OBJECTIVES: CD44 comprises a family of isoforms involved in tumorigenesis. Here we investigate the role of CD44 isoforms in head and neck squamous cell carcinoma (HNSCC) progression. MATERIALS AND METHODS: HNSCC specimens underwent reverse transcriptase-polymerase chain reaction (RT-PCR) followed by Southern blot analysis. After surface biotinylation, FaDu (hypopharyngeal HNSCC) and CD44v3-transfected COS-7 cells were CD44 antibody-precipitated and compared by Western blot analysis. FaDu cells underwent double immunofluorescence staining and growth assays. RESULTS: Southern blot analysis suggested differential CD44v3 isoform expression in tumor and normal tissue. Cloning and sequencing revealed 2 novel CD44v isoforms. Western blot analysis suggested CD44v3 expression in COS-7 transfectants and FaDu. Double immunofluorescence staining revealed co-localization of CD44v3 and actin in FaDu projections. Anti-CD44v3 antibody decreased FaDu growth. CONCLUSION: HNSCC tissue and FaDu appear to express CD44v3 isoforms. These isoforms may promote tumorigenesis. CLINICAL SIGNIFICANCE: CD44v3 isoforms may be effective tumor markers and targets for HNSCC therapy.
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