Identification of molecular mechanisms and the targets using in vitro carcinogenesis model of endometrial cancer.

在本研究中，我们利用tert永生化的子宫内膜上皮细胞建立的具有致癌KRAS突变的致瘤细胞，研究了KRAS信号的分子靶点。我们首先证实了Raf-Erk通路在kras致瘤细胞中被激活，而不是PI3K-Akt通路。然而，将组成型活性MEK引入永生化细胞以模拟Raf-Erk激活未能获得致瘤表型，这表明KRAS触发的其他致癌途径的存在。最近的证据表明与KRAS信号的联系促使我们研究NF-κB在子宫内膜癌发生中的作用。我们发现，与tert永活细胞相比，kras致瘤细胞中NF-κB的DNA结合活性明显升高。此外，NF-κB激活靶基因启动子的能力在kras致瘤细胞中显著增加。引入抗降解的i -κB突变体，从而增强对NF-κB的抑制作用，在很大程度上消除了kras致瘤细胞的转化表型。因此，致癌KRAS信号通过激活NF-κB的转录功能，促进了子宫内膜细胞的致瘤表型。这些发现清楚地表明，NF-κB激活是子宫内膜癌发生中致癌KRAS的新靶点，这意味着NF-κB抑制剂在子宫内膜癌化学预防方面的潜在效用，特别是在KRAS突变的情况下。

In the present study, we investigated the molecular targets of KRAS signals using tumorigenic cells with oncogenic KRAS mutation established from TERT-immortalized endometrial epithelial cells. We first confirmed that the Raf-Erk pathway, but not the PI3K-Akt pathway, was activated in KRAS-tumorigenic cells. However, the introduction of constitutively active MEK into immortalized cells to mimic Raf-Erk activation failed to obtain tumorigenic phenotypes, indicating the existence of other carcinogenic pathways triggered by KRAS Recent evidence suggestive of linkage with KRAS signals prompted us to examine the involvement of NF-κB in endometrial carcinogenesis. We found that the DNA binding activity of NF-κB was markedly elevated in KRAS-tumorigenic cells compared to TERT-immortalized cells. Furthermore, the ability of NF-κB to activate the target gene promoters significantly increased in KRAS-tumorigenic cells. Introduction of a mutant IκB that is resistant to degradation and thereby enhances the inhibitory effect on NF-κB largely abrogated the transformed phenotypes of KRAS-tumorigenic cells. Thus, oncogenic KRAS signals contributed to the tumorigenic phenotypes of endometrial cells by activating the transcription function of NF-κB. These findings clearly show that NF-κB activation is a novel target of oncogenic KRAS in endometrial carcinogenesis, implying the potential utility of NF-κB inhibitors for endometrial cancer chemoprevention, especially with KRAS mutation.