Improving Detection Accuracy of Lung Cancer Serum Proteomic Profiling via Two-Stage Training Process

Background  

Surface-Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS) is a frequently used technique for cancer biomarker research. The specificity of biomarkers detected by SELDI can be influenced by concomitant inflammation. This study aimed to increase detection accuracy using a two-stage analysis process.     

Using the longest significance run to estimate region-specific p-values in genetic association mapping studies

Background  

Association testing is a powerful tool for identifying disease susceptibility genes underlying complex diseases. Technological advances have yielded a dramatic increase in the density of available genetic markers, necessitating an increase in the number of association tests required for the analysis of disease susceptibility genes. As such, multiple-tests corrections have become a critical issue. However the conventional statistical corrections on locus-specific multiple tests usually result in lower power as the number of markers increases. Alternatively, we propose here the application of the longest significant run (LSR) method to estimate a region-specific p-value to provide an index for the most likely candidate region.     

Tandem mass spectrometry identifies proteins phosphorylated by cyclic AMP-dependent protein kinase when sea urchin sperm undergo the acrosome reaction

The exocytotic acrosome reaction (AR), which is required for fertilization, occurs when sea urchin sperm contact the egg jelly (EJ) layer. Among other physiological changes, increases in adenylyl cyclase activity, cAMP and cAMP-dependent protein kinase (PKA) activity occur coincident with the AR. By using inhibitors of PKA, a permeable analog of cAMP and the phosphodiesterase inhibitor IBMX, we show that PKA activity is required for AR induction by EJ. A minimum of six sperm proteins are phosphorylated by PKA upon exposure to EJ, as detected by a PKA substrate-specific antibody. The phosphorylation of these proteins and the percentage of acrosome reacted sperm can be regulated by PKA modulators. The fucose sulfate polymer (FSP), a major component of EJ, is the molecule that triggers sperm PKA activation. Extracellular Ca(2+) is required for PKA activation. Six sperm proteins phosphorylated by PKA were identified by tandem mass spectrometry (MS/MS) utilizing the emerging sea urchin genome. Based on their identities and localizations in sperm head and flagellum, the putative functions of these proteins in sperm physiology and AR induction are discussed.     

A functional genomic and proteomic perspective of sea urchin calcium signaling and egg activation

The sea urchin egg has a rich history of contributions to our understanding of fundamental questions of egg activation at fertilization. Within seconds of sperm-egg interaction, calcium is released from the egg endoplasmic reticulum, launching the zygote into the mitotic cell cycle and the developmental program. The sequence of the Strongylocentrotus purpuratus genome offers unique opportunities to apply functional genomic and proteomic approaches to investigate the repertoire and regulation of Ca(2+) signaling and homeostasis modules present in the egg and zygote. The sea urchin "calcium toolkit" as predicted by the genome is described. Emphasis is on the Ca(2+) signaling modules operating during egg activation, but the Ca(2+) signaling repertoire has ramifications for later developmental events and adult physiology as well. Presented here are the mechanisms that control the initial release of Ca(2+) at fertilization and additional signaling components predicted by the genome and found to be expressed and operating in eggs at fertilization. The initial release of Ca(2+) serves to coordinate egg activation, which is largely a phenomenon of post-translational modifications, especially dynamic protein phosphorylation. Functional proteomics can now be used to identify the phosphoproteome in general and specific kinase targets in particular. This approach is described along with findings to date. Key outstanding questions regarding the activation of the developmental program are framed in the context of what has been learned from the genome and how this knowledge can be applied to functional studies.     

Cyclic GMP-specific phosphodiesterase-5 regulates motility of sea urchin spermatozoa

Motility, chemotaxis, and the acrosome reaction of animal sperm are all regulated by cyclic nucleotides and protein phosphorylation. One of the cyclic AMP-dependent protein kinase (PKA) substrates in sea urchin sperm is a member of the phosphodiesterase (PDE) family. The molecular identity and in vivo function of this PDE remained unknown. Here we cloned and characterized this sea urchin sperm PDE (suPDE5), which is an ortholog of human PDE5. The recombinant catalytic domain of suPDE5 hydrolyzes only cyclic GMP (cGMP) and the activity is pH-dependent. Phospho-suPDE5 localizes mainly to sperm flagella and the phosphorylation increases when sperm contact the jelly layer surrounding eggs. In vitro dephosphorylation of suPDE5 decreases its activity by approximately 50%. PDE5 inhibitors such as Viagra block the activity of suPDE5 and increase sperm motility. This is the first PDE5 protein to be discovered in animal sperm. The data are consistent with the hypothesis that suPDE5 regulates cGMP levels in sperm, which in turn modulate sperm motility.     

α-Mangostin attenuates stemness and enhances cisplatin-induced cell death in cervical cancer stem-like cells through induction of mitochondrial-mediated apoptosis

Cancer stem cells (CSCs) exhibit specific characteristics including decontrolled self-renewal, tumor-initiating, promoting, and metastatic potential, abnormal stemness signaling, and chemotherapy resistance. Thus, targeting CSC is becoming an emerging cancer treatment. α-Mangostin has been shown to have potent and multiple anticancer activities. Accordingly, we hypothesized that α-mangostin may diminish the stemness and proliferation of CSC-like cervical cancer cells. In our results, comparing to the parent cells, CSC-like SiHa and HeLa cells highly expressed CSC marker Sox2, Oct4, Nanog, CK-17, and CD49f. α-Mangostin significantly reduced the cell viability, sphere-forming ability, and expression of the CSC stemness makers of CSC-like cervical cancer cells. Further investigation showed that α-mangostin induced mitochondrial depolarization and mitochondrial apoptosis signaling, including upregulation of Bax, downregulation of Mcl-1 and Bcl-2, and activation of caspase-9/3. Moreover, α-mangostin synergically enhanced the cytotoxicity of cisplatin on CSC-like SiHa cells by promoting mitochondrial apoptosis and inhibiting the expression of CSC markers. Consistent with in vitro findings, in vivo tumor growth assay revealed that α-mangostin administration significantly inhibited the growth of inoculated CSC-like SiHa cells and synergically enhanced the antitumor effect of cisplatin. Our findings indicate that α-mangostin can reduce the stemness and proliferation of CSC-like SiHa and HeLa cells and promote the cytotoxicity of cisplatin, which may attribute to the mitochondrial apoptosis activation. Thus, it suggests that α-mangostin may have clinical potential to improve chemotherapy for cervical cancer by targeting cervical CSC.