Cross-resistance and glutathione-S-transferase-π levels among four human melanoma cell lines selected for alkylating agent resistance

• Published in: Cancer research (Chicago, Ill.) Ill.), 1989-11, Vol.49 (22), p.6185-6192
• Main Authors: YENYUN WANG, TEICHER, B. A, SHEA, T. C, HOLDEN, S. A, ROSBE, K. W, AL-ACHI, A, HENNER, W. D
• Format: Article
• Language: English
• Subjects: Alkylating Agents - pharmacology; Antineoplastic agents; Antineoplastic Agents - pharmacology; Biological and medical sciences; Blotting, Northern; Carmustine - pharmacology; Cell Line; Cell Survival - drug effects; Clone Cells; Cyclophosphamide - pharmacology; Drug Resistance; General aspects; glutathione transferase; Glutathione Transferase - metabolism; Humans; Medical sciences; Melanoma; Melphalan - pharmacology; Pharmacology. Drug treatments; RNA, Neoplasm - isolation & purification; Tumor Cells, Cultured - cytology; Tumor Cells, Cultured - drug effects; Tumor Cells, Cultured - enzymology
• ISSN: 0008-5472; 1538-7445

A panel of four cell sublines, each selected for resistance to a different antineoplastic agent, has been developed from a human malignant melanoma cell line G3361. Following repeated exposure to escalating doses of the drug of interest, cloned sublines were developed that are 9-fold resistant to cisplatin (G3361/CP), 11-fold resistant to 4-hydroxyperoxy-cyclophosphamide (4-HC) (G3361/HC), 4-fold resistant to carmustine (BCNU) (G3361/BCNU), and 4-fold resistant to melphalan (G3361/PAM). The cross-resistance of each resistant cell line was determined for cisplatin, BCNU, 4-HC, melphalan, carboplatin, nitrogen mustard, and Adriamycin. In general, the alkylating agent-resistant cell lines were specifically resistant to the drug used for selection with the exception of the G3361/CP line, which was greater than 10-fold resistant to the cisplatin analogue carboplatin, 4-fold resistant to 4-HC, and slightly (1.5-fold) resistant to melphalan, and the G3361/BCNU line, which was slightly (1.8-fold) resistant to melphalan. Collateral sensitivity of the G3361/CP, G3361/PAM, and G3361/4HC lines to killing by BCNU was also observed. Glutathione-S-transferase activity was elevated in each of the alkylating agent-resistant cell lines by 3- to 5-fold with chlorodinitrobenzene substrate. On Western blotting, the glutathione-S-transferase-pi (GST-pi) isoenzyme protein was elevated in the resistant cells by 3- to 5-fold. A complementary DNA (pTS4-10) coding for GST-pi has been cloned from a lambda gt11 library, sequenced, and used as a probe to determine the relative levels of GST-pi mRNA in the alkylating agent-resistant cell lines. GST-pi mRNA levels were elevated (8- to 15-fold) in the resistant cell lines, indicating that the GST-pi increases were mediated through an increase in mRNA levels. GST-pi elevations are a frequent event in cells selected for alkylating agent resistance, and in some cases, of multiple drug resistance. However, the lack of cross-resistance among cell lines selected for resistance to different alkylating agents, all of which have elevated GST-pi levels, indicates that increased levels of GST-pi cannot be the predominate mechanism for resistance to the tested drugs in these cell lines.