HISTOCHEMICAL AND BIOCHEMICAL ASPECTS OF LECTIN-BINDING GLYCOPROTEINS IN PRIMARY AND METASTATIC ADENOCARCINOMA IN THE LUNG

It is often difficult to differentiate between primary adenocarcinoma and metastatic adenocarcinoma in the lung. At least three lectins-peanut treated with neuraminidase, Ricinus communis-I and succinylated wheat germ-showed highly positive glycoprotein binding pattern along the plasma membrane of primary and metastatic adenocarcinoma in the lung. In order to distinguish primary pulmonary adenocarcinoma from metastatic adenocarcinoma in the lung with the three lectins, 40 pulmonary adenocarcinomas, seven extrapulmonary metastatic adenocarcinomas, and 16 metastatic adenocarcinoma in the lung were studied. Extracts from fresh tissue homogenate, after fractionation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were transferred by Western blotting and stained with lectin, and the lectin-bound glycoconjugates were read by a densitometer. The results showed all three lectin-bound glycoconjugate of primary pulmonary adenocarcinoma cases to be concentrated at about 200 Kd, but those of normal lung;tissue had different molecular weights. Metastatic adenocarcinoma in the lung had lectin-bound glycoconjugate of about 120 Kd as well as 200 Kd. The amount of lectin binding high molecular weight substance was lower in metastatic adenocarcinoma in the lung than in primary pulmonary adenocarcinoma, especially succinylated wheat germ (P < 0.001). Therefore, decreased expression of the lectin binding high molecular weight glycoprotein may be a biochemical change associated with metastatic potential.