CD147 interacts with NDUFS6 in regulating mitochondrial complex I activity and the mitochondrial apoptotic pathway in human malignant melanoma cells

Malignant melanoma (MM) is one of the most lethal tumors and is characterized by high invasiveness, frequent metastasis, and resistance to chemotherapy. The risk of metastatic MM is accompanied by disordered energy metabolism involving the oxidative phosphorylation (OXPHOS) process, which is largely carried out in mitochondrial complexes. Complex I is the first and largest mitochondrial enzyme complex associated with this process. CD147 is a transmembrane glycoprotein mainly expressed on the cell surface, and also appears in the cytoplasm in some tumors. We found that CD147 is often translocated to the cytoplasm in metastatic MM specimens as compared to primary MM. We also demonstrated high expression of CD147 in isolated mitochondrial fractions of A375 cells. The yeast two-hybrid (Y2H) assay identified NDUFS6 (which encodes a subunit of mitochondrial respiratory chain complex I) as a candidate that interacts with CD147 and depletion of CD147 in A375 cells significantly decreased complex I enzyme activity. We also showed that CD147 increased the viability of A375 cells exposed to berberine-induced mitochondrial damage, and protected them from apoptosis through a mitochondrial-dependent pathway. This finding was confirmed by adding exogenous Bcl-2 to A375 cell cultures. In summary, our results identify the existence of CD147 in human melanoma cell mitochondria. They indicate that CD147 appears to regulate complex I activity and apoptosis in MM by interacting with mitochondrial NDUFS6. Our findings provide new insight into the function of CD147 and identify it as a promising therapeutic target in melanoma through disruption of the energy metabolism.

Activation of the SIRT1/p66shc antiapoptosis pathway via carnosic acid-induced inhibition of miR-34a protects rats against nonalcoholic fatty liver disease

Recent studies have demonstrated that miR-34a expression is significantly upregulated and associated with apoptosis in nonalcoholic fatty liver disease (NAFLD). Carnosic acid (CA) is a novel antioxidant and a potential inhibitor of apoptosis in organ injury, including liver injury. This study aimed to investigate the signaling mechanisms underlying miR-34a expression and the antiapoptotic effect of CA in NAFLD. CA treatment significantly reduced the high-fat diet (HFD)-induced elevations in aminotransferase activity as well as in serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and malondialdehyde (MDA) levels but increased serum high-density lipoprotein cholesterol (HDL-C) and hepatic superoxide dismutase (SOD) levels. Moreover, CA treatment ameliorated the increase in cleaved caspase-3 caused by HFD exposure and completely reversed the HFD-induced decreases in manganese superoxide dismutase (MnSOD) and B-cell lymphoma-extra large expression. CA also counteracted the HFD- or palmitic acid (PA)-induced increases in caspase-3 and caspase-9 activity. Mechanistically, CA reversed the HFD- or PA-induced upregulation of miR-34a, which is the best-characterized regulator of SIRT1. Importantly, the decrease in miR-34a expression was closely associated with the activation of the SIRT1/p66shc pathway, which attenuates hepatocyte apoptosis in liver ischemia/reperfusion injury. A dual luciferase assay in L02 cells validated the modulation of SIRT1 by CA, which occurs at least partly via miR-34a. In addition, miR-34a overexpression was significantly counteracted by CA, which prevented the miR-34a-dependent repression of the SIRT1/p66shc pathway and apoptosis. Collectively, our results support a link between liver cell apoptosis and the miR-34a/SIRT1/p66shc pathway, which can be modulated by CA in NAFLD.

MRI assessment of paraspinal muscles in patients with acute and chronic unilateral low back pain

OBJECTIVE

To investigate the changes in paraspinal muscle cross-sectional area (CSA) and composition, using the digital data from lumbar spine MRIs of patients with acute and chronic low back pain (LBP).

