Osimertinib is the first-line therapy for EGFR-mutated non-small cell lung cancer, but acquired resistance emerges in most patients and remains a major barrier for complete cure. This phenomenon is most likely associated with the drug-tolerant persister (DTP) cell phenotype, a reversible state that enables survival under treatment and leads to irreversible drug resistance. To uncover the molecular mechanism driving this distinct phenotype, we applied data-independent acquisition mass spectrometry (DIA-MS) to establish the dynamic proteomic and phosphoproteomic landscape in the osimertinib DTPs. While osimertinib initially blocks EGFR signaling, ribosome synthesis and protein translation related pathways arise in DTP phase, and resistance developed through the reactivation of EGFR downstream pathways and anti-apoptotic mechanisms such as YAP1 and mTOR-BAD hyperphosphorylation, as validated by growth combination assays. Kinase enrichment revealed elevated phosphorylation of multiple CDK1 substrates in DTP phase and pharmacological or genetic inhibition of CDK1-mediated SAMHD1 activation significantly impair DTP growth and survival. This study illuminates the dynamic landscape underlying the DTPs biology and identifies biomarker and new targets to potentially prevent or delay the onset of resistance.

Application of B-cell receptor (BCR) pathway inhibitor ibrutinib for chronic lymphocytic leukemia (CLL) is a major breakthrough, yet the downstream effects following inhibition of BCR signaling and during relapse await further clarification. By comparative phosphoproteomic profiling of B cells from patients with CLL and healthy donors, as well as CLL B cells collected at multiple time points during the course of ibrutinib treatment, we provided the landscape of dysregulated phosphoproteome in CLL and its dynamic alterations associated with ibrutinib treatment. Particularly, differential phosphorylation events associated with several signaling pathways, including BCR pathway, were enriched in patient CLL cells. A constitutively elevated phosphorylation level of KAP1 at serine 473 (S473) was found in the majority of CLL samples prior to treatment. Further verification showed that BCR activation promoted KAP1 S473 phosphorylation, whereas ibrutinib treatment abolished it. Depletion of KAP1 in primary CLL cells decelerated cell-cycle progression and ectopic expression of a KAP1 S473 phospho-mimicking mutant accelerated G2–M cell-cycle transition of CLL cells. Moreover, temporal phosphoproteomic profiles using a series of CLL cells isolated from one patient during the ibrutinib treatment revealed the dynamic changes of several molecules associated with BCR signaling in the ibrutinib responsive and recurrent stages. Implications: This phosphoproteomic analysis and functional validation illuminated the phosphorylation of KAP1 at S473 as an important downstream BCR signaling event and a potential indicator for the success of ibrutinib treatment in CLL.

Isoflurane is a widely used volatile anesthetic with context-dependent effects on neuronal survival, particularly in neurodegenerative conditions. Increasing evidence suggests that brief, sublethal stress exposure can induce adaptive cellular responses through hormesis-based preconditioning mechanisms. In this study, we investigated whether isoflurane preconditioning enhances neuronal tolerance to amyloid-β (Aβ)-induced toxicity and explored the underlying redox-dependent molecular pathways. Using HT-22 murine hippocampal neuronal cells, we demonstrate that short-term exposure to low-dose isoflurane induces a delayed neuroprotective phenotype characterized by improved cell viability, reduced apoptotic signaling, and maintained mitochondrial membrane potential following Aβ challenge. Mechanistically, isoflurane preconditioning elicited a mild and transient increase in intracellular reactive oxygen species (ROS), which is critical for the activation of the PI3K/Akt signaling pathway. Pharmacological scavenging of reactive oxygen species abolished Akt phosphorylation and reduced the protective effects of preconditioning, supporting a hormetic signaling model rather than direct antioxidant action. Following Akt activation, isoflurane preconditioning promoted the inhibitory phosphorylation of glycogen synthase kinase-3β (GSK-3β), decreased Keap1 protein levels, and facilitated nuclear translocation and transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2). Consequently, the expression of Nrf2-regulated antioxidant genes, including heme oxygenase-1, NAD(P)H quinone dehydrogenase 1 (NQO1), superoxide dismutase 1 and 2 (SOD1/2), and catalase, was significantly upregulated. Collectively, these findings indicate that isoflurane preconditioning confers neuroprotection through hormesis-like mild oxidative signaling and coordinated activation of endogenous antioxidant defenses rather than via direct antioxidant scavenging.

Supplementary Data from Phosphoproteomics Reveals the Role of Constitutive KAP1 Phosphorylation by B-cell Receptor Signaling in Chronic Lymphocytic Leukemia

Supplementary Data from Phosphoproteomics Reveals the Role of Constitutive KAP1 Phosphorylation by B-cell Receptor Signaling in Chronic Lymphocytic Leukemia

Supplementary Data from Phosphoproteomics Reveals the Role of Constitutive KAP1 Phosphorylation by B-cell Receptor Signaling in Chronic Lymphocytic Leukemia