Cross-resistance and glutathione-S-transferase-pi levels among four human melanoma cell lines selected for alkylating agent resistance.
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.
Wang
Y Y
YY
Division of Cancer Pharmacology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115.
Teicher
B A
BA
Shea
T C
TC
Holden
S A
SA
Rosbe
K W
KW
al-Achi
A
A
Henner
W D
WD
D000477:Alkylating Agents / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015152:Blotting, Northern; D002330:Carmustine / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D002999:Clone Cells; D003520:Cyclophosphamide / Q000494:pharmacology / Q000031:analogs & derivatives; D004351:Drug Resistance; D005982:Glutathione Transferase / Q000378:metabolism*; D006801:Humans; D008545:Melanoma; D008558:Melphalan / Q000494:pharmacology; D012334:RNA, Neoplasm / Q000302:isolation & purification; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology
D000477:Alkylating Agents; D000970:Antineoplastic Agents; D012334:RNA, Neoplasm; D003520:Cyclophosphamide; D005982:Glutathione Transferase; D008558:Melphalan; D002330:Carmustine; C011272:perfosfamide