title: Treatment of LS174T colorectal cancer stem-like cells with n-3 PUFAs induces growth suppression through inhibition of survivin expression and induction of caspase-3 activation.
abstract: OBJECTIVE
  Colorectal cancer stem cells (CCSCs) are thought to contribute to tumor initiation, progression, metastasis, chemo-resistance and therapy failure. Therefore, assessment of the effectiveness of agents with anti-proliferative activities against CCSCs is warranted. Several studies have shown that different tumorigenic steps, ranging from initiation to metastasis, can be affected by n-3 polyunsaturated fatty acids (PUFAs). Here, we evaluated the effects of the PUFA components docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), alone or in combination, on LS174T cells that serve as a model for colorectal cancer initiating cells with stem cell-like properties.
  
  
  METHODS
  LS174T cells were treated with 50, 100 and 150 μM DHA and EPA, or equal mixtures of DHA/EPA (i.e., 25/25, 50/50 and 75/75 μM), after which cell number, viability, growth inhibition, survivin expression, caspase-3 activation and apoptotic rate were evaluated.
  
  
  RESULTS
  We found that treatment of LS174T cells with increasing PUFA concentrations significantly increased growth inhibition in a dose- and time-dependent manner. After a 72 h treatment with 150 μM DHA and EPA, or their combination (75/75 μM), growth rates were inhibited by 80.3 ± 5.5%, 79.3 ± 5% and 71.1 ± 1%, respectively, compared to untreated cells. We also found that treatment for 48 h with 100 μM DHA and EPA, or their combination (50/50 μM), resulted in 2.9-, 3- and 2.6-fold increases in caspase-3 activation, as well as 54, 62.4 and 100% decreases in survivin mRNA expression levels, respectively, compared to untreated cells. Low survivin mRNA levels combined with high caspase-3 activity levels were found to correlate with a higher growth inhibition in PUFA-treated cells. DHA appears to be a more potent growth inhibitor than EPA and the DHA/EPA combination. An increase in the number of apoptotic cells (early + late), ranging from 12.9 to 44.7%, was observed with increasing DHA doses.
  
  
  CONCLUSIONS
  From our data we conclude that PUFAs induce growth inhibition via targeting survivin expression in LS174T cells, which serve as a model for CCSCs.
authors.affiliation: Department of Histology and Embryology, Faculty of Science, Urmia University, Urmia, Iran. m.sam@urmia.ac.ir.|Department of Cellular and Molecular Biotechnology, Institute of Biotechnology, Urmia University, Urmia, Iran, P.O. Box: 165. m.sam@urmia.ac.ir.|Royan Stem Cell Technology Company, West Azerbaijan Cord Blood Bank, Urmia, Iran. m.sam@urmia.ac.ir.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Sam
authors.affiliation: Department of Histology and Embryology, Faculty of Science, Urmia University, Urmia, Iran.|Department of Cellular and Molecular Biotechnology, Institute of Biotechnology, Urmia University, Urmia, Iran, P.O. Box: 165.
authors.forename: Parinaz
authors.initials: P
authors.lastname: Ahangar
authors.affiliation: Department of Histology and Embryology, Faculty of Science, Urmia University, Urmia, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Nejati
authors.affiliation: Department of Microbiology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Habibian
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism*; D002452:Cell Count; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology*; D004281:Docosahexaenoic Acids / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D004789:Enzyme Activation / Q000187:drug effects; D015525:Fatty Acids, Omega-3 / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D015525:Fatty Acids, Omega-3; D051034:Inhibitor of Apoptosis Proteins; D012333:RNA, Messenger; D000077022:Survivin; D004281:Docosahexaenoic Acids; D053148:Caspase 3
keywords: Caspase-3; Colorectal cancer; Colorectal cancer stem cells; Growth inhibition; Survivin; n-3 Polyunsaturated fatty acids (n-3 PUFAs)