Two
tumors, human
sarcoma #1 (HS #1) and human
epidermoid carcinoma #3 (HEp #3), were cultured on the chorioallantoic membrane of chick embryos. Under experimental conditions, HS #1 does not metastasize, whereas HEp #3 metastasizes extensively to chick embryo lungs and other organs. The
glycosphingolipid profiles of these
tumors were studied and HEp #3 wad found to contain about 2.5-fold less
lipid-bound
sialic acid per 100 mg of total
lipid extracted than did HS #1, due mainly to smaller levels of monosialoganglioside (3.7-fold) and disialoganglioside (3.8-fold) in HEp #3. The total amount of
neutral glycosphingolipids was approximately the same in both
tumors, but their profiles differed. Treatment of these
tumors with 6,7,8,9-tetrahydro-1-mercapto-1,2,4-triazolo-[4,3-a]quinazolin-5-ol (2.5 mg/egg/
tumor) completely inhibited the formation of
metastases in HEp #3 and increased the total content of
lipid-bound
sialic acid in the
tumor by 63% (
hematoside, monosialoganglioside, and disialoganglioside by 71, 99, and 67%, respectively). No change was seen in the content of
lipid-bound
sialic acid in HS #1. Treatment of HEp #3 with a smaller dose of te quinazolinol derivative (1.25 mg/egg) caused an average of 88% inhibition of
metastasis, with a 37% increase in
lipid-bound
sialic acid. Another compound, 2,5-diphenylthiazolo-[5,4-d]
thiazole (500 microgram/egg), completely inhibited the formation of
metastasis and caused a substantial increase in the amount of
lipid-bound
sialic acid (77%). The data showed the existence of a correlation between the level of
gangliosides in HEp #3 and the ability of these
tumors to metastasize.