Autophagy-Related LC3 Accumulation Interacted Directly With LIR Containing RIPK1 and RIPK3, Stimulating Necroptosis in Hypoxic Cardiomyocytes.

The exact relationships and detailed mechanisms between autophagy and necroptosis remain obscure. Here, we demonstrated the link between accumulated autophagosome and necroptosis by intervening with autophagic flux. We first confirmed that the LC3 interacting region (LIR) domain is present in the protein sequences of RIPK1 and RIPK3. Mutual effects among LC3, RIPK1, and RIPK3 have been identified in myocardium and cardiomyocytes. Direct LC3-RIPK1 and LC3-RIPK3 interactions were confirmed by pull-down assays, and their interactions were deleted after LIR domain mutation. Moreover, after disrupting autophagic flux under normoxia with bafilomycin A1 treatment, or with LC3 or ATG5 overexpression adenovirus, RIPK1, RIPK3, p-RIPK3, and p-MLKL levels increased, suggesting necroptosis activation. Severe disruptions in autophagic flux were observed under hypoxia and bafilomycin A1 co-treated cardiomyocytes and myocardium and led to more significant activation of necroptosis. Conversely, after alleviating hypoxia-induced autophagic flux impairment with LC3 or ATG5 knockdown adenovirus, the effects of hypoxia on RIPK1 and RIPK3 levels were reduced, which resulted in decreased p-RIPK3 and p-MLKL. Furthermore, necroptosis was inhibited by siRNAs against RIPK1 and RIPK3 under hypoxia or normoxia. Based on our results, LIR domain mediated LC3-RIPK1 and LC3-RIPK3 interaction. Besides, autophagosome accumulation under hypoxia lead to necrosome formation and, in turn, necroptosis, while when autophagic flux was uninterrupted, RIPK1 and RIPK3 were cleared through an autophagy-related pathway which inhibited necroptosis. These findings provide novel insights for the role of LC3 in regulating cardiomyocyte necroptosis, indicating its therapeutic potential in the prevention and treatment of hypoxic myocardial injury and other hypoxia-related diseases.

The Lysosomal Membrane Protein Lamp2 Alleviates Lysosomal Cell Death by Promoting Autophagic Flux in Ischemic Cardiomyocytes.

Lysosomal membrane permeabilization (LMP) has recently been recognized as an important cell death pathway in various cell types. However, studies regarding the correlation between LMP and cardiomyocyte death are scarce. Lysosomal membrane-associated protein 2 (Lamp2) is an important component of lysosomal membranes and is involved in both autophagy and LMP. In the present study, we found that the protein content of Lamp2 gradually decreased in response to oxygen, glucose and serum deprivation (OGD) treatment in vitro. To further elucidate its role in ischemic cardiomyocytes, particularly with respect to autophagy and LMP, we infected cardiomyocytes with adenovirus carrying full-length Lamp2 to restore its protein level in cells. We found that OGD treatment resulted in the occurrence of LMP and a decline in the viability of cardiomyocytes, which were remarkably reversed by Lamp2 restoration. Exogenous expression of Lamp2 also significantly alleviated the autophagic flux blockade induced by OGD treatment by promoting the trafficking of cathepsin B (Cat B) and cathepsin D (Cat D). Through drug intervention and gene regulation to alleviate and exacerbate autophagic flux blockade respectively, we found that impaired autophagic flux in response to ischemic injury contributed to the occurrence of LMP in cardiomyocytes. In conclusion, our present data suggest that Lamp2 overexpression can improve autophagic flux blockade probably by promoting the trafficking of cathepsins and consequently conferring cardiomyocyte resistance against lysosomal cell death (LCD) that is induced by ischemic injury. These results may indicate a new therapeutic target for ischemic heart damage.

Tumor necrosis factor receptor-associated protein 1 regulates hypoxia-induced apoptosis through a mitochondria-dependent pathway mediated by cytochrome c oxidase subunit II.

