Insights into PI3K/AKT signaling in B cell development and chronic lymphocytic leukemia.

The phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signaling pathway is a central regulator of B cell biology, influencing survival, proliferation, metabolism, and immune responses. This Review explores how in both normal and malignant B cells, signaling operates within a finely tuned "comfort zone", where appropriate levels support cell growth and survival. This comfort zone is dynamically modulated by the developmental stage, costimulatory signals, and the duration, magnitude, and subcellular localization of signaling events. In chronic lymphocytic leukemia, aberrant PI3K/AKT activation drives disease progression and resistance to therapy. Notably, deviations from the comfort zone-whether through excessive hyperactivation or insufficient signaling-can trigger cell death, presenting therapeutic opportunities. Signaling thresholds influence normal B cell development and chronic lymphocytic leukemia pathogenesis, including mechanisms of immune escape and Richter's transformation, an aggressive progression from chronic lymphocytic leukemia. Therapeutic strategies targeting PI3K/AKT are evaluated, with a focus on challenges such as toxicity. By understanding the nuanced modulation of the signaling comfort zone, we can refine therapies to selectively eliminate leukemic cells while preserving normal B cell function, offering new hope for improved treatment outcomes.