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P38 mitogen-activated protein kinases (p38 MAPK) and tumor necrosis factor-α (TNF-α) play important roles in oxidative stress-induced apoptosis in cardiac myocytes. However, the regulation and functional role of cross-talk between p38 MAPK and TNF-α pathways have not yet been fully characterized in cardiac myocytes. In this study, we found that inhibition of p38 MAPK with SB-203580 (SB) reduced H(2)O(2)-stimulated secretion of TNF-α, whereas pre-activation of p38 MAPK with sodium arsenite (SA) enhanced H(2)O(2)-stimulated secretion of TNF-α. In addition, pretreatment of cells with TNF-α increased basal and H(2)O(2)-stimulated p38 MAPK and apoptosis of cardiac myocytes, and p38 MAPK-associated apoptosis of cardiac myocytes induced by TNF-α was blocked by inhibition of p38 MAPK with SB. Finally, H(2)O(2)-induced apoptosis was attenuated by the inhibitors of p38 MAPK or reactive oxygen species (ROS), whereas it was enhanced by p38 MAPK agonist SA. These results suggest that H(2)O(2)-induced secretion of TNF-α increases apoptosis of cardiac myocytes through ROS-dependent activation of p38 MAPK. This may represent a novel mechanism that TNF-α partly interplays with p38 MAPK pathways during oxidative stress-modulated apoptosis in cardiac myocytes.

Patatin-like phospholipases (PNPLAs) comprise a protein family whose members contain a conserved patatin-like domain with lipid acyl hydrolase activity. The cloning and characterization of full-length cDNAs of PNPLA3 and PNPLA4 in pigs is reported and, for the first time, an alternative splicing variant of porcine PNPLA4, which skips exon 5 of the normal transcript, was identified. Subsequently, tissue expression analysis by quantitative PCR indicated that porcine PNPLA3 was mainly expressed in both adipose and liver whereas porcine PNPLA4 was abundant in liver. Porcine PNPLA3 and PNPLA4 were assigned respectively to chromosome 5p11-p15 and Xp24.

The hormone resistin, which was originally shown to induce insulin resistance, has been implicated in the regulation of inflammatory processes, but the molecular mechanism underlying such regulation has not been clearly defined. The goal of our study was to determine whether the expression of COX-2 can be induced by resistin and what the potential signaling pathway involved in this process is. Compared with controls, resistin significantly upregulated COX-2 expression in RAW264.7 macrophage cells. Administration of anti-resistin antibody could significantly reduce this effect. Induction of COX-2 by resistin was also markedly reduced in the presence of either dominant negative mutant IkappaBalpha or PDTC, a pharmacological inhibitor of NF-kappaB. On the other hand, NF-kappaB subunit p65 was upregulated by resistin. Moreover, we found that transforming growth factor-beta-activated kinase 1 (TAK1), a mitogen-activated protein kinase kinase kinase (MAPKKK), could be activated in response to resistin. These results suggest that resistin enhances COX-2 expression in mouse macrophage cells in a TAK1-IKK-NF-kappaB-dependent manner and therefore plays a critical role in inflammatory processes.

Epstein-Barr virus (EBV) infection is associated with salivary gland lymphoepithelial carcinoma (SLEC) and nasopharyngeal carcinoma (NPC). EBV is a ubiquitous herpes virus world wide, but EBV-associated SLEC and NPC are prevalent in restricted regions such as south areas of China, Southeastern Asia and Greenland (Eskimos). To examine whether particular EBV variants play roles in the development of SLEC and NPC, we isolated the complete EBV LMP1 genes from 12 paraffin-embedded biopsy samples of SLECs isolated from China, Taiwan and Russia, and compared these LMP1 genes with those of NPC (CAO) and the prototype B95-8 EBV. Nucleotide sequence analysis showed that SLECs LMP1 is more similar to that of CAO than that of prototype B95-8. The analysis also identified several conserved (67-100%) variations in SLEC-LMP1 and CAO-LMP1 distinct from B95-8-LMP1. These included 10-amino acid deletion, 5-amino acid deletion and 12-single amino acid variations. A SLEC-LMP1 gene with the aforementioned conserved variations inhibited the growth of an embryonic kidney cell line (293T), highly activated the NF-kappaB pathway, and these activities were equivalent to those of B95-8 and CAO. These findings suggest that the biological functions of SLEC-LMP 1 are similar to those of B95-8-LMP1 and CAO-LMP1, and that these amino acid variations including the well-known 10-aa deletion did not affect these two prominent activities. While the present results could not uncover functional differences between SLEC-LMP1 and B95-8-LMP1, the nucleotide sequences and the molecular clone of LMP1 directly isolated from SLEC patients will be a useful tool to identify the high-pathogenic EBV strain(s), associated with SLEC and NPC.

Background: To investigate the effects of cisplatin on proliferation, telomerase activity, cell cycle, p53, bcl-2 and proliferating cell nuclear antigen (PCNA) expressions of human lung adenocarcinoma SLC-89 cells induced by cisplatin and to find out the possible mechanisms., Methods: SLC-89 cells were treated with cisplatin of different concentrations for 72 h. Then, the proliferation of the cells was measured by MTT method, telomerase activity was measured by telomeric repeat amplification protocol with ELISA (TRAP-ELISA), and cell cycle, p53, bcl-2 and PCNA expressions of the cells were detected by flow cytometry (FCM) respectively., Results: Cisplatin could obviously inhibit the proliferation of the cells, and IC₅₀ value for cisplatin treatment was 18.47 mg/L. Cisplatin could obviously down-regulate telomerase activity, decrease S phase cells, increase G₀/G₁ phase cells, decline the expressions of bcl-2 and PCNA proteins and induce the expression of p53 protein of SLC-89 cells in a concentration-dependent fashion., Conclusions: Cisplatin can obviously inhibit the proliferation of SLC-89, change the distribution of cell cycle, decline telomerase activity and expressions of bcl-2 and PCNA proteins, and induce expression of p53 protein, which may be the important mechanisms of cisplatin's anticancer action.

Riboflavin, suggested to be a radiosensitizer, was studied in murine thymocytes and human hepatoma L02 cell line in vitro with MTT method and fluorescence microscopy. When the murine thymocytes treated with 5-400 mumol/L riboflavin were irradiated by 5 Gy (60)Co gamma ionizing radiation, the low concentration groups, i.e. treated with 5-50 mumol/L riboflavin, showed a different surviving fractions-time relating correlation compared with the high concentration groups, i.e. treated with 100-400 mumol/L riboflavin. The former had a high survival level at the end of irradiation, but which, after 4-h incubation, decreased rapidly to a low level. On the contrary, the high concentration groups showed a low survival level at the end of irradiation, and a poor correlation was found between the surviving fraction and the incubation time, after 4 h a little difference was observed. The results of fluorescence microscopy indicated that under low concentration conditions, the riboflavin localized mainly in nucleus (both perinuclear area and inside of nuclear membrane), while under high concentration conditions, intensive riboflavin also localized around cytoplasmic membranes. Thus we can conclude: the riboflavin had radiosensitivity effect on DNA under low concentration conditions, and enhanced the damage to cytoplasmic membrane under high concentration conditions. Also the most effective concentration of riboflavin can be evaluated to be approximate 100 mumol/L.

Objective: To investigate the effect of luteolin on the proliferation and collagen expression of hepatic stellate cells., Methods: The effect of luteolin on proliferation and collagen synthesis of hepatic stellate cells isolated from the liver of Wistar rats were determined by (3)H-TdR and (3)H-Pro, and procollagen gene expression was also detected by DIG-labeled gene probe and in situ hybridization., Results: The proliferation and collagen synthesis were significantly and dose-dependently inhibited by luteolin when the concentrations reached 10 micromol/L and 20 micromol/L respectively (t=2.542, P<0.05; t=3.650, P<0.01). The type I, III procollagen mRNA expression was decreased by 25 micromol/L luteolin, in which the type I procollagen mRNA was reduced with statistical significance (x(2)=6.850, P<0.01)., Conclusions: Luteolin inhibits the proliferation and collagen expression of hepatic stellate cells in vitro. It may have a preventive or therapeutic role in liver fibrosis.