[Stress Medicine and Human Health].

Stress is an nonspecific adaptive response to endogenous or exogenous stimuli, which is commonly applied by organisms to maintain their internal homeostasis and normal physiological functions. When the extent of stress response surpasses the threshold that the organism can adjust to, a variety of physiological or psychological diseases can be induced by stress response. Stress medicine focuses on investigating the mechanisms underlying the development and progression of the diseases induced by stress response, aiming to find ways to prevent and treat stress-related diseases. Here, we will start with an introduction of stress response, then review the recent advances of stress medicine by discussing the latest research advances in the regulatory mechanisms and biological functions of stress response under various physiological or pathological conditions.

[A Review of the Redox Regulation of Tumor Metabolism].

Metabolic aberrance is one of the hallmarks of cancer. The metabolic patterns in cancer cells are well reprogrammed to provide building blocks and energy for their sustained growth. During tumor metabolic reprogramming, reactive oxygen species (ROS) are generated and the antioxidant systems are activated. High levels of ROS lead to oxidative damage and even cell death, whereas ROS at low levels act as second messenger to regulate many signaling pathways. Recently, with the revisiting of oxidative stress, it has been found that ROS can directly mediate the redox modifications of proteins, resulting in protein conformational and functional alterations. However, only a very small portion of metabolic enzymes, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and PKM2, etc., has been reported to undergo redox modifications. Whether other metabolic enzymes are regulated by redox modifications and thus exhibit critical functions remain largely unknown. Moreover, the specific spatio-temporal targeting of redox modifications of metabolic enzymes, as well as overcoming the existed redox and metabolic adaptation, are key points to be solved. Here, we will review the reported redox modification patterns of metabolic enzymes, the involved regulatory mechanisms and their roles in tumorigenesis and tumor progress. In addition, we will discuss the future therapeutic strategies targeting redox modifications of metabolic enzymes for tumor treatment.

Orlistat, a novel potent antitumor agent for ovarian cancer: proteomic analysis of ovarian cancer cells treated with Orlistat.

Orlistat is an orally administered anti-obesity drug that has shown significant antitumor activity in a variety of tumor cells. To identify the proteins involved in its antitumor activity, we employed a proteomic approach to reveal protein expression changes in the human ovarian cancer cell line SKOV3, following Orlistat treatment. Protein expression profiles were analyzed by 2-dimensional polyacrylamide gel electrophoresis (2-DE) and protein identification was performed on a MALDI-Q-TOF MS/MS instrument. More than 110 differentially expressed proteins were visualized by 2-DE and Coomassie brilliant blue staining. Furthermore, 71 proteins differentially expressed proteins were positively identified via mass spectrometry (MS)/MS analysis. In particular, PKM1/2, a key enzyme involved in tumorigenesis, was found to be significantly downregulated in SKOV3 cells following treatment with Orlistat. Moreover, PKM1/2 was proved to be downregulated in SKOV3 cells by western blot analysis after treatment with Orlistat. Taken together, using proteomic tools, we identified several differentially expressed proteins that underwent Orlistat-induced apoptosis, particularly PKM2. These changes confirmed our hypothesis that Orlistat is a potential inhibitor of ovarian cancer and can be used as a novel adjuvant antitumor agent.

Keratin 17 identified by proteomic analysis may be involved in tumor angiogenesis.

Angiogenesis is crucial for solid tumor growth. By secreting angiogenic factors, tumor cells induce angiogenesis. However, targeting these angiogenic factors for cancer therapy is not always successful, suggesting that other factors may be involved in tumor angiogenesis. This work shows that 25 protein spots were differentially expressed by two-dimensional gel electrophoretic analysis when HepG2 cells induced endothelial cell differentiation to tube in vitro, and most of them were upregulated. Twenty-one proteins were identified with MALDI-TOF-MS, and the other four were identified by LTQ-MS/MS. Keratins were identified as one class of these upregulated proteins. Further study indicated that the expression of keratin 17 in cultured endothelial cells is likely microenvironment regulated, because its expression can be induced by HepG2 cells and bFGF as well as serum in culture media. Increased expression of keratins in endothelial cells, such as keratin 17, may contribute to the angiogenesis induced by HepG2 cells.

