Cytosolic chloride ion is a key factor in lysosomal acidification and function of autophagy in human gastric cancer cell

J Cell Mol Med. 2014 Jun;18(6):1124-33. doi: 10.1111/jcmm.12257. Epub 2014 Apr 12.


The purpose of the present study was to clarify roles of cytosolic chloride ion (Cl(-) ) in regulation of lysosomal acidification [intra-lysosomal pH (pHlys )] and autophagy function in human gastric cancer cell line (MKN28). The MKN28 cells cultured under a low Cl(-) condition elevated pHlys and reduced the intra-lysosomal Cl(-) concentration ([Cl(-) ]lys ) via reduction of cytosolic Cl(-) concentration ([Cl(-) ]c ), showing abnormal accumulation of LC3II and p62 participating in autophagy function (dysfunction of autophagy) accompanied by inhibition of cell proliferation via G0 /G1 arrest without induction of apoptosis. We also studied effects of direct modification of H(+) transport on lysosomal acidification and autophagy. Application of bafilomycin A1 (an inhibitor of V-type H(+) -ATPase) or ethyl isopropyl amiloride [EIPA; an inhibitor of Na(+) /H(+) exchanger (NHE)] elevated pHlys and decreased [Cl(-) ]lys associated with inhibition of cell proliferation via induction of G0 /G1 arrest similar to the culture under a low Cl(-) condition. However, unlike low Cl(-) condition, application of the compound, bafilomycin A1 or EIPA, induced apoptosis associated with increases in caspase 3 and 9 without large reduction in [Cl(-) ]c compared with low Cl(-) condition. These observations suggest that the lowered [Cl(-) ]c primarily causes dysfunction of autophagy without apoptosis via dysfunction of lysosome induced by disturbance of intra-lysosomal acidification. This is the first study showing that cytosolic Cl(-) is a key factor of lysosome acidification and autophagy.

Keywords: apoptosis; autophagy; chloride ion; lysosome; pH.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids / metabolism*
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects*
  • Blotting, Western
  • Cell Cycle / drug effects
  • Cell Proliferation / drug effects
  • Chlorides / pharmacology*
  • Cytosol / metabolism*
  • Homeostasis / drug effects
  • Humans
  • Lysosomes / metabolism*
  • Stomach Neoplasms / drug therapy
  • Stomach Neoplasms / metabolism
  • Stomach Neoplasms / pathology*
  • Tumor Cells, Cultured


  • Acids
  • Apoptosis Regulatory Proteins
  • Chlorides