Tumor resistance to chemotherapy is the major obstacle to employ cisplatin, one of the broadly used chemotherapeutic drugs, for effective treatment of various tumors in the clinic. to sensitize cisplatin resistance. It was found that mitaplatin induced more apoptosis in CP-r KB-CP 20 and BEL 7404-CP 20 cells than that of cisplatin, DCA and cisplatin/DCA compared on an equal molar basis. There was more platinum accumulation in mitaplatin-treated CP-r cells due to enhanced transmembrane permeability of lipophilicity, and mitaplatin also showed special targeting to mitochondria. Moreover, in the case of treatment with mitaplatin, the dramatic collapse of m was shown in a dose-dependent manner, which was confirmed by FACS and NKSF confocal microscopic measurements. Reduced glucose utilization of CP-r cells was detected with specifically inhibited phosphorylation of pyruvate dehydrogenase (PDH) at Ser-232, Ser-293, and Ser-300 of the E1 subunit when treated with mitaplatin, which was indicated to modulate the abnormal glycolysis of resistant cells. The present study suggested novel mitochondrial mechanism of mitaplatin circumventing cisplatin resistance toward CP-r cells as a carrier across buy RPI-1 membrane to produce CP-like cytotoxicity and DCA-like mitochondria-dependent apoptosis. Therefore, mitochondria targeting compounds would be more vulnerable and selective to overcome cisplatin resistance due to the unique metabolic properties of CP-r cancer cells. test. < 0.05 was considered statistically significant. RESULTS Characterization of Mitochondrial Membrane Potentials (MMPs, m) with Sensitive and Resistant Cells In order to address the distinction between sensitive and resistant cells, the MMPs were measured by JC-1 staining (Figure 1). Changed MMPs were indicated by a fluorescence emission shift from J-monomers with green fluorescence (~529 nm) to J-aggregates with red fluorescence (~590 nm). The higher mitochondrial membrane potentials were defined with the higher ratio of red fluorescent intensity and green fluorescent intensity. Two independently selected CP-resistant (CP-r) cell populations (KB-CP 20 and BEL 7404-CP 20 cells), derived from human KB epidermoid adenocarcinoma cells (KB-3-1) and human BEL 7404 hepatoma cells (BEL 7404), were used. The CP-r cancer cells showed increased m compared to parental CP-sensitive (CP-s) KB-3-1 and BEL 7404 cells, similarly as cancer cells had hyperpolarized m compared to noncancerous (normal) cells.22 Therefore, based on hyperpolarization of resistant cells, designing a drug with mitochondrial targeting was reasonable to sensitive chemotherapy and may selectively destroy tumor resistant cells. Modulating mitochondria-related metabolism may be a promising new approach to reversing cancer resistance to chemotherapeutic agents. Figure 1 The mitochondrial membrane potentials (MMPs or m) of CP-sensitive (CP-s) and CP-resistant (CP-r) cells were characterized by JC-1 staining. (A) The different MMPs in CP-r KB-CP 20/BEL 7404-CP 20 cells and CP-s KB-3-1/BEL 7404 cells were ... Mitaplatin Was More Effective on Inhibiting CP-r Cancer Cells To measure the activity of mitaplatin on chemotherapeutic sensitivity, who has DCA units as mitochondrial targeting motif, the viability of CP-r and buy RPI-1 CP-s cells were measured by MTT assay. The IC50 value of mitaplatin was much lower than that of cisplatin in CP-r KB-CP 20 and BEL 7404-CP 20 cells measured at 72 h (Figure 2A). As expected, CP-r KB-CP 20 and BEL 7404-CP 20 cells buy RPI-1 were more susceptible to mitaplatin than cisplatin treatments in a concentration-dependent manner. The IC50 values of mitaplatin were 50 M and 42 M for KB-CP 20 and BEL 7404-CP 20, respectively, approximately 2.5- and 4-fold lower than those of cisplatin (Table 1). There was no significant difference between mitaplatin and cisplatin treatment of CP-s KB-3-1 and BEL 7404 cells. However, differences were observed in CP-r KB-CP 20 and BEL 7404-CP 20 cells. These results suggest the enhanced potency of mitaplatin to inhibit CP-r cancer cells. Figure 2 Mitaplatin selectively overcame chemoresistance and induced concentration-dependent apoptosis in CP-r cells. (A) Cytotoxicity of mitaplatin on KB-CP 20 cells and BEL 7404-CP 20 cells was measured at different concentrations. Data represent the means … Table 1 Comparison of IC50 Values for Mitaplatin, Cisplatin, and DCA to CP-s and CP-r Cells as Determined by the MTT Assaya Mitaplatin Promoted More Apoptosis in CP-r Cells To explore.