IRF-1 expression induces apoptosis and inhibits tumor growth in mouse mammary cancer cells in vitro and in vivo.
Interferon regulatory factor-1 (IRF-1) is a nuclear transcription factor that mediates interferon and other cytokine effects and appears to have antitumor activity in vitro and in vivo in cancer cells. We have constructed a recombinant adenoviral vector (Ad-IRF-1) that infects mammary cells with high efficiency and results in high levels of functional IRF-1 protein in transfected cells. Overexpression of IRF-1 in two mouse breast cancer cell lines, C3-L5 and TS/A, resulted in apoptosis in these cell lines as assessed by Annexin V staining. The involvement of caspases was confirmed by significant inhibition of apoptosis by a caspase inhibitor, and by demonstration of caspase-3 activity, cleavage of caspase-3, and PARP cleavage. Interestingly, the growth of nonmalignant breast cell lines C127I and NMuMG did not appear to be inhibited by IRF-1 overexpression. Suppression of growth for breast cancer cell lines in vivo was demonstrated by both preinfection of breast cancer cells ex vivo and by intratumoral injection of Ad-IRF-1 into established tumors in their natural hosts. The mechanism of apoptosis may involve the transcriptional upregulation of bak, caspase-8, and caspase-7 expression. These data support the antitumor potential of IRF-1 and the use of agents that increase IRF-1 in breast cancer.
Kim
Peter K M
PK
Department of Surgery, University of Pittsburgh Medical Center, 497 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
Armstrong
Michaele
M
Liu
Ye
Y
Yan
Peng
P
Bucher
Brian
B
Zuckerbraun
Brian S
BS
Gambotto
Andrea
A
Billiar
Timothy R
TR
Yim
John H
JH
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D020169:Caspases / Q000032:analysis; D002460:Cell Line; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D007279:Injections, Subcutaneous; D050856:Interferon Regulatory Factor-1; D008321:Mammary Glands, Animal; D015674:Mammary Neoplasms, Animal / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000032:analysis; D014185:Transplantation, Isogeneic
D004268:DNA-Binding Proteins; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D010750:Phosphoproteins; D011506:Proteins; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases