Expression of neural cell adhesion molecules in the mouse anterior pituitary gland and pituitary tumor cells

Neural cell adhesion molecules (NCAMs) were immunocytochemically detected in the pituitary glands of female ICR mice and in the pituitary tumor cell lines (GH₃ cells and AtT-20 cells) using the antibody against mouse NCAM. Immunoreactive NCAMs (ir-NCAMs) were detected in the cell membranes of mouse pituitary cells, GH₃ cells and AtT-20 cells. Fifty four percent of anterior pituitary cells, 58% of neurointermediate cells (cells of both posterior and intermediate lobes), 13% of GH₃ cells and 43% of AtT-20 cells expressed ir-NCAMs. Anterior pituitary cell types of NCAM-expressing cells were identified. Most of somatotrophs, gonadotrophs, and thyrotrophs showed NCAM-immunoreactivity, while parts of mammotrophs and corticotrophs did. The cell-type-specific pattern of NCAM expression in the mouse pituitary may be closely associated with physiological roles of pituitary NCAMs. For clarifying roles of pituitary NCAM, AtT-20 cells were treated with antisense oligodeoxynucleotide (ODN) which was complementary to the translation initiation site of NCAM mRNA, or with sense ODN which corresponded to the sense sequence for 7 days. Antisense ODN treatment (100 nM) decreased the percentage of NCAM-expressing cells, and surprisingly increased the cell number of AtT-20 cells compared with sense ODN treatment and non-treatment. This result suggests that NCAM is involved in the growth control of AtT-20 cells.