Tsuzuki T, Tsunoda S, Sakaki T, Konishi N, Hiasa Y, Nakamura M
Department of Neurosurgery, Nara Medical University, Japan.
Cancer. 1996 Jul 15;78(2):287-93. doi: 10.1002/(SICI)1097-0142(19960715)78:2<287::AID-CNCR15>3.0.CO;2-S.
Alterations of the suppressor genes, such as the retinoblastoma (RB), p53, p16(CDKN2), and p15 genes, have been reported in human gliomas. These genes have been suggested as the cell cycle regulatory genes at the G1-S checkpoint.
Alterations of the RB, p53, p16(CDKN2), and p15 genes in human astrocytomas were screened by single strand conformation polymorphism analysis of polymerase chain reaction products (PCR-SSCP analysis) and then confirmed by dideoxy sequencing. In addition, the expression of RB and p16 protein was examined by Western blot analysis.
Aberrations of the RB gene were found in 3 of 23 surgical astrocytoma specimens (13%). Mutations were found at codon 754 in exon 22 (Val-->Gly), codon 519 in exon 17 (Thr-->Pro), and one base deletion at codon 903 resulting in stop codon at codon 905 in exon 26. These mutational locations were all near the regions associated with the functional domains of the RB gene. Aberrations of the p53 gene were found in 4 cases (17.4%). These mutations were found at codons 146 (Trp-->Gly) and 165 (Gln-->His) in exon 5, codon 73 (Val-->Glu) in exon 4, and codon 313 (Ser-->Asn) in exon 9. In addition, alterations of the p16(CDKN2) gene were found, with 5 cases (21.7%) having homozygous deletions, and 2 cases (8.7%) harboring point mutations. No p15 gene alteration was detected. The expression of p16 protein was undetectable in 10 cases (43.5%) by Western blot analysis, demonstrating an inverse correlation with the expression of RB protein.
A few cases had overlapping alterations, and the incidence of one or more RB, p53, or p16(CDKN2) changes appeared to be relatively high in human astrocytomas. These results suggest that cell cycle regulatory gene alterations may play an important role in the development of gliomas.
在人类胶质瘤中已报道了诸如视网膜母细胞瘤（RB）、p53、p16（CDKN2）和p15基因等抑癌基因的改变。这些基因被认为是G1-S期检查点的细胞周期调控基因。
通过聚合酶链反应产物的单链构象多态性分析（PCR-SSCP分析）筛选人类星形细胞瘤中RB、p53、p16（CDKN2）和p15基因的改变，然后通过双脱氧测序进行确认。此外，通过蛋白质印迹分析检测RB和p16蛋白的表达。
在23例手术切除的星形细胞瘤标本中有3例（13%）发现RB基因异常。在第22外显子的第754密码子（Val→Gly）、第17外显子的第519密码子（Thr→Pro）以及第26外显子的第903密码子处发生一个碱基缺失，导致第905密码子处出现终止密码子。这些突变位点均靠近与RB基因功能域相关的区域。4例（17.4%）发现p53基因异常。这些突变分别位于第5外显子的第146密码子（Trp→Gly）和第165密码子（Gln→His）、第4外显子的第73密码子（Val→Glu）以及第9外显子的第313密码子（Ser→Asn）。此外，发现p16（CDKN2）基因改变，5例（21.7%）存在纯合缺失，2例（8.7%）存在点突变。未检测到p15基因改变。通过蛋白质印迹分析，10例（43.5%）未检测到p16蛋白表达，表明其与RB蛋白表达呈负相关。
少数病例存在重叠改变，在人类星形细胞瘤中一种或多种RB、p53或p16（CDKN2）改变的发生率似乎相对较高。这些结果表明细胞周期调控基因改变可能在胶质瘤的发生发展中起重要作用。
