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In this article, the author name Shih-Chin Cheng was incorrectly written as Shin-Chin Cheng.

Increased expression level of the Forkhead Box M1 (FOXM1) transcription factor is found in multiple types of cancers, and its expression is correlated with poor prognosis in patients with cancers, including non-small cell lung cancers and pancreatic cancers. We and others have shown that FoxM1 transcriptionally regulates a variety of genes essential for cell cycle progression, inflammation, angiogenesis, tumor cell invasiveness and survival. Published studies demonstrated that genetic deletion of Foxm1 gene from SPC-rtTA/tetO-KrasG12D/Foxm1 fl/fl mouse lung epithelial cells conferred resistance to tumorigenesis caused by oncogenic KrasG12D, indicating Foxm1 is a critical regulator of Kras signaling pathway during lung cancer initiation. When treated SPC-rtTA/tetO-KrasG12D/tetO-FOXM1 mice with Doxycycline, lung epithelial cell-specific expressed transgenic FOXM1 and Kras cooperate to promote tumor growth in mouse lungs. In the present study, we determine whether expression of FoxM1 affects proliferation of human cancer cells harboring oncogenic Kras. Here, we show that depletion of FOXM1 expression using inducible shFOXM1 diminished proliferation of Kras-mutated human non-small cell adenocarcinoma (A549 and NCI-H23) and pancreatic cancer (PANC-1 and AsPC-1) cell lines. In contrast, increased expression of FOXM1 caused increased proliferation of Kras mutated cancer cells. Scratch wound healing assay demonstrated that FOXM1 stimulates the migration of these cells, which is associated with elevated epithelial-mesenchymal transition (EMT) markers. Our studies demonstrate that FOXM1 transcription factor is required for Kras mutated human cancer cells proliferation during tumor progression. Citation Format: I-Ching Wang, Hsin Chih Chien, Sheng-Yang Chao, Chien-Cheng Li. Inhibition of Foxm1 transcription factor diminished Kras-mutated tumor development. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A44.

Oncogenic mutation of Kras gene is one of the major causes of non-small cell lung cancer (NSCLC), and there is no effective chemotherapy agent available for targeting cancers harboring oncogenic Kras mutations. Hence, identifying new downstream molecular targets of KRAS signaling is critical for improving current therapeutic outcomes. Previous research has demonstrated that increased activity and expression of Forkhead box M1 (FOXM1) transcription factor are associated with poor prognosis in NSCLC patients. We and others have reported that FOXM1 regulates gene transcription network of cell cycle, angiogenesis, epithelial-to-mesenchymal transition (EMT), cell migration, and cancer stemness. Deletion of Foxm1 alleles in respiratory epithelial cells diminished the lung tumor initiation in SPC-rtTA/tetO-KrasG12D/Foxm1-/- mice; however, whether Foxm1 is critical for Kras mutant tumor maintenance and progression remains unclear. Herein, we report that intratracheal (IT) injected adenoviral Ad-Cre to CCSP-rtTA/tetO-KrasG12D/Foxm1fl/fl mice that bear induced KRAS mutant lung tumors, causing 75% of preexisting lung tumor regression as detected by micro-computed tomography (μCT). IT treatment with Ad-Cre that mediated genetically deletion of Foxm1 alleles in lungs, resulted in reduced proliferation of tumor cells. Moreover, in vitro disruption of FOXM1 expression by shRNA diminished cell proliferation on plate and anchorage-independent growth in soft agar of KRAS-mutated lung cancer NCI-H23 as well as KRASG12D-transformed BEAS-2B cells. Accordingly, these results demonstrated that Foxm1 is critical for oncogenic KRAS signaling pathway in both maintenance and progression of lung adenocarcinoma, suggesting that Foxm1 could be a potential therapeutic target to improve the outcome of KRAS mutant lung cancer treatment. Citation Format: Sheng-Yang Chao, Chien-Cheng Li, Sheng-Kai Liang, Yi-Shiuan Chiu, Yi-Kai Lin, Chia-Chan Hsu, Jen-Kun Chen, Tsui-Chun Tsou, I-Ching Wang. Foxm1 mediates maintenance and progression of mouse lung tumor driven by oncogenic Kras [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B11.