Nrf2 Overexpression Increases Risk of Venetoclax Resistance in Acute Myeloid Leukemia By Promoting Glycolysis

Backgroud and objective: Recurrence and drug resistance is still to be the primary barrier to acute myeloid leukemia (AML). Glycolysis is elevated in the tumor environment, which contributes to reduce the sensitivity of leukemia cells to chemotherapeuticsy. Venetoclax is a BCL-2 inhibitor that effectively improves clinical outcomes in the poor-prognosis category of AML patients unfit for intensive chemotherapy. Though the majority of patients respond to venetoclax-based treatment, duration of response remain inadequate. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a pleiotropic transcription factor, which plays an important role in regulating the metabolic homeostasis. The mechanism by which NRF2 mediated venetoclax-resistance of AML through promoting the metabolic homeostasis are poorly understood.

Methods: The possible glycolysis related genes regulating by NRF2 were confirmed with Gene Transcription Regulation Database (GTRD) and Knock TF. Venetoclax-resistant MV4-11 cells(MV4-11/VEN cells) were newly established through continuous exposure of MV4-11 cells to venetoclax. Drug sensitivity were compared between MV4-11 and MV4-11/VEN cells by Cell Counting Kit-8 (CCK8). In addition, flow cytometry was used to observe the apoptosis process. Glucose and lactate kits were utilized to detect glucose consumption and lactate levels. The expression of NRF2 and glycolysis related genes were examined by quantitative reverse transcription-PCR (RT-PCR) and Western blot. Finally, we transfected AML cell lines by constructing LV-NRF2 lentiviral vector, and integrating siRNA of glycolysis related gene separately to detect the above index changes in leukemia cells.

Results: MV4-11/VEN cells displayed more than 10-fold resistance to venetoclax compared with MV4-11 cells (P<0.05). MV4-11/VEN cells also exhibited a higher glycolysis rate and increased expression level of NRF2. These effectsIt could be reversed by knock down of NRF2 in MV4-11/VEN cells. Further, NRF2 overexpression could protect the AML cells from apoptosis induced by venetoclax in vitro and increased the rate of drug resistance associated with glycolysis. Bioinformatics analysis suggested that glycolytic genes that may be transcriptionally regulated by NRF2 include G6PD, PKFP, SOD1, GCLC, and GOT1. Among these candidates, the expression of SOD1 was significantly decreased after knockdown of NRF2. Furthermore, Nrf2 overexpression induced the expression of SOD1, which enhanced the rate of glycolysis. Inhibition of SOD1 could reverse the changes in leukemia cells induced by NRF2.

Conclusion: As an important component of the metabolic homeostasis, glycolysis are closely related to the venetoclax resistance of AML. NRF2 could be a key component mediating the interaction between glycolysis and leukemia cells of AML This results might provide a new entry point for deepening the mechanism of AML progression and provides a new strategy for clinical practice.

No relevant conflicts of interest to declare.