title: Multidrug-resistant cells overexpressing P-glycoprotein are susceptible to DNA crosslinking agents due to attenuated Src/nuclear EGFR cascade-activated DNA repair activity.
abstract: We synthesized several novel bifunctional alkylating derivatives of 3a-aza-cyclopenta[a]indene (BO-1012, BO-1005, BO-1099 and BO-1101) that are potent DNA interstrand crosslinking agents. In in vitro cytotoxicity assay, these compounds were more cytotoxic to multidrug-resistant (MDR) cells, such as KBvin10, KBtax50 and CEM/VBL, than their parental cells. Using a xenograft model, BO-1012, at a dose of 5 mg/kg, partially suppressed the growth of parental KB cells but completely suppressed the growth of KBvin10 cells in nude mice. In exploring the possible mechanism, we found that DNA double-strand break (DSB) repair activity in MDR cells, KBvin10 and CEM/VBL, was significantly reduced compared with their parental cells, KB and CEM. Reduced DSB repair activity in KBvin10 cells was likely due to a defect in nuclear translocation of DNA-dependent protein kinase (DNA-PK), a component of the non-homologous end-joining repair machinery. Furthermore, BO-1012-induced DNA-PK translocation from the cytosol into the nucleus in KB cells is associated with the activation of the Src/nuclear epidermal growth factor receptor (EGFR) cascade, which is defective in MDR cells. As knockdown of P-glycoprotein (P-gp) by siRNA reactivated the Src/nuclear EGFR cascade, DNA-PK translocation and DNA repair activity in MDR cells, overexpression of P-gp attenuates the activity of DNA DSB repair through suppression of Src/nuclear EGFR cascade. Therefore, DNA interstrand crosslinking agents may have potential therapeutic use against P-gp-overexpressing MDR cells.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: P-C
authors.initials: PC
authors.lastname: Lee
authors.forename: H-J
authors.initials: HJ
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Kakadiya
authors.forename: K
authors.initials: K
authors.lastname: Sanjiv
authors.forename: T-L
authors.initials: TL
authors.lastname: Su
authors.forename: T-C
authors.initials: TC
authors.lastname: Lee
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000477:Alkylating Agents / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004260:DNA Repair; D018432:Drug Resistance, Multiple; D066246:ErbB Receptors / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000477:Alkylating Agents; D066246:ErbB Receptors; D015688:Oncogene Protein pp60(v-src)