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Multifactorial resistance in LS174T human colon carcinoma cells selected with doxorubicin
Author(s) -
Rabier Mireille J.,
Bruno Nicholas A.,
Slate Doris L.
Publication year - 1991
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910490423
Subject(s) - doxorubicin , buthionine sulfoximine , topoisomerase , glutathione , p glycoprotein , biology , cell culture , microbiology and biotechnology , vinblastine , etoposide , cancer research , biochemistry , drug resistance , in vitro , multiple drug resistance , chemotherapy , enzyme , genetics
A series of doxorubicin‐resistant variants of the human LS 174T colon carcinoma cell line was generated by stepwise selection. These variants also exhibited increased resistance to vinblastine, etoposide, cis ‐platinum, and melphalan, suggesting that resistance was multifactorial. The parental LS 174T cell line and 3 resistant variants were examined for over‐expression of P‐glycoprotein, changes in total cellular glutathione content, and the level of topoisomerase‐II expression. Changes in all of these parameters were observed in the doxorubicin‐selectants, along with a marked shift in the intracellular distribution of doxorubicin. P‐glycoprotein RNA and protein levels were increased 2‐ to 3‐fold in the resistant variants, while total glutathione levels increased 1.4‐ to 2.1‐fold. Treatment with DL‐buthionine‐[S,R]‐sulfoximine, an inhibitor of glutathione biosynthesis, was able to reverse resistance to cis ‐platinum and melphalan in these variants, but had little effect on doxorubicin resistance. Immunoblot analysis of cell extracts indicated that the level of DNA topoisomerase II (EC 5.99.1.3) in the doxorubicin‐resistant LS174T cells was decreased by approximately 50% compared with the parental cell line. Doxorubicin was mainly localized to the cytoplasm in resistant cells, while in the parent line it was mostly found in the nucleus. This constellation of changes suggests that selection with doxorubicin activated several mechanisms of resistance involving drug transport, metabolism, and ability to reach nuclear target sites.