AIM: To explore the expression of differential gene expression profiles of target cell between non-invasive submucosal and invasive advanced tumor in colon carcinoma using laser microdissection (LMD) in combination with polypeptide analysis.
METHODS: Normal colon tissue samples from 20 healthy individuals and 30 cancer tissue samples from early non-invasive colon cancer cells were obtained. The cells from these samples were used LMD independently after P27-based amplification. aRNA from advanced colon cancer cells and metastatic cancer cells of 40 cases were applied to LMD and polypeptide analysis, semiquantitative reverse transcribed polymerase chain reaction (RT-PCR) and immunohistochemical assays were used to verify the results of microarray and further identify differentially expressed genes in non-invasive early stages of colon cancer.
RESULTS: Five gene expressions were changed in colon carcinoma cells compared with that of controls. Of the five genes, three genes were downregulated and two were upregulated in invasive submucosal colon carcinoma compared with non-invasive cases. The results were confirmed at the level of aRNA and gene expression. Five genes were further identified as differentially expressed genes in the majority of cases (> 50%, 25/40) in progression of colon cancer, and their expression patterns of which were similar to tumor suppressor genes or oncogenes.
CONCLUSION: This study suggested that combined use of polypeptide analysis might identify early expression profiles of five differential genes associated with the invasion of colon cancer. These results reveal that this gene may be a marker of submucosal invasion in early colon cancer.
Colon cancer; Laser microdissection; Polypeptide analysis
AIM: To explore the molecular mechanisms of action of paclitaxel and NM-3 on human gastric cancer in severe combined immune deficiency (SCID) mice.
METHODS: Human gastric cancer cells SGC-7901 were implanted into SCID mice and mice were treated with paclitaxel and NM-3. The effects of paclitaxel and NM-3 on apoptosis of human gastric cancer cells were analyzed using flow cytometry, TUNEL assays, and DNA fragment analyses.
RESULTS: Apoptosis of SGC-7901 cells was successfully induced by paclitaxel, NM-3, and the combination of paclitaxel and NM-3 24 h after injection as shown by the presence of apoptotic hypodiploid peaks on the flow cytometer before G1-S and a characteristic apoptotic band pattern in the DNA electrophoresis. The apoptotic rate detected by TUNEL assay was found to be significantly higher in the paclitaxel/NM-3 compared to the control group (38.5% ± 5.14% vs 13.2% ± 1.75%, P < 0.01).
CONCLUSION: Paclitaxel in combination with NM-3 is able to induce apoptosis of the human gastric cancer cells in SCID mice effectively and synergistically.
Gastric cancer; NM-3; Paclitaxel
Heterodimeric transcription factor hypoxia inducible factor-1 (HIF-1) functions as a master regulator of oxygen homeostasis in almost all nucleated mammalian cells. The fundamental process adapted to cellular oxygen alteration largely depends on the refined regulation on its alpha subunit, HIF-1α. Recent studies have unraveled expanding and critical roles of HIF-1α, involving in a multitude of developmental, physiological, and pathophysiological processes. This review will focus on the current knowledge of HIF-1α-targeting genes and its interacting proteins, as well as the concomitant functional relationships between them.
Hypoxia inducible factor-1alpha; targeting gene; interacting protein
Autophagy is a highly conserved, closely regulated homeostatic cellular activity that allows for the bulk degradation of long-lived proteins and cytoplasmic organelles. Its roles in cancer initiation and progression and in determining the response of tumor cells to anticancer therapy are complicated, and only limited investigation has been conducted on the potential significance of autophagy in the pathogenesis and therapeutic response of acute myeloid leukemia. Here we demonstrate that the inducible or transfected expression of the acute promyelocytic leukemia (APL)-specific PML-RARα, but not PLZF-RARα or NPM-RARα, fusion protein upregulates constitutive autophagy activation in leukemic and nonleukemic cells, as evaluated by hallmarks for autophagy including transmission electron microscopy. The significant increase in autophagic activity is also found in the leukemic cells-infiltrated bone marrow and spleen from PML-RARα-transplanted leukemic mice. The autophagy inhibitor 3-methyladenine significantly abrogates the autophagic events upregulated by PML-RARα, while the autophagic flux assay reveals that the fusion protein induces autophagy by increasing the on-rate of autophagic sequestration. Furthermore, this modulation of autophagy by PML-RARα is possibly mediated by a decreased activation of the Akt/mTOR pathway. Finally, we also show that autophagy contributes to the anti-apoptotic function of the PML-RARα protein. Given the critical role of the PML-RARα oncoprotein in APL pathogenesis, this study suggests an important role of autophagy in the development and treatment of this disease.
