Biology subjects

Racioppi, L.

Publications and source records attributed to Racioppi, L..

4 recordsLinked to original sources

bioRxiv2026

CaMKK2 Identifies Biologically Aggressive Chronic Lymphocytic Leukemia and Regulates Leukemic Survival and Nurse-Like Cell Support

Background/ObjectivesIdentification of prognostic biomarkers that capture biologically aggressive disease remains a major need in chronic lymphocytic leukemia (CLL). Aberrant calcium signaling contributes to leukemic survival; however, the clinical relevance of Ca{superscript 2}/calmodulin-dependent protein kinase kinase 2 (CaMKK2), a calcium-responsive kinase, has not been defined. This study evaluated CaMKK2 as a candidate prognostic biomarker and functional regulator in CLL. MethodsCaMKK2 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. ResultsElevated CaMKK2 expression was enriched in IGHV-unmutated CLL and associated with shorter time-to-treatment and inferior overall survival. CaMKK2 inhibition reduced primary CLL viability in a dose-dependent manner and induced apoptosis, with sensitivity correlating with CaMKK2 expression levels. Inhibition also attenuated CD163 macrophage polarization and impaired NLC-mediated support of leukemic cells. ConclusionsCaMKK2 expression identifies biologically aggressive CLL and functionally contributes to leukemic persistence. These findings position CaMKK2 as a prognostically relevant biomarker with therapeutic implications, supporting further evaluation of CaMKK2-targeted strategies in high-risk CLL. Sample SummaryChronic lymphocytic leukemia (CLL) shows marked variability in clinical outcome, highlighting the need for biomarkers that identify patients at higher risk of progression and guide therapeutic strategies. Calcium signaling supports leukemia cell survival, yet the clinical relevance of the calcium-responsive enzyme CaMKK2 has not been established. In this study, we demonstrate that elevated CaMKK2 expression in patient-derived leukemia cells is associated with more aggressive disease and earlier need for treatment. Laboratory experiments further show that inhibiting CaMKK2 reduces leukemia cell survival and disrupts supportive macrophage-like cells within the tumor microenvironment. These results position CaMKK2 as a candidate prognostic biomarker that reflects biologically high-risk disease and may inform therapeutic development. Future studies are warranted to determine whether CaMKK2-based risk stratification or targeted inhibition could improve management of patients with CLL.

immunology↗

bioRxiv2022

SGC-CAMKK2-1: A chemical probe for CAMKK2

The serine/threonine protein kinase calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) plays critical roles in a range of biological processes. Despite its importance, only a handful of inhibitors of CAMKK2 have been disclosed. Having a selective small molecule tool to interrogate this kinase will help demonstrate that CAMKK2 inhibition can be therapeutically beneficial. Herein, we disclose SGC-CAMKK2-1, a selective chemical probe that targets CAMKK2.

cancer biology↗

bioRxiv2022

Increased CaMKK2 expression is an adaptive response that maintains the fitness of tumor-infiltrating natural killer cells

Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a key regulator of energy homeostasis in several cell types. Expression of this enzyme in tumor cells promotes proliferation and migration, and expression in tumor-associated immune cells facilitates M2 macrophage polarization and the development of myeloid-derived suppressor cells. Thus, there has been considerable interest in developing CaMKK2 inhibitors as potential cancer therapeutics. However, the roles of CaMKK2 in other cellular compartments within the tumor immune environment remain to be established, an impediment to the clinical development of these agents. We report that CaMKK2 is expressed at low basal levels in natural killer (NK) cells but is significantly upregulated in tumor-infiltrating NK cells where it suppresses apoptosis and promotes proliferation. It was further demonstrated that NK cell-intrinsic deletion of CaMKK2 increased metastatic progression across several murine models, establishing a critical role for this enzyme in NK cell tumor immunity. Interestingly, ablation of the CaMKK2 protein, but not inhibition of its kinase activity, resulted in decreased NK cell survival. These results indicate an important scaffold function for CaMKK2 in NK cells and suggest that competitive CaMKK2 inhibitors and ligand-directed degraders (LDDs) are likely to have distinct therapeutic utilities. Finally, we determined that intracellular lactic acid is a key driver of CaMKK2 expression, suggesting that upregulated expression of this enzyme is an adaptive mechanism by which tumor-infiltrating NK cells mitigate the deleterious effects of a lactate-rich tumor environment. The findings of this study should inform strategies to manipulate the CaMKK2 signaling axis as a therapeutic approach in cancer.

cancer biology↗

bioRxiv2021

Calcium/Calmodulin Dependent Protein Kinase Kinase 2 Regulates the Expansion of Tumor-induced Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of cells, which can suppress the immune response, promote tumor progression and impair the efficacy of immunotherapies. Consequently, the pharmacological targeting of MDSC is emerging as a new immunotherapeutic strategy to stimulate the natural anti-tumor immune response and potentiate the efficacy of immunotherapies. Herein, we leveraged genetically modified models and a small molecule inhibitor to validate Calcium-Calmodulin Kinase Kinase 2 (CaMKK2) as a druggable target to control MDSC accumulation in tumor-bearing mice. The results indicated that deletion of CaMKK2 in the host attenuated the growth of engrafted tumor cells, and this phenomenon was associated with increased antitumor T cell response and decreased accumulation of MDSC. The adoptive transfer of MDSC was sufficient to restore the ability of the tumor to grow in Camkk2-/- mice, confirming the key role of MDSC in the mechanism of tumor rejection. In vitro studies indicated that blocking of CaMKK2 is sufficient to impair the yield of MDSC. Surprisingly, MDSC generated from Camkk2-/- bone marrow cells also showed a higher ability to terminally differentiate toward more immunogenic cell types (e.g inflammatory macrophages and dendritic cells) compared to wild type (WT). Higher intracellular levels of reactive oxygen species (ROS) accumulated in Camkk2-/- MDSC, increasing their susceptibility to apoptosis and promoting their terminal differentiation toward more mature myeloid cells. Mechanistic studies indicated that AMP-activated protein kinase (AMPK), which is a known CaMKK2 proximal target controlling the oxidative stress response, fine-tunes ROS accumulation in MDSC. Accordingly, failure to activate the CaMKK2-AMPK axis can account for the elevated ROS levels in Camkk2-/- MDSC. These results highlight CaMKK2 as an important regulator of the MDSC lifecycle, identifying this kinase as a new druggable target to restrain MDSC expansion and enhance the efficacy of anti-tumor immunotherapy.

immunology↗