Differential and epigenetic gene expression profiling identifies frequent disruption of the RELN pathway in pancreatic cancers.
OBJECTIVE
Recently described genome-wide approaches robustly detect many candidate genes that are regulated by DNA methylation, but many of these genes do not represent important targets for functional inactivation. Here we used a microarray-based strategy to identify biologically relevant genes associated with epigenetic silencing in pancreatic cancer.


METHODS
We compared information from differential gene expression analysis with the transcriptional responses to epigenetic modifiers.


RESULTS
Using this approach, we identified 7 novel targets for aberrant methylation in pancreatic cancer. One of the genes identified, RELN (Reelin), a key regulator of neuronal migration, is frequently silenced in pancreatic cancers, as are several of its downstream mediators. Importantly, small interfering RNA-mediated knockdown of RELN in pancreatic cancer cells that retain RELN expression resulted in greatly enhanced cell motility, invasiveness, and colony-forming ability. Increased cell motility was also induced by knockdown of downstream components of the RELN pathway, including ApoER2, VLDLR, and DAB1. Treatment of pancreatic cancer cells with histone deacetylase inhibitors, valproic acid and suberoylanilide hydroxamic acid, restored the expression of RELN and DAB1 and markedly inhibited their migration.


CONCLUSIONS
The high prevalence of the silencing of RELN pathway components and its reversal by histone deacetylase inhibitors suggest the importance of this pathway as a diagnostic and therapeutic target for pancreatic cancer.
Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA.
Norihiro
N
Sato
Noriyoshi
N
Fukushima
Rubens
R
Chang
Hiroyuki
H
Matsubayashi
Michael
M
Goggins
D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D019175:DNA Methylation; D017931:DNA Primers; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D020868:Gene Silencing; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000235:genetics; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D012334:RNA, Neoplasm / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000235:genetics*; D014162:Transfection
D015816:Cell Adhesion Molecules, Neuronal; D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D000091042:Reelin Protein; D008156:Luciferases; C000717127:RELN protein, human; D012697:Serine Endopeptidases