title: ALDH1A1 maintains ovarian cancer stem cell-like properties by altered regulation of cell cycle checkpoint and DNA repair network signaling.
abstract: OBJECTIVE
  Aldehyde dehydrogenase (ALDH) expressing cells have been characterized as possessing stem cell-like properties. We evaluated ALDH+ ovarian cancer stem cell-like properties and their role in platinum resistance.
  
  
  METHODS
  Isogenic ovarian cancer cell lines for platinum sensitivity (A2780) and platinum resistant (A2780/CP70) as well as ascites from ovarian cancer patients were analyzed for ALDH+ by flow cytometry to determine its association to platinum resistance, recurrence and survival. A stable shRNA knockdown model for ALDH1A1 was utilized to determine its effect on cancer stem cell-like properties, cell cycle checkpoints, and DNA repair mediators.
  
  
  RESULTS
  ALDH status directly correlated to platinum resistance in primary ovarian cancer samples obtained from ascites. Patients with ALDHHIGH displayed significantly lower progression free survival than the patients with ALDHLOW cells (9 vs. 3 months, respectively p<0.01). ALDH1A1-knockdown significantly attenuated clonogenic potential, PARP-1 protein levels, and reversed inherent platinum resistance. ALDH1A1-knockdown resulted in dramatic decrease of KLF4 and p21 protein levels thereby leading to S and G2 phase accumulation of cells. Increases in S and G2 cells demonstrated increased expression of replication stress associated Fanconi Anemia DNA repair proteins (FANCD2, FANCJ) and replication checkpoint (pS317 Chk1) were affected. ALDH1A1-knockdown induced DNA damage, evidenced by robust induction of γ-H2AX and BAX mediated apoptosis, with significant increases in BRCA1 expression, suggesting ALDH1A1-dependent regulation of cell cycle checkpoints and DNA repair networks in ovarian cancer stem-like cells.
  
  
  CONCLUSIONS
  This data suggests that ovarian cancer cells expressing ALDH1A1 may maintain platinum resistance by altered regulation of cell cycle checkpoint and DNA repair network signaling.
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Erhong
authors.initials: E
authors.lastname: Meng
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Aparna
authors.initials: A
authors.lastname: Mitra
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Kaushlendra
authors.initials: K
authors.lastname: Tripathi
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Finan
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Scalici
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Steve
authors.initials: S
authors.lastname: McClellan
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Luciana
authors.initials: L
authors.lastname: Madeira da Silva
authors.affiliation: National Institutes of Health, National Institute on Minority Health and Health Disparities, Bethesda, Maryland, United States of America.
authors.forename: Eddie
authors.initials: E
authors.lastname: Reed
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors.forename: Lalita A
authors.initials: LA
authors.lastname: Shevde
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Komaraiah
authors.initials: K
authors.lastname: Palle
authors.affiliation: University of South Alabama Mitchell Cancer Institute, Mobile, Alabama, United States of America.
authors.forename: Rodney P
authors.initials: RP
authors.lastname: Rocconi
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000378:metabolism*; D000080924:Aldehyde Dehydrogenase 1 Family; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects; D018572:Disease-Free Survival; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000473:pathology*; D010641:Phenotype; D010984:Platinum / Q000494:pharmacology / Q000627:therapeutic use; D050697:Retinal Dehydrogenase; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D007527:Isoenzymes; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D010984:Platinum; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase