Antimetastatic gene expression profiles mediated by retinoic acid receptor beta 2 in MDA-MB-435 breast cancer cells.
BACKGROUND
The retinoic acid receptor beta 2 (RARbeta2) gene modulates proliferation and survival of cultured human breast cancer cells. Previously we showed that ectopic expression of RARbeta2 in a mouse xenograft model prevented metastasis, even in the absence of the ligand, all-trans retinoic acid. We investigated both cultured cells and xenograft tumors in order to delineate the gene expression profiles responsible for an antimetastatic phenotype.


METHODS
RNA from MDA-MB-435 human breast cancer cells transduced with RARbeta2 or empty retroviral vector (LXSN) was analyzed using Agilent Human 1A Oligo microarrays. The one hundred probes with the greatest differential intensity (p < 0.004, jointly) were determined by selecting the top median log ratios from eight-paired microarrays. Validation of differences in expression was done using Northern blot analysis and quantitative RT-PCR (qRT-PCR). We determined expression of selected genes in xenograft tumors.


RESULTS
RARbeta2 cells exhibit gene profiles with overrepresentation of genes from Xq28 (p = 2 x 10(-8)), a cytogenetic region that contains a large portion of the cancer/testis antigen gene family. Other functions or factors impacted by the presence of exogenous RARbeta2 include mediators of the immune response and transcriptional regulatory mechanisms. Thirteen of fifteen (87%) of the genes evaluated in xenograft tumors were consistent with differences we found in the cell cultures (p = 0.007).


CONCLUSIONS
Antimetastatic RARbeta2 signalling, direct or indirect, results in an elevation of expression for genes such as tumor-cell antigens (CTAG1 and CTAG2), those involved in innate immune response (e.g., RIG-I/DDX58), and tumor suppressor functions (e.g., TYRP1). Genes whose expression is diminished by RARbeta2 signalling include cell adhesion functions (e.g, CD164) nutritional or metabolic processes (e.g., FABP6), and the transcription factor, JUN.
Wallden
Brett
B
Department of Pathology, University of Washington, Box 357470, Seattle, WA, USA. bwallden@u.washington.edu
Emond
Mary
M
Swift
Mari E
ME
Disis
Mary L
ML
Swisshelm
Karen
K
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D041321:Chromosomes, Human, X; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D005838:Genotype; D006801:Humans; D007372:Interferons / Q000378:metabolism; D008024:Ligands; D051379:Mice; D015233:Models, Statistical; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009693:Nucleic Acid Hybridization; D010641:Phenotype; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014158:Transcription, Genetic; D014212:Tretinoin / Q000378:metabolism
D008024:Ligands; D016755:Proto-Oncogene Proteins c-jun; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; D014212:Tretinoin; D012313:RNA; D007372:Interferons