autophagy; acute promyelocytic leukemia (APL); PML-RARα; mTOR; apoptosis
In this study, we report the functional characterization of a new ent-kaurene diterpenoid termed pharicin A, which was originally isolated from Isodon, a perennial shrub frequently used in Chinese folk medicine for tumor treatment. Pharicin A induces mitotic arrest in leukemia and solid tumor-derived cells identified by their morphology, DNA content and mitotic marker analyses. Pharicin A-induced mitotic arrest is associated with unaligned chromosomes, aberrant BubR1 localization and deregulated spindle checkpoint activation. Pharicin A directly binds to BubR1 in vitro, which is correlated with premature sister chromatid separation in vivo. Pharicin A also induces mitotic arrest in paclitaxel-resistant Jurkat and U2OS cells. Combined, our study strongly suggests that pharicin A represents a novel class of small molecule compounds capable of perturbing mitotic progression and initiating mitotic catastrophe, which merits further preclinical and clinical investigations for cancer drug development.
pharicin A; mitotic arrest; leukemia; tumor cells; spindle checkpoint
Caspases, a family of aspartate-specific cysteine proteases, play a major role in apoptosis and a variety of physiological and pathological processes. Fourteen mammalian caspases have been identified and can be divided into two groups: inflammatory caspases and apoptotic caspases. Based on the structure and function, the apoptotic caspases are further grouped into initiator/apical caspases (caspase-2, -8, -9, and -10) and effector/executioner caspases (caspase-3, -6, and -7). In this paper, we discuss what we have learned about the role of individual effector caspase in mediating both apoptotic and nonapoptotic events, with special emphasis on leukemia-specific oncoproteins in relation to effector caspases.
AIM: To investigate the effect of N-desulfated heparin on tumor metastasis and angiogenesis, and expression of vascular endothelial growth factor (VEGF) of orthotopic implantation of human gastric carcinoma in male severe combined immune deficiency (SCID) mice.
METHODS: Human gastric cancer SGC-7901 cells were orthotopically implanted into the stomach of SCID mice. The mice were randomly divided into normal saline group and N-desulfated heparin group. One week after operation, the mice in N-desulfated heparin group received i.v. injections of N-desulfated heparin (Shanghai Institute of Cell Biology, Chinese Academy of Sciences, 10 mg/kg.d) twice weekly for 3 wk. The mice in normal saline group received i.v. injections of normal saline (100 μL) twice weekly for 3 wk. The mice were sacrificed six weeks after implantation. Tumor metastasis was evaluated histologically for metastasis under microscope. Intratumoral microvessel density (MVD) and VEGF expression were evaluated immuohistochemically. VEGF mRNA expression in gastric tissue of SCID mice was detected by real time PCR.
RESULTS: The tumor metastasis rate was 80% in normal saline group and 20% in N-desulfated heparin group (P < 0.05). MVD was 8.0 ± 3.1 in normal saline group and 4.3 ± 1.8 in N-desulfated heparin group (P < 0.05). VEGF positive immunostaining was found in cytoplasm of cancer cells. The rate of VEGF positive expression was higher in normal saline group than in N-desulfated heparin treated group (90% vs 20%, P < 0.05). VEGF mRNA expression was significantly inhibited by N-desulfated heparin and was higher in normal saline group than in N-desulfated heparin group (Ct value 19.51 ± 1.01 vs 22.55 ± 1.36, P < 0.05). N-desulfated heparin significantly inhibited the expression of VEGF mRNA in cancer cells. No bleeding occurred in N-desulfated heparin group.
CONCLUSION: N-desulfated heparin can inhibit metastasis of gastric cancer by suppressing tumor VEGF expression and tumor angiogenesis, but has no obvious anticoagulant activity.
N-desulfated heparin; Gastric carcinoma; Metastasis; Tumor angiogenesis; Vascular endothelial growth factor
AIM: To study the differential gene expression profiles of target cells in primary gastric cancer and its metastatic lymph nodes using laser microdissection (LMD) in combination with cDNA microarray.
