STI571 sensitizes breast cancer cells to 5-fluorouracil, cisplatin and camptothecin in a cell type-specific manner

Jonathan T. Sims, Sourik Ganguly, Leann S. Fiore, Chris J. Holler, Eun Sil Park, Rina Plattner

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Previously, we demonstrated that Abl kinases are highly active in invasive breast cancer cell lines, and contribute to survival in response to nutrient deprivation, invasion and proliferation. To determine whether an Abl kinase inhibitor, STI571 (Gleevec; imatinib mesylate) sensitizes breast cancer cells to chemotherapeutic agents, we treated three breast cancer cell lines (BT-549, MDA-MB-231, and MDA-MB-468) that have active Abl kinases, with STI571 in combination with several conventional chemotherapeutic drugs frequently used to treat breast cancer, and assessed the effect on cell viability, proliferation, and apoptosis. We found that STI571 had synergistic effects with cisplatin in BT-549 and to some extent in MDA-MB-468 cells; synergized with camptothecin using an alternate dosing regimen in MDA-MB-231 cells; and STI571 synergistically sensitized MDA-MB-468 cells to paclitaxel and to high doses of 5-fluorouracil. Significantly, STI571 increased the ability of cisplatin to inhibit constitutive activation of PI3K/Akt in BT-549 cells, synergized with camptothecin to increase the stability of IκB in MDA-MB-231 cells, and in MDA-MB-468 cells, camptothecin and 5-fluorouracil inhibited STI571-dependent activation of STAT3. In other cell line/drug combinations, STI571 had additive or antagonistic effects, indicating that the ability of STI571 to sensitize breast cancer cells to chemotherapeutic agents is cell type-dependent. Significantly, unlike cisplatin, paclitaxel, and camptothecin, mechloroethamine was strongly antagonistic to STI571, and the effect was not cell line-dependent. Taken together, these data indicate that the cellular milieu governs the response of breast cancer cells to STI571/chemotherapeutic combination regimens, which suggests that treatment with these combinations requires individualization.

Original languageEnglish
Pages (from-to)249-260
Number of pages12
JournalBiochemical Pharmacology
Issue number3
StatePublished - Aug 1 2009

Bibliographical note

Funding Information:
We thank Prashant Tripathi for assisting the laboratory with Western blots. This work was supported by NIH Grant P20 RR20171 from the National Center for Research Resources, and National Institutes of Health/National Cancer Institute Grant 1R01CA116784 to R.P. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIH.


  • 5-Fluorouracil
  • Breast cancer
  • Camptothecin
  • Cisplatin
  • STI571

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology


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