Comparison of the inhibition of an OCT3 transporter inhibitor, Nilotinib, on Doxorubicin’s effects on cardiac and cancer cell lines

Philadelphia, PA

Introduction

Doxorubicin (DOX)-induced cardiotoxicity remains a significant barrier limiting its clinical application due to a lack of effective resolution. Targeting how DOX enters cardiac and cancer cells is a promising new strategy. Research suggests that an OCT3 transporter significantly contributes to DOX entry into the heart tissue. By contrast, it expresses much lower on breast cancer cell lines. Moreover, Nilotinib (NIB) can suppress OCT3 transporter function by 80%. Therefore, exploring the impact of NIB on the DOX’s effects on cardiac and cancer cell lines by altering DOX intracellular accumulation is intriguing.

Objective

First, we would establish a dose-response curve of DOX and NIB alone to assess their individual effects on cell viability. Secondly, we would record the impact of NIB on DOX entry within cardiac myoblasts (H9C2) and breast cancer cells (MCF7) through OCT3 transporter antagonism to assess if NIB can exert cardioprotective effects while maintaining DOX’s anticancer effect.

Methods

H9C2 myoblast and MCF7 breast cancer cells were seeded in 96-well black plates. Cells were treated with only DOX or NIB to establish a dose-response curve. Moreover, NIB was combined with DOX as a cotreatment or pretreatment regimen to evaluate the impacts of NIB on DOX’s effect. Titrated combinations of NIB (10 nM, 50 nM, 100 nM, 500 nM, 1 µM, 2 µM, 5 µM) and DOX (10 µM and 40µM) were used. Bioassays were conducted after cells were treated for 24 hours. Intracellular DOX fluorescence intensity was measured at 488/590 nm by fluoroskan. Subsequently, cell viability was detected by measuring absorbance at 450 nm after adding a cell counting reagent. The data were expressed as a ratio relative to untreated or the DOX control.

Results

DOX dose-dependently reduced viability of H9c2 and MCF7 cells. H9c2 cell showed significantly lower cell viability at 1 µM (0.86±0.04, n=10, p<0.05) and 40 µM (0.40±0.02, n=10, p<0.05) when compared to those of MCF7 cells (1.07±0.05 and 0.68±0.08 for 1 µM and 40 µM, respectively, n=7). By contrast, NIB (10 nM-2 µM) only slightly increased cell viability to 1.13±0.05 (n=11) in H9c2 cells and to 1.16±0.13 (n=7) in MCF7 cells, respectively, when compared to untreated control. The highest tested dose of NIB (5 µM) showed a similar reduction of cell viability to 0.83±0.07 in H9c2 cells and to 0.81±0.10 in MCF7 cells. Furthermore, NIB cotreatment mitigated DOX-induced damages in H9c2 by increasing cell viability to 1.28±0.07 (n=5) and 1.26±0.11 (n=7) when compared to the DOX controls (10 µM and 40µM), respectively. Interestingly, NIB cotreatment enhanced DOX’s anti-cancer effects in by decreasing MCF7 cell viability to 0.66±0.10 (n=7) and 0.70±0.09 (n=6) when compared to the DOX controls (10 µM and 40µM), respectively. The intracellular DOX fluorescence data and NIB pretreatment results are still being gathered.

Conclusion

DOX, not NIB, dose-dependently induced H9c2 and MCF7 cell death. Moreover, DOX-induced damage was more potent in H9c2 cells than in MCF7 cells. NIB cotreatment mildly protected H9c2 cells against DOX, whereas it increased DOX’s anti-cancer effects in MCF7 cells.