METHODS: Normal gastric tissue samples from 30 healthy individuals, 36 cancer tissue samples from primary gastric carcinoma and lymph node metastasis tissue samples from 58 patients during gastric cancer resection were obtained using LMD in combination with cDNA microarray independently. After P27-based amplification, aRNA from 36 of 58 patients (group 1) with lymph node metastasis and metastatic tissue specimens from the remaining 22 patients (group 2) were applied to cDNA microarray. Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemical assay verified the results of microarray in group 2 and further identified genes differentially expressed in the progression of gastric cancer.
RESULTS: The expression of 10 genes was up-regulated while the expression of 15 genes was down-regulated in 22 gastric carcinoma samples compared with that of genes in the normal controls. The results were confirmed at the level of mRNA and protein, and suggested that four genes (OPCML, RNASE1, YES1 and ACK1) could play a key role in the tumorigenesis and metastasis of gastric cancer. The expression pattern of 3 genes (OPCML, RNASE1 and YES1) was similar to tumor suppressor genes. For example, the expression level of these genes was the highest in normal gastric epithelium, which was decreased in primary carcinoma, and further decreased in metastatic lymph nodes. On the contrary, the expression pattern of gene ACK1 was similar to that of oncogene. Four genes were further identified as differentially expressed genes in the majority of the cases in the progression of gastric cancer.
CONCLUSION: LMD in combination with cDNA microarray provides a unique support foe the identification of early expression profiles of differential genes and the expression pattern of 3 genes (OPCML, RNASE1 and YES1) associated with the progression of gastric cancer. Further study is needed to reveal the molecular mechanism of lymph node metastasis in patients with gastric cancer.
Gastric cancer; cDNA microarray; Laser microdissection; Reverse transcriptase polymerase chain reaction; P27
It is a routine task in metabolic engineering to introduce multicomponent pathways into a heterologous host for production of metabolites. However, this process sometimes may take weeks to months due to the lack of standardized genetic tools. Here, we present a method for the design and construction of biological parts based on the native genes and regulatory elements in Saccharomyces cerevisiae. We have developed highly efficient protocols (termed YeastFab Assembly) to synthesize these genetic elements as standardized biological parts, which can be used to assemble transcriptional units in a single-tube reaction. In addition, standardized characterization assays are developed using reporter constructs to calibrate the function of promoters. Furthermore, the assembled transcription units can be either assayed individually or applied to construct multi-gene metabolic pathways, which targets a genomic locus or a receiving plasmid effectively, through a simple in vitro reaction. Finally, using β-carotene biosynthesis pathway as an example, we demonstrate that our method allows us not only to construct and test a metabolic pathway in several days, but also to optimize the production through combinatorial assembly of a pathway using hundreds of regulatory biological parts.
Retinoic acid receptor alpha (RARα) plays an essential role in the regulation of many biological processes, such as hematopoietic cell differentiation, while abnormal RARα function contributes to the pathogenesis of certain diseases including cancers, especially acute promyelocytic leukemia (APL). Recently, oridonin, a natural diterpenoid isolated from Rabdosia rubescens, was demonstrated to regulate RARα by increasing its protein level. However, the underlying molecular mechanism for this action has not been fully elucidated.
In the APL cell line, NB4, the effect of oridonin on RARα protein was analyzed by western blot and real-time quantitative RT-PCR analyses. Flow cytometry was performed to detect intracellular levels of reactive oxygen species (ROS). The association between nuclear factor-kappa B (NF-κB) signaling and the effect of oridonin was assessed using specific inhibitors, shRNA gene knockdown, and immunofluorescence assays. In addition, primary leukemia cells were treated with oridonin and analyzed by western blot in this study.
RARα possesses transcriptional activity in the presence of its ligand, all-trans retinoic acid (ATRA). Oridonin remarkably stabilized the RARα protein, which retained transcriptional activity. Oridonin also moderately increased intracellular ROS levels, while pretreatment with the ROS scavenger, N-acetyl-l-cysteine (NAC), dramatically abrogated RARα stabilization by oridonin. More intriguingly, direct exposure to low concentrations of H2O2 also increased RARα protein but not mRNA levels, suggesting a role for ROS in oridonin stabilization of RARα protein. Further investigations showed that NAC antagonized oridonin-induced activation of NF-κB signaling, while the NF-κB signaling inhibitor, Bay 11–7082, effectively blocked the oridonin increase in RARα protein levels. In line with this, over-expression of IκΒα (A32/36), a super-repressor form of IκΒα, or NF-κB-p65 knockdown inhibited oridonin or H2O2-induced RARα stability. Finally, tumor necrosis factor alpha (TNFα), a classical activator of NF-κB signaling, modulated the stability of RARα protein.
