In Vitro Evaluation of ALDH1A3-Affinic Compounds on Breast and Prostate Cancer Cell Lines as Single Treatments and in Combination with Doxorubicin

Abstract

Aldehyde dehydrogenase (ALDH) enzymes are involved in the growth and development of several tissues, including cancer cells. It has been reported that targeting the ALDH family, including the ALDH1A subfamily, enhances cancer treatment outcomes. Therefore, we aimed to investigate the cytotoxicity of ALDH1A3-affinic compounds that have been recently discovered by our group, on breast (MCF7 and MDA-MB-231) and prostate (PC-3) cancer cell lines. These compounds were investigated on the selected cell lines as single treatments and in combination with doxorubicin (DOX). Results showed that the combination treatment experiments of the selective ALDH1A3 inhibitors (compounds 15 and 16) at variable concentrations with DOX resulted in significant increases in the cytotoxic effect on the MCF7 cell line for compound 15, and to a lesser extent for compound 16 on the PC-3 cell line, compared to DOX alone. The activity of compounds 15 and 16 as single treatments on all cell lines was found to be non-cytotoxic. Therefore, our findings showed that the investigated compounds have a promising potential to target cancer cells, possibly via an ALDH-related pathway, and sensitize them to DOX treatment.

Keywords: ALDH inhibitors; breast cancer; combination treatment; doxorubicin; prostate cancer.

Figure 1

Chemical structures of ALDH-affinic compounds, adapted from Ibrahim et al. [21].

Figure 2

Western blot membranes showing the expression of (a) ALDH1A3 enzyme and (b) GAPDH loading control on MDA-MB-231, MCF7, and PC-3 cell lines.

Figure 3

Cell viability assays using compounds (a) 15, (b) 16, (c) 24, and (d) 33 alone at various concentrations (μM) (dark grey bars) and in combination with 5 μM DOX (light grey bars) on MCF7 cell line. Control bar chart (black bar) means no treatments were added. DOX at 5 μM alone is presented as a white bar. Experiments were performed in triplicates at three independent experiments with controls (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001).

Figure 4

Cell viability assays using compounds (a) 15, (b) 16, (c) 24, and (d) 27 alone at various concentrations (dark grey bars) and in combination with 1 μM DOX (light grey bars) on PC-3 cell line. Control bar chart (black bar) means no treatments were added. DOX at 1 μM alone is presented as a white bar. Experiments were performed in triplicates in three independent experiments with controls (* p < 0.05, *** p < 0.001, and **** p < 0.0001).

Figure 5

Cell viability assays using DEAB on (a) MCF7 and (b) PC-3 cell lines alone at various concentrations (dark grey bars) and in combination with (a) 5 μM DOX and (b) 1 μM DOX (light grey bars). Control bar charts (black bars) mean no treatments were added. DOX at (a) 5 μM and (b) 1 μM alone are presented as white bars. Experiments were performed in triplicates in three independent experiments with controls.