BACKGROUND: Tumor necrosis factor receptor-associated protein 1 (TRAP1) plays a protective effect in hypoxic cardiomyocytes, but the precise mechanisms are not well clarified. The study is aimed to identify the mechanism of TRAP1 on hypoxic damage in cardiomyocytes. METHODS: In this study, the effects of TRAP1 and cytochrome c oxidase subunit II (COXII) on apoptosis in hypoxia-induced cardiomyocytes were explored using overexpression and knockdown methods separately. RESULTS: Hypoxia induced cardiomyocyte apoptosis, and TRAP1 overexpression notably inhibited apoptosis induced by hypoxia. Conversely, TRAP1 silencing promoted apoptosis in hypoxic cardiomyocytes. Further investigation revealed that the proapoptotic effects caused by the silencing of TRAP1 were prevented by COXII overexpression, whereas COXII knockdown reduced the antiapoptotic function induced by TRAP1 overexpression. Additionally, changes in the release of cytochrome c from mitochondria into the cytosol and the caspase-3 activity in the cytoplasm, as well as reactive oxygen species production, were found to be correlated with the changes in apoptosis. CONCLUSIONS: The current study uncovered that TRAP1 regulates hypoxia-induced cardiomyocyte apoptosis through a mitochondria-dependent apoptotic pathway mediated by COXII, in which reactive oxygen species presents as an important component.

PI3K-AKT Pathway Protects Cardiomyocytes Against Hypoxia-Induced Apoptosis by MitoKATP-Mediated Mitochondrial Translocation of pAKT.

BACKGROUND/AIMS: The phosphatidylinositol-3-kinase -AKT (PI3K-AKT) is an important intracellular signal pathway in regulating cell proliferation, differentiation and apoptosis. In previous studies, we've demonstrated that PI3K-AKT pathway protects cardiomyocytes from ischemic and hypoxic apoptosis through mitochondrial function. However, the molecular mechanisms underlying hypoxia-induced cardiomyocyte apoptosis via PI3K-AKT pathway remain ill-defined. Here, we addressed this question. METHODS: Cardiomyocytes were exposed to hypoxia, with/without different inhibitors and then protein levels were assessed by Western blotting. RESULTS: We found that the PI3K-AKT pathway was activated in cardiomyocytes that were exposed to hypoxia. Moreover, the phospho-AKT (pAKT) translocated from cytosol to mitochondria via mitochondrial adenosine triphosphate-dependent potassium (mitoKATP), leading to an increase in cytochrome c oxidase (CcO) activity to suppress apoptosis. On the other hand, the mitoKATP specific blocker, 5-hydroxydecanote (5-HD), or suppression of CcO using siRNA, inhibited the pAKT mitochondrial translocation to maintain the CcO activity, resulting in mitochondrial dysfunction and cellular apoptosis induced by hypoxia. CONCLUSION: These findings suggest that the anti-apoptotic effect of the PI3K-AKT pathway through pAKT translocation to mitochondrial via mitoKATP may be conducted through modification of CcO activity.

Tumor necrosis factor receptor-associated protein 1 improves hypoxia-impaired energy production in cardiomyocytes through increasing activity of cytochrome c oxidase subunit II.

Tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes against hypoxia, but the underlying mechanisms are not completely understood. In the present study, we used gain- and loss-of-function approaches to explore the effects of tumor necrosis factor receptor-associated protein 1 and cytochrome c oxidase subunit II on energy production in hypoxic cardiomyocytes. Hypoxia repressed ATP production in cultured cardiomyocytes, whereas overexpression of tumor necrosis factor receptor-associated protein 1 significantly improved ATP production. Conversely, knockdown of tumor necrosis factor receptor-associated protein 1 facilitated the hypoxia-induced decrease in ATP synthesis. Further investigation revealed that tumor necrosis factor receptor-associated protein 1 induced the expression and activity of cytochrome c oxidase subunit II, a component of cytochrome c oxidase that is important in mitochondrial respiratory chain function. Moreover, lentiviral-mediated overexpression of cytochrome c oxidase subunit II antagonized the decrease in ATP synthesis caused by knockdown of tumor necrosis factor receptor-associated protein 1, whereas knockdown of cytochrome c oxidase subunit II attenuated the increase in ATP synthesis caused by overexpression of tumor necrosis factor receptor-associated protein 1. In addition, inhibition of cytochrome c oxidase subunit II by a specific inhibitor sodium azide suppressed the ATP sy nthesis induced by overexpressed tumor necrosis factor receptor-associated protein 1. Hence, tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes from hypoxia at least partly via potentiation of energy generation, and cytochrome c oxidase subunit II is one of the downstream effectors that mediates the tumor necrosis factor receptor-associated protein 1-mediated energy generation program.

