Effect of Connective Tissue Growth Factor on Hypoxia-Inducible Factor 1 Alpha Degradation and Tumour Angiogenesis
Resource
JOURNAL OF THE NATIONAL CANCER INSTITUTE v.98 n.14 pp.984-995
Journal
JOURNAL OF THE NATIONAL CANCER INSTITUTE
Journal Volume
v.98
Journal Issue
n.14
Pages
984-995
Date Issued
2006
Date
2006
Author(s)
CHANG, CHENG-CHI
LIN, MING-TSAN
Abstract
Background: Connective tissue growth factor (CTGF) inhibits the metastatic activity of human lung cancer cells in a mouse model; however, the mechanism of this modulation is unclear. We investigated the role of angiogenesis in this process. Methods: CL1-5 and A549 human lung adenocarcinoma cells were stably transfected with vectors containing CTGF or hypoxia-inducible factor (HIF) la or with vector controls . Transfected cells were injected into nude mice (n = 10 per group), and tumor growth, metastasis, and mouse survival were measured. Excised xenograft tumors and primary human lung adenocarcinomas (n = 24) were subjected to immunohistochemistry with antibodies to the endothelial cell marker CD31 and to CTGF. Expression of HIF-1 alpha and vascular endothelial growth factor (VEGF) A was assessed in vitro by using reporter gene assays. Cells were transiently transfected with HIF-1 alpha mutant and antisense arrest - defective 1 protein (ARD-1), and HIF-1 alpha acetylation was assayed by immunoprecipitation. All statistical tests were two-sided. Results: Xenograft tumors derived from CTGF transfectants grew more slowly than those from control- transfected cells and had reduced expression of HIF-1a and VEGF-A, vascularization (as assessed by CD31 expression), and metastasis (all P <.001). Xenograft tumors derived from CTGF- overexpressing cells that were transfected with HIF-1 alpha had higher VEGF-A expression than CTGF-overexpressing xenografts. Mice with CTGF/HIF- 1 alpha xenografts had lower survival than mice carrying CTGF- overexpressing xenografts ( CL1-5/Neo, mean = 69.6 days, 95% confidence interval [CI] - 53.9 to 85.3 days versus CL1-5/CTGF, mean = 102.1 days, 95 % CI = 92.1 to 112.1 days; P =.001, CL1-5/CTGF, mean = 102.1 days, 95% CI = 92.1 to 112.1 days versus CL1-5/CTGF/HIF-1 alpha, mean = 81.7 days, 95% CI = 66.5 to 96.9 days; P =.011 , CL1-5/Neo, mean = 69.6 days, 95% CI = 53 .9 to 85.3 days versus CL1-5/CTGF/HIF-1 alpha, mean =81.7 days, 95% CI = 66. 5 to 96.9 days; P =.122). Tumors of patients with the same disease stage but with high CTGF protein expression had reduced microvessel density compared with tumors with low expression. Transfection with antisense-ARDI decreased the level of acetylated HIF-1 alpha and restored HIF-1 alpha and VEGF-A expression in CTGF-overexpressing cells. Conclusion : CTGF inhibition of metastasis involves the inhibition of VEGF-A- dependent angiogenesis, possibly by promoting HIF-1 alpha protein degradation.
Subjects
VASCULAR ENDOTHELIAL-CELLS
CHONDROCYTE-SPECIFIC GENE
COLON- CANCER CELLS
LUNG-CANCER
PROLYL HYDROXYLATION
FACTOR EXPRESSION
SDGs
Type
journal article