Idarubicin-bromelain combination sensitizes cancer cells to conventional chemotherapy

Abstract

Objectives: The primary cytotoxic effects of anticancer drugs like idarubicin, a chemotherapeutic agent, are not limited to neoplastic cells; they also produce similar effects in normal cells. In this study, we hypothesized that the combination of idarubicin-bromelain could make cancer cells more susceptible to cytotoxicity and genotoxicity.

Materials and methods: To test our hypothesis, the optimal concentrations of idarubicin and bromelain were combined and incubated in the HL-60 cancer cell line and normal human mononuclear leukocytes (PBMC) for 24, 48, and 72 hr. Cytotoxicity and genotoxicity were evaluated by measurement of ATP cell viability test, DNA damage, Caspase-3, Acridine orange/ethidium bromide (AO/EB), and DAPI fluorescent dyes in both cell types.

Results: The combination of idarubicin-bromelain significantly reduced cell proliferation in the more potent HL-60 compared to PBMC in all incubation times (P<0.05). DNA damage and Caspase-3 levels (except for 24 hr) were also higher in the HL-60 cell line in comparison with PBMC and were statistically significant (P<0.05). The percentages of apoptotic images obtained by DAPI and AO / EB morphological examination were increased in both cells, depending on the combination dose.

Conclusion: Based on these results, it can be concluded that idarubicin combined with bromelain produces more cytotoxic effects in low concentrations in comparison with when it was used per se in the HL-60 cells. Conversely, it was found that this combination in PBMC caused less cytotoxicity and less genotoxicity. Taken together, it can be said that this new combination makes cancer cells more sensitive to conventional therapy.

Keywords: Apotosis; Bromelain; Cell survival; DNA damage; Drug interactions; Idarubicin.

Figure 1

The structure of IDA and daunorubicin (7)

Figure 2

(a-d) Effect of IDA and BRO on HL-60 (a, c) and PBMC (b, d) after 24, 48, and 72 hr incubation. Data are representative of three independent experiments

Figure 3

(a-c). Growth inhibition of PBMC and HL-60 cell lines treated with IDA-BRO combinations by The CellTiter-Glo Luminescent Cell Viability Assay after 24 (a), 48 (b), and 72 (c) hr incubation. Each point represents a mean±SD of three experiments with three replicates per combination. Values marked with * indicate significant differences between HL-60 and PBMC for the same combination

Figure 4

(a-c). DNA damage levels in the HL-60 cell line and PBMC after 24 (a), 48 (b), and 72 (c) hr incubation. Each point represents a mean±SD of three experiments with two replicates per combination. The levels of DNA damage of HL-60 are significantly (*) different (P<0.05) from PBMC at the same combination

Figure 5

(a-c). Caspase-3 levels after 24 (a), 48 (b), and 72 (c) hr incubation. Each point represents a mean±SD of three experiments with three replicates per combination. Values marked with * indicate significant differences between HL-60 and PBMC at the same combination (P<0.05)

Figure 6

(a-g). Detection of apoptosis by AO/EB dual staining. (a) Viable cells, early apoptotic cells, late apoptotic cells, and necrotic cells were detected using fluorescence microscope observation following AO/EB staining. Magnification was 40X. Significant changes were observed in HL-60 and PBMC exposed to IDA-BRO combinations at 24 (b and c), 48 (d and e), and 72 (f and g) hr incubation, respectively. Each column represents a mean±SD of three experiments with three replicates per combination. *P<0.05 vs Control group (HL-60 or PBMC)

Figure 7

(a-d). Apoptotic and normal cell percentages determined by DAPI fluorescence staining method. (a) Normal cells and apoptotic cells. Magnification was 40X. (b) 24, (c) 48, (d) 72 hr incubation. Each column represents a mean±SD of three experiments with three replicates per combination. *P<0.05 vs Control group (HL-60 or PBMC)