Infection-stimulated anemia results primarily from interferon gamma-dependent, signal transducer and activator of transcription 1-independent red cell loss.

BACKGROUND: Although the onset of anemia during infectious disease is commonly correlated with production of inflammatory cytokines, the mechanisms by which cytokines induce anemia are poorly defined. This study focused on the mechanism research. METHODS: Different types of mice were infected perorally with Toxoplasma gondii strain ME49. At the indicated times, samples from each mouse were harvested, processed, and analyzed individually. Blood samples were analyzed using a Coulter Counter and red blood cell (RBC) survival was measured by biotinylation. Levels of tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), and inducible protein 10 (IP-10) mRNA in liver tissue were measured by real-time polymerase chain reaction. RESULTS: T. gondii-infected mice exhibited anemia due to a decrease in both erythropoiesis and survival time of RBC in the circulation (P < 0.02). In addition, infection-stimulated anemia was associated with fecal occult, supporting previous literature that hemorrhage is a consequence of T. gondii infection in mice. Infection-induced anemia was abolished in interferon gamma (IFNγ) and IFNγ receptor deficient mice (P < 0.05) but was still evident in mice lacking TNF-α, iNOS, phagocyte NADPH oxidase or IP-10 (P < 0.02). Neither signal transducer and activator of transcription 1 (STAT1) deficient mice nor 129S6 controls exhibited decreased erythropoiesis, but rather suffered from an anemia resulting solely from increased loss of circulating RBC. CONCLUSIONS: Infection-stimulated decrease in erythropoiesis and losses of RBC have distinct mechanistic bases. These results show that during T. gondii infection, IFNγ is responsible for an anemia that results from both a decrease in erythropoiesis and a STAT1 independent loss of circulating RBC.

[Protein and mRNA expression of CTGF, CYR61, VEGF-C and VEGFR-2 in bone marrow of leukemia patients and its correlation with clinical features].

This study was aimed to investigate the mRNA and protein expression of CTGF, CYR61, VEGF-C and VEGFR-2 in bone marrow of patients with leukemia, and to analyze the role and clinical significance of these 4 factors in genesis and development of leukemia, infiltration and metastasis of leukemic cells. A total of 100 cases of newly diagnosed leukemia, 26 cases of acute leukemia in complete remission and 30 controls were enrolled in this study. The mononuclear cells of bone marrow were collected, the mRNA and protein expression levels of CTGF, CYR61, VEGF-C, VEGFR-2 in leukemia patients and controls were detected by real time PCR and Western blot, respectively. The results showed that the mRNA and protein expression levels of above mentioned 4 factors were significantly higher than those in control (P < 0.05), only CTGF mRNA expression in AL patients after complete remission showed statistical difference as compared with control (P < 0.05), but the expression of CTGF mRNA showed statistical significance in different bone marrow hyperplasia of acute leukemia (P < 0.05). The expression level of CTGF protein showed difference in different chromosome karyotypes of leukemia (P < 0.05). The expression levels of CYR61 and VEGF-C proteins showed statistical difference in different bone marrow hyperplasia of acute leukemia (P < 0.05). The expression level of CTGF, CYR61, VEGF-C mRNA and protein in CML group were higher than that in control group. The expression levels of CTGF and CYR61 protein were higher than that in control. The mRNA and protein expression levels of above-mentioned 4 factors in sex and infiltration lf leukemic cells did not show statistical significance(P < 0.05). In correlative analysis, the mRNA expressions of above mentioned 4 factors were positively correlated with bone marrow blast count(P < 0.05), the protein expression of CTGF, CYR61 and VEGF-C were positively correlated with bone marrow blast count. It is concluded that the CTGF, CYR61, VEGF-C and VEGFR-2 mRNA and protein play a role in acute leukemia. In acute leukemia (AML/ALL), the expression of above mentioned factor was high, but except VEGFR-2. Most of them were positively correlated with bone marrow blast count. Joint block of these angiogenesis-related factors is likely to play an important role in targeting treatment of leukemia.

