Functional analysis of wild-type and malignant glioma derived CDKN2Abeta alleles: evidence for an RB-independent growth suppressive pathway.
Functional analysis of wild-type and malignant glioma derived CDKN2Abeta alleles: evidence for an RB-independent growth suppressive pathway.
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野生型和恶性胶质瘤衍生的 CDKN2Abeta 等位基因的功能分析：独立于 RB 的生长抑制途径的证据。
DOI：
10.1038/sj.onc.1201389
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发表时间：
1997
期刊：
影响因子：
8
通讯作者：
Cavenee,WK
中科院分区：
文献类型：
--
作者：
Arap,W;Knudsen,E;Sewell,DA;Sidransky,D;Wang,JY;Huang,HJ;Cavenee,WK
肿瘤抑制基因CDKN2A （p16/MTS1/INK4A）编码细胞周期蛋白依赖性激酶抑制剂p16 INK4A，是人类胶质瘤恶性进展过程中9p21缺失的靶标。该基因还编码第二种蛋白产物（人类p16β，小鼠p19 ARF），其起源于CDKN2A的一个不相关的外显子（外显子1β），该外显子在另一个阅读框中剪切到外显子2上。p16β阻滞细胞周期是由一种尚未确定的途径引起的。为了测试p16β作为胶质瘤抑制因子的候选性，我们将p16 INK4a， p15 INK4b和p16β野生型以及一系列7个胶质瘤来源的p16β等位基因（R87H, A112V, R120H, A121V, G125R， A128A和A128V）替换为具有CDKN2A−/RB+（U-87MG和U-251MG）或CDKN2A+/RB−(LN-319)内源性背景的胶质瘤细胞系，并证明p16β可以作为功能性胶质瘤细胞生长抑制因子。此外，p16β而非p16 INK4a或p15 INK4b抑制rb阴性LN-319细胞的生长，表明p16β可能通过rb非依赖性途径发挥其作用。体外和体内对pRB磷酸化的分析与这一解释一致。由于胶质瘤衍生的p16β突变没有使其生长抑制活性失活，因此CDKN2A外显子2的突变（p16 INK4a和p16β的编码序列共享）可能只针对p16 INK4a。
The tumor suppressor gene CDKN2A (p16/MTS1/INK4A), which encodes the cyclin-dependent kinase inhibitor p16 INK4a, is a target of 9p21 deletions during the malignant progression of human gliomas. This gene also encodes a second protein product (human p16β, murine p19 ARF), which originates from an unrelated exon of CDKN2A (exon 1β) spliced onto exon 2 in an alternate reading frame. Cell cycle arrest by p16β is caused by an as yet unidentified pathway. In order to test the candidacy of p16β as a glioma suppressor, we replaced p16 INK4a, p15 INK4b and p16β wild-type as well as a series of seven glioma-derived p16β alleles (R87H, A112V, R120H, A121V, G125R, A128A and A128V), into glioma cell lines that had either CDKN2A−/RB+(U-87MG and U-251MG) or CDKN2A+/RB−(LN-319) endogenous backgrounds and demonstrated that p16β can act as a functional glioma cell growth suppressor. Moreover, p16β, but not p16 INK4a or p15 INK4b inhibited the growth of RB-negative LN-319 cells, indicating that p16β likely exerts its effects through an RB-independent pathway. In vitro and in vivo assays of pRB phosphorylation were consistent with this interpretation. Since none of the glioma-derived p16β mutations inactivated their growth suppressive activities, it appears that mutations in CDKN2A exon 2 (which is shared in the coding sequences of p16 INK4a and p16β) likely exclusively target p16 INK4a.