Hippo-Lats-Yorkie signaling regulates tissue overgrowth and tumorigenesis in Drosophila. We show that the Mst1 and Mst2 protein kinases, the mammalian Hippo orthologs, are cleaved and constitutively activated in the mouse liver. Combined Mst1/2 deficiency in the liver results in loss of inhibitory Ser127 phosphorylation of the Yorkie ortholog, Yap1, massive overgrowth, and hepatocellular carcinoma (HCC). Reexpression of Mst1 in HCC-derived cell lines promotes Yap1 Ser127 phosphorylation and inactivation, and abrogates their tumorigenicity. Notably, Mst1/2 inactivates Yap1 in liver through an intermediary kinase distinct from Lats1/2. Approximately 30% of human HCCs show low Yap1(Ser127) phosphorylation and a majority exhibit loss of cleaved, activated Mst1. Mst1/2 inhibition of Yap1 is an important pathway for tumor suppression in liver relevant to human HCC. Significance The pathways that regulate quiescence and tumor suppression in the liver have not been fully elucidated. We show that the Mst1 and Mst2 kinases are tumor suppressors and regulators of liver size in adults and that negative regulation of the transcriptional coactivator, Yap1, is central to Mst1/2 tumor suppressor function. Loss of both Mst1 and Mst2 is sufficient to initiate hepatocyte proliferation, resulting in dramatic liver overgrowth, resistance to pro-apoptotic stimuli, and the development of HCC. Mst1 and Mst2 promote phosphorylation of Yap1 and thereby suppress its oncogenic activity. Mst1/2 regulation of Yap1 is tissue-specific and, in the liver, involves an Mst1/2-regulated Yap1 kinase distinct from Lats1/2. Significantly, the Mst-Yap1 pathway is disrupted in a substantial fraction of human HCCs.

These analyses demonstrate that first-line erlotinib provides a statistically significant improvement in PFS versus GP in Asian patients with EGFR mutation-positive NSCLC (NCT01342965).

These results establish that MST1 and MST2 are activated in mitosis and catalyze the mitotic phosphorylation of MOBKL1A/MOBKL1B. MOBKL1A/MOBKL1B phosphorylation, in turn, is sufficient to inhibit proliferation through actions at several points in the cell cycle.

In mice lacking both Mst1 and Mst2 in the lymphoid compartment, thymocyte development is normal, but single-positive thymocytes exhibit excessive apoptosis and greatly diminished thymic egress, accompanied by loss of chemokine activation of RhoA and Rac1.

Purpose To compare standard-of-care (SoC) trastuzumab plus chemotherapy with higher-dose (HD) trastuzumab plus chemotherapy to investigate whether HD trastuzumab increases trastuzumab serum trough concentration (C) levels and increases overall survival (OS) in first-line human epidermal growth factor receptor 2-positive metastatic gastric or gastroesophageal junction adenocarcinoma. Patients and Methods Patients with Eastern Cooperative Oncology Group performance status 2, no prior gastrectomy, and ≥ two metastatic sites were randomly assigned at a one-to-one ratio to loading-dose trastuzumab 8 mg/kg followed by SoC trastuzumab maintenance 6 mg/kg every 3 weeks or loading-dose trastuzumab 8 mg/kg followed by HD trastuzumab maintenance 10 mg/kg every 3 weeks until progression; treatment in each arm was combined with cisplatin 80 mg/m plus capecitabine 800 mg/m twice per day in cycles 1 to 6. The primary objective was HD trastuzumab OS superiority (all randomly assigned patients [full-analysis set]). Final results are from an interim analysis for futility (boundary hazard ratio [HR] ≥ 0.95) at 125 deaths. Results At clinical cutoff, 248 patients had been randomly assigned. A marked increase in mean trastuzumab C was observed after the first HD trastuzumab cycle versus SoC trastuzumab. In the full-analysis set, median OS was 12.5 months in the SoC trastuzumab arm and 10.6 months in the HD trastuzumab arm (stratified HR, 1.24; 95% CI, 0.86 to 1.78; P = .2401). Results were similar in the per-protocol set (cycle 1 trastuzumab C < 12 µg/mL). Safety was comparable between arms. Conclusion HD trastuzumab maintenance dosing was associated with higher trastuzumab concentrations, no increased efficacy, and no new safety signals. HELOISE confirms standard-dose trastuzumab (loading dose of 8 mg/kg followed by 6 mg/kg maintenance dose every 3 weeks) with chemotherapy as the SoC for first-line treatment of human epidermal growth factor receptor 2-positive metastatic gastric or gastroesophageal junction adenocarcinoma.

