CD29 and CD7 mediate galectin-3-induced type II T-cell apoptosis

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Galectin-3 (Gal-3) is a multifunctional protein involved in various biological processes, including cancer progression.
• Extracellular Gal-3's role in T-cell apoptosis and its implications in cancer immunity remain incompletely understood.

Purpose of the Study:

• To investigate the pro-apoptotic effects of extracellular Galectin-3 on human and mouse T cells.
• To elucidate the mechanisms and cellular receptors involved in Gal-3-mediated T-cell apoptosis.
• To explore the potential role of Gal-3 in cancer immune evasion.

Main Methods:

• Treatment of human T leukemia cell lines, peripheral blood mononuclear cells, and activated mouse T cells with exogenous Gal-3.
• Assessment of apoptosis using lactose inhibition and dose-dependency studies.
• Analysis of Gal-3 expression in different cell lines and its effect on ceramide-induced apoptosis.
• Identification of Gal-3 cell surface receptors (CD7, CD29) and investigation of downstream signaling pathways (mitochondrial apoptosis, caspase activation).

Main Results:

• Secreted Gal-3 induces apoptosis in T cells in a dose-dependent and carbohydrate-specific manner.
• T cells lacking intracellular Gal-3 (Gal-3-null) are more sensitive to exogenous Gal-3-induced apoptosis.
• Gal-3 binding to CD7 and CD29 triggers mitochondrial apoptosis, including cytochrome c release and caspase-3 activation.
• Gal-3-transfected cells exhibit resistance to ceramide-induced apoptosis.

Conclusions:

• Extracellular Gal-3 can induce T-cell apoptosis, mediated by specific cell surface receptors and mitochondrial pathways.
• The interplay between intracellular and extracellular Gal-3 influences T-cell apoptosis sensitivity.
• Gal-3-induced T-cell apoptosis may represent a mechanism for tumor immune evasion by targeting cancer-infiltrating T cells.