Sibin M K, Bhat Dhananjaya I, Lavanya Ch, Manoj M Jeru, Aakershita S, Chetan G K
Department of Human Genetics, National Institute of Mental Health and Neuro Sciences, Bangalore, 560029, India.
Tumour Biol. 2014 Feb;35(2):1467-72. doi: 10.1007/s13277-013-1201-5. Epub 2013 Sep 25.
Over the years, deletions of CDKN2A (p16) tumor suppressor gene has been studied using FISH and multiplex PCR, with major focus on exon 2 in various cancers, and the frequency of mutation is found to be varied in different studies. In this study, we analyzed the deletion status of all three exons of p16 and frequency of exon 2 somatic point mutations in glioma from the Indian population and its clinical implications. Multiplex PCR was carried out in order to check deletion of all 3 exons in 50 glioma samples. Nonconventional PCR-SSCP analysis and sequencing was done to identify mutations in 48 cases. Deletion of at least one of the three exons of p16 INK4A was observed in ten cases (20 %). The frequencies of exon-wise deletions were 10 % for exon 1, 4 % for exon 2, and 8 % for exon 3. Two out of 48 samples were positive for mutations in p16 exon 2. One sample had a transition of G to C on position 147 with a codon change TGG to TGC which does not contribute to the protein structure. Another sample had a transversion of A to G on the position 154 with a codon change ATG to GTG with change in amino acid methionine to valine in 52nd position. Deletion pattern was found to be varied in three exons. Frequency of p16 gene mutation was less in the Indian population (4.2 %), and this mutation does not contribute to any remarkable change in protein structure.
多年来，一直使用荧光原位杂交（FISH）和多重聚合酶链反应（PCR）研究细胞周期蛋白依赖性激酶抑制剂2A（CDKN2A，p16）肿瘤抑制基因的缺失情况，主要聚焦于各种癌症中的第2外显子，且不同研究中发现的突变频率有所不同。在本研究中，我们分析了来自印度人群的胶质瘤中p16所有三个外显子的缺失状态以及第2外显子体细胞点突变的频率及其临床意义。进行多重PCR以检测50例胶质瘤样本中所有3个外显子的缺失情况。对48例样本进行了非传统的PCR-单链构象多态性（SSCP）分析和测序以鉴定突变。在10例（20%）样本中观察到p16 INK4A的三个外显子中至少有一个缺失。外显子缺失的频率分别为：第1外显子10%，第2外显子4%，第3外显子8%。48个样本中有2个p16第2外显子突变呈阳性。一个样本在第147位发生了G到C的转换，密码子由TGG变为TGC，这对蛋白质结构无影响。另一个样本在第154位发生了A到G的颠换，密码子由ATG变为GTG，第52位氨基酸由甲硫氨酸变为缬氨酸。发现三个外显子的缺失模式各不相同。印度人群中p16基因突变频率较低（4.2%），且这种突变对蛋白质结构没有造成任何显著变化。
