França Monica Malheiros, Ferraz-de-Souza Bruno, Lerario Antonio Marcondes, Fragoso Maria Candida Barisson Villares, Lotfi Claudimara Ferini Pacicco
Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, 05508-000 São Paulo, SP, Brazil.
Laboratory of Medical Investigation 18 (LIM-18), School of Medicine, University of São Paulo, 01246-903 São Paulo, SP, Brazil.
Biomed Res Int. 2015;2015:841784. doi: 10.1155/2015/841784. Epub 2015 Sep 2.
POD-1/TCF21 may play a crucial role in adrenal and gonadal homeostasis and represses Sf-1/SF-1 expression in adrenocortical tumor cells. SF-1 and LRH-1 are members of the Fzt-F1 subfamily of nuclear receptors. LRH-1 is involved in several biological processes, and both LRH-1 and its repressor SHP are involved in many types of cancer. In order to assess whether POD-1 can regulate LRH-1 via the same mechanism that regulates SF-1, we analyzed the endogenous mRNA levels of POD-1, SHP, and LRH-1 in hepatocarcinoma and adrenocortical tumor cells using qRT-PCR. Hereafter, these tumor cells were transiently transfected with pCMVMycPod-1, and the effect of POD-1 overexpression on E-box elements in the LRH-1 and SHP promoter region were analyzed by ChIP assay. Also, Cyclin E1 protein expression was analyzed to detect cell cycle progression. We found that POD-1 overexpression significantly decreased SHP/SHP mRNA and protein levels through POD-1 binding to the E-box sequence in the SHP promoter. Decreased SHP expression affected LRH-1 regulation and increased Cyclin E1. These findings show that POD-1/TCF21 regulates SF-1 and LRH-1 by distinct mechanisms, contributing to the understanding of POD-1 involvement and its mechanisms of action in adrenal and liver tumorigenesis, which could lead to the discovery of relevant biomarkers.
POD-1/TCF21可能在肾上腺和性腺稳态中发挥关键作用，并抑制肾上腺皮质肿瘤细胞中Sf-1/SF-1的表达。SF-1和LRH-1是核受体Fzt-F1亚家族的成员。LRH-1参与多种生物学过程，并且LRH-1及其抑制因子SHP都与多种类型的癌症有关。为了评估POD-1是否能通过调节SF-1的相同机制来调节LRH-1，我们使用qRT-PCR分析了肝癌和肾上腺皮质肿瘤细胞中POD-1、SHP和LRH-1的内源性mRNA水平。此后，用pCMVMycPod-1对这些肿瘤细胞进行瞬时转染，并通过染色质免疫沉淀法分析POD-1过表达对LRH-1和SHP启动子区域E-box元件的影响。此外，分析细胞周期蛋白E1的蛋白表达以检测细胞周期进程。我们发现，POD-1过表达通过POD-1与SHP启动子中的E-box序列结合，显著降低了SHP/SHP的mRNA和蛋白水平。SHP表达的降低影响了LRH-1的调节并增加了细胞周期蛋白E1。这些发现表明，POD-1/TCF21通过不同机制调节SF-1和LRH-1，有助于理解POD-1在肾上腺和肝脏肿瘤发生中的作用及其作用机制，这可能会导致发现相关生物标志物。
