Downregulation of BCRP and anti-apoptotic proteins by proadifen (SKF-525A) is responsible for the enhanced mitoxantrone accumulation and toxicity in mitoxantrone-resistant human promyelocytic leukemia cells

Abstract

Multidrug resistance caused by the overexpression of ABC transporter proteins in cancer cells remains a major obstacle limiting chemotherapy efficacy. Drugs inhibiting these transporters have been shown to increase the anti-proliferative properties of chemotherapeutics. As we previously described, proadifen, a P450 monooxygenase inhibitor, might also be able to inhibit some ABC transporters, including breast cancer resistance protein (BCRP). Because mitoxantrone (MTX) is a strong BCRP substrate and is often used in the treatment of leukemia, we investigated the effect of 24 h proadifen pre-treatment on the cytotoxicity of MTX in leukemic cell lines that are sensitive to MTX (HL-60) and MTX-resistant ABCG2-overexpressing subclone (cBCRP). We show for the first time that proadifen is able to enhance the cytotoxic properties of MTX in cBCRP cells, particularly through the inhibition of BCRP expression and activity. This proadifen-MTX synergism was also mediated by the inhibition of various cellular proteins engaged in apoptosis, including Mc-1, Bcl-xL, survivin and activation of procaspase-3. Proadifen also decreased the expression of γH2AX, which is involved in the recruitment of reparation proteins. Moreover, the inhibition of DNA damage repair proteins Ku86 and B23 after proadifen treatment indicate a possible role of proadifen in DNA repair blockage, thus suppressing the reparation rate of MTX-induced DSBs.

In vitro investigating of anticancer activity of new 7-MEOTA-tacrine heterodimers

“…For the flow cytometry analysis, HL-60 cells were seeded in six-well plates (TPP, Trasadingen, Switzerland) at 1 × 10 6 per well and changes in the total cell number, metabolic activity, MMP, cell cycle distribution and cell death were analyzed at 24, 48 and 72 h after treatment with the studied 7-MEOTA-THA thio-/ureas 12 – 22 , as described previously 87 , 88 . Human dermal fibroblasts (5 × 10 4 ) were seeded into a 12-well plate (Sarstedt, Deutschland) and treated with the studied 7-MEOTA-THA thio-/ureas 12 – 22 for 72 h, and changes in MMP were analyzed.…”

“…For detection of ΔΨ m , HL-60 cells/fibroblasts were treated with various concentrations of the studied 7-MEOTA-THA thio-/ureas (HL-60: 12 – 17 : 5–25 µM, 18 – 22 : 1–15 µM; fibroblasts: 12 – 17 : 15 and 25 µM, 18 – 22 : 2.5 and 5 µM) for 24, 48 and 72 h (for fibroblasts only 72 h). The method used to perform the experiment has been published according to a previously described protocol 87 , 89 .…”

Using LC–MS/MS-based targeted proteomics to monitor the pattern of ABC transporters expression in the development of drug resistance

“…To induce drug resistance, cells are treated with the drug until they become resistant, and then protein expression in the resistance cell line is detected and compared with that in the parental cell line. 7 , 9 , 11 – 17 However, there are many contradictory results from different studies that cannot be explained. For example, in the studies of the induction effects of adriamycin (ADM) on MRP1 (short-term drug exposure), Louisa et al 7 proved that the resistance of MCF-7/ADM is closely related to the overexpression of MRP1, while Yan et al 15 claimed that the MRP1 expression in HepG-2/ADM and SMMC-7721/ADM was not significantly higher than that in the parental cells.…”