Vaccinia virus is a large enveloped poxvirus with more than 200 genes in its genome. Although many poxvirus genomes have been sequenced, knowledge of the host and viral protein components of the virions remains incomplete. In this study, we used gel-free liquid chromatography and tandem mass spectroscopy to identify the viral and host proteins in purified vaccinia intracellular mature virions (IMV). Analysis of the proteins in the IMV showed that it contains 75 viral proteins, including structural proteins, enzymes, transcription factors, and predicted viral proteins not known to be expressed or present in the IMV. We also determined the relative abundances of the individual protein components in the IMV. Finally, 23 IMV-associated host proteins were also identified. This study provides the first comprehensive structural analysis of the infectious vaccinia virus IMV.

Severe acute respiratory syndrome (SARS) is caused by a newly emerged coronavirus that infected more than 8000 individuals and resulted in more than 800 fatalities in 2003. Currently, there is no effective treatment for this epidemic. SARS-3CL(pro) has been shown to be essential for replication and is thus a target for drug discovery. Here, a class of stable benzotriazole esters was reported as mechanism-based inactivators of 3CL(pro), and the most potent inactivator exhibited a k(inact) of 0.0011 s(-1) and a K(i) of 7.5 nM. Mechanistic investigation with kinetic and mass spectrometry analyses indicates that the active site Cys145 is acylated, and that no irreversible inactivation was observed with the use of the C145A mutant. In addition, a noncovalent, competitive inhibition became apparent by using benzotriazole ester surrogates in which the bridged ester-oxygen group is replaced with carbon.

Prohibitin (PHB) is indispensable for Ras-induced Raf-1 activation, cell migration and growth; however, the exact role of PHB in the molecular pathogenesis of cancer metastasis remains largely unexamined. Here, we found a positive correlation between plasma membrane-associated PHB and the clinical stages of cancer. The level of PHB phosphorylated at threonine 258 (T258) and tyrosine 259 (Y259) in human cancer-cell membranes correlated with the invasiveness of cancer cells. Overexpression of phosphorylated PHB (phospho-PHB) in the lipid-raft domain of the cell membrane enhanced cell migration/invasion through PI3K/Akt and Raf-1/ERK activation. It also enhanced epithelial-mesenchymal transition, matrix metalloproteinase-2 activity and invasiveness of cancer cells in vitro. Immunoprecipitation analysis demonstrated that phospho-PHB associated with Raf-1, Akt and Ras in the membrane and was essential for the activation of Raf-1 signaling by Ras. Mice implanted with cancer cells stably overexpressing PHB in the plasma membrane showed enlarged cervical tumors, enhanced metastasis and shorter survival time compared with mice implanted with cancer cells without PHB overexpression. Dephosphorylation of PHB at T258 by site-directed mutagenesis diminished the in vitro and in vivo effects of PHB. These results suggest that increase in phospho-PHB T258 in the raft domain of the plasma membrane has a role in the Ras-driven activation of PI3K/Akt and Raf-1/ERK-signaling cascades and results in the promotion of cancer metastasis.

Background: Glucosylceramide synthase catalyzes ceramide glycosylation that regulates the synthesis of glycosphingolipids. Results: Increased globo-series glycosphingolipids in breast cancer stem cells activate c-Src signaling and ␤-catenin-mediated transcription up-regulating stem cell factors. Conclusion: Ceramide glycosylation maintains the stemness of cancer stem cells. Significance: Glycosphingolipids in cell membrane actively participate in maintaining cancer stem cells.

More effective treatments for metastatic lung cancer remain a pressing clinical need. In this study, we identified migration inducting gene-7 (MIG-7) protein as critical for COX-2/prostaglandin E2 (PGE2)-and Akt/GSK-3b-dependent tumor invasion/metastasis. COX-2/PGE2 activated EP4 to enhance Akt and GSK-3b phosphorylation and b-catenin/T-cell factor/lymphoid enhancer factor signaling leading to MIG-7 upregulation. RNAi-mediated attenuation of MIG-7 blocked COX-2/PGE2-and Akt/GSK-3b-mediated migration/ invasion effects. Furthermore, MIG-7 protein inhibited protein phosphatase 2A to sustain Akt/GSK-3b phosphorylation and cancer-cell migration/invasion. Cancer cells overexpressing MIG-7 exhibited increased expression of ZEB-1 and Twist in parallel with epithelial-mesenchymal transition, metastasis and cancer lethality. MIG-7 protein level positively correlated with advanced stages of human lung cancers. MIG-7 thus offers a theranostic target for cancer metastases arising from aberrant activation of the cellular COX-2/PGE2 and Akt/GSK-3b signaling pathways. Cancer Res; 73(1); 439-49. Ó2012 AACR.