title: cMyc increases cell number through uncoupling of cell division from cell size in CHO cells.
abstract: BACKGROUND
  Over the past decades, the increase in maximal cell numbers for the production of mammalian derived biologics has been in a large part due to the development of optimal feeding strategies. Engineering of the cell line is one of probable approaches for increasing cell numbers in bioreactor.
  
  
  RESULTS
  We have demonstrated that the over-expression of the c-myc gene in immortalised CHO cells can increase proliferation rate and maximal cell density in batch culture compared to the control. The changes were attributed to a rapid transition into S-phase from a shortened duration of G1 phase and to the uncoupling of cell size from cell proliferation. To achieve the >70% increase in maximal cell density without additional supply of nutrients the cells underwent an overall reduction of 14% in size as well as a significant decrease in glucose and amino acid consumption rate. Consequently, the total biomass accumulation did not show a significant change from the control. The amount of hSEAP-hFc activity of the over expressing c-myc cell line was found to be within 0.7% of the control.
  
  
  CONCLUSIONS
  It is shown that the manipulation of cell cycle kinetics and indirectly cell metabolism gives higher cell densities in CHO batch cultures. The unaltered apoptotic rate supported the proposition that the increase in cell number was a result of enhance cell cycle kinetics and cellular metabolism rather than increasing viability. Production of hSEAP-hFc from a constitutive c-myc over-expressing cell line did not increase with the increase in cell number.
authors.affiliation: School of Chemical and Bioprocess Engineering, University College Dublin, Delfield, Dublin 4, Ireland.
authors.forename: Darrin
authors.initials: D
authors.lastname: Kuystermans
authors.forename: Mohamed
authors.initials: M
authors.lastname: Al-Rubeai
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D019149:Bioreactors; D016466:CHO Cells; D002452:Cell Count; D018929:Cell Culture Techniques; D002455:Cell Division; D049109:Cell Proliferation; D048429:Cell Size; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media; D016193:G1 Phase; D005947:Glucose / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D003470:Culture Media; D016271:Proto-Oncogene Proteins c-myc; D005947:Glucose