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Structure, function, and targeting of interleukin 4 receptors on human head and neck cancer cells
K Kawakami1, P Leland, R K Puri
1Division of Cellular and Gene Therapies, Center for Biologistics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA.
Abstract:
Despite advances in diagnosis and treatment, survival rates for patients with head and neck cancer have remained unchanged for the last 30 years. In an attempt to develop novel therapeutic agents, we have observed that a variety of murine and human carcinoma cells expresses high levels of receptors for interleukin 4 (IL-4) in vitro and in vivo. Here, we demonstrate that 17 head and neck cancer cell lines also express surface IL-4 receptors (IL-4R) and IL-4 binds to IL-4R on one cell line studied with low affinity ((k)d = 37.9 +/- 0.4 nM). The investigation of the subunit structure of IL-4R demonstrated that head and neck cancer cell lines expressed mRNA for IL-4R beta chain (also known as IL-4R alpha) and IL-13R alpha' chain (also known as IL-13R alpha1). However, no cell line expressed IL-2R common gamma-chain, which is known to be shared with IL-4R in immune cells. IL-4R is functional because IL-4 strongly induced activation of signal transducers and activators of transcription 6 (STAT-6) in these cell lines. A fusion protein, IL4(38-37)-PE38KDEL, containing translocation and enzymatic domains of Pseudomonas exotoxin and a circularly permuted human IL-4 was found to be highly and specifically cytotoxic to IL-4R-positive head and neck cancer cells, as determined by protein synthesis inhibition assay and confirmed by clonogenic assay. IL4(38-37)-PE38KDEL induced DNA fragmentation and condensation of nuclei indicative of apoptotic cell death. These results establish uniform expression of IL-4R on head and neck cancer cell lines and IL-4 toxin IL4(38-37)-PE38KDEL as a novel therapeutic agent for the possible treatment of human head and neck cancers.
Insights
Head and neck cancer cells express interleukin-4 receptors (IL-4R). A novel IL-4 toxin specifically targets and kills these IL-4R-positive cancer cells, offering a new therapeutic approach.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Head and neck cancer survival rates have stagnated despite treatment advances.
- Interleukin-4 receptors (IL-4R) are expressed on various carcinoma cells.
Purpose of the Study:
- To investigate IL-4R expression on head and neck cancer cell lines.
- To evaluate a novel IL-4-based fusion toxin for head and neck cancer therapy.
Main Methods:
- Analysis of IL-4R expression and subunit structure in 17 head and neck cancer cell lines.
- Assessment of IL-4 binding affinity and STAT-6 activation.
- Cytotoxicity assays (protein synthesis inhibition, clonogenic assay) using the fusion protein IL4(38-37)-PE38KDEL.
Main Results:
- All 17 head and neck cancer cell lines expressed IL-4R mRNA and surface receptors.
- IL-4R on these cells showed functional signaling via STAT-6 activation.
- The fusion protein IL4(38-37)-PE38KDEL demonstrated high, specific cytotoxicity against IL-4R-positive cells, inducing apoptosis.
Conclusions:
- Head and neck cancer cells uniformly express functional IL-4 receptors.
- The IL-4 fusion toxin IL4(38-37)-PE38KDEL is a promising novel therapeutic agent for head and neck cancers.