[Mechanism study of antisense cyclin B1 in tumorigenesis inhibition using proteomic technique].

BACKGROUND & OBJECTIVE: Previous researches showed that down-regulating the expression of cyclin B1 in tumor cells by RNA interference may inhibit tumorigenesis, but the mechanism remains to be clarified. This study was to reveal the molecular mechanism of antisense cyclin B1 in tumorigenesis inhibition by comparative proteomic technique. METHODS: A recombinant plasmid containing the full-length antisense cDNA of mouse cyclin B1 was transfected into mouse colon carcinoma cell line CT26. Total proteins of transfected cells and control cells were extracted and separated by two-dimensional gel electrophoresis (2-DE). The differential expression proteins were analyzed with PDQuest software, and identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and Mascot database searching. The 2 differential proteins with the highest confidence of the peptides were selected and verified by Western blot. RESULTS: Seven differentially expressed proteins were identified: Axin2, CCTtheta, DR5, and HPCM27 were up-regulated in transfected cells, while RFP17, mKIAA1195, and LOC77035 were down-regulated. The expression abundance differences of Axin2 and DR5, with the highest confidence, were verified by Western blot. CONCLUSIONS: Several proteins expressed differentially in CT26 cells after transfection of antisense cyclin B1, which take part in some signal pathways in cell proliferation, differentiation, migration, apoptosis, and transcriptional control. The antitumor effect of antisense cyclin B1 may relate to the interplay of the above proteins.

Functional genomics analysis of Singapore grouper iridovirus: complete sequence determination and proteomic analysis.

Here we report the complete genome sequence of Singapore grouper iridovirus (SGIV). Sequencing of the random shotgun and restriction endonuclease genomic libraries showed that the entire SGIV genome consists of 140,131 nucleotide bp. One hundred sixty-two open reading frames (ORFs) from the sense and antisense DNA strands, coding for lengths varying from 41 to 1,268 amino acids, were identified. Computer-assisted analyses of the deduced amino acid sequences revealed that 77 of the ORFs exhibited homologies to known virus genes, 23 of which matched functional iridovirus proteins. Forty-two putative conserved domains or signatures were detected in the National Center for Biotechnology Information CD-Search database and PROSITE database. An assortment of enzyme activities involved in DNA replication, transcription, nucleotide metabolism, cell signaling, etc., were identified. Viruses were cultured on a cell line derived from the embryonated egg of the grouper Epinephelus tauvina, isolated, and purified by sucrose gradient ultracentrifugation. The protein extract from the purified virions was analyzed by polyacrylamide gel electrophoresis followed by in-gel digestion of protein bands. Matrix-assisted laser desorption ionization-time of flight mass spectrometry and database searching led to identification of 26 proteins. Twenty of these represented novel or previously unidentified genes, which were further confirmed by reverse transcription-PCR (RT-PCR) and DNA sequencing of their respective RT-PCR products.

Cloning, characterization and tissue specific expression of a sucrose synthase gene from tropical epiphytic CAM orchid Mokara Yellow.

A full-length cDNA encoding sucrose synthase was isolated from the tropical epiphytic CAM orchid Mokara Yellow. The cDNA is 2748bp in length containing an open reading frame of 2447bp encoding 816 amino acids with a predicted molecular mass of 93.1 kDa. The deduced amino acid sequence of M. Yellow sucrose synthase (Msus1) shares more than 80% identity with those from other monocotyledonous plants. The sucrose synthase gene was demonstrated to encode a functional sucrose synthase protein by expression as recombinant protein in Escherichia coli. Northern blot analysis showed that the expression pattern of Msus1 mRNA is tissue specific with highest levels in strong sinks such as expanding leaves and root tips, but not detectable in mature leaves and flowers. Incubation with sugars resulted in a significant increase in the steady-state Msus1 mRNA levels in shoots of seedlings.