[Mouse fetal brain specific protein "GP68" is expressed in human tumor cells].

It is well known that some fetal antigens are expressed in malignant tumor cells. Likewise, brain tumors, especially histologically malignant cases, may have any antigenic relationships with fetal brain. So, we investigated the relationship by immunohistochemical technique, utilizing a polyclonal antibody to mouse fetal stage-specific polypeptide "GP68". We prepared GP68 from homogenate of head part of embryos at the 14th day of gestation mice by RCA-1 agarose column chromatography. And immunized it to Japanese white rabbits and the titer was measured by enzyme-linked immunosorbent assay. We analyzed operatively resected brain tumors and autopsy brain tissues. Frozen tissues were fixed in cold acetone and immunostained with anti-GP68 serum according to biotin-streptavidin peroxidase method. Remained tissues were homogenized in Laemmli's sample buffer and electrophoresed. The proteins were transferred to nitrocellulose membrane and immunostained with anti-GP68. Normal brain tissues were not positively stained, except for capillary endothelium which showed a weak staining. On the other hand, brain tumors of neuroectodermal origin were positively stained in varying degrees, and other tumors were negative. It is especially noteworthy that, in astrocytoma cases, there exists a definite correlation between the intensity of stain and the degree of histological malignancy. Immunoblot studies demonstrated a very weak band at 68 KD in normal brain and meningioma. In contrast, very strong band at the same position was seen in malignant astrocytomas. These results suggested that in brain tumors, especially those of neuroectodermal origin, GP68 antigen is expressed and the degree of expression is related to their histological malignancy. So this fetal antigen may be useful for evaluation of biological malignancy of gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)