A Cytogenetical analysis of the malignant transformation of primary intracranial germ cell tumor

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To investigate the details of the malignant transformation of intracranial germ cell tumors, we established 4 cell lines derived from surgical or autopsied specimen of brain tumors, and studied cytogenetic charactors and tumor supressor gene alterations.Cytokeratin was expressed in 4 of 4. HCG was expressed in 1 of 4. AFP was expressed in 3 of 4. It was suggested that they corresponded to one of choricarcinoma, one of embryonal carcinoma, and two of yolk tumor each.Cytogenetic investigation of the tumor diagnosed as choriocarcinoma revealed a highly abnormal chromosomal pattern. A chromosomal number in the hypotetraploid/hypertetraploid range was found. We analyzed 10 metaphases with the following modal composite karyotype: 88-94 <4n>, XX, +X, -Y, -Y, add (1) (p11), add (2) (q21), -2, add (2)(p25), -3, add (3) (p21), add (3), add (4) (p11), add (4) (ql 1), add (4), -5, -5, -5, del (6) (p21p23), add (7) (ql1), -8, -8, add (8) (q2?), add (9) (ql1), -10, del (10) (q24), del (10), -12, add (12) (p13), add (12), -13, add (14) (q21), -15, -16, -18, -18, t (18; 20) (p10; p10), t (18; 20) (p10; p10), +21, +21, -22, +13 mar. These karyotypes were shown by trypsin G-banding and confirmed by multi-colored FISH analysis.The mutation of p53 gene was not detected by PCR-SSCP method as far as the analysis from exon 4 to exon 9. p16 and p14 genes were detected normally by Southern blot analysis using p16 exons 1 to 3 and p14 exon probes. Thus, the major 2 pathways of tumor suppression seemed to be normal though Rb gene was not examined.