METHODS

In total, 178 patients with unilateral LBP who had lumbar MRI examination were recruited. The data were obtained by a retrospective documentation audit. The CSAs and mean signal intensities of the bilateral paraspinal muscles [psoas major (PM), quadratus lumborum, multifidus (MF) and erector spinae (ES)] were measured, and the percentage of fat infiltration was calculated. The data between the painful side and non-painful side were compared, and between-group comparisons were tested. 42 patients with chronic unilateral LBP could indicate the problem level, and the CSA and mean signal intensity of the MF muscle were analysed at the problem level, and one vertebral above and one vertebral level below the problem level.

RESULTS

The CSAs of the PM and ES muscles were significantly decreased in the acute LBP group, while in the chronic LBP group, significant reduction in CSA was found in the MF and ES muscles on the painful side compared with the non-painful side. The mean signal intensity and fat content of the ES muscle on the painful side in the chronic LBP group was significantly higher than that on the painful side in the acute LBP group. The significant decrease of CSA in the MF muscle was found at multiple levels on the painful side.

CONCLUSION

The present findings show that there is selective ipsilateral atrophy of paraspinal muscles, specific to the symptomatic side, in patients with acute and chronic LBP. The reduction of the muscle CSA and increased fatty infiltration occurred synchronously, and the extent of change is significantly greater in chronic LBP in the ES muscle. Atrophy of the MF muscle appears to be at multiple levels but side specific in relation to symptoms in patients with chronic LBP, and the decreased muscle CSA may occur prior to fatty infiltration.

ADVANCES IN KNOWLEDGE

There are specific paraspinal muscles undergoing atrophy and fatty infiltration in patients with acute and chronic LBP on the symptomatic side. The CSA of the MF muscle decreased at multiple levels on the symptomatic side in patients with chronic unilateral LBP, which may occur prior to fatty infiltration.

Identification of APOH polymorphisms as common genetic risk factors for venous thrombosis in the Chinese population

BACKGROUND

Venous thrombosis (VT) is a worldwide medical problem. In order to identify individuals at high risk early, it is necessary to find more genetic risk factors. Nowadays, the studies on genetic factors of thrombosis are mainly focused on coagulation and anticoagulation factors. The exploration of other proteins involved in thrombosis and hemostasis may lead to a breakthrough.

OBJECTIVES

We used APOH as a candidate gene to investigate the existence of genetic variation that could increase the risk of thrombosis.

METHODS/RESULTS

In the current study, with a resequencing method followed by a case-control study, four polymorphisms (c.-32C>A, c.422T>C, c.461G>A, and c.1004G>C) in APOH (encoding β2 -glycoprotein I) were found to be in high linkage disequilibrium, which could result in three haplotypes. The H2 heterozygotes and H3 homozygotes had approximately 1.5-fold and seven-fold increased risks for VT, respectively. The minor allele frequency in the general population was ~ 10%. In addition, H3 individuals showed a significantly decreased level of β2 -glycoprotein I, but an increased level of thrombin generation. Functional tests indicated that the mutant β2 -glycoprotein I had a significantly lower capacity to extend thrombin clotting time and increase thrombin generation potential.

CONCLUSIONS

This study revealed APOH as a new candidate gene associated with thrombosis, and further genetic research on this gene in patients in whom the cause of thrombophilia is unknown is therefore warranted.

CD147 promotes melanoma progression through hypoxia-induced MMP2 activation

Hypoxia enhances MMP2 expression and the invasion and metastatic potential of melanoma cells. CD147 has been shown to induce MMP2 in multiple cancers. To investigate the role of CD147 in hypoxiainduced MMP2 activation, we performed immunohistochemistry (IHC) staining in 206 normal and melanoma tissue samples, and analyzed the correlation between HIF1α and CD147. ChIP (chromosome Immunoprecipitation) in melanoma cell lines supports that HIF1α directly binds to CD147 promoter. Moreover, we made a series of deletion mutants of CD147 promoter, and identified a conserved HIF1α binding site. Point mutation in this site significantly decreased CD147 response to hypoxia. Importantly, knocking down CD147 attenuates MMP2 response to hypoxia in melanoma cell lines. MMP2 could not be efficiently activated by hypoxia in CD147 depletion cells. ELISA data showed that MMP2 secretion was reduced in CD147 depletion cells than control under hypoxia condition. To verify the data from cell culture model, we performed in vivo mouse xenograft experiment. IHC staining showed reduced MMP2 level in CD147 depleted xenografts compared to the control group, with the HIF1α level being comparable. Our study demonstrates a novel pathway mediated by CD147 to promote the MMP2 activation induced by hypoxia, and helps to understand the interplay between hypoxia and melanoma progression.

