title: Epithelial mesenchymal transition and hedgehog signaling activation are associated with chemoresistance and invasion of hepatoma subpopulations.
abstract: OBJECTIVE
  Our previous studies showed that CD133, EpCAM, and aldehyde dehydrogenase (ALDH) are useful markers to identify cancer stem cells (CSCs) in hepatocellular carcinoma (HCC) tissues. The present study aims to evaluate chemosensitivity and invasion capability of HCC based on CSC marker profiles, and to explore the underlying molecular mechanisms.
  
  
  METHODS
  Hepatoma cell lines were separated into subpopulations according to CD133, EpCAM, and ALDH expression profiles. Epithelial mesenchymal transition (EMT) and hedgehog (Hh) signaling were examined to identify their links with chemoresistance and aggressive invasion.
  
  
  RESULTS
  Well-differentiated cell lines were positive for CD133(+)/ALDH(high) and CD133(+)/EpCAM(+) at 1.5-15% and 2.3-8.3%; whereas, poorly-differentiated cells were almost all negative for these markers. FACS-enriched CD133(+)/ALDH(high) and CD133(+)/EpCAM(+) Hep3B and Huh-7 cells formed more spheroids in vitro. CD133(-)/ALDH(low) HLE cells were more resistant to cisplatin, doxorubicin or sorafenib than their positive counterparts. CD133(-)/EpCAM(-) Huh-7 cells or CD133(-)/ALDH(-) HLE cells exhibited a higher invasion rate than their positive counterparts. HLE and HLF cells acquired EMT in double negative subpopulations. Hh activity in Huh-7 CD133(-)/EpCAM(-) cells was higher than in their positive counterparts, and the inhibition of Hh activity by cyclopamine resulted in reduced cell proliferation.
  
  
  CONCLUSIONS
  Well-differentiated CD133(+)/ALDH(high) or CD133(+)/EpCAM(+) cells appear to be a CSC/initiating subpopulation; whereas, in poorly-differentiated hepatoma cells, EMT and enhanced hedgehog signaling activity may be responsible for their chemoresistance and invasion. These findings underscore the significance of EMT and enhanced Hh signaling in liver cancer stem or initiating cells.
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of California, Davis Medical Center, Sacramento, CA 95817, USA.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chen
authors.forename: Shilpa
authors.initials: S
authors.lastname: Lingala
authors.forename: Shiva
authors.initials: S
authors.lastname: Khoobyari
authors.forename: Jan
authors.initials: J
authors.lastname: Nolta
authors.forename: Mark A
authors.initials: MA
authors.lastname: Zern
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
mesh_terms: D000071916:AC133 Antigen; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D002454:Cell Differentiation / Q000502:physiology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D009361:Neoplasm Invasiveness; D010455:Peptides / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014945:Wound Healing / Q000502:physiology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D000970:Antineoplastic Agents; D006023:Glycoproteins; D053823:Hedgehog Proteins; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse