Institute of Toxicology, Medical Center of the Johannes Gutenberg-University, Obere Zahlbacherstr 67, 55131 Mainz, Germany.
J Cell Biochem. 2010 Aug 1;110(5):1234-43. doi: 10.1002/jcb.22638.
Proliferation of non-transformed cells is regulated by cell-cell contacts, which are referred to as contact-inhibition. Vice versa, transformed cells are characterised by a loss of contact-inhibition. Despite its generally accepted importance for cell-cycle control, little is known about the intracellular signalling pathways involved in contact-inhibition. Unravelling the molecular mechanisms of contact-inhibition and its loss during tumourigenesis will be an important step towards the identification of novel target genes in tumour diagnosis and treatment. To better understand the underlying molecular mechanisms we identified the transcriptional programme of contact-inhibition in NIH3T3 fibroblast using high-density microarrays. Setting the cut off: >or=1.5-fold, P <or= 0.05, 853 genes and 73 cDNA sequences were differentially expressed in confluent compared to exponentially growing cultures. Importing these data into GenMAPP software revealed a comprehensive list of cell-cycle regulatory genes mediating G0/G1 arrest, which was confirmed by RT-PCR and Western blot. In a narrow analysis (cut off: >or=2-fold, P <or= 0.002), we found 110 transcripts to be differentially expressed representing 107 genes and 3 cDNA sequences involved, for example, in proliferation, signal transduction, transcriptional regulation, cell adhesion and communication. Interestingly, the majority of genes was upregulated indicating that contact-inhibition is not a passive state, but actively induced. Furthermore, we confirmed differential expression of eight genes by semi-quantitative RT-PCR and identified the potential tumour suppressor transforming growth factor-beta (TGF-beta)-1-induced clone 22 (TSC-22; tgfb1i4) as a novel protein to be induced in contact-inhibited cells.
非转化细胞的增殖受细胞-细胞接触的调节，这种接触被称为接触抑制。相反，转化细胞的特征是失去接触抑制。尽管接触抑制对于细胞周期控制具有普遍的重要性，但对于涉及接触抑制的细胞内信号通路知之甚少。阐明接触抑制及其在肿瘤发生过程中丧失的分子机制将是鉴定肿瘤诊断和治疗中新靶基因的重要步骤。为了更好地理解潜在的分子机制，我们使用高密度微阵列鉴定了 NIH3T3 成纤维细胞接触抑制的转录程序。设定截止值：>或=1.5 倍，P <或=0.05，与指数生长培养物相比，在汇合培养物中有 853 个基因和 73 个 cDNA 序列差异表达。将这些数据导入 GenMAPP 软件中，揭示了一个综合的细胞周期调控基因列表，这些基因介导 G0/G1 期阻滞，通过 RT-PCR 和 Western blot 得到了证实。在一个狭隘的分析中（截止值：>或=2 倍，P <或=0.002），我们发现 110 个转录本差异表达，代表了 107 个基因和 3 个 cDNA 序列，这些基因涉及增殖、信号转导、转录调节、细胞黏附和通讯。有趣的是，大多数基因上调表明接触抑制不是一种被动状态，而是主动诱导的。此外，我们通过半定量 RT-PCR 证实了八个基因的差异表达，并鉴定了潜在的肿瘤抑制因子转化生长因子-β（TGF-β）-1 诱导克隆 22（TSC-22；tgfb1i4）作为一种在接触抑制细胞中诱导的新蛋白。
