Identification of Cytoskeletal [14C]Carboplatin-Binding Proteins Reveals Reduced Expression and Disorganization of Actin and Filamin in Cisplatin-Resistant Cell Lines

• Published in: Molecular pharmacology 2004-10, Vol.66 (4), p.789-793
• Main Authors: Shen, Ding-Wu, Liang, Xing-Jie, Gawinowicz, Mary Ann, Gottesman, Michael M
• Format: Article
• Language: English
• Subjects: Actins - isolation & purification; Actins - metabolism; Amino Acid Sequence; Antineoplastic Agents - pharmacology; Carbon Radioisotopes; Carboplatin - metabolism; Cisplatin - pharmacology; Contractile Proteins - isolation & purification; Contractile Proteins - metabolism; Cytoskeleton - chemistry; Cytoskeleton - drug effects; Drug Resistance, Neoplasm - physiology; Dynamin II - metabolism; Filamins; Gene Expression; Humans; Keratins - metabolism; Microfilament Proteins - isolation & purification; Microfilament Proteins - metabolism; Molecular Sequence Data; Tubulin - metabolism; Tumor Cells, Cultured
• ISSN: 0026-895X; 1521-0111
• DOI: 10.1124/mol.66.4.789

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.