Oridonin stabilizes RARα protein by increasing cellular ROS levels, which causes activation of the NF-κB signaling pathway.
RARα; Oridonin; ROS; NF-κB
With the rapid development of synthetic biology, the demand for assembling multiple DNA (genes) fragments into a large circular DNA structure in one step has dramatically increased. However, for constructions of most circular DNA, there are two contradictions in the ligation/assembly and transformation steps. The ligation/assembly consists of two different reactions: 1) the ligation/assembly between any two pieces of a linear form DNA; 2) the cyclization (or self-ligation) of a single linear form DNA. The first contradiction is that the bimolecular ligation/assembly requires a higher DNA concentration while the cyclization favors a lower one; the second contradiction is that a successful transformation of a ligation/assembly product requires a relatively high DNA concentration again. This study is the first attempt to use linear plasmid and Cyclization After Transformation (CAT) strategy to neutralize those contradictions systematically.
The linear assembly combined with CAT method was demonstrated to increase the overall construction efficiency by 3–4 times for both the traditional ligation and for the new in vitro recombination-based assembly methods including recombinant DNA, Golden Gate, SLIC (Sequence and Ligation Independent Cloning) and Gibson Isothermal Assembly. Finally, the linear assembly combined with CAT method was successfully applied to assemble a pathway of 7 gene fragments responsible for synthesizing precorrin 3A which is an important intermediate in VB12 production.
The linear assembly combined with CAT strategy method can be regarded as a general strategy to enhance the efficiency of most existing circular DNA construction technologies and could be used in construction of a metabolic pathway consisting of multiple genes.
Electronic supplementary material
The online version of this article (doi:10.1186/s12934-015-0204-x) contains supplementary material, which is available to authorized users.
Synthetic biology; DNA assembling; Circular DNA; DNA ligation; Sequence and ligation independent cloning
Previously we reported that the expression of promyelocytic leukemia (PML)-retinoic acid receptor alpha (RARα) fusion gene, which is caused by specific translocation (15;17) in acute promyelocytic leukemia, can enhance constitutive autophagic activity in leukemic and nonleukemic cells, and PML overexpression can sequestrate part of microtubule-associated protein light chain 3 (LC3) protein in PML nuclear bodies, suggesting that LC3 protein also distributes into nuclei although it is currently thought to function primarily in the cytoplasm, the site of autophagosomal formation. However, its potential significance of nucleoplasmic localizations remains greatly elusive. Here we demonstrate that PML interacts with LC3 in a cell type-independent manner as assessed by Co-IP assay and co-localization observation. Overexpressed PML significantly coprecipitates with endogenous and nuclear LC3 protein. Furthermore, a fraction of endogenous PML protein is found to be co-localized with LC3 protein under steady state condition, which is further enhanced by IFNα induction, indicating that PML up-regulation potentiates this interaction. Additionally, DsRed-PML associates with EGFP-LC3 during telophase and G1 phase but not in metaphase and anaphase. Two potential LC3-interacting region (LIR) motifs in PML are required for interaction of PML with LC3 while this association is independent of autophagic activity. Finally, we show that interaction between PML and LC3 contributes to cell growth inhibition function of PML. Considering that PML is an important tumor suppressor, we propose that nuclear portion of LC3 protein may associate with PML to control cell growth for prevention and inhibition of cancer occurrence and development.
To investigate the effects of pyrroloquinoline quinone (PQQ), an oxidoreductase cofactor, on high glucose-induced mouse endothelial cell damage in vitro.
Mouse brain microvascular endothelial bEND.3 cells were exposed to different glucose concentrations (5.56, 25 and 40 mmol/L) for 24 or 48 h. The cell viability was examined using MTT assay. Flow cytometry was used to analyze the apoptosis and ROS levels in the cells. MitoTracker Green staining was used to examine the mitochondria numbers in the cells. Western blot analysis was used to analyze the expression of HIF-1α and the proteins in JNK pathway.
