CD44 Variant 3

The CD44 molecule belongs to a family of cellular adhesion molecules found on a wide range of normal and malignant cells in epithelial, mesothelial and hemopoiesis tissues. CD44 is a single gene with 20 exons, of which 10 are normally expressed to encode the basic CD44 (H-CAM) molecule. The additional 10 exons (v1 to v10) are only expressed by alternative splicing of the nuclear RNA. The expression of specific cell adhesion molecule CD44 splice variants has been reported to be associated with metastasis in certain human malignancies, such as breast cancer. A complex pattern of CD44 variant expression in different tumors compared to the CD44 expression of the normal cell of origin has been reported (Fox SB et al., Cancer Research (53): 4539-4546, (1994)). High levels of expression were observed with the variant exons by breast carcinomas that arise from breast ductal epithelium which do not normally express CD44. Conversely, normal gastrointestinal epithelium were reported to express low levels of many of the CD44 variants and the derived colon cancers expressed low and variable levels of the variants. Respiratory epithelium which expressed variants at high levels in normal cells were reported to express the same variants at similar levels in lung carcinomas.