Unlike early transcriptional responses to mitogens, later events are less well-characterized. Here, we identified delayed down-regulated genes (DDGs) in mammary cells after prolonged treatment with epidermal growth factor (EGF). The expression of these DDGs was low in mammary tumors and correlated with prognosis. The proteins encoded by several DDGs directly bind to and inactivate oncoproteins and might therefore act as tumor suppressors. The transcription factor teashirt zinc finger homeobox 2 (TSHZ2) is encoded by a DDG, and we found that overexpression of TSHZ2 inhibited tumor growth and metastasis and accelerated mammary gland development in mice. Although the gene TSHZ2 localizes to a locus (20q13.2) that is frequently amplified in breast cancer, we found that hypermethylation of its promoter correlated with down-regulation of TSHZ2 expression in patients. Yeast two-hybrid screens and protein-fragment complementation assays in mammalian cells indicated that TSHZ2 nucleated a multiprotein complex containing PRC1/Ase1, cyclin B1, and additional proteins that regulate cytokinesis. TSHZ2 increased the inhibitory phosphorylation of PRC1, a key driver of mitosis, mediated by cyclin-dependent kinases. Furthermore, similar to the tumor suppressive transcription factor p53, TSHZ2 inhibited transcription from the PRC1 promoter. By recognizing DDGs as a distinct group in the transcriptional response to EGF, our findings uncover a group of tumor suppressors and reveal a role for TSHZ2 in cell cycle regulation.

与有丝分裂原的早期转录反应不同，后期事件的特征不太清楚。在这里，我们在用表皮生长因子 (EGF) 长时间处理后鉴定了乳腺细胞中的延迟下调基因 (DDG)。这些 DDGs 在乳腺肿瘤中的表达较低，并与预后相关。由几种 DDG 编码的蛋白质直接结合癌蛋白并使癌蛋白失活，因此可能充当肿瘤抑制因子。转录因子 teashirt 锌指同源框 2 (TSHZ2) 由 DDG 编码，我们发现 TSHZ2 的过表达抑制了小鼠的肿瘤生长和转移并加速了乳腺发育。虽然基因TSHZ2定位于在乳腺癌中经常扩增的基因座 (20q13.2)，我们发现其启动子的高甲基化与患者TSHZ2表达的下调相关。哺乳动物细胞中的酵母双杂交筛选和蛋白质片段互补测定表明，TSHZ2 成核了一个多蛋白复合物，其中包含 PRC1/Ase1、细胞周期蛋白 B1 和调节胞质分裂的其他蛋白。TSHZ2 增加了 PRC1 的抑制性磷酸化，PRC1 是有丝分裂的关键驱动因素，由细胞周期蛋白依赖性激酶介导。此外，类似于肿瘤抑制转录因子 p53，TSHZ2 抑制 PRC1 的转录发起人。通过将 DDGs 识别为对 EGF 的转录反应中的一个独特组，我们的研究结果揭示了一组肿瘤抑制因子并揭示了 TSHZ2 在细胞周期调节中的作用。