title: LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast and colorectal cancer.
abstract: Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, using both loss of heterozygosity analysis and customized microarray comparative genomic hybridization. LARG (leukemia-associated Rho guanine-nucleotide exchange factor) (also called ARHGEF12), identified from the analysed region, is frequently underexpressed in breast and colorectal carcinomas with a reduced expression observed in all breast cancer cell lines (n=11), in 12 of 38 (32%) primary breast cancers, 5 of 10 (50%) colorectal cell lines and in 20 of 37 (54%) primary colorectal cancers. Underexpression of the LARG transcript was significantly associated with genomic loss (P=0.00334). Hypermethylation of the LARG promoter was not detected in either breast or colorectal cancer, and treatment of four breast and four colorectal cancer cell lines with 5-aza-2'-deoxycytidine and/or trichostatin A did not result in a reactivation of LARG. Enforced expression of LARG in breast and colorectal cancer cells by stable transfection resulted in reduced cell proliferation and colony formation, as well as in a markedly slower cell migration rate in colorectal cancer cells, providing functional evidence for LARG as a candidate tumor suppressor gene.
authors.affiliation: Division of Medical Sciences, National Cancer Centre, Singapore.
authors.forename: D C T
authors.initials: DC
authors.lastname: Ong
authors.forename: Y M
authors.initials: YM
authors.lastname: Ho
authors.forename: C
authors.initials: C
authors.lastname: Rudduck
authors.forename: K
authors.initials: K
authors.lastname: Chin
authors.forename: W-L
authors.initials: WL
authors.lastname: Kuo
authors.forename: D K H
authors.initials: DK
authors.lastname: Lie
authors.forename: C L M
authors.initials: CL
authors.lastname: Chua
authors.forename: P H
authors.initials: PH
authors.lastname: Tan
authors.forename: K W
authors.initials: KW
authors.lastname: Eu
authors.forename: F
authors.initials: F
authors.lastname: Seow-Choen
authors.forename: C Y
authors.initials: CY
authors.lastname: Wong
authors.forename: G S
authors.initials: GS
authors.lastname: Hong
authors.forename: J W
authors.initials: JW
authors.lastname: Gray
authors.forename: A S G
authors.initials: AS
authors.lastname: Lee
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics; D000077209:Decitabine; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008297:Male; D009693:Nucleic Acid Hybridization; D011401:Promoter Regions, Genetic / Q000235:genetics; D011500:Protein Synthesis Inhibitors; D064067:Rho Guanine Nucleotide Exchange Factors; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C577222:ARHGEF12 protein, human; D000964:Antimetabolites, Antineoplastic; D020662:Guanine Nucleotide Exchange Factors; D006877:Hydroxamic Acids; D011500:Protein Synthesis Inhibitors; D064067:Rho Guanine Nucleotide Exchange Factors; D025521:Tumor Suppressor Proteins; C012589:trichostatin A; D000077209:Decitabine; D001374:Azacitidine