αNAC inhibition of the FADD-JNK axis plays anti-apoptotic role in multiple cancer cells

Nascent polypeptide-associated complex α (αNAC) is reportedly overexpressed in several types of cancers and regulates cell apoptosis under hypoxic conditions in HeLa cells. The aim of our study was to investigate the apoptotic function of αNAC in cancer progression. First, we observed the cellular effects of αNAC depletion. Mouse αNAC was used to restore the protein level and verify the effect. An Annexin V assay, a caspase activity reporter assay, an apoptotic molecular marker, and a colony formation assay were used as markers to investigate the mechanisms of cell death caused by αNAC depletion. The Cancer 10-pathway reporter assay was used to screen downstream pathways. PCR site-directed deletion based on the functional domains of αNAC was used to construct deletion mutants. Those functional domain deletion mutants were used to recover the apoptotic phenotype caused by αNAC depletion. Finally, the role of αNAC in TNF-related apoptosis-inducing ligand (TRAIL) treatment was investigated in vitro. We found that depletion of αNAC in multiple types of cancer cells induce typical apoptotic cell death. This anti-apoptotic function is mediated by the FADD/c-Jun N-terminal kinase pathway. Intact αNAC is required for the direct binding of FADD as well as its anti-apoptosis function. Either αNAC depletion or the deletion of the ubiquitin-associated domain of αNAC sensitizes L929 cancer cells to mTRAIL treatment. Our study revealed a αNAC anti-apoptotic function in multiple types of cancer cells and suggested its potential in cancer therapy.

The histone methyltransferase ESET is required for the survival of spermatogonial stem/progenitor cells in mice

Self-renewal and differentiation of spermatogonial stem cells (SSCs) are the foundation of spermatogenesis throughout a male's life. SSC transplantation will be a valuable solution for young male patients to preserve their fertility. As SSCs in the collected testis tissue from the patients are very limited, it is necessary to expansion the SSCs in vitro. Previous studies suggested that histone methyltransferase ERG-associated protein with SET domain (ESET) represses gene expression and is essential for the maintenance of the pool of embryonic stem cells and neurons. The objective of this study was to determine the role of ESET in SSCs using in vitrocell culture and germ cell transplantation. Cell transplantation assay showed that knockdown of ESET reduced the number of seminiferous tubules with spermatogenesis when compared with that of the control. Knockdown of ESET also upregulated the expression of apoptosis-associated genes (such as P53, Caspase9, Apaf1), whereas inhibited the expression of apoptosis-suppressing genes (such as Bcl2l1, X-linked inhibitor of apoptosis protein). In addition, suppression of ESET led to increase in expression of Caspase9 and activation of Caspase3 (P17) as well as cleavage of poly (ADP-ribose) polymerase. Among the five ESET-targeting genes (Cox4i2, spermatogenesis and oogenesis Specific Basic Helix-Loop-Helix 2, Nobox, Foxn1 and Dazl) examined by ChIP assay, Cox4i2 was found to regulate SSC apoptosis by the rescue experiment. BSP analyses further showed that DNA methylation in the promoter loci of Cox4i2was influenced by ESET, indicating that ESET also regulated gene expression through DNA methylation in addition to histone methylation. In conclusion, we found that ESET regulated SSC apoptosis by suppressing of Cox4i2 expression through histone H3 lysine 9 tri-methylation and DNA methylation. The results obtained will provide unique insights that would broaden the research on SSC biology and contribute to the treatment of male infertility.

