TY - JOUR T1 - Identification of Cytoskeletal [<sup>14</sup>C]Carboplatin-Binding Proteins Reveals Reduced Expression and Disorganization of Actin and Filamin in Cisplatin-Resistant Cell Lines JF - Molecular Pharmacology JO - Mol Pharmacol SP - 789 LP - 793 DO - 10.1124/mol.66.4.789 VL - 66 IS - 4 AU - Ding-Wu Shen AU - Xing-Jie Liang AU - Mary Ann Gawinowicz AU - Michael M. Gottesman Y1 - 2004/10/01 UR - http://molpharm.aspetjournals.org/content/66/4/789.abstract N2 - Cisplatin resistant (CP-r) cells often show decreased uptake of cisplatin in association with reduced cell surface proteins and decreased endocytosis. In this report, two major [14C]carboplatin-binding proteins were identified as filamin and actin by photoaffinity labeling and mass spectrometry. Decreased expression of these two proteins was found in two different human CP-r cell lines (KB-CP20 and 7404-CP20), in comparison with their parental cell lines (KB-3-1 and BEL-7404), respectively. Disorganization of β-actin and filamin 250 and 90 was also detected in these CP-r cells by confocal microscopy. Transfection of a wild-type actin-enhanced green fluorescent protein (EGFP) expression vector into 7404-CP20 cells resulted in a nonfilamentous actin-EGFP distribution compared with a normal distribution in the cisplatin-sensitive BEL-7404 cells, suggesting that cytoskeletal organization is disturbed in the CP-r cells. The identification of actin and filamin as [14C]carboplatin-binding proteins and decreased expression and disorganization of several cytoskeletal proteins in CP-r cells provide a molecular and cellular basis for the known defect in endocytosis in these cells. ER -