title: Verification of ALDH Activity as a Biomarker in Colon Cancer Stem Cells-Derived HT-29 Cell Line.
abstract: BACKGROUND
  Recent evidence has suggested that epithelial cancers including colorectal cancer (CRC) have driven by a small population of self-renewing, multi-potent cells termed cancer stem cells (CSCs) which could be responsible for recurrence of cancer. Aldehyde dehydrogenase 1 (ALDH1) activity has used as a functional stem cell biomarker to isolate CSCs in different cancers such as colorectal cancer.
  
  
  OBJECTIVE
  The main aim of this research was to determine the utility of ALDH1 activity along with CD44 and EPCAM in identifying stem cell-like cells in human HT-29 colonic adenocarcinoma cell line.
  
  
  METHODS
  In this experimental study, colon CSCs biomarkers including CD44, EPCAM and ALDH1 in colonospheres and parent cells have analyzed by flow cytometry. The expression levels of stemness genes in spheroid and parental cells have investigated using SYBR Green real-time PCR. In addition, in vivo xenografts assay has performed to determine tumorigenic potential of tumor spheroid cells in nude mice.
  
  
  RESULTS
  According to results, over 92% of spheroids were CD44+/EpCAM+, while parent cells only have expressed 38% of CD44/EpCAM biomarkers (P < 0.001). Controversially, ALDH activity was about 2-fold higher in the parent cells than spheroid cells (P < 0.05). In comparison with the parental cells, expression levels of ''stemness'' genes, like Sox2, Oct4, Nanog, C-myc, and Klf4 have significantly increased in colonosphere cells (P < 0.05). Further, administration of 2500 spheroids could be sufficient to initiate tumor growth in nude mice, while 1x106 of parental cells has needed to form tumor.
  
  
  CONCLUSIONS
  For the first time, we have shown that colonospheres with low ALDH1 activity has indicated increased tumorigenic potential and stemness properties. So, it hasn't seemed that ALDH1 could become a useful biomarker to identify CSCs population in HT-29 cell line.
authors.affiliation: Department of Immunology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran.
authors.forename: Samaneh
authors.initials: S
authors.lastname: Khorrami
authors.affiliation: Department of Immunology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zavaran Hosseini
authors.affiliation: Department of Molecular Genetics, Faculty of Biological Sciences , Tarbiat Modares University, Tehran, IR Iran.
authors.forename: Seyed Javad
authors.initials: SJ
authors.lastname: Mowla
authors.affiliation: Digestive Oncology Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Malekzadeh
keywords: ALDH; Biomarker; Cancer Stem Cell; Colorectal Cancer; HT-29