Melatonin Can Modulate the Effect of Navitoclax (ABT-737) in HL-60 Cells

Abstract

Melatonin (N-acetyl-5-methoxytryptamine MEL) is an indolamine that has antioxidant, anti-inflammatory and anti-tumor properties. Moreover, MEL is capable of exhibiting both anti-apoptotic and pro-apoptotic effects. In the normal cells, MEL possesses antioxidant property and has an anti-apoptotic effect, while in the cancer cells it has pro-apoptotic action. We investigated the combined effect of MEL and navitoclax (ABT-737), which promotes cell death, on the activation of proliferation in acute promyelocytic leukemia on a cell model HL-60. The combined effect of these compounds leads to a reduction of the index of mitotic activity. The alterations in the level of anti- and pro-apoptotic proteins such as BclxL, Bclw, Mcl-1, and BAX, membrane potential, Ca2+ retention capacity, and ROS production under the combined action of MEL and ABT-737 were performed. We obtained that MEL in combination with ABT-737 decreased Ca2+ capacity, dropped membrane potential, increased ROS production, suppressed the expression of anti-apoptotic proteins such as BclxL, Bclw, and Mcl-1, and enhanced the expression of pro-apoptotic BAX. Since, MEL modulates autophagy and endoplasmic reticulum (ER) stress in cancer cells, the combined effect of MEL and ABT-737 on the expression of ER stress and autophagy markers was checked. The combined effect of MEL and ABT-737 (0.2 μM) increased the expression of protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), leading to a decrease in the level of binding immunoglobulin protein (BIP) followed by an increase in the level of C/EBP homologous protein (CHOP). In this condition, the expression of ERO1 decreased, which could lead to a decrease in the level of protein disulfide isomerase (PDI). The obtained data suggested that melatonin has potential usefulness in the treatment of cancer, where it is able to modulate ER stress, autophagy and apoptosis.

Melatonin as a Potential Multitherapeutic Agent

“…In addition, the effects of MEL on cells resulted in the activation and association of the proapoptotic proteins Bax and Bid and also contributed to detectable increases in the expression of both proteins [ 26 ]. Later, we observed the ability of MEL to enhance the proapoptotic effects of some chemotherapeutic agents, such as retinoic acid (ATRA), Navitoclax (ABT-737), and cytarabine (CYT), in HL-60 cells [ 58 , 59 , 60 ]. We showed that MEL has the ability to not only suppress the expression of antiapoptotic proteins of the Bcl family (Bcl-2 and Bcl-xL) but also to regulate the expression of proteins considered to be the most important regulators of the mPTP (VDAC, TSPO, and CNPase) [ 59 ].…”

“…Later, we observed the ability of MEL to enhance the proapoptotic effects of some chemotherapeutic agents, such as retinoic acid (ATRA), Navitoclax (ABT-737), and cytarabine (CYT), in HL-60 cells [ 58 , 59 , 60 ]. We showed that MEL has the ability to not only suppress the expression of antiapoptotic proteins of the Bcl family (Bcl-2 and Bcl-xL) but also to regulate the expression of proteins considered to be the most important regulators of the mPTP (VDAC, TSPO, and CNPase) [ 59 ]. This gives us reason to believe that the proapoptotic effect of MEL under these conditions is associated with the functioning of the mPTP, and we suggest that MEL could be used as a potential proapoptotic and oncostatic agent.…”

“…However, combined therapy with MEL and chemotherapy drugs is poorly understood. In our work, we investigated the combined effect of MEL and chemotherapeutic agents from different pharmacological groups—retinoic acid (ATRA), cytarabine (CYT), and navitoclax (ABT-737)—on the proliferation, differentiation, and expression of mitochondrial target proteins in HL-60 cells used as a model of acute promyelocytic leukemia (APL) [ 58 , 59 , 60 ]. It is known that ATRA is used clinically for the treatment of APL as a differentiating agent in combination with chemotherapeutic drugs [ 96 , 97 ].…”

“…We showed the effect of MEL in combination with ATRA, CYT, and ABT-737 at concentrations lower than those used in medical practice (10, 2, and 0.2 μM, respectively) on the activation of HL-60 cell proliferation. MEL reduced cell viability; however, combined treatment of MEL (1 mM) with ATRA (10 nM), MEL (1 mM) with CYT (2 nM), and MEL (1 mM) with ABT-737 (0.2 μM) at non-toxic concentrations increased cytotoxicity towards HL-60 cells compared to treatment with MEL, ATRA (10 nM), CYT (2 nM), and ABT-737 (0.2 μM) applied separately [ 58 , 59 , 60 ].…”

“…Treatment with MEL in combination with ABT-737 (0.2 μM) reduced the Ca 2+ capacity, increased the decrease in membrane potential while increasing the production of ROS, and suppressed the expression of antiapoptotic proteins, such as Bcl xL , Bcl w , and Mcl-1, but increased the expression of proapoptotic BAX. In addition, MEL in combination with ABT-737 (0.2 μM) caused depolarization of the mitochondrial membrane, increasing the decrease in membrane potential, which could lead to an increase in ROS production with a subsequent increase in autophagy [ 59 ].…”