A case of salivary gland-type mixed tumor of the lung differentiating toward type II alveolar epithelial cells in glandular components with a literature review.

Salivary gland-type mixed tumor primarily arising in the lung is extremely rare. We report here a case of this type of tumor that occurred in the periphery of S4 of the right middle lobe in a 74-year-old man. Light-microscopically, this lung tumor, 15x9mm in size, exhibited almost the same features as those of mixed tumor of the salivary gland intermingled with chondromyxoid stroma, glandular component, solid growth pattern of myoepithelial components and well-developed cartilage formation, exhibiting a sharp margin. Immunohistochemical study revealed that the glandular components in the tumor was positive for thyroid transcription factor-1, TTF-1, a marker of epithelial cells of the thyroid as well as the lung. Furthermore, surface lining cells of the glandular components and luminal contents were positive for surfactant apoprotein A, PE-10, used as a marker of type II alveolar epithelial cells. These findings clearly demonstrate for the first time that glandular epithelial cells in the present salivary gland-type mixed tumor exhibited differentiation toward type II alveolar epithelial cells.

Glutamine and arginine affect Caco-2 cell proliferation by promotion of nucleotide synthesis.

OBJECTIVE: We tested our hypothesis that 1) the major effect of Gln is as a nitrogen donor, not an energy source, for nucleotides (NT) and 2) the supplementation of culture medium with arginine (Arg) decreases the flux of glutamine (Gln) for conversion to Arg, thus accelerating NT synthesis. METHODS: Various concentrations of nucleosides (NS+NT) Gln, and glutamate (Glu) in culture were tested for their effect on Caco-2 cell proliferation. (Arg was tested in media with and without Gln to evaluate the Gln pathway. The incorporation of (15)N from L-[5-(15)N]-Gln into NTs of DNA was measured under different NS + NT and Arg concentrations.) RESULTS: The proliferation of Caco-2 cells was increased by NS + NT and Gln supplementation, but not by Glu. The effective concentration of NS + NT was 100-fold smaller than that of Gln. An Arg effect was observed only in the presence of Gln. The NT synthesis from Gln, as indicated by (15)N incorporation from L-[5-(15)N]-Gln, was increased by Arg supplementation and decreased by NS + NT supplementation. CONCLUSION: These results support our hypothesis that the effects of Gln and Arg on Caco-2 cell proliferation are by the promotion of NT synthesis and that the major role of Gln is not energy supply.