Platelet-activating factor contributes to Bacillus anthracis lethal toxin-associated damage

The lethal toxin (LeTx) of Bacillus anthracis plays a central role in the pathogenesis of anthrax-associated shock. Platelet-activating factor (PAF) is a potent lipid mediator that has been implicated in endotoxin-associated shock. In this study, we examined the contribution of PAF to the manifestations of lethal toxin challenge in WT mice. LeTx challenge resulted in transient increase in serum PAF levels and a concurrent decrease in PAF acetylhydrolase activity. Inhibition of PAF activity using PAF antagonists or toxin challenge of PAF receptor negative mice reversed or ameliorated many of the pathologic features of LeTx-induced damage, including changes in vascular permeability, hepatic necrosis, and cellular apoptosis. In contrast, PAF inhibition had minimal effects on cytokine levels. Findings from these studies support the continued study of PAF antagonists as potential adjunctive agents in the treatment of anthrax-associated shock.

Diagnostic exome sequencing identifies two novel IQSEC2 mutations associated with X-linked intellectual disability with seizures: implications for genetic counseling and clinical diagnosis

Intellectual disability is a heterogeneous disorder with a wide phenotypic spectrum. Over 1,700 OMIM genes have been associated with this condition, many of which reside on the X-chromosome. The IQSEC2 gene is located on chromosome Xp11.22 and is known to play a significant role in the maintenance and homeostasis of the brain. Mutations in IQSEC2 have been historically associated with nonsyndromic X-linked intellectual disability. Case reports of affected probands show phenotypic overlap with conditions associated with pathogenic MECP2, FOXG1, CDKL5, and MEF2C gene mutations. Affected individuals, however, have also been identified as presenting with additional clinical features including seizures, autistic-behavior, psychiatric problems, and delayed language skills. To our knowledge, only 5 deleterious mutations and 2 intragenic duplications have been previously reported in IQSEC2. Here we report two novel IQSEC2 de novo truncating mutations identified through diagnostic exome sequencing in two severely affected unrelated male probands manifesting developmental delay, seizures, hypotonia, plagiocephaly, and abnormal MRI findings. Overall, diagnostic exome sequencing established a molecular diagnosis for two patients in whom traditional testing methods were uninformative while expanding on the mutational and phenotypic spectrum. In addition, our data suggests that IQSEC2 may be more common than previously appreciated, accounting for approximately 9 % (2/22) of positive findings among patients with seizures referred for diagnostic exome sequencing. Further, these data supports recently published data suggesting that IQSEC2 plays a more significant role in the development of X-linked intellectual disability with seizures than previously anticipated.

Biochemical parameters of Saccharopolyspora erythraea during feeding ammonium sulphate in erythromycin biosynthesis phase

The physiology of feeding ammonium sulphate in erythromycin biosynthesis phase of Saccharopolyspora erythraea on the regulation of erythromycin A (Er-A) biosynthesis was investigated in 50 L fermenter. At an optimal feeding ammonium sulphate rate of 0.03 g/L per h, the maximal Er-A production was 8281 U/mL at 174 h of growth, which was increased by 26.3% in comparison with the control (6557 U/mL at 173 h). Changes in cell metabolic response of actinomycete were observed, i.e. there was a drastic increase in the level of carbon dioxide evolution rate and oxygen consumption. Assays of the key enzyme activities and organic acids of S. erythraea and amino acids in culture broth revealed that cell metabolism was enhanced by ammonium assimilation, which might depend on the glutamate transamination pathway. The enhancement of cell metabolism induced an increase of the pool of TCA cycle and the metabolic flux of erythromycin biosynthesis. In general, ammonium assimilation in the erythromycin biosynthesis phase of S. erythraea exerted a significant impact on the carbon metabolism and formation of precursors of the process for dramatic regulation of secondary metabolites biosynthesis.

