Adenovirus-mediated wild-type p53 gene expression radiosensitizes non-small cell lung cancer cells but not normal lung fibroblasts.
OBJECTIVE
We compared the ability of adenoviral-mediated wild-type p53 RPR/INGN201(Ad5/CMV/p53) to radiosensitize non-small cell lung carcinoma (NSCLC) and normal lung fibroblast cells.


METHODS
NSCLC cell lines (A549 and H322) and human lung fibroblast cells (MRC-9 and CCD-16) were used in this study. Radiosensitivity was determined by clonogenic assay and tumor growth delay. Expression of p53, Bax, and p21WAF1 protein were evaluated by immunoblot. A FITC conjugate of annexin V was used for flow cytometric detection of apoptosis.


RESULTS
Clonogenic and apoptotic assays indicated that Ad5/CMV/p53 enhanced the radiosensitivity of both NSCLC cell lines. On the other hand, the two normal human fibroblast cell lines appeared to be resistant to the cytotoxic effects of Ad5/CMV/p53 and were not radiosensitized compared to the NSCLC cells. According to immunoblot analysis, Bax expression was increased in the NSCLC cells treated with the combination therapy; Bax expression, however, was unchanged in normal cells. In in vivo studies, tumor growth suppression was enhanced by this combination strategy in xenograft tumors growing in nude mice compared to Ad5/CMV/p53 or radiation therapy when used alone.


CONCLUSIONS
Our data indicate that therapy using Ad5/CMV/p53 and irradiation in combination is more effective than either treatment when used alone on NSCLC cells, is not limited to cells with defective endogenous p53, and does not enhance the radiosensitivity of normal cells.
Department of Experimental Radiation Oncology, The University of Texas, M. D. Anderson Cancer Center, Houston 77030, USA.
S
S
Kawabe
A
A
Munshi
L A
LA
Zumstein
D R
DR
Wilson
J A
JA
Roth
R E
RE
Meyn
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D017304:Annexin A5 / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D002455:Cell Division; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis; D004307:Dose-Response Relationship, Radiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000528:radiation effects*; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D018014:Gene Transfer Techniques; D016158:Genes, p53 / Q000235:genetics*; D006801:Humans; D008168:Lung / Q000528:radiation effects*; D008175:Lung Neoplasms; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2; D011836:Radiation Tolerance / Q000235:genetics; D013997:Time Factors; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*; D051028:bcl-2-Associated X Protein
D017304:Annexin A5; C494826:BAX protein, human; C494827:Bax protein, mouse; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D016650:Fluorescein-5-isothiocyanate