title: [The level of superoxide dismutase expression in primary and metastatic colorectal cancer cells in hypoxia and tissue normoxia].
abstract: Superoxide oxidase (SOD) is a key antioxidant enzyme protecting cells against oxidative stress, which might induce cancerogenesis. In tumor cells SOD influences the level of the reactive oxygen species (ROS) allowing for survival and proliferation. High rate of cells proliferation in tumor leads to their temporary hypoxia due to lower rate of angiogenesis. Therefore during tumor development, cancer cells function in conditions of hypoxia or tissue normoxia.
  
  
  OBJECTIVE
  The aim of study was to evaluate of SOD isoenzymes (SOD1 and SOD2) expression level in cell lines of primary (SW 480) and metastatic (SW 620) colorectal cancer, cultured in hypoxia (1% oxygen), tissue normoxia (10% oxygen), and atmospheric normoxia (21% oxygen).
  
  
  METHODS
  Cells were cultured in MEM medium in different oxygen concentrations (1%, 10%, 21%) in hypoxic chamber with oxygenation regulator. The number of living cells in lines SW 480 and 620 was determined by trypan blue method. Expression of SOD1 and SOD2 at the mRNA level was determined by RT-PCR and PCR.
  
  
  RESULTS
  In both studied cell lines (SW 480 and SW 620), the number of living cells (viability) was increased in hypoxia and atmospheric normoxia. The expression level of SOD1 and SOD2 in studied cell lines was different. The lowest level of expression of both SOD isoenzymes was observed in hypoxia. In conditions of atmospheric normoxia the expression level of SOD1 in SW480 cell line was increased, and similar in SW620 cell line comparing to tissue normoxia. Whereas the SOD2 expression level in atmospheric normoxia conditions in both cell lines was significantly increased. Observed differences were statistically significant (p ≤ 0,05).
  
  
  CONCLUSIONS
  The profile of expression of SOD1 and SOD2 in cell lines SW480 and SW620 indicates differentiated response of tumor cells depending on access to oxygen. Low level of SOD isoenzymes expression in SW480 and SW620 cells in hypoxia indicates decreased production of ROS. Differences of SOD isoenzymes expression level in tissue normoxia indicate their compensatory action, allowing to maintain the balance between O₂- removal and H₂O₂production in studied tumor cells. In atmospheric normoxia conditions increased expression level of SOD1 and SOD2 observed in studied cell lines points to oxidative stress.
authors.affiliation: Chair and Department of Biochemistry, Medical University of Warsaw, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Skrzycki
authors.affiliation: Chair and Department of Biochemistry, Medical University of Warsaw, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Czeczot
authors.affiliation: Chair and Department of Biochemistry, Medical University of Warsaw, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Chrzanowska
authors.affiliation: Chair and Department of Biochemistry, Medical University of Warsaw, Poland.
authors.forename: Dagmara
authors.initials: D
authors.lastname: Otto-Ślusarczyk
mesh_terms: D015687:Cell Hypoxia; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology*; D006801:Humans; D009362:Neoplasm Metastasis / Q000473:pathology* / Q000503:physiopathology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D014407:Tumor Cells, Cultured; D000099156:Superoxide Dismutase 2
chemical_list: D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2; C000606290:SOD1 protein, human
keywords: colorectal cancer; hypoxia; oxidative stress; superoxide dismutase