A new CD44V3-containing isoform is involved in tumor cell growth and migration during human breast carcinoma progression.

CD44 isoforms belong to a family of cell adhesion molecules expressed on the cell surface of many tumor cells during human breast cancer progression. In this study we have analyzed the expression of CD44v3-containing isoforms [containing heparan sulfate addition sites for growth factor binding] in primary breast tumors, axillary nodal metastases and normal breast tissue. Using reverse transcriptase-polymerase chain reaction (RT-PCR) followed by Southern blot, cloning, nucleotide sequencing and RT-in situ-PCR analyses, we have found that at least two CD44v3-containing isoforms, including one new species of CD44v2,deltav3-10 (deltav3 defined as a v3 exon lacking the first 24 base pairs) and another previously reported CD44v3,8-10 are preferentially expressed in human primary breast tumor and axillary nodal metastases but not in normal breast tissues. These finding suggest that these CD44v3-containing isoforms are closely associated with breast cancer metastasis.