Downregulation of HOPX controls metastatic behavior in sarcoma cells and identifies genes associated with metastasis.
Comparing the gene expression profiles of metastatic and nonmetastatic cells has the power to reveal candidate metastasis-associated genes, whose involvement in metastasis can be experimentally tested. In this study, differentially expressed genes were explored in the v-src-transformed metastatic cell line PR9692 and its nonmetastatic subclone PR9692-E9. First, the contribution of homeodomain only protein X (HOPX) in metastasis formation and development was assessed. HOPX-specific knockdown decreased HOPX expression in the nonmetastatic subclone and displayed reduced cell motility in vitro. Critically, HOPX knockdown decreased the in vivo metastatic capacity in a syngeneic animal model system. Genomic analyses identified a cadre of genes affected by HOPX knockdown that intersected significantly with genes previously found to be differentially expressed in metastatic versus nonmetastatic cells. Furthermore, 232 genes were found in both screens with at least a two-fold change in gene expression, and a number of high-confidence targets were validated for differential expression. Importantly, significant changes were demonstrated in the protein expression level of three metastatic-associated genes (NCAM, FOXG1, and ITGA4), and knockdown of one of the identified HOPX-regulated metastatic genes, ITGA4, showed marked inhibition of cell motility and metastasis formation. These data demonstrate that HOPX is a metastasis-associated gene and that its knockdown decreases the metastatic activity of v-src-transformed cells through altered gene expression patterns.


CONCLUSIONS
This study provides new mechanistic insight into a HOPX-regulated metastatic dissemination signature.
Institute of Molecular Genetics, Videnska 1083, CZ-14220 Prague 4, Czech Republic. hejnar@img.cas.cz.
Denisa
D
Kovárová
Jirí
J
Plachy
Jan
J
Kosla
Katerina
K
Trejbalová
Vladimír
V
Čermák
Jiří
J
Hejnar
D000818:Animals; D030161:Avian Proteins / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002465:Cell Movement; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002645:Chickens; D015536:Down-Regulation; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D016391:Genes, src; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D009362:Neoplasm Metastasis / Q000235:genetics*; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D012513:Sarcoma, Experimental / Q000235:genetics* / Q000473:pathology / Q000556:secondary
D030161:Avian Proteins; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D019006:Neural Cell Adhesion Molecules