Development of Ad-mda7/IL-24-resistant lung cancer cell lines.
Many cancers can become resistant to repeated administration of even the most effective therapeutic agents. In developing adenoviral mda-7/IL-24 (Ad-mda-7/IL-24) therapy for lung cancer, we have anticipated this potential clinical problem by attempting to identify the molecular mechanisms of Ad-mda7/IL-24 resistance in several Ad-mda7/IL-24-resistant lung cancer cell lines that we have developed. For the present study, we established four Admda7- resistant cell lines by repeated selection of resistant clones of parental Ad-mda7-sensitive A549 cells: two lines (A549R1 and A549R2) resistant to both adenoviral vector and the mda-7 gene and two (A549R3 and A549R4) resistant to the therapeutic mda-7 gene only. As shown by western blot analysis of several known anti-apoptotic proteins, parental A549 and resistant A549R3 cells expressed similar levels of AKT and phosphorylated AKT (p-AKT), whereas resistant A549R3 and A549R4 cells expressed higher levels of bcl-2 and lower levels of bcl-xL than did their parental cells. As shown by flow-cytometric analysis, treating resistant A549R3 and A549R4 cells with a combination of Ad-mda7 and 17-allyl-amino-17-demethoxygeldanamycin (17AAG) (50 nM) for 48 hours enhanced apoptosis. Together, these in vitro findings indicate that an antiapoptotic mechanism may underlie Ad-mda7 resistance and that such resistance can be overcome by addition of 17AAG. Further investigations along these lines are warranted.
Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA. apataer@mdanderson.org
Abujiang
A
Pataer
Sunil
S
Chada
Jack A
JA
Roth
Kelly K
KK
Hunt
Stephen G
SG
Swisher
D000256:Adenoviridae / Q000235:genetics; D016227:Benzoquinones / Q000627:therapeutic use; D045744:Cell Line, Tumor; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D015316:Genetic Therapy; D006801:Humans; D007378:Interleukins / Q000032:analysis / Q000235:genetics*; D047029:Lactams, Macrocyclic / Q000627:therapeutic use; D008175:Lung Neoplasms / Q000628:therapy*; D051057:Proto-Oncogene Proteins c-akt / Q000032:analysis; D011991:Receptors, Virus / Q000032:analysis; D000099180:Interleukin-24
D016227:Benzoquinones; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D007378:Interleukins; D047029:Lactams, Macrocyclic; D051057:Proto-Oncogene Proteins c-akt; D011991:Receptors, Virus; D000099180:Interleukin-24; C568771:CLMP protein, human; C112765:tanespimycin