A homeobox gene related to Drosophila distal-less promotes ovarian tumorigenicity by inducing expression of vascular endothelial growth factor and fibroblast growth factor-2.
Homeobox genes control developmental patterning and are increasingly being found to be deregulated in tumors. The DLX4 homeobox gene maps to the 17q21.3-q22 region that is amplified in some epithelial ovarian cancers. Because amplification of this region correlates with poor prognosis, we investigated whether DLX4 overexpression contributes to aggressive behavior of this disease. DLX4 was not detected in normal ovary and cystadenomas, whereas its expression in ovarian carcinomas was strongly associated with high tumor grade and advanced disease stage. Overexpression of DLX4 in ovarian cancer cells promoted growth in low serum and colony formation. Imaging of mice bearing intraperitoneal tumors revealed that DLX4 overexpression substantially increased tumor burden. Tumors that overexpressed DLX4 were more vascularized than vector-control tumors. Conditioned medium of DLX4-overexpressing tumor cells was more effective than medium conditioned by vector-control cells in stimulating endothelial cell growth. These observations were associated with the ability of DLX4 to induce expression of vascular endothelial growth factor as well as intracellular and secreted isoforms of fibroblast growth factor-2. Moreover, increased levels of these fibroblast growth factor-2 isoforms induced vascular endothelial growth factor expression in tumor cells. This study reveals a novel role for a homeobox gene in ovarian tumorigenicity by its induction of a proangiogenic, growth-stimulatory molecular program.
Hara
Fumikata
F
Department of Molecular Therapeutics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77054, USA.
Samuel
Shaija
S
Liu
Jinsong
J
Rosen
Daniel
D
Langley
Robert R
RR
Naora
Honami
H
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis*; D015870:Gene Expression; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D010051:Ovarian Neoplasms / Q000378:metabolism*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
C105304:DLX4 protein, human; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2