Abrogation of lung metastasis of human fibrosarcoma cells by ribozyme-mediated suppression of integrin alpha6 subunit expression.
The interaction of tumor cells with the basement membrane plays a crucial role in tumor metastasis. VLA-6 (alpha6beta1) integrin is one of the major surface receptors for the basement membrane, specifically recognizing laminin. To study the role of VLA-6 integrin in tumor invasion and metastasis, we synthesized a ribozyme that selectively degrades the integrin alpha6 subunit mRNA. The catalytic activity of the ribozyme was verified by in vitro cleavage of alpha6 subunit mRNA. Introduction of the anti-alpha6 ribozyme gene into the human fibrosarcoma cell line HT1080 yielded stable transfectants, which expressed a significantly reduced level of integrin alpha6 mRNA. Flow cytometric analysis showed that the surface expression of VLA-6, but not other integrins, was reduced by approximately 70% in transfected cells. Ribozyme-transfected cells were less adherent to laminin-coated substrata and less invasive into reconstituted basement membrane than mock-transfected cells. When injected i.v. into nude mice, ribozyme-transfected cells produced no lung metastasis in all except 1 of 35 mice, though mock-transfected cells produced multiple lung metastases in 22 of 29 mice. Our results indicate that VLA-6 integrin plays a critical role in tumor invasion and metastasis and may serve as a potential target for eradication of tumor metastasis in the lung.
Yamamoto
H
H
Research Institute, Osaka, Japan.
Irie
A
A
Fukushima
Y
Y
Ohnishi
T
T
Arita
N
N
Hayakawa
T
T
Sekiguchi
K
K
D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002448:Cell Adhesion; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology*; D006801:Humans; D039503:Integrin alpha6; D008175:Lung Neoplasms / Q000556:secondary*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D016337:RNA, Catalytic / Q000494:pharmacology*; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; D039503:Integrin alpha6; D016337:RNA, Catalytic