COMPLEX EFFECT OF THE ALDEHYDE DEHYDROGENASE INHIBITOR DEAB AND SPERMINE ON ANDROGEN-RESISTANT PROSTATE CANCER CELLS

Abstract

Summary. Changes in a number of parameters of androgen-resistant human prostate cancer (PCa) cells under the influence of 4-(Diethylamino)benzaldehyde (DEAB) and its combination with spermine (Spn) in vitro have been determined. DEAB is a reversible inhibitor of aldehyde dehydrogenase (ALDH) and is used in biology and medicine, in particular in stem cell activity tests (Aldefluor Assay). This work continues studies that prove the enhancement of the cytotoxic and proapoptotic effects of Spn under the condition of parallel inhibition of ALDH activity in tumor cells. Aim: study of changes in viability, ζ-potential, sign and magnitude of total surface charge (TSC), cytomorphological characteristics, as well as modifications of the profile of basic and acetylated polyamines (PA) caused by the influence of DEAB or its combination with Spn in androgen-resistant prostate cancer cells. Object and methods: the objects of the research were cultures of poorly differentiated androgen-resistant prostate cancer cells of the DU-145 line. Cell survival was determined using trypan blue, the level of proliferation - crystal violet. ζ-potential and total surface charge (TSC) density at pH 7.4 were calculated based on the linear velocity of cell movement in the electric field, the sign - according to its direction. Cytomorphological changes were studied on fixed preparations of cells grown on coverslips and stained with hematoxylin and eosin. The profile of the main PAs - putrescine, spermidine, spermine and their acetylated forms - was determined by high-performance liquid chromatography (HPLC). Results: It was shown that in the case of use in monomode IC₅₀ DEAB = 4.0 mM, IC₅₀ Spn = 5.0 mM; in the case of combined exposure IC₅₀ DEAB = 1.0 mM, IC₅₀ Spn = 2.5 mM. DEAB and Spn, applied both separately and in combination, caused an inversion of the sign of the TSC from negative to positive. Pure DEAB reduced the ζ-potential of DU-145 cell line by 68.5%, while pure Spn – only by 21.2%, because the positive TSC of cells under the action of Spn acquired on average 2.5 times greater value than the positive charge of cells exposed to DEAB. The combination of DEAB with Spn in inhibitory concentrations returned the value of the ζ-potential to control values. The predominant role of Spn in this combination was shown, as is to varying degrees inherent in the combined action of Spn with other ALDH inhibitors. DEAB exerted a cytotoxic and proapoptotic effect on DU-145 cell line. Simultaneous addition of Spn and DEAB had a less pronounced cytotoxic effect, but caused the appearance of a larger number of cells with apoptotic changes. DEAB at a concentration of 4.0 mM had practically no effect on the content of Put, the levels of Spd and Spn increased by 14.5% and 40.9%, respectively. A decrease in the content of N¹-AcSpd and N¹-AcSpn by 18–19% was also noted. The mixture of DEAB and Spn caused a significant decrease in the levels of all PAs by 1.2–,04 times. Conclusions: pure DEAB inverted the sign of TSC from negative to positive, as did its mixture with Spn. With the combined action of these compounds, Spn played a quantitatively more significant role, competing with DEAB for binding sites with the cell surface. Pure DEAB exerted cytotoxic and proapoptotic effects on androgen-resistant PCa cells. The combined action of Spn and DEAB caused less pronounced cytotoxic and more pronounced proapoptotic effects. The increase in the content of Spd and, to a greater extent, Spn against the background of a stably low level of Put, as well as the decrease in the content of their acetylated forms, was shown. The decrease in the levels of all PAs under the combined influence of Spn and DEAB indicated the inhibition of their synthesis, which negatively affected the proliferation and survival of tumor cells. Aldehyde dehydrogenase (ALDH) inhibitors, particularly DEAB, can be used as adjunctive drugs in chemotherapy for PCa.