Downregulation of CD9 in keratinocyte contributes to cell migration via upregulation of matrix metalloproteinase-9.

Tetraspanin CD9 has been implicated in various cellular and physiological processes, including cell migration. In our previous study, we found that wound repair is delayed in CD9-null mice, suggesting that CD9 is critical for cutaneous wound healing. However, many cell types, including immune cells, endothelial cells, keratinocytes and fibroblasts undergo marked changes in gene expression and phenotype, leading to cell proliferation, migration and differentiation during wound repair, whether CD9 regulates kerationcytes migration directly remains unclear. In this study, we showed that the expression of CD9 was downregulated in migrating keratinocytes during wound repair in vivo and in vitro. Recombinant adenovirus vector for CD9 silencing or overexpressing was constructed and used to infect HaCaT cells. Using cell scratch wound assay and cell migration assay, we have also demonstrated that downregulation of CD9 promoted keratinocyte migration in vitro, whereas CD9 overexpression inhibited cell migration. Moreover, CD9 inversely regulated the activity and expression of MMP-9 in keratinocytes, which was involved in CD9-regulated keratinocyte migration. Importantly, CD9 silencing-activated JNK signaling was accompanied by the upregulation of MMP-9 activity and expression. Coincidentally, we found that SP600125, a JNK pathway inhibitor, decreased the activity and expression of MMP-9 of CD9-silenced HaCaT cells. Thus, our results suggest that CD9 is downregulated in migrating keratinocytes in vivo and in vitro, and a low level of CD9 promotes keratinocyte migration in vitro, in which the regulation of MMP-9 through the JNK pathway plays an important role.

Phosphorylation of DYNLT1 at serine 82 regulates microtubule stability and mitochondrial permeabilization in hypoxia.

Hypoxia-induced microtubule disruption and mitochondrial permeability transition (mPT) are crucial events leading to fatal cell damage and recent studies showed that microtubules (MTs) are involved in the modulation of mitochondrial function. Dynein light chain Tctex-type 1 (DYNLT1) is thought to be associated with MTs and mitochondria. Previously we demonstrated that DYNLT1 knockdown aggravates hypoxia-induced mitochondrial permeabilization, which indicates a role of DYNLT1 in hypoxic cytoprotection. But the underlying regulatory mechanism of DYNLT1 remains illusive. Here we aimed to investigate the phosphorylation alteration of DYNLT1 at serine 82 (S82) in hypoxia (1% O2). We therefore constructed recombinant adenoviruses to generate S82E and S82A mutants, used to transfect H9c2 and HeLa cell lines. Development of hypoxia-induced mPT (MMP examining, Cyt c release and mPT pore opening assay), hypoxic energy metabolism (cellular viability and ATP quantification), and stability of MTs were examined. Our results showed that phosph-S82 (S82-P) expression was increased in early hypoxia; S82E mutation (phosphomimic) aggravated mitochondrial damage, elevated the free tubulin in cytoplasm and decreased the cellular viability; S82A mutation (dephosphomimic) seemed to diminish the hypoxia-induced injury. These data suggest that DYNLT1 phosphorylation at S82 is involved in MTs and mitochondria regulation, and their interaction and cooperation contribute to the cellular hypoxic tolerance. Thus, we provide new insights into a DYNLT1 mechanism in stabilizing MTs and mitochondria, and propose a potential therapeutic target for hypoxia cytoprotective studies.

Nicotinamide pretreatment protects cardiomyocytes against hypoxia-induced cell death by improving mitochondrial stress.

