The impact of the combination of BRD4 and BCL-2 inhibitors on oxidative stress in acute myeloid leukemia cell lines

• Grant number: 25/04861-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2025
• End date: February 28, 2027
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Mariane Tami Amano
• Grantee: Thais Nascimento Kimmemgs
• Host Institution: Hospital Sírio-Libanês. Sociedade Beneficente de Senhoras (SBSHSL). São Paulo , SP, Brazil

Abstract

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the disordered differentiation of hematopoietic stem cells, resulting in the accumulation of myeloblasts in the bone marrow and peripheral blood. The main treatment is intensive chemotherapy, but ineligible patients require alternative therapeutic options. Venetoclax (VEN), a selective inhibitor of the anti-apoptotic protein BCL-2, has been explored to treat these cases, although resistance mechanisms have already been associated with its use. Although, the oxidative stress in AML is not yet fully understood. Oxidative stress results from the imbalance between reactive oxygen species (ROS) and antioxidant agents, which can lead to the accumulation of ROS or tissue damage. AML cells are chronically under oxidative stress, with high ROS production. However, increased oxidative stress has been demonstrated as a potential therapeutic opportunity in AML. The inhibition of the transcription factor NRF2, which leads to increased ROS levels, sensitizes AML cells to better respond to VEN. Also, several studies have shown that inhibiting the epigenetic regulator BRD4 could be a potential therapeutic strategy for AML. BRD4 is a protein that contains structural bromodomains, with the ability to regulate gene expression, and is part of the BET family. It has been shown that BRD4 inhibition increased peroxisomal ROS production, as well as mitochondrial and cytosolic ROS, leading to peroxophagy in HeLa cells. There are still few studies on the role of BRD4 in oxidative stress in leukemic cells. Given that BRD4 inhibition has the potential to alter the oxidative homeostasis of cells, this project hypothesizes that the inhibition of BRD4 may increase oxidative stress and sensitize AML cells to treatment with VEN. Our objective is to evaluate the effect of oxidative stress modulation through BRD4 inhibition on the response to Venetoclax in AML and to clarify some of the mechanisms involved in oxidative stress modulation. To do this, we will use AML cell lines (HL-60; MOLM-13; THP-1; HEL; U937) to assess the expression of genes and proteins involved in the antioxidant response, as well as the expression of pro- and anti-apoptotic genes. We will investigate the total and mitochondrial ROS production in the cell lines treated with BRD4 inhibitor and VEN. We will evaluate the effects of treatments on heme oxygenase-1 (HO-1) production in AML cell lines and the impact of HO-1 inhibition on the response to VEN treatment. The development of this project may clarify the importance of oxidative stress in the response to VEN and serve as a basis for future therapeutic strategies for patients with AML.