Recombinant PTD-Cu/Zn SOD attenuates hypoxia-reoxygenation injury in cardiomyocytes

BACKGROUND

Oxidative stress plays a pivotal role in myocardial ischemia-reperfusion injury. Increasing the protein expression of intracellular Cu/Zn SOD, which is the major endogenous antioxidant enzyme, may attenuate or prevent hypoxia-reoxygenation injury (HRI) in cultured cardiomyocytes. However, ectogenic Cu/Zn-SOD can hardly be transferred into cells to exert biological effects. In this study, we constructed PTD-Cu/Zn SOD plasmid with a kind of translocation structure-Protein transduction domain (PTD) and detected its transmembrane ability and antioxidant effects in H9c2 rat cardiomyocytes subjected to hypoxia/reoxygenation injury (HRI).

METHODS

We constructed the pET-PTD-Cu/Zn SOD (CDs) prokaryotic expression vectors in plasmid that were inserted into E. coli BL21 to induce the protein expression of PTD-Cu/Zn SOD. H9c2 cardiomyocyte HRI was achieved by exposing cardiomyocytes to 12 h hypoxia followed by 2 h reoxygenation. Protein expression of PTD-Cu/Zn SOD in cardiomyocytes was assayed by Western blot and their enzyme activities were investigated by immunohistochemistry and flow cytometry.

RESULTS

In cultured cardiomyocytes hypoxia-reoxygenation injury model, exogenous PTD-Cu/Zn SOD could penetrate cell membrane to clear superoxide anion and decrease hydrogen peroxide level in H9c2 cardiomyocytes subjected to HRI. The level of mitochondrial membrane potential was restored to normal, and the cell apoptosis was reduced in cardiomyocytes with PTD-Cu/Zn SOD treatment during HRI.

CONCLUSION

Recombinant PTD-Cu/Zn SOD could scavenge intracellular-free superoxide anion, protect mitochondria from damages, and attenuate the hypoxia-reoxygenation injury in cultured cardiomyocytes.

Abstract P4-05-01: Oncolytic Herpes Simplex Virus Vector G47Δ Effectively Targets Breast Cancer Stem Cells

Breast tumors can be classified according to their gene-expression profiles into different molecular subtypes with distinct biological and clinical features. Moreover, different subtypes show distinct responses to different therapeutic regimens, thereby resulting in markedly different outcomes. Recently, accumulating evidence has suggested that breast cancer originates from cancer stem cells (CSCs), which comprise a small percentage of the overall tumor but are highly tumorigenic and pluripotent with unlimited proliferation potential. Furthermore, cancer stem cells are highly resistant to conventional treatment, which potentially explains certain difficulties in treating cancer with current therapy options. The use of oncolytic viruses is a relatively new strategy in cancer therapy, oncolytic herpes simplex virus (oHSV) has been shown to be a safe and effective therapeutic approach for a variety of different cancers.

In this study, different types of breast cancer cell lines were cultured in anchorage-independent conditions, the cells typically form mammospheres within 10 days of anchorage-independent culture, which showed properties of CSCs. The mammospheres are capable of being passaged indefinitely and single dissociated mammosphere cells were able to regenerate spheres. Moreover, compared to the parental cell lines, mammoshpere cells were enriched for CD44+CD24− cells and highly expression of the alternative breast cancer stem cell marker ALDH-1.

The third generation oHSV vector G47Δ effectively killed different subtypes of breast cancer cells in vitro, with more than 98% of the tumor cells killed by day 5, even at multiplicities of infection(MOI) 0.01. Moreover, G47Δ equally targeted non-cancer stem cells (NCSCs) and CSCs which showed resistance to paclitaxel. We also demonstrated that G47Δ effectively replicated and spread among CSCs. Moreover, G47Δ impaired the self-renewal ability of CSCs, as the viable cells unable to form secondary tumor spheres. We also showed that G47Δ was able to induce the regression of tumor xenografts in BALB/c nude mice and demonstrated the ability of G47Δ to synergize with paclitaxel for killing both NCSCs and CSCs. This is the first report that oHSV effectively targets different breast cancer NCSCs and CSCs, thereby suggesting that oHSV may be an effective treatment modality for patients with breast cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-05-01.