BACKGROUND/AIMS: Nicotinamide plays a protective role in hypoxia-induced cardiomyocyte dysfunction. However, the underlying molecular mechanisms remain poorly understood. The purpose of this study was to investigate these and the effect of nicotinamide pretreatment on hypoxic cardiomyocytes. METHODS: Cultured rat cardiomyocytes were pretreated with nicotinamide, subjected to hypoxia for 6 h, and then cell necrosis and apoptosis were examined. The effects of nicotinamide pretreatment on hypoxia-induced reactive oxygen species (ROS) formation, antioxidant enzyme expression, nicotinamide adenine dinucleotide (NAD(+)) and nicotinamide adenine dinucleotide phosphate (NADP(+)) levels, adenosine triphosphate (ATP) production and mitochondrial membrane potential were tested to elucidate the underlying mechanisms. RESULTS: Based on the findings that nicotinamide treatment decreased protein expression of receptor-interacting protein (RIP; a marker for cell necrosis) and cleaved caspase-3 (CC3; a marker for cell apoptosis) in normoxic cardiomyocytes, we found that it dramatically reduced hypoxia-induced necrosis and apoptosis in cardiomyocytes. The underlying mechanisms of these effects are associated with the fact that it increased protein expression of superoxide dismutase and catalase, increased intracellular levels of NAD(+) and ATP concentration, decreased mitochondrial ROS generation and prevented the loss of mitochondrial membrane potential. CONCLUSION: All of these results indicate that nicotinamide pretreatment protects cardiomyocytes by improving mitochondrial stress. Our study provides a new clue for the utilization of nicotinamide in therapies for ischemic heart disease.

Microtubular stability affects pVHL-mediated regulation of HIF-1alpha via the p38/MAPK pathway in hypoxic cardiomyocytes.

BACKGROUND: Our previous research found that structural changes of the microtubule network influence glycolysis in cardiomyocytes by regulating the hypoxia-inducible factor (HIF)-1α during the early stages of hypoxia. However, little is known about the underlying regulatory mechanism of the changes of HIF-1α caused by microtubule network alternation. The von Hippel-Lindau tumor suppressor protein (pVHL), as a ubiquitin ligase, is best understood as a negative regulator of HIF-1α. METHODOLOGY/PRINCIPAL FINDINGS: In primary rat cardiomyocytes and H9c2 cardiac cells, microtubule-stabilization was achieved by pretreating with paclitaxel or transfection of microtubule-associated protein 4 (MAP4) overexpression plasmids and microtubule-depolymerization was achieved by pretreating with colchicine or transfection of MAP4 siRNA before hypoxia treatment. Recombinant adenovirus vectors for overexpressing pVHL or silencing of pVHL expression were constructed and transfected in primary rat cardiomyocytes and H9c2 cells. With different microtubule-stabilizing and -depolymerizing treaments, we demonstrated that the protein levels of HIF-1α were down-regulated through overexpression of pVHL and were up-regulated through knockdown of pVHL in hypoxic cardiomyocytes. Importantly, microtubular structure breakdown activated p38/MAPK pathway, accompanied with the upregulation of pVHL. In coincidence, we found that SB203580, a p38/MAPK inhibitor decreased pVHL while MKK6 (Glu) overexpression increased pVHL in the microtubule network altered-hypoxic cardiomyocytes and H9c2 cells. CONCLUSIONS/SIGNIFICANCE: This study suggests that pVHL plays an important role in the regulation of HIF-1α caused by the changes of microtubular structure and the p38/MAPK pathway participates in the process of pVHL change following microtubule network alteration in hypoxic cardiomyocytes.

Activation of the prolyl-hydroxylase oxygen-sensing signal cascade leads to AMPK activation in cardiomyocytes.

The proline hydroxylase domain-containing enzymes (PHD) act as cellular oxygen sensors and initiate a hypoxic signal cascade to induce a range of cellular responses to hypoxia especially in the aspect of energy and metabolic homeostasis regulation. AMP-activated protein kinase (AMPK) is recognized as a major energetic sensor and regulator of cardiac metabolism. However, the effect of PHD signal on AMPK has never been studied before. A PHD inhibitor (PHI), dimethyloxalylglycine and PHD2-specific RNA interference (RNAi) have been used to activate PHD signalling in neonatal rat cardiomyocytes. Both PHI and PHD2-RNAi activated AMPK pathway in cardiomyocytes effectively. In addition, the increased glucose uptake during normoxia and enhanced myocyte viability during hypoxia induced by PHI pretreatment were abrogated substantially upon AMPK inhibition with an adenoviral vector expressing a dominant negative mutant of AMPK-α1. Furthermore, chelation of intracellular Ca2+ by BAPTA, inhibition of calmodulin-dependent kinase kinase (CaMKK) with STO-609, or RNAi-mediated down-regulation of CaMKK α inhibited PHI-induced AMPK activation significantly. In contrast, down-regulation of LKB1 with adenoviruses expressing the dominant negative form did not affect PHI-induced AMPK activation. We establish for the first time that activation of PHD signal cascade can activate AMPK pathway mainly through a Ca(2+)/CaMKK-dependent mechanism in cardiomyocytes. Furthermore, activation of AMPK plays an essential role in hypoxic protective responses induced by PHI.

