Cariporide Enhances the DNA Damage and Apoptosis in Acid-tolerable Malignant Mesothelioma H-2452 Cells

  • Lee, Yoon-Jin (Department of Biochemistry, College of Medicine, Soonchunhyang University) ;
  • Bae, Jin-Ho (Division of Molecular Cancer Research, Soonchunhyang Medical Research Institute, Soonchunhyang University) ;
  • Kim, Soo-A (Department of Physical Medicine and Rehabilitation, Cheonan Hospital) ;
  • Kim, Sung-Ho (Department of Chemistry, College of Natural Sciences, Soonchunhyang University) ;
  • Woo, Kee-Min (Department of Biochemistry, College of Medicine, Soonchunhyang University) ;
  • Nam, Hae-Seon (Division of Molecular Cancer Research, Soonchunhyang Medical Research Institute, Soonchunhyang University) ;
  • Cho, Moon-Kyun (Division of Molecular Cancer Research, Soonchunhyang Medical Research Institute, Soonchunhyang University) ;
  • Lee, Sang-Han (Department of Biochemistry, College of Medicine, Soonchunhyang University)
  • Received : 2017.04.17
  • Accepted : 2017.07.09
  • Published : 2017.08.31


The $Na^+/H^+$ exchanger is responsible for maintaining the acidic tumor microenvironment through its promotion of the reabsorption of extracellular $Na^+$ and the extrusion of intracellular $H^+$. The resultant increase in the extracellular acidity contributes to the chemoresistance of malignant tumors. In this study, the chemosensitizing effects of cariporide, a potent $Na^+/H^+-exchange$ inhibitor, were evaluated in human malignant mesothelioma H-2452 cells preadapted with lactic acid. A higher basal level of phosphorylated (p)-AKT protein was found in the acid-tolerable H-2452AcT cells compared with their parental acid-sensitive H-2452 cells. When introduced in H-2452AcT cells with a concentration that shows only a slight toxicity in H-2452 cells, cariporide exhibited growth-suppressive and apoptosis-promoting activities, as demonstrated by an increase in the cells with pyknotic and fragmented nuclei, annexin V-PE(+) staining, a $sub-G_0/G_1$ peak, and a $G_2/M$ phase-transition delay in the cell cycle. Preceding these changes, a cariporide-induced p-AKT down-regulation, a p53 up-regulation, an ROS accumulation, and the depolarization of the mitochondrial-membrane potential were observed. A pretreatment with the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 markedly augmented the DNA damage caused by the cariporide, as indicated by a much greater extent of comet tails and a tail moment with increased levels of the p-histone H2A.X, $p-ATM^{Ser1981}$, $p-ATR^{Ser428}$, $p-CHK1^{Ser345}$, and $p-CHK2^{Thr68}$, as well as a series of pro-apoptotic events. The data suggest that an inhibition of the PI3K/AKT signaling is necessary to enhance the cytotoxicity toward the acidtolerable H-2452AcT cells, and it underlines the significance of proton-pump targeting as a potential therapeutic strategy to overcome the acidic-microenvironment-associated chemotherapeutic resistance.


cariporide;LY294002;malignant mesothelioma;p53;phosphatidylinositol-3-kinase


Supported by : National Research Foundation of Korea (NRF)


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