conclude that 1) retroviral gene transduction can be used to 
express anti-sense constructs in human tumor cells at levels that 
mediate a biologic effect; 2) AS-mediated inhibition of activated K- 
ras expression effectively inhibits proliferation and tumorigenicity of 
human cancer cells. Expression of the AS-LNSX expression in the 
H460a cells has been stable up to 6 months. 
In a second experiment, H460a cells (10 5 /mouse) were injected 
into the right mainstem bronchus via a tracheostomy incision. 
Three days later mice were inoculated endobronchially with 0.15 
ml of retroviral supernate or control medium for 3 days. Tumor 
growth was suppressed in the group receiving supernate from 
LNSX-AS producer cells (Table 1). Histologic light microscopic 
study of 3 specimens from the LNSX-AS group did not reveal any 
residual H460a cells. 
Table 1: Endotracheal inoculation of retroviral supernate for treatment of established (3 day) 
H460a human lung cancers growing endobronchially in nu/nu mice. The H460a cells were 
injected at 10 5 per mouse. The titer of the retroviral supernate was 5X1 0 6 CFU/ml. Mice 
were injected with 0.15ml of supernate daily for 3 days. 
Producer Cell 
s CFU/dose 
No, of Tumors/ 
No, of Mice (%) 
Mean Tumor Volume _+ SE 
H460a 
0 
7/8 
(87.5%) 
42.3 _+ 7.9 
LNSX 
7.5X1 0 5 
7/8 
(87.5%) 
44.9 ± 10.1 
LNSX-AS 
7.5X1 0 5 
1/6 
(16.7%) 
7.7' 
* Volume of the single tumor that occurred in this group 
Recombinant DNA Research, Volume 16 
[427] 