MAP4 mechanism that stabilizes mitochondrial permeability transition in hypoxia: microtubule enhancement and DYNLT1 interaction with VDAC1.

Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption. In this study, we established the hypoxic (1% O(2)) cell models of rat cardiomyocytes, H9c2 and HeLa cells to further test MAP4 function. We demonstrated that increase in the pool of MAP4 could promote the stabilization of MT networks by increasing the synthesis and polymerization of tubulin in hypoxia. Results showed MAP4 overexpression could enhance cell viability and ATP content under hypoxic conditions. Subsequently we employed a yeast two-hybrid system to tag a protein interacting with mitochondria, dynein light chain Tctex-type 1 (DYNLT1), by hVDAC1 bait. We confirmed that DYNLT1 had protein-protein interactions with voltage-dependent anion channel 1 (VDAC1) using co-immunoprecipitation; and immunofluorescence technique showed that DYNLT1 was closely associated with MTs and VDAC1. Furthermore, DYNLT1 interactions with MAP4 were explored using a knockdown technique. We thus propose two possible mechanisms triggered by MAP4: (1) stabilization of MT networks, (2) DYNLT1 modulation, which is connected with VDAC1, and inhibition of hypoxia-induced mitochondrial permeabilization.

[Expression of CYR61, CTGF, VEGF-C, VEGFR-2 mRNA in bone marrow of leukemia patients and its clinical significance].

The study was aimed to detect the levels of CYR61, CTGF, VEGF-C, VEGFR-2 mRNA in bone marrow (BM) of leukemia patients and investigate the interaction of CYR61, CTGF, VEGF-C, VEGFR-2 proteins in occurrence, development, infiltration and metastasis of leukemia and its clinical significance, to find a new tumor marker for diagnosis and treatment of leukemia with some new directions. 74 patients with leukemia were enrolled in this study, 38 out of them were males and 36 were females, aged from 6 to 77 years old with the median age of 45 years old. In the control group, 7 males and 5 females, aged from 16 to 78 years old with the median age of 46. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to detect the levels of CYR61, CTGF, VEGF-C, VEGFR-2 mRNA. The results showed that the levels of CYR61, CTGF, VEGF-C, VEGFR-2 mRNA in BM of newly diagnosed patients with acute and chronic leukemia of each group were significantly higher as compared with the control group (p < 0.05). The levels of CYR61, CTGF mRNA in acute leukemia remission group were significantly higher than those in control group (p = 0.039, 0.025). The level of CTGF mRNA was highest in B-ALL group, and was higher than that in AML, CML, CLL, T-ALL groups (p = 0.002, 0.034, 0.002, 0.010). In AML group, mRNA expressions of CYR61 and CTGF, CYR61 and VEGF-C, CTGF and VEGFR-2 were positively correlated (r = 0.452, 0.466, 0.464; p = 0.045, 0.038, 0.039), and in CML group mRNA expression of CYR61 and VEGF-C was positively correlated (r = 0.882, p = 0.000). The expression levels of VEGF-C, VEGFR-2 mRNA in acute leukemia patients with extramedullary infiltration were higher than those in acute leukemia patients without extramedullary infiltration (p = 0.028, 0.047). VEGF-C mRNA expression and the original cell counts in AML group were positively correlated (r = 0.418, p = 0.034). It is concluded that CYR61, CTGF, VEGF-C and VEGFR-2 interact each other in the pathogenesis of leukemia, promote the development, metastasis and infiltration of leukemia; and these factors in different types of leukemia and extramedullary infiltration are different, which may become tumor markers of leukemia; and blocking VEGF-C and VEGFR-2 may block tumor growth and metastasis.

Expression of the stem cell marker, Nanog, in human endometrial adenocarcinoma.

