Antitumor Effect of Brusatol in Acute Lymphoblastic Leukemia Models Is Triggered by Reactive Oxygen Species Accumulation

Abstract

Acute lymphoblastic leukemia (ALL) is one of the most common hematological malignancies at pediatric ages and is characterized by different chromosomal rearrangements and genetic abnormalities involved in the differentiation and proliferation of lymphoid precursor cells. Brusatol is a quassinoid plant extract extensively studied due to its antineoplastic effect through global protein synthesis and nuclear factor erythroid 2-related factor-2 (NRF2) signaling inhibition. NRF2 is the main regulator of cellular antioxidant response and reactive oxygen species (ROS), which plays an important role in oxidative stress regulation. This study aimed to evaluate the effect of brusatol in in vitro models of ALL. KOPN-8 (B-ALL), CEM (T-ALL), and MOLT-4 (T-ALL) cell lines were incubated with increasing concentrations of brusatol, and the metabolic activity was evaluated using the resazurin assay. Flow cytometry was used to evaluate cell death, cell cycle, mitochondrial membrane potential (Δψmit), and to measure ROS and reduced glutathione (GSH) levels. Our results show that brusatol promoted a decrease in metabolic activity in ALL cell lines in a time-, dose-, and cell-line-dependent manner. Brusatol induced a cytostatic effect by cell cycle arrest in G0/G1 in all cell lines; however, cell death mediated by apoptosis was only observed in T-ALL cells. Brusatol leads to an oxidative stress imbalance by the increase in ROS levels, namely, superoxide anion. Redox imbalance and cellular apoptosis induced by brusatol are highly modulated by mitochondria disruption as a decrease in mitochondrial membrane potential is detected. These data suggest that brusatol might represent a new therapeutic approach for acute lymphoblastic leukemia, particularly for ALL T-cell lineage.

Preparation, Optimization, and In-Vitro Evaluation of Brusatol- and Docetaxel-Loaded Nanoparticles for the Treatment of Prostate Cancer

“…Because of this characteristic, it is used as a marker for apoptotic and necrotic cells [ 56 ]. As shown in Figure 8 and Figure 9 , treatment of LNCaP cells with brusatol as a single agent at about 40 nM resulted in 66.6% of the cells being arrested in the G1-phase of the cell cycle at 24 h. This is supported by previous studies where antitumor and anticancer activities of brusatol have been shown to induce cell cycle arrest in the G1-phase before promoting tumor cell death [ 54 , 55 ]. At 72 h ( Supplementary Information; Figure S7 ) post treatment, about 60.7% of LNCaP cells show G1-phase arrest with 11.2% of cells observed in the sub-G1 phase, indicative of cell death.…”

“…Further, analysis of the cell cycle at 120 h ( Supplementary information; Figure S8 ) shows that brusatol treatment caused considerable cell death due to a large increase in the subG1 phase cell population (about 54.2%). This cell death by brusatol has been reported [ 54 , 55 , 57 ].…”

“…Docetaxel and brusatol are two chemical compounds that have been extensively studied for their anti-cancer properties. These drugs work by targeting different phases of the cell cycle, with docetaxel primarily inducing arrest in the G2/M phase [ 50 ], and brusatol arresting cells in the G1 phase of the cell cycle [ 54 , 55 ].…”

“…Pharmaceutics 2024, 16, x FOR PEER REVIEW 20 of 31 the cell cycle, with docetaxel primarily inducing arrest in the G2/M phase [50], and brusatol arresting cells in the G1 phase of the cell cycle [54,55].…”

Identification of NRF2 Activation as a Prognostic Biomarker in T-Cell Acute Lymphoblastic Leukaemia

“…In B-ALL, inhibition of NRF2 with brusatol sensitises tumour cells to vincristine [ 27 ]. In T-ALL cell lines, brusatol promotes a decrease in cell metabolism and induces apoptosis [ 38 ]. Our enhanced understanding of NRF2 biology in T-ALL may allow us to propose targeted therapeutic approaches, which could be used in combination with standard chemotherapy in order to improve the outcome of relapsed/refractory T-ALL patients.…”