Alkylator resistance in human B lymphoid cell lines: (2). Increased levels of topoisomerase II expression and function in a melphalan-resistant B-CLL cell line.
AffiliationPaterson Institute for Cancer Research, Christie Hospital, Manchester, U.K. email@example.com
MetadataShow full item record
AbstractPrevious studies have demonstrated alkylating (melphalan) resistance in the B-CLL derived WSU-CLL cell line as compared to WIL2 B lymphocytic cells. Nuclear extracts from WSU-CLL cells demonstrate a highly significant increase in DNA topoisomerase II activity as compared to WIL2 cells. Western blot analysis showed the level of topoisomerase II proteins expressed in WSU-CLL cells to be increased as compared to WIL2 cells. WSU-CLL cells were 5.24-fold more sensitive than WIL2 cells to the cytotoxic effect of the topoisomerase II inhibitor doxorubicin. No difference in topoisomerase I activity or of the level of topoisomerase I protein expression was observed comparing the two cell lines. The sensitivity to the cytotoxic effects of topoisomerase I inhibitor, camptothecin, did not differ in WSU-CLL and WIL2 cell lines. Pre-incubation with doxorubicin significantly increased melphalan induced interstrand-DNA-crosslink formation and cytotoxicity in WSU-CLL cells as compared to WIL2 cells. The affinity of topoisomerase II for WSU-CLL UV-irradiated-crosslinked DNA was increased 2.84-fold as compared to that of WSU-CLL native DNA. The affinity of topoisomerase II for both UV-irradiated (crosslinked) and for native DNA was significantly decreased after doxorubicin-pretreatment. Measurement of DNA polymerase beta and DNA polymerase beta revealed significant elevations in DNA polymerase beta (58.82 +/- 3.67 units/mg protein in WSU-CLL cells, as compared to 27.82 +/- 4.39 units/mg protein in WIL 2 cells; p < 0.01) but not DNA polymerase beta (0.82 +/- 0.11 units/mg protein in WSU-CLL cells, compared to 0.74 +/- 0.09 units/mg protein in WIL2, p > 0.05). However, exposure to aphidicolin (an inhibitor of DNA polymerase a) failed to increase melphalan induced cytotoxicity suggesting that although DNA polymerase a activity was increased in WSU-CLL cells the mechanisms of resistance does not involve this specific DNA repair pathway. Elevated topoisomerase II activity and the increased affinity of topoisomerase II for crosslinked DNA in melphalan resistant cells appears to be the major factor responsible for alkylator resistance by changing DNA topology and thereby facilitating DNA repair.
CitationAlkylator resistance in human B lymphoid cell lines: (2). Increased levels of topoisomerase II expression and function in a melphalan-resistant B-CLL cell line., 20 (4):2569-78 Anticancer Res.
- Alkylator resistance in human B lymphoid cell lines: (1). Melphalan accumulation, cytotoxicity, interstrand-DNA-crosslinks, cell cycle analysis, and glutathione content in the melphalan-sensitive B-lymphocytic cell line (WIL2) and in the melphalan-resistant B-CLL cell line (WSU-CLL).
- Authors: Pu Q, Bianchi P, Bezwoda WR
- Issue date: 2000 Jul-Aug
- Induction of alkylator (melphalan) resistance in HL60 cells is accompanied by increased levels of topoisomerase II expression and function.
- Authors: Pu QQ, Bezwoda WR
- Issue date: 1999 Jul
- Elevated DNA polymerase alpha, DNA polymerase beta, and DNA topoisomerase II in a melphalan-resistant rhabdomyosarcoma xenograft that is cross-resistant to nitrosoureas and topotecan.
- Authors: Friedman HS, Dolan ME, Kaufmann SH, Colvin OM, Griffith OW, Moschel RC, Schold SC, Bigner DD, Ali-Osman F
- Issue date: 1994 Jul 1
- Altered topoisomerase I and II activities in suramin-resistant lung fibrosarcoma cells.
- Authors: Lelièvre S, Benchokroun Y, Larsen AK
- Issue date: 1995 May
- Topoisomerase II beta levels are a determinant of melphalan-induced DNA crosslinks and sensitivity to cell death.
- Authors: Emmons M, Boulware D, Sullivan DM, Hazlehurst LA
- Issue date: 2006 Jun 28