title: Impact of Cellular Genetic Make-up on Colorectal Cancer Cell Lines Response to Ellagic Acid: Implications of Small Interfering RNA.
abstract: BACKGROUND
  K-Ras activation is an early event in colorectal carcinogenesis and associated mutations have been reported in about 40% of colorectal cancer patients. These mutations have always been responsible for enhancing malignancy and silencing them is associated with attenuation of tumorigenicity. Among downstream effectors are the RAF/MEK/ERK and the PI3K/Akt signaling pathways. PI3K/Akt signaling leads to reduction of apoptosis, stimulated cell growth and enhanced proliferation. Ellagic acid (EA), a naturally occurring antioxidant, has recently emerged as a promising anti-cancer agent.
  
  
  OBJECTIVE
  To evaluate the impact of cellular genetic make- up of two colon cancer cell lines with different genetic backgrounds, HCT-116 (K-Ras-/p53+) and Caco-2 (K-Ras+/ p53-), on response to potential anti-tumour effects of EA. In addition, the influence of K-Ras silencing in HCT- 116 cells was investigated.
  
  
  METHODS
  Cellular proliferation, morphology and cell cycle analysis were carried out in addition to Western blotting for detecting total Akt and p-Akt (at Thr308 and Ser473) in the presence and absence of different concentrations of EA. Cell proliferation was also assessed in cells transfected with different concentrations of K-Ras siRNA or incubated with ellagic acid following transfection.
  
  
  RESULTS
  The results of the present study revealed that EA exerts anti-proliferative and dose-dependent pro-apoptotic effects. Cytostatic and cytotoxic effects were also observed. p-Akt (at Thr308 and Ser473) was downregulated. Moreover, EA treatment was found to (i) reduce K-Ras protein expression; (ii) in cells transfected with siRNA and co-treated with EA, pronounced anti-proliferative effects as well as depletion of p-Akt (at Thr308) were detected.
  
  
  CONCLUSIONS
  Cellular genetic makeup (K-Ras-/p53-) was not likely to impose limitations on targeting EA in treatment of colon cancer. EA had a multi-disciplinary pro-apoptotic anti-proliferative approach, having inhibited Akt phosphorylation, induced cell cycle arrest and showed an anti-proliferative potential in HCT-116 cells (expressing mutant K-Ras).
authors.affiliation: Department of Applied Medical Chemistry, Medical Research Institute, University of Alexandria, Egypt E-mail : oselmasry@uod.edu.sa.
authors.forename: Amany I
authors.initials: AI
authors.lastname: Yousef
authors.forename: Omar S
authors.initials: OS
authors.lastname: El-Masry
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Abdel Mohsen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D018938:Caco-2 Cells; D049109:Cell Proliferation / Q000187:drug effects*; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D004610:Ellagic Acid / Q000494:pharmacology*; D045325:HCT116 Cells; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: C117307:KRAS protein, human; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D004610:Ellagic Acid; D051057:Proto-Oncogene Proteins c-akt; D016283:Proto-Oncogene Proteins p21(ras)