Kater, A. P. | Search bioRxiv

bioRxiv2026

Glutamine-driven mTORC1 activity enforces glycolytic bias, hyperactivation and aberrant proliferation in T cells in chronic B-cell leukemia

T-cell metabolic dysfunction is increasingly recognized as a hallmark of poor antitumor responses. Still, how distinct metabolic states shape T-cell function and which signaling pathways sustain them remains unclear. Here, we show that T cells from patients with chronic lymphocytic leukemia (CLL) adopt a hyperactivated phenotype characterized by high cytokine production, aberrant proliferation and a bias toward glycolysis, supported by sustained glutamine-driven mTORC1 activity. In parallel, T cells from these patients display alterations in mitochondrial network and cristae architecture, which further limit oxidative phosphorylation. mTORC1 inhibition reduces glucose dependence, restores mitochondrial metabolic engagement and normalizes T-cell activation and proliferation. Together, these findings identify metabolic disbalance as a central contributor to the hyperactivated state of T cells in CLL. We propose a model in which reduced OXPHOS reflects both mitochondrial defects that pre-exist in T cells from patients before TCR engagement, and a failure to engage mitochondrial metabolism upon activation supported by the actionable target mTORC1. HighlightsO_LIT cells from patients with chronic lymphocytic leukemia display high cytokine production and excessive division cycles upon CD3/28 engagement. C_LIO_LImTORC1-sustained glycolysis and defects in mitochondrial structure compromise OXPHOS in hyperactivated T cells. C_LIO_LIExogenous glutamine uptake sustains non-lysosomal mTORC1 activity in T cells. C_LI

immunology↗

bioRxiv2024

Disruption of basal CXCR4 oligomers impairs oncogenic properties in lymphoid neoplasms

The chemokine receptor CXCR4 is overexpressed in many cancers and contributes to pathogenesis, disease progression, and resistance to therapies. CXCR4 is known to form oligomers, but the potential functional relevance in malignancies remain elusive. Using a newly established nanobody-based BRET method, we demonstrate that oligomerization of endogenous CXCR4 on lymphoid cancer cell lines correlates with enhanced expression levels. Specific disruption of CXCR4 oligomers reduced basal cell migration and pro-survival signaling via changes in the phosphoproteome, indicating the existence of basal CXCR4-oligomer-mediated signaling. Oligomer disruption also inhibited growth of primary CLL 3D spheroids and sensitized primary malignant cells to clinically used Bcl-2 inhibitor venetoclax. Given its limited efficacy in some patients and the ability to develop resistance, sensitizing malignant B-cells to venetoclax is of clinical relevance. Taken together, we established a new, non-canonical and critical role for CXCR4 oligomers in lymphoid neoplasms and demonstrated that selective targeting thereof has clinical potential. Significance statementClass A GPCRs, including the chemokine receptor CXCR4, can form oligomers, but their functional relevance remains poorly understood. This study provides evidence for the role of basal CXCR4 oligomers in lymphoid neoplasms, where they drive pro-survival signaling, migration, and tumor growth. We use a novel nanobody-based BRET method to demonstrate that endogenous CXCR4 constitutively oligomerizes in lymphoid cancer cells, correlating with receptor expression levels. Pharmacological disruption of these oligomers reduces tumor- associated signaling, impairs spheroid growth, and sensitizes patient-derived malignant cells to the apoptosis-inducing drug Venetoclax. Since CXCR4 is frequently overexpressed and potentially clustered in various malignancies, this work offers broader implications for enhancing treatment efficacy, overcoming drug resistance, and potentially reducing side effects across multiple cancer types.

biochemistry↗