Aberrant histone methylation is a frequent event during tumor development and progression. KMT1E (also known as SETDB1) is a histone H3K9 methyltransferase that contributes to epigenetic silencing of both oncogenes and tumor suppressor genes in cancer cells. In this report, we demonstrate that KMT1E acts as a metastasis suppressor that is strongly downregulated in highly metastatic lung cancer cells. Restoring KMT1E expression in this setting suppressed filopodia formation, migration, and invasive behavior. Conversely, loss of KMT1E in lung cancer cells with limited metastatic potential promoted migration in vitro and restored metastatic prowess in vivo. Mechanistic investigations indicated that KMT1E cooperates with the TGFb-regulated complex SMAD2/3 to repress metastasis through ANXA2. Together, our findings defined an essential role for the KMT1E/ SMAD2/3 repressor complex in TGFb-mediated lung cancer metastasis. Cancer Res; 74(24); 7333-43. Ó2014 AACR.

BackgroundTo explore whether combining inhibitors that target the insulin-like growth factor receptor (IGFR)/PI3K/Akt/mTOR signaling pathway (vertical blockade) can improve treatment efficacy for hepatocellular carcinoma (HCC).MethodsHCC cell lines (including Hep3B, Huh7, and PLC5) and HUVECs (human umbilical venous endothelial cells) were tested. The molecular targeting therapy agents tested included NVP-AEW541 (IGFR kinase inhibitor), MK2206 (Akt inhibitor), BEZ235 (PI3K/mTOR inhibitor), and RAD001 (mTOR inhibitor). Potential synergistic antitumor effects were tested by median dose-effect analysis in vitro and by xenograft HCC models. Apoptosis was analyzed by flow cytometry (sub-G1 fraction analysis) and Western blotting. The activities of pertinent signaling pathways and expression of apoptosis-related proteins were measured by Western blotting.ResultsVertical blockade induced a more sustained inhibition of PI3K/Akt/mTOR signaling activities in all the HCC cells and HUVEC tested. Synergistic apoptosis-inducing effects, however, varied among different cell lines and drug combinations and were most prominent when NVP-AEW541 was combined with MK2206. Using an apoptosis array, we identified survivin as a potential downstream mediator. Over-expression of survivin in HCC cells abolished the anti-tumor synergy between NVP-AEW541 and MK2206, whereas knockdown of survivin improved the anti-tumor effects of all drug combinations tested. In vivo by xenograft studies confirmed the anti-tumor synergy between NVP-AEW541 and MK2206 and exhibited acceptable toxicity profiles.ConclusionsVertical blockade of the IGFR/PI3K/Akt/mTOR pathway has promising anti-tumor activity for HCC. Survivin expression may serve as a biomarker to predict treatment efficacy.

Purpose: Sorafenib has proved survival benefit for patients with advanced hepatocellular carcinoma (HCC). This study explored whether the efficacy of sorafenib can be improved by adding the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor CI-1040 to vertically block the Raf/MEK/ERK pathway. Experimental Design: The growth inhibitory effects of sorafenib and CI-1040 were tested in HCC cell lines (Huh-7 and Hep3B) and human umbilical vascular endothelial cells (HUVEC). The potential synergistic growth inhibitory effects were measured by median effect analysis. Apoptosis was measured by flow cytometry. The effects on ERK phosphorylation and levels of apoptosis regulatory proteins were measured by Western blotting. The in vivo antitumor activity of sorafenib and CI-1040 were tested in xenograft HCC models. Results: Combination of sorafenib and CI-1040 synergistically inhibited ERK phosphorylation and cell growth and induced apoptosis in both HCC cells and HUVECs. Increased expression of Bim protein, which correlated with the extent of ERK inhibition, was found in both HCC cells and HUVECs. Knockdown of Bim expression by small interfering RNA partially abrogated the synergistic proapoptotic effects of sorafenib and CI-1040. Combination therapy inhibited tumor growth significantly better than either single agent in the xenograft models. Conclusion: The antitumor effects of sorafenib in HCC can be improved by vertical blockade of Raf/MEK/ERK signaling with CI-1040. (Clin Cancer Res 200915(18):5820-8) Molecular targeted therapy has emerged as a new treatment for advanced hepatocellular carcinoma (HCC; ref. 1). Sorafenib, an oral multitargeted kinase inhibitor targeting Raf kinase, vascular endothelial growth factor receptor-2 (VEGFR-2), VEGFR-3, and platelet-derived growth factor receptor (2), is approved for the treatment of advanced HCC because of its survival benefit shown in two randomized, placebo-controlled trials (3, 4). Sorafenib prolonged the overall survival of advanced HCC patients from 7.9 months to 10.7 months in the Western trial and from 4.2 to 6.5 months in the Asian trial.The success of the sorafenib trials represents a major breakthrough in the treatment of advanced HCC. However, several important issues remain unresolved. First, most patients who received sorafenib treatment had tumor progression within relatively short periods. The median time-to-tumor progression was 5.5 and 2.6 months in the Western and the Asian trials, respectively. Therefore, combination with other systemic therapy to improve the efficacy of sorafenib is needed. Second, the role of Raf kinase as the molecular target of sorafenib treatment remains controversial. Sorafenib can inhibit Raf-1 and both wild-type and mutant B-Raf kinase activity, but in preclinical models, the antitumor activity of sorafenib did not correlate completely with its inhibitory effect on extracellular Sorafenib can induce apoptosis of cancer cells through regulation of multiple proapoptotic and...