Treatment of bEND.3 cells with high glucose significantly decreased the cell viability, while addition of PQQ (1 and 10 μmol/L) reversed the high glucose-induced cell damage in a concentration-dependent manner. Furthermore, PQQ (100 μmol/L) significantly suppressed the high glucose-induced apoptosis and ROS production in the cells. PQQ significantly reversed the high glucose-induced reduction in both the mitochondrial membrane potential and mitochondria number in the cells. The high glucose treatment significantly increased the expression of HIF-1α and JNK phosphorylation in the cells, and addition of PQQ led to a further increase of HIF-1α level and a decrease of JNK phosphorylation. Addition of JNK inhibitor SP600125 (10 μmol/L) also significantly suppressed high glucose-induced apoptosis and JNK phosphorylation in bEND.3 cells.
PQQ protects mouse brain endothelial cells from high glucose damage in vitro by suppressing intracellular ROS and apoptosis via inhibiting JNK signaling pathway.
diabetes mellitus; pyrroloquinoline quinone; oxidoreductase cofactor; high glucose; endothelial cell; ROS; HIF-1α; JNK
The benefits associated with polyhydroxyalkanoates (PHA) in tissue engineering include high immunotolerance, low toxicity, and biodegradability. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a molecule from the PHA family of biopolymers, shares these features. In this study, the applicability of human embryonic stem cells (hESCs), spontaneously differentiated hESCs (SDhESCs), and mesenchymal stem cells (hMSCs) in conjunction with PHBHHx and collagen as a biocompatible replacement strategy for damaged tissues was exploited. Collagen gel contraction was monitored by seeding cells at controlled densities (0, 103, 104, and 105 cells/mL) and measuring length and diameter at regular time intervals thereafter when cultured in a complete medium. Cell viability was measured by trypan blue exclusion assay. Porous PHBHHx tube scaffolds were prepared using a dipping method followed by salt leaching. PHBHHx/collagen composites were generated via syringe injection of collagen/cell mixtures into sterile PHBHHx porous tubes. Reverse transcription polymerase chain reaction was used to determine the fate of cells within PHBHHx/collagen scaffolds with tendon, bone, cartilage, and fat-linked transcript expression being explored at days 0, 5 10, and 20. The capacity of PHBHHx/collagen scaffolds to support differentiation was explored using a medium specific for osteogenic, chondrogenic, and adipogenic lineage generation. Collagen gel tube contraction required initial seeding densities of ≥105 hMSCs or SDhESCs in 1.5 mg/mL collagen gel tubes. Gels with a collagen concentration of 3 mg/mL did not display contraction across the examined cell seeding densities. Cell viability was ∼50% for SDhESC and 90% for hMSCs at all cell densities tested in porous PHBHHx tube/3 mg/mL collagen hybrid scaffolds after 20 days in vitro culture. Undifferentiated hESCs did not contract collagen gel tubes and were unviable after 20 days culture. In the absence of additional stimuli, SOX9 was sporadically found, while RUNX2 was not present in both hMSC and SDhESC. Hybrid scaffolds were shown to promote retention of osteogenic, chondrogenic, and adipogenic differentiation by expression of RUNX2, SOX9, and PPARγ genes, respectively, following exposure to the appropriate induction medium. PHBHHx/collagen scaffolds have been successfully used to culture hMSC and SDhESC over an extended period supporting the potential of this scaffold combination in future tissue engineering applications.
Tumor suppressor in lung cancer 1 (TSLC1) is a novel tumor suppressor gene whose inactivation is implicated in the occurrence, invasion, metastasis and prognosis of esophageal cancer. TSLC1 was studied by comparing the tumor formation of TSLC1 transfectant and control cells in nude mice. Compared with blank group and mock group, tumor size and infiltrating range of transfected group was less, differentiation of tumor tissue was slightly better, and differences of tumor angiogenesis was worse. There was no obvious difference between blank group and mock group. We have shown TSLC1 gene inhibited the growth proliferation, infiltration and angiogenesis of Eca109 cells.
