title: Harmal Extract Induces Apoptosis of HCT116 Human Colon Cancer Cells, Mediated by Inhibition of Nuclear Factor-κB and Activator Protein-1 Signaling Pathways and Induction of Cytoprotective Genes.
abstract: BACKGROUND
  Colorectal cancer (CRC) is a major cause of morbidity and mortality, being the second most common type of cancer worldwide in both men and women. It accounts yearly for approximately 9% of all new cases of cancers. Furthermore, the current chemotherapeutic regimens seem unsatisfactory, so that exploration of novel therapeutic modalities is needed. The present study was undertaken to investigate the inhibitory effects of a crude alkaloid extract (CAERS) of a medicinal herb, Rhazya stricta, on proliferation of CRC HCT116 cells and to elucidate mechanisms of action. To achieve these aims, we utilized MTT, comet, DNA laddering and gene reporter assays, along with Western blot and RT-PCR analyses.
  
  
  RESULTS
  We found that CAERS inhibited cell proliferation and induced apoptotic cell death in HCT116 cells. Hallmarks of morphological and biochemical signs of apoptosis were clearly evident. CAERS down-regulated DNA-binding and transcriptional activities of NF-κB and AP-1 proteins, while up-regulating expression of the Nrf-2 protein. It also down-regulated expression levels of the ERK MAPK, Bcl-2, cyclin D1, CDK-4, survivin and VEGF and up-regulated levels of Bax, caspase-3/7 and -9, p53, p21, Nrf-2. Markedly, it promoted mRNA expression levels of cytoprotective genes including the hemeoxygenase-1, NAD(P)H quinine oxidoreductase 1 and UDP-glucuronyltransferase.
  
  
  CONCLUSIONS
  These findings indicate that CAERS exerts antiproliferative action on CRC cells through induction of apoptotic mechanisms, and suggest CAERS could be a promising agent for studying and developing novel chemotherapeutic agents aimed at novel molecular targets for the treatment of CRC.
authors.affiliation: Department of Biological Sciences, Faculty of Sciences, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia E-mail : elassouli@yahoo.com.
authors.forename: Ayman I
authors.initials: AI
authors.lastname: Elkady
authors.forename: Rania A
authors.initials: RA
authors.lastname: Hussein
authors.forename: Sufian M
authors.initials: SM
authors.lastname: El-Assouli
mesh_terms: D029062:Apocynaceae / Q000737:chemistry*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D019610:Cytoprotection / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D016328:NF-kappa B; D010936:Plant Extracts; D012333:RNA, Messenger; D018808:Transcription Factor AP-1