The variegated expression of the KIR family of class I MHC receptors generates specialized natural killer (NK) cells capable of allele-specific HLA recognition. Understanding the mechanism of KIR gene activation will lead to improved methods for the generation of fully functional NK cells. A central RUNX-binding site in the KIR proximal promoter is required for gene activation. RUNX proteins recruit ten-eleven translocation (TET) proteins that generate 5-hydroxymethylcytosine (5hmC) and drive DNA demethylation. Assessment of 5-methylcytosine (5mC) and 5hmC residues at four stages of NK cell development reveals deposition of 5hmC primarily in a CREB site next to the RUNX site at the CD56Bright stage but not the subsequent CD56Dim stage representing fully mature NK cells. KIR promoter demethylation is delayed relative to other lineage-associated genes, indicating a high threshold for KIR gene demethylation in developing NK cells, and a window of opportunity for RUNX/TET-dependent KIR gene activation in CD56Bright NK cells.

BACKGROUND/OBJECTIVES: Chronic lymphocytic leukemia (CLL) is characterized by clinical and biological heterogeneity shaped by intrinsic signaling programs and microenvironmental interactions. Established biomarkers, including IGHV mutation status and TP53 alterations, provide important clinical and molecular information, but do not fully capture the diversity of pathways that sustain leukemic cell fitness. Aberrant calcium signaling contributes to leukemic survival; however, the clinical relevance of Ca2+/calmodulin-dependent protein kinase kinase 2 (CaMKK2), a calcium-responsive kinase, has not been defined. This study evaluated CaMKK2 as a candidate marker associated with high-risk disease biology and a pathway of interest for further study. METHODS: CaMKK2 expression was quantified in purified CD19+ CLL cells from a clinically annotated cohort balanced by immunoglobulin heavy chain variable region (IGHV) mutation status. Associations with time to treatment and overall survival were analyzed. Functional relevance was assessed by pharmacologic inhibition of CaMKK2 in primary CLL cells using metabolic (MTS) and apoptosis (Annexin V/PI) assays. Correlations between CaMKK2 expression and inhibitor sensitivity were determined. The impact of CaMKK2 inhibition on nurse-like cell (NLC) differentiation and macrophage-mediated leukemic support was evaluated in ex vivo culture systems. RESULTS: Elevated CaMKK2 expression was enriched in IGHV-unmutated CLL and associated with shorter time to treatment and inferior overall survival. Pharmacological inhibition of CaMKK2 was associated with reduced primary CLL viability in a dose-dependent manner and increased Annexin V/PI-defined total cell death with sensitivity correlating with CaMKK2 expression levels. Inhibition also attenuated CD163+ macrophage polarization and impaired NLC-mediated support of leukemic cells. CONCLUSIONS: CaMKK2 expression is associated with IGHV-unmutated, high-risk CLL biology. Pharmacologic inhibition of CaMKK2 was associated with reduced leukemic cell viability and altered macrophage phenotypes in ex vivo systems. These findings are exploratory, derived from a limited cohort, and support further investigation into the role of CaMKK2 in CLL biology, but do not establish independent prognostic value or direct on-target causality.

Cancer drug resistance poses a significant challenge in oncology, often driven by intricate cross-talk among membrane-bound receptors that compromise mono-targeted therapies. We develop a dual membrane receptor degradation strategy leveraging Folate Receptor α (FRα) to address this issue. Folate Receptor α Targeting Chimeras-dual (FolTAC-dual) are engineered degraders designed to selectively and simultaneously degrade distinct receptor pairs: (1) EGFR/HER2 and (2) PD-L1/VISTA. Through modular optimization of modality configurations and geometries, we identify the “string” format as the most effective construct. Mechanistic studies demonstrate an ~85% increase in EGFR-binding affinity compared to the conventional knob-into-hole design, likely contributing to the improved efficiency of dual-target degradation. Proof-of-concept studies reveal that EGFR and HER2 FolTAC-dual effectively counteracts resistance in Trastuzumab/Lapatinib-resistant HER2-positive breast cancer models, while PD-L1 and VISTA FolTAC-dual rejuvenates immune responses in PD-L1 antibody-resistant syngeneic mouse models. These findings establish FolTAC-dual as a promising dual-degradation platform for clinical translation. Subject terms: Cancer immunotherapy, Targeted therapies, Protein design, Drug discovery and development