The embryonic stem cell self-renewal gene, Nanog, has been shown to be expressed in several tumor types and to regulate tumor development. The aim of this study was to carry out a detailed analysis of Nanog expression in human endometrial adenocarcinoma (EAC). Immunohistochemical analysis and reverse transcription-polymerase chain reaction were used to characterize Nanog, Sox2, and Oct4 expression in tissue arrays containing EAC, benign endometrium samples, and tumorosphere cells. Tumorosphere formation of EAC-derived cells in the stem cell culture medium was also analyzed. Nanog expression was then analyzed in secondary tumors initiated by the injection of tumorospheres or tumorosphere-derived differentiated cells into 15 female nude mice. Apoptosis and cell proliferation were detected in the fluorescence-activated cell sorter and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide experiments, respectively. The Nanog protein was expressed in a majority of EAC samples (45 of 55, 81.8%), but not in benign endometrium samples (0 of 26, 0.0%). Oct4 and Sox2 were also commonly expressed in EAC samples (42 of 55, 76.4% and 39 of 55, 70.9%, respectively). Subsets of cancer cells from all EAC samples (15 of 15, 100%) exhibited the capacity to form Nanog-positive tumorospheres. The tumorospheres also expressed Nanog, Oct4, and Sox2 mRNA and showed a higher proliferation potential than differentiated cells. All 15 mice that were injected with tumorosphere cell-formed tumors, whereas only 3 of 15 mice injected with differentiated cells derived from tumorospheres developed tumors. All secondary xenograft tumors still expressed Nanog protein and Nanog, Oct4, and Sox2 mRNA, and had higher proliferation and lower apostosis than did differentiated cells. Overexpression of Nanog in EACs suggests that Nanog may represent a potential therapeutic target for EAC. In addition, Nanog may be useful as a biomarker in an immunohistochemical panel to differentiate between EAC and benign endometrial tissues. The expression of Nanog in tumorospheres may be indicative of the presence of a population of endometrial cancer stem cells, and its expression in xenograft tumors suggests that Nanog may also be associated with tumor metastasis.

Adenosine A1 receptor activation reduces opening of mitochondrial permeability transition pores in hypoxic cardiomyocytes.

1. Adenosine A(1) receptors (A(1)R) play an important role in cardioprotection against hypoxic damage and the opening of mitochondrial permeability transition pores (MPTP) is central to the regulation of cell apoptosis and necrosis. However, it is still unclear whether A(1)R open MPTP in hypoxic cardiomyocytes. 2. The present study used primary cardiomyocyte cultures from neonatal rats to investigate the mechanisms of A(1)R activation and the effects of A(1)R on MPTP opening under hypoxic conditions. 3. Hypoxia increased both MPTP opening and the production of reactive oxygen species (ROS), while decreasing cell viability and mitochondrial membrane potential (Deltapsi). The A(1)R agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA; 500 nmol/L) blocked the increase in MPTP opening and ROS production and maintained cell viability and Deltapsi under hypoxic conditions. 4. The protective effects of CCPA were eliminated by both the protein kinase C (PKC) inhibitor chelerythine (2 micromol/L) and the mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)) inhibitor 5-hydroxydecanoate (500 micromol/L). Moreover, CCPA significantly increased the PKC content in both total protein and membrane protein of cardiomyocytes. 5-Hydroxydecanoate did not prevent these CCPA-induced increases in PKC. 5. These results demonstrate that CCPA reduces MPTP opening in hypoxic cardiomyocytes, possibly by activating PKC, stabilizing Deltapsi and reducing ROS production following the opening of mitoK(ATP). Consequently, fewer MPTP open.

[Expression of cyclooxygenase-2 in bone marrow cells of leukemia patients and its association with angiogenesis].

The objective of this study was to investigate the effect of cyclooxygenase-2 (COX-2) in the angiogenesis of bone marrow in leukemia patients. 51 patients with newly diagnosed acute leukemia were taken as study objects, 18 healthy volunteers were enrolled in the control group. Bone marrow microvessel density (MVD) in bone marrow biopsy tissue section was determined with immunohistochemistry method, the vascular endothelial growth factor level in serum was detected with ELISA method and the expression of cyclooxygenase-2 in bone marrow cells was assayed by flow cytometry. The results showed that the MVD, VEGF level, positive rate of COX-2 expression in leukemia group all obviously increased as compared with the control group (p < 0.05). The correlative coefficients of MVD, VEGF level and COX-2 expression rate were 0.614, 0.423 and 0.577 respectively (p < 0.05). In conclusion, as well as solid tumors, leukemia may be also a angiogenesis-dependent malignant tumor. Coordination of COX-2 with VEGF may promote angiogenesis in bone marrow.