Tumor suppressor gene; tumor suppressor in lung cancer -1 (TSLC1); esophageal cancer; tumorigenicity; nude mice
Prostate cancer is a major cause of cancer mortality in American males. Once prostate cancer has metastasized, there is currently no curative therapy available. The development of effective agents is therefore a continuing effort to combat this disease. In the present study, the effects and potential mechanisms of NSC606985 (NSC), a water-soluble camptothecin analog, in prostate cancer cells were investigated.
Prostatic tumor cells, DU-145, LNCaP and PC-3, were used for the study. Cell proliferation, cell cycle, cell apoptosis and caspase 3/7 activity were determined in the presence or absence of NSC. The levels of Bax and Bak, and the release of cytochrome c from mitochondria were analyzed by Western blot.
Treatment with NSC at nanomolar concentrations produced a time- and dose-dependent decrease in viable cell numbers of multiple prostate cancer cells. In DU-145 cells, NSC produced a time-and dose-dependent induction of cell apoptosis and cell cycle arrest as evidenced by cell morphological changes, increases in S-phase and sub-G1 cell fractions, an elevation of caspase 3/7 activity, DNA fragmentation and apoptotic cells. NSC increased the levels of apoptotic proteins, Bax and Bak, and induced a release of cytochrome c from mitochondria to cytosol in DU-145 cells. Co-administration of Z-VAD-FMK, a pan-caspase inhibitor, blocked NSC-induced caspase 3/7 activity and cell apoptosis without affecting NSC-induced cell cycle arrest. In contrast, co-administration of a PKCδ inhibitor, rottlerin, had no significant effect on NSC induction of caspase activity, and slightly potentiated NSC-induced cell death. Furthermore, like camptothecin, a mutation of topoi-somerase 1 that prevents the binding of camptothecin to the enzyme completely abolished the NSC effect in DU-145 cells.
The data obtained suggest that NSC is able to decrease cell growth, induce cell apoptosis and cause growth arrest in prostatic tumor cells, which may involve an interaction with topoisomerase 1 and an activation of mitochondrial apoptotic pathway.
Prostate cancer; Camptothecin analog; Apoptosis; Topoisomerase 1; Mitochondria
Whether arterial or venous compression or arachnoid adhesions are primarily responsible for compression of the trigeminal nerve in patients with trigeminal neuralgia is unclear. The aim of this study was to determine the causes of trigeminal nerve compression in patients with trigeminal neuralgia. The surgical findings in patients with trigeminal neuralgia who were treated by micro vascular decompression were compared to those in patients with hemifacial spasm without any signs or symptoms of trigeminal neuralgia who were treated with microvascular decompression. The study included 99 patients with trigeminal neuralgia (median age, 57 years) and 101 patients with hemifacial spasm (median age, 47 years). There were significant differences between the groups in the relationship of artery to nerve (p < 0.001) and the presence of arachnoid adhesions (p < 0.001) but no significant difference in relationship of vein to nerve. After adjustment for age, gender, and other factors, patients with vein compression of nerve or with artery compression of nerve were more likely to have trigeminal neuralgia (OR = 5.21 and 42.54, p = 0.026 and p < 0.001, respectively). Patients with arachnoid adhesions were less likely to have trigeminal neuralgia (OR = 0.15, p = 0.038). Arterial compression of the trigeminal nerve is the primary cause of trigeminal neuralgia and therefore, decompression of veins need not be a priority when performing microvascular dissection in patients with trigeminal neuralgia.
Demyelination; Hemifacial spasm; Microsurgical decompression; Nerve compression; Trigeminal neuralgia
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
LC3; autolysosome; autophagosome; flux; lysosome; phagophore; stress; vacuole
A couple of DNA ligation-independent cloning (LIC) methods have been reported to meet various requirements in metabolic engineering and synthetic biology. The principle of LIC is the assembly of multiple overlapping DNA fragments by single-stranded (ss) DNA overlaps annealing. Here we present a method to generate single-stranded DNA overlaps based on Nicking Endonucleases (NEases) for LIC, the method was termed NE-LIC. Factors related to cloning efficiency were optimized in this study. This NE-LIC allows generating 3′-end or 5′-end ss DNA overlaps of various lengths for fragments assembly. We demonstrated that the 10 bp/15 bp overlaps had the highest DNA fragments assembling efficiency, while 5 bp/10 bp overlaps showed the highest efficiency when T4 DNA ligase was added. Its advantage over Sequence and Ligation