Purpose: To identify the characteristics and function of a cadherin-like molecule, cloned from a human dendritic cell (DC) cDNA library and designated DC-derived cadherin-like molecule (DC-CLM).
Methods: The mRNA expression of DC-CLM in tissues and cells was analyzed by Northern blot and RT-PCR, respectively. In order to express DC-CLM in target cells, we constructed a pcDNA3.1/DC-CLM expression vector and transfected it into MCF-7 human breast cancer cells. Tumor growth was demonstrated by cell proliferation and colony formation.
Results: DC-CLM cDNA encoded a protein of 260 amino acids and the gene was localized to chromosome 5q31. The predicted protein possessed a definitive cadherin-specific sequence motif and shared homology with classical cadherin. However, no transmembrane segment was observed in DC-CLM. Northern blot revealed the ubiquitous nature of DC-CLM transcripts in human tissues, with high expression in heart, brain, prostate, testis and ovary. RT-PCR demonstrated that DC-CLM was widely expressed in hematopoietic and epithelial tumor cell lines, but was not expressed in MCF-7. Interestingly, DC-CLM expression was upregulated in DC activated by lipopolysaccharides. DC-CLM expression in the stable transfectant (MCF-7/DC-CLM) was confirmed by RT-PCR and Western blot. DC-CLM protein was found to be secreted by MCF-7/DC-CLM but not expressed on the membrane of MCF-7/DC-CLM. DC-CLM transfection resulted in significant inhibition of in vitro growth and colony formation of MCF-7 cells.
Conclusions: A cadherin-like molecule DC-CLM was cloned from human DC and it may be a soluble cadherin-like molecule for tumor suppression. DC-CLM was upregulated in activated DC and may be involved in the effector function of activated DC.