Fas Ligand–Positive Membranous Vesicles Isolated from Sera of Patients with Oral Cancer Induce Apoptosis of Activated T Lymphocytes

• Published in: Clinical cancer research Vol. 11; no. 3; pp. 1010 - 1020
• Main Authors: JEONG WHUN KIM, WIECKOWSKI, Eva, TAYLOR, Douglas D, REICHERT, Torsten E, WATKINS, Simon, WHITESIDE, Theresa L
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01-02-2005
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal - immunology; Antineoplastic agents; Apoptosis; Biological and medical sciences; Blotting, Western; cancer evasion; Carcinoma, Squamous Cell - blood; Carcinoma, Squamous Cell - immunology; Carcinoma, Squamous Cell - pathology; Caspase 3; Caspases - metabolism; Cell Line, Tumor; Cytochromes c - secretion; Cytoplasmic Vesicles - metabolism; Cytoplasmic Vesicles - ultrastructure; Down-Regulation; Fas Ligand Protein; fas Receptor - immunology; fas Receptor - metabolism; FasL; Female; Flow Cytometry; Humans; Jurkat Cells; Male; Medical sciences; Membrane Glycoproteins - blood; Membrane Glycoproteins - immunology; Membrane Glycoproteins - metabolism; Membrane Proteins - metabolism; Microscopy, Electron; microvesicles; Middle Aged; Mitochondria - metabolism; Mitochondria - ultrastructure; Mouth Neoplasms - blood; Mouth Neoplasms - immunology; Mouth Neoplasms - pathology; oral carcinoma; Pharmacology. Drug treatments; Receptors, Antigen, T-Cell - metabolism; T-Lymphocytes - immunology; T-Lymphocytes - pathology; Human; Vesicle; Oral cavity; Fas ligand; Oral cancer; Tumor necrosis factor; Cell death; Cytokine; T-Lymphocyte; Serum; Tumor necrosis factor α; Apoptosis
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.1010.11.3

Objective: In patients with oral squamous cell carcinoma, a high proportion of T cells in the tumor undergo apoptosis, which correlates
with Fas ligand (FasL) expression on tumor cells. The present study was done to identify mechanisms responsible for apoptosis
of T cells seen in the peripheral circulation of these patients.
Methods: Sera of 27 patients, normal donor sera, and supernatants of cultured normal or tumor cells were fractionated by size exclusion
chromatography and ultracentrifugation to isolate microvesicles. The presence of microvesicle-associated FasL was studied
by Western blots, blocking with anti-Fas reagents, and immunoelectron microscopy. Biological activities of microvesicles were
tested including the ability to induce apoptosis of Jurkat and T-cell blasts. Semiquantitative analysis of FasL in microvesicles
was correlated with caspase-3 activity, DNA fragmentation, cytochrome c release, loss of mitochondrial membrane potential, and TCR-ζ chain expression in lymphocytes.
Results: FasL-positive (FasL+) microvesicles were detected in sera of 21 of 27 patients. Microvesicles contained 42 kDa FasL. These
microvesicles induced caspase-3 cleavage, cytochrome c release, loss of mitochondrial membrane potential, and reduced TCR-ζ chain expression in target lymphocytes. Biological activity
of the FasL+ microvesicles was partially blocked by ZB4 anti-Fas monoclonal antibody. Microvesicle-associated FasL levels
correlated with the patients' tumor burden and nodal involvement.
Conclusion: Sera of patients with active oral squamous cell carcinoma contain FasL+ microvesicles, which induce the receptor and mitochondrial
apoptotic pathways in Jurkat and activated T cells.