Combined targeted inhibition of bcl-2, bcl-XL, epidermal growth factor receptor, and protein kinase A type I causes potent antitumor, apoptotic, and antiangiogenic activity.
OBJECTIVE
This study investigated whether the functional and structural interactions between epidermal growth factor receptor (EGFR), protein kinase AI (PKAI), and bcl-2/bcl-xL could be exploited to obtain cooperative antitumor effects against models of human colon and breast cancer.


METHODS
Antisense bcl-2/bcl-xL (4625), antisense PKAI (AS-PKAI), and ZD1839 ("Iressa"), a selective EGFR tyrosine kinase inhibitor, were administered as single agents and in combination against GEO colon and ZR-75-1 breast cancer cell lines in vitro and to mice bearing s.c. GEO human tumor xenografts in vivo. Effects on growth inhibition, vascular endothelial growth factor secretion, and induction of apoptosis were assessed.


RESULTS
Antisense bcl-2/bcl-xL inhibited the growth of GEO and ZR-75-1 cells in vitro, reducing bcl-2 and bcl-xL expression and vascular endothelial growth factor secretion. Supra-additive growth inhibition and apoptosis induction were observed when 4625 was combined with ZD1839 or AS-PKAI. Combining all three agents resulted in a complete growth inhibitory effect in vitro. Antisense bcl-2/bcl-xL, AS-PKAI, and ZD1839 administered in vivo as single agents caused growth inhibition of GEO xenografts. Combining all three agents caused a marked and sustained effect, with 50% growth inhibition and 50% of mice tumor free 5 weeks after treatment withdrawal. The combination was well tolerated.


CONCLUSIONS
The combination of 4625, AS-PKAI, and ZD1839 resulted in a strong antiproliferative, proapoptotic, and antiangiogenic response, suggestive of a functional interaction between EGFR, PKAI, and bcl-2/bcl-xL and providing a rationale for the selection of specific molecular treatments for the development of therapeutic strategies. Iressa is a trademark of the AstraZeneca group of companies.
Tortora
Giampaolo
G
Dipartimento di Endocrinologia e Oncologia Molecolare e Clinica, Università di Napoli Federico II, 80131 Napoli, Italy. gtortora@unina.it
Caputo
Rosa
R
Damiano
Vincenzo
V
Caputo
Roberta
R
Troiani
Teresa
T
Veneziani
Bianca Maria
BM
De Placido
Sabino
S
Bianco
Angelo Raffaele
AR
Zangemeister-Wittke
Uwe
U
Ciardiello
Fortunato
F
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001943:Breast Neoplasms / Q000098:blood supply* / Q000473:pathology*; D016923:Cell Death; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D003110:Colonic Neoplasms / Q000098:blood supply* / Q000473:pathology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D016228:Endothelial Growth Factors / Q000378:metabolism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008222:Lymphokines / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors*; D011799:Quinazolines / Q000633:toxicity*; D014162:Transfection; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051020:bcl-X Protein
D000970:Antineoplastic Agents; C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D009841:Oligonucleotides; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D011799:Quinazolines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051020:bcl-X Protein; C423963:oligonucleotide 4625; D066246:ErbB Receptors; D017868:Cyclic AMP-Dependent Protein Kinases; D000077156:Gefitinib