title: Targeting aldehyde dehydrogenase cancer stem cells in ovarian cancer.
abstract: Aldehyde dehydrogenase-1A1 (ALDH1A1) expression characterizes a subpopulation of cells with tumor-initiating or cancer stem cell properties in several malignancies. Our goal was to characterize the phenotype of ALDH1A1-positive ovarian cancer cells and examine the biological effects of ALDH1A1 gene silencing. In our analysis of multiple ovarian cancer cell lines, we found that ALDH1A1 expression and activity was significantly higher in taxane- and platinum-resistant cell lines. In patient samples, 72.9% of ovarian cancers had ALDH1A1 expression in which the percentage of ALDH1A1-positive cells correlated negatively with progression-free survival (6.05 vs. 13.81 months; P < 0.035). Subpopulations of A2780cp20 cells with ALDH1A1 activity were isolated for orthotopic tumor-initiating studies, where tumorigenicity was approximately 50-fold higher with ALDH1A1-positive cells. Interestingly, tumors derived from ALDH1A1-positive cells gave rise to both ALDH1A1-positive and ALDH1A1-negative populations, but ALDH1A1-negative cells could not generate ALDH1A1-positive cells. In an in vivo orthotopic mouse model of ovarian cancer, ALDH1A1 silencing using nanoliposomal siRNA sensitized both taxane- and platinum-resistant cell lines to chemotherapy, significantly reducing tumor growth in mice compared with chemotherapy alone (a 74%-90% reduction; P < 0.015). These data show that the ALDH1A1 subpopulation is associated with chemoresistance and outcome in ovarian cancer patients, and targeting ALDH1A1 sensitizes resistant cells to chemotherapy. ALDH1A1-positive cells have enhanced, but not absolute, tumorigenicity but do have differentiation capacity lacking in ALDH1A1-negative cells. This enzyme may be important for identification and targeting of chemoresistant cell populations in ovarian cancer.
authors.affiliation: Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. clanden@uab.edu
authors.forename: Charles N
authors.initials: CN
authors.lastname: Landen
authors.forename: Blake
authors.initials: B
authors.lastname: Goodman
authors.forename: Ashwini A
authors.initials: AA
authors.lastname: Katre
authors.forename: Adam D
authors.initials: AD
authors.lastname: Steg
authors.forename: Alpa M
authors.initials: AM
authors.lastname: Nick
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Stone
authors.forename: Lance D
authors.initials: LD
authors.lastname: Miller
authors.forename: Pablo Vivas
authors.initials: PV
authors.lastname: Mejia
authors.forename: Nicolas B
authors.initials: NB
authors.lastname: Jennings
authors.forename: David M
authors.initials: DM
authors.lastname: Gershenson
authors.forename: Robert C
authors.initials: RC
authors.lastname: Bast
authors.forename: Robert L
authors.initials: RL
authors.lastname: Coleman
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lopez-Berestein
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D015894:Genome, Human / Q000235:genetics; D006801:Humans; D051379:Mice; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D034741:RNA, Small Interfering / Q000378:metabolism; D050697:Retinal Dehydrogenase; D016896:Treatment Outcome; D023041:Xenograft Model Antitumor Assays
chemical_list: D034741:RNA, Small Interfering; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase; D002945:Cisplatin