The Rassf1-6 polypeptides each contain a Ras/Rap association domain, which enables binding to several GTP-charged Ras-like GTPases, at least in vitro or when overexpressed. The Ras/Rap association domains are followed by SARAH domains, which mediate Rassf heterodimerization with the Mst1/2 protein kinases. Rassf1A is unequivocally a tumor suppressor, and all Rassf proteins behave like tumor suppressors, exhibiting epigenetic silencing of expression in many human cancers and proapoptotic and/or anti-proliferative effects when re-expressed in tumor cell lines. Herein, we review the binding of the Rassf polypeptides to Ras-like GTPases and the Mst1/2 kinases and their role in Rassf function.The Rassf (Ras association domain family) polypeptides, a family of non-catalytic proteins encoded by six genes, each expressed as multiple splice variants, were founded with the description of Nore1 (now designated Rassf5) as a Ras-GTPbinding protein (1). The description of the Rassf1 polypeptides followed shortly thereafter (2) and elicited considerable attention because of their identification as the products of a tumor suppressor gene (3, 4). Thus, the gene encoding Rassf1 is located on chromosome 3p21.3, in a region that exhibits loss of heterozygosity in Ͼ90% of small cell lung cancers and in nearly 50% of non-small cell lung cancers. The striking finding is that the expression of the longer Rassf1A mRNA splice variant is extinguished in nearly all small cell lung cancer cell lines and in ϳ40% of non-small cell lung cancer cell lines, whereas the expression of the shorter Rassf1C transcript is maintained (2). The loss of Rassf1A expression in tumors is due to selective CpG methylation of the promoter upstream of the exon encoding the unique N-terminal segment of the Rassf1A isoform, whereas the alternative, Rassf1C-specific promoter remains unmethylated. Rassf1A is firmly established as an epigenetically silenced tumor suppressor gene in a wide variety of cancers (4 -6). Re-expression of Rassf1A in tumor cell lines lacking Rassf1A expression inhibits proliferation and tumor growth in nude mice. Most persuasively, specific knock-outs of the exon encoding the unique N terminus of Rassf1A result in increased numbers of tumors in older mice, specifically lymphomas, lung tumors, and gastrointestinal tumors (7, 8); increased numbers of tumors have also been reported in Rassf1A heterozygotes (7). This review will emphasize Nore1/Rassf5 and Rassf1, the most extensively characterized members of the Rassf1-6 polypeptide family, focusing on their structure and binding to Ras-like GTPases and on the Mst1/2 protein kinases as likely physiologic effectors. Excellent recent reviews of the entire Rassf family in human cancers (6) and of Rassf1A (5) are recommended. Rassf Sequence Features and Domain OrganizationThe Rassf polypeptides align into two groups; Rassf1, Rassf3, and Rassf5 (Nore1) exhibit ϳ50% amino acid sequence identity, whereas Rassf2 and Rassf4 are nearly 60% identical to each other and ϳ40% identical to Rassf6. Identity bet...

Lipid remodeling is crucial for hypoxic tolerance in animals, whilst little is known about the hypoxia-induced lipid dynamics in plants. Here we performed a mass spectrometry-based analysis to survey the lipid profiles of Arabidopsis rosettes under various hypoxic conditions. We observed that hypoxia caused a significant increase in total amounts of phosphatidylserine, phosphatidic acid and oxidized lipids, but a decrease in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Particularly, significant gains in the polyunsaturated species of PC, PE and phosphatidylinositol, and losses in their saturated and mono-unsaturated species were evident during hypoxia. Moreover, hypoxia led to a remarkable elevation of ceramides and hydroxyceramides. Disruption of ceramide synthases LOH1, LOH2 and LOH3 enhanced plant sensitivity to dark submergence, but displayed more resistance to submergence under light than wild type. Consistently, levels of unsaturated very-long-chain (VLC) ceramide species (22:1, 24:1 and 26:1) predominantly declined in the loh1, loh2 and loh3 mutants under dark submergence. In contrast, significant reduction of VLC ceramides in the loh1-1 loh3-1 knockdown double mutant and lacking of VLC unsaturated ceramides in the ads2 mutants impaired plant tolerance to both dark and light submergences. Evidence that C24:1-ceramide interacted with recombinant CTR1 protein and inhibited its kinase activity in vitro, enhanced ER-to-nucleus translocation of EIN2-GFP and stabilization of EIN3-GFP in vivo, suggests a role of ceramides in modulating CTR1-mediated ethylene signaling. The dark submergence-sensitive phenotypes of loh mutants were rescued by a ctr1-1 mutation. Thus, our findings demonstrate that unsaturation of VLC ceramides is a protective strategy for hypoxic tolerance in Arabidopsis.

Aim: Inflammation and oxidative stress are now recognized to be two important contributing factors to the development of atherosclerosis (AS). NADPH oxidase-4 (Nox4)-derived reactive oxygen species (ROS), NF-κB and MAPK play crucial roles in these processes. Luteolin, a flavone rich in many plants, can interrupt the molecular expression and inhibit the progression of inflammation and oxidative stress. The present study was designed to test whether luteolin inhibits TNF-α-induced inflammation and oxidative stress in human umbilical vein endothelial cells (HUVECs) and identify some of the mechanisms underlying these effects.