[The influence of insulin growth factor-I on the apoptosis of cardiomyocytes subjected to ischemia and hypoxia].

OBJECTIVE: To investigate the influence of insulin growth factor-I (IGF-I) on apoptosis of cardiomyocytes subjected to ischemia and hypoxia and its possible mechanism. METHODS: Cardiomyocytes were cultured in vitro, and randomized into hypoxia group, treatment group (T, the cells were treated with IGF-1 before subjected to hypoxia and ischemia) and control group (C, normal cardiomyocytes as controls). Changes in the OD value of cell apoptosis, mitochondrial membrane potential and relative amount of phospho-Akt protein were observed at different time-points by ELISA, laser scanning with TMRE staining and Western blot, respectively. RESULTS: The OD value of cell apoptosis in control group was 0.18 +/- 0.03, while that in hypoxia group was gradually increased to 0.33 +/- 0.05, 0.61 +/- 0.06, 1.17 +/- 0.08, 2.25 +/- 0.11, respectively at 1, 3, 6, 12 post-hypoxia hours (PHH), showing an increasing tendency (P < 0.01). The OD values of cell apoptosis in T group were 0.26 +/- 0.04, 0.49 +/- 0.05, 0.84 +/- 0.06, 1.63 +/- 0.09, respectively, which were obviously lower than those in hypoxia group (P < 0.05 or P < 0.01). The mitochondrial membrane potential (Dymt) values in hypoxia group at 6 and 12 PHH were 18.7 +/- 5.1 and 6.3 +/- 1.9, respectively, which were obviously lower than that in control group (40.2 +/- 10.1, P < 0.01). The DYmt in T group at 6 and 12 PHH were 28.8 +/- 6.2, 12.5 +/- 3.1, respectively, which were obviously higher compared with those in hypoxia group (P < 0.05). The amount of phospho-Akt protein was increased by IGF-I administration. CONCLUSION: IGF-I exhibits an anti-apoptotic effect on cardiomyocytes subjected to ischemia and hypoxia, and this may be related to the activation of PI3K/Akt signal pathway and stabilization of mitochondrial membrane potential.

[Study on the mechanism of alleviation of myocardial injury after early escharectomy en masse of several burns in rat].

OBJECTIVE: To investigate the alleviation of myocardial injury of rats after early escharectomy en masse of severe burns, and to explore its molecular mechanism. METHODS: Totally 66 SD rats were randomly divided into normal control (n=6), non-escharectomy (NE, n=30) and escharectomy (E, n=30, with total escharectomy 20 minutes after burns ) groups. The rats in the NE and E groups were inflicted with 30% TBSA full-thickness scald. The content of ATP in mitochondria, troponin I (Tn I) in serum and 4.8-kb deletion of myocardial mitochondrial DNA (mtDNA) of the rats in each group were determined at 1, 3, 6, 12 and 24 post-scald hours (PSH). RESULTS: (1) The content of ATP in myocardial mitochondria was decreased in both E and NE groups, but it was obviously increased at 1 and 6 PSH (0.90 +/- 0.27 microg/mg 0.66 +/- 0.19 microg/mg) in E group when compared with those in NE group (0.74 +/- 0.18 microg/mg, 0.46 +/- 0.21 microg/mg, P < 0.05). (2) There was no obvious change in the serum content of Tn I in E group at 1 and 3 PSH, but the respective content in 1, 3 and 6 PSH was markedly lower than those in NE group (P < 0.05). (3) The 4.8 kb deletion of myocardial mtDNA was found at 1, 3, 24 PSH in NE group, while it was observed only at 1, 12 PSH in E group. The partial and whole deletion rate in E group was lower than that in NE group. CONCLUSION: Early escharectomy en masse can significantly alleviate the myocardial injury after burns,which might be related to its effect in lowering the deletion rate of myocardial mtDNA at early postburn stage.