title: Expression of BRCC3, a novel cell cycle regulated molecule, is associated with increased phospho-ERK and cell proliferation.
abstract: Raf-1 protein serine/threonine kinase plays an important role in ERK signal transduction pathway of cell survival and proliferation. Raf-induced transcriptional changes are dependent on phosphorylation/activation of ERK. However, regulation of phospho-ERK (p-ERK) via Raf transcriptome is as yet unknown. We report the initial characterization of BRCC3, a novel gene discovered previously by mRNA expression profiling in MDA-MB 231 human breast cancer cells treated with Raf antisense oligonucleotide. BRCC3 is localized at human chromosome 5q12.1. BRCC3 open reading frame consists of 529 amino acids, coding for an approximate 60-kDa predominantly membrane-associated protein. Expression levels of BRCC3 mRNA and protein are high during G2/M phase of the cell cycle in breast cancer cells. Treatment of MDA-MB 231 cells with Raf-1 siRNA resulted in decreased expression of Raf-1, BRCC3 and p-ERK, but not B-Raf. Transient or stable expression of the epitope-tagged BRCC3 cDNA was associated with increased p-ERK in three different cell lines. Consistently, BRCC3 siRNA treatment of MDA-MB 231 cells caused decreased expression of BRCC3 and p-ERK. Furthermore, exogenous BRCC3 expression was associated with a delay in etoposide-induced cell death and an increase in cell proliferation. These findings demonstrate that BRCC3 is a novel effector of Raf-1, and implicate a role of BRCC3 in modulation of p-ERK, cell survival and proliferation.
authors.affiliation: Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington DC 20057, USA.
authors.forename: Howard E
authors.initials: HE
authors.lastname: Boudreau
authors.forename: Constantinos G
authors.initials: CG
authors.lastname: Broustas
authors.forename: Prafulla C
authors.initials: PC
authors.lastname: Gokhale
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.forename: Rajshree R
authors.initials: RR
authors.lastname: Mewani
authors.forename: Janice D
authors.initials: JD
authors.lastname: Rone
authors.forename: Bassem R
authors.initials: BR
authors.lastname: Haddad
authors.forename: Usha
authors.initials: U
authors.lastname: Kasid
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002522:Chlorocebus aethiops; D002874:Chromosome Mapping; D000072017:Deubiquitinating Enzymes; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D034741:RNA, Small Interfering; D014162:Transfection
chemical_list: D018797:Cell Cycle Proteins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; C518017:BRCC3 protein, human; D000072017:Deubiquitinating Enzymes