title: LeftyA sensitive cytosolic pH regulation and glycolytic flux in Ishikawa human endometrial cancer cells.
abstract: OBJECTIVE
  LeftyA, a powerful regulator of stemness, embryonic differentiation, and reprogramming of cancer cells, counteracts cell proliferation and tumor growth. Key properties of tumor cells include enhanced glycolytic flux, which is highly sensitive to cytosolic pH and thus requires export of H(+) and lactate. H(+) extrusion is in part accomplished by Na(+)/H(+) exchangers, such as NHE1. An effect of LeftyA on transport processes has, however, never been reported. The present study thus explored whether LeftyA modifies regulation of cytosolic pH (pHi) in Ishikawa cells, a well differentiated endometrial carcinoma cell model.
  
  
  METHODS
  NHE1 transcript levels were determined by qRT-PCR, NHE1 protein abundance quantified by Western blotting, pHi estimated utilizing (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence, Na(+)/H(+) exchanger activity from Na(+) dependent realkalinization after an ammonium pulse, and lactate concentration in the supernatant utilizing an enzymatic assay and subsequent colorimetry.
  
  
  RESULTS
  A 2 h treatment with LeftyA (8 ng/ml) significantly decreased NHE1 transcript levels (by 99.6%), NHE1 protein abundance (by 71%), Na(+)/H(+) exchanger activity (by 55%), pHi (from 7.22 ± 0.02 to 7.05 ± 0.02), and lactate release (by 41%).
  
  
  CONCLUSIONS
  LeftyA markedly down-regulates NHE1 expression, Na(+)/H(+) exchanger activity, pHi, and lactate release in Ishikawa cells. Those effects presumably contribute to cellular reprogramming and growth inhibition.
authors.affiliation: Department of Physiology, University of Tuebingen, 72076 Tuebingen, Germany.
authors.forename: Madhuri S
authors.initials: MS
authors.lastname: Salker
authors.affiliation: Department of Physiology, University of Tuebingen, 72076 Tuebingen, Germany.
authors.forename: Yuetao
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Physiology, University of Tuebingen, 72076 Tuebingen, Germany.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Singh
authors.affiliation: Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK.
authors.forename: Jan
authors.initials: J
authors.lastname: Brosens
authors.affiliation: Department of Physiology, University of Tuebingen, 72076 Tuebingen, Germany. Electronic address: florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D003600:Cytosol / Q000378:metabolism*; D017931:DNA Primers; D016889:Endometrial Neoplasms / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006019:Glycolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D055458:Left-Right Determination Factors / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D055458:Left-Right Determination Factors
keywords: Cytosolic pH regulation; Glycolysis; NHE1; Na(+)/H(+) exchanger; Tumor cells