Division of Colorectal Surgery, Third Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, China.
Cancer. 2012 Feb 15;118(4):1110-8. doi: 10.1002/cncr.26330. Epub 2011 Jul 14.
The human double minute 2 (hdm2) oncogene is a negative regulator of the p53 gene. Expression and alternative splicing of the hdm2 gene may contribute to colorectal cancer development or progression. This study aimed to determine the presence and identification of aberrant mRNA transcripts of hdm2 in colorectal cancer tissues and cell lines, and determine the nature of their association with clinicopathological characteristics and survival of patients.
A total of 69 colorectal cancer and corresponding normal tissue specimens and 10 colon cancer cell lines were recruited for polymerase chain reaction and DNA sequencing analyses of hdm2 mRNA. Genomic DNA from these tissues and cells was also extracted for p53 gene mutation analysis. The association of hdm2 fragmented transcripts and p53 gene mutation with clinicopathological data was then statistically analyzed.
In 62 cases (89.9%; 62 of 69) of colorectal cancer tissues the full-length hdm2 was amplified, whereas 7 cases had no hdm2 transcripts. Thirty-two of 62 cases (51.6%) and 6 of 10 cell lines (60%) showed at least 1 hdm2 spliced variant. A total of 4 hdm2 splicing variants were found in colorectal cancer tissues and cells, that is, lack of nucleotides between 157 and 292 bp in hdm2/1338, 81 to 901 bp in hdm2/707, 157 to 292, 407 to 505, and 668 to 901 bp in hdm2/1007, and 610 to 883 in hdm2/1200. Of these, hdm2/1338 is a novel hdm2 variant in colorectal cancer. Mutation in p53 was detected in 21 cases (33.8%; 21 of 62). Although there was no association found between expression of hdm2 splicing variants and p53 gene mutations, expression of hdm2 splicing variants was associated with advanced tumor stage (P = .022) and distant metastasis (P = .004) in wild-type p53 cases, and with poor survival of patients (P = .039).
The data from the current study provide the first evidence that hdm2 mRNA is frequently mutated by alternative splicing in colorectal cancer, and may play a role in colorectal tumorigenesis or cancer progression.
人类双微体 2 基因（hdm2）是 p53 基因的负调控因子。hdm2 基因的表达和选择性剪接可能有助于结直肠癌的发生或发展。本研究旨在确定结直肠癌组织和细胞系中 hdm2 异常 mRNA 转录本的存在和鉴定，并确定其与患者临床病理特征和生存的关系。
共招募 69 例结直肠癌及相应正常组织标本和 10 例结肠癌细胞系进行 hdm2 mRNA 的聚合酶链反应和 DNA 测序分析。从这些组织和细胞中提取基因组 DNA 进行 p53 基因突变分析。然后对 hdm2 片段转录物和 p53 基因突变与临床病理数据的关系进行统计学分析。
在 69 例结直肠癌组织中，有 62 例（89.9%；62/69）扩增出全长 hdm2，7 例无 hdm2 转录物。在 62 例中有 32 例（51.6%）和 10 个细胞系中有 6 个（60%）显示至少 1 种 hdm2 剪接变体。在结直肠癌组织和细胞中发现了 4 种 hdm2 剪接变体，即 hdm2/1338 中缺失 157-292 个核苷酸、hdm2/707 中缺失 81-901 个核苷酸、hdm2/157-292、407-505 和 668-901 个核苷酸，以及 hdm2/1200 中缺失 610-883 个核苷酸。其中，hdm2/1338 是结直肠癌中一种新的 hdm2 变体。在 21 例（33.8%；21/62）中检测到 p53 基因突变。尽管 hdm2 剪接变体的表达与 p53 基因突变之间没有发现关联，但 hdm2 剪接变体的表达与野生型 p53 病例的晚期肿瘤分期（P=0.022）和远处转移（P=0.004）相关，与患者的不良预后相关（P=0.039）。
本研究结果首次提供了证据，表明 hdm2 mRNA 在结直肠癌中经常通过选择性剪接发生突变，可能在结直肠肿瘤发生或癌症进展中发挥作用。
