Cancer cells, frequently exploit proteins involved in programmed cell death pathways to endure cellular stressors such as pharmacological or serum starvation. This ability to circumvent death signals is a hallmark of cancer and plays a critical role in the development of therapeutic resistance. The apoptosis evasion can be addressed by targeting anti-apoptotic proteins like Bcl-2. The BCL2 inhibitors (Venetoclax) have shown effectiveness in various blood cancers including acute myeloid leukaemia (AML), by inducing rapid apoptosis. However, growing evidence suggests that patients with AML develop therapeutic resistance through dysregulation of the apoptotic machinery, posing a persistent challenge in the clinic.
Similarly, the pathogenesis of AML likely depends on unique properties that allow cell survival in the challenging environment of bone marrow with limited cytokine exposure. While genetic mechanisms underpinning these processes are well characterized, the efficacy of BCL2 inhibition and cell resilience against stressors are likely to be strongly influenced by epigenetic mechanisms. To determine the role of epigenetic factors in these processes, we utilized a focused CRISPR library designed to target 1145 epigenetic regulators, with each gene represented by six guide RNAs. We conducted pooled CRISPR screens in the AML cell line MV4:11 under various conditions including Venetoclax treatment and serum starvation to identify mediators of survival under cellular stress and drug sensitivity and resistance. Our screens identified several interesting hits associated with Venetoclax resistance or sensitization, including JMJD6 and ZNF740. Knockout of JMJD6 sensitized AML cells to Venetoclax, while knockout of ZNF740 conferred resistance. Additionally, the knockout of TRIM28 improved cell survival under low-serum conditions.
Collectively, these results provide valuable insights into the epigenetic regulation of cell survival in response to cellular stress and the process of apoptosis in AML. Finally, targeting these proteins could offer novel therapeutic strategies to enhance the efficacy of apoptosis induction in AML.