title: Specific synthetic lethal killing of RAD54B-deficient human colorectal cancer cells by FEN1 silencing.
abstract: Mutations that cause chromosome instability (CIN) in cancer cells produce "sublethal" deficiencies in an essential process (chromosome segregation) and, therefore, may represent a major untapped resource that could be exploited for therapeutic benefit in the treatment of cancer. If second-site unlinked genes can be identified, that when knocked down, cause a synthetic lethal (SL) phenotype in combination with a somatic mutation in a CIN gene, novel candidate therapeutic targets will be identified. To test this idea, we took a cross species SL candidate gene approach by recapitulating a SL interaction observed between rad54 and rad27 mutations in yeast, via knockdown of the highly sequence- and functionally-related proteins RAD54B and FEN1 in a cancer cell line. We show that knockdown of RAD54B, a gene known to be somatically mutated in cancer, causes CIN in mammalian cells. Using high-content microscopy techniques, we demonstrate that RAD54B-deficient human colorectal cancer cells are sensitive to SL killing by reduced FEN1 expression, while isogenic RAD54B proficient cells are not. This conserved SL interaction suggests that extrapolating SL interactions observed in model organisms for homologous genes mutated in human cancers will aid in the identification of novel therapeutic targets for specific killing of cancerous cells exhibiting CIN.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, Canada, V6T 1Z4.
authors.forename: Kirk J
authors.initials: KJ
authors.lastname: McManus
authors.forename: Irene J
authors.initials: IJ
authors.lastname: Barrett
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Nouhi
authors.forename: Philip
authors.initials: P
authors.lastname: Hieter
mesh_terms: D017209:Apoptosis; D043171:Chromosomal Instability / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D004265:DNA Helicases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D009687:Nuclear Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D013379:Substrate Specificity; D046509:Tissue Culture Techniques
chemical_list: D009687:Nuclear Proteins; C491221:RAD54B protein, human; D045585:Flap Endonucleases; C468317:FEN1 protein, human; D004265:DNA Helicases