RELATIONSHIP BETWEEN BLOOD GROUP-A ANTIGEN EXPRESSION AND MALIGNANT POTENTIAL IN HAMSTER PANCREATIC CANCERS

The loss of expression of the ABH blood group antigens is suggested to be associated with more aggressive behavior of cancers. We have compa red the growth behaviors of two hamster pancreatic cancer cell lines w ith different blood group-A expressions. PC-1.0 cells, which expressed blood group-A antigen poorly, showed a faster growth in vitro and in vivo when implanted into the pancreas of homologous animals, whereas P C-1.2 cells, all of which express the antigen, had a slower growth rat e both in vitro and in vivo. PC-1.0 also tended to metastasize, wherea s PC-1.2 cells grew primarily locally. The allografts of both PC-1.2 c ells (PC-1.2AG) and PC-1.0 cells (PC-1.0AG) and the metastases of PC-1 .0 cells expressed blood group A antigen in a similar rate. There was no significant difference in the number of A-antigen positive cells (A + ) between the PC-1.2AG and PC-1.0AG, although the expression of A a ntigen in PC-1.0AG showed a greater heterogeneity. The combined immuno histochemistry and autoradiography did not show any significant differ ences in the labeling index of A + or A- cells between the two allogra fts. Thus, the results indicate that blood group A antigen expression is unrelated to malignancy in this model. The faster growth rate of PC -1.0 cells may be due to their shorter cell cycle. (C) 1993 Wiley-Liss , Inc.