ITK overexpression enhances T cell cytotoxicity against DLBCL through the TCR-Ca(2+)-Calcineurin-NFAT-IFN-γ pathway.

Diffuse Large B-Cell Lymphoma (DLBCL) is the most prevalent pathological subtype of non-Hodgkin lymphoma (NHL). Patients with DLBCL often experience extremely poor prognoses due to drug resistance or relapse, and the limitations of existing treatment regimens are evident. This study focuses on the mechanistic role and clinical significance of interleukin-2-inducible T-cell kinase (ITK) in DLBCL. Through bioinformatics analysis, it was found that ITK, as a key molecule in the T Cell Receptor (TCR) signaling pathway, is significantly underexpressed in DLBCL. This underexpression is associated with a poorer overall survival (OS) of patients and exhibits a negative correlation with the expression of the immune checkpoint molecule Programmed Death Ligand 1 (PD-L1), suggesting its potential involvement in the regulation of T cell exhaustion. In vitro experiments demonstrated that overexpression of Itk significantly enhanced the immunological activity of mouse T lymphocytes (CTLL-2), activating the TCR-Ca(2+)-Calcineurin-NFAT-IFN-γ signaling pathway. This led to improved calcium ion responsiveness in T cells, increased calcineurin activity, and nuclear translocation of Nuclear Factor of Activated T Cells (NFAT). It also enhanced cytokine secretion levels and proliferative capacity of cytotoxic T lymphocytes (CD8(+) T cells), thereby driving an anti-tumor immune response. In a co-culture model, overexpression of Itk significantly augmented the killing effect of CTLL-2 cells on DLBCL, inducing apoptosis in DLBCL cells. Furthermore, T cells overexpressing Itk exhibited a synergistic effect when combined with Rituximab, significantly enhancing the inhibition of DLBCL cell proliferation. This provides a clinically feasible approach to address the challenge of drug resistance in DLBCL treatment. This study unveils the molecular mechanism by which ITK enhances anti-tumor immunity through remodeling the T cell receptor signaling pathway, offering new theoretical grounds for the development of T cell function-activating combined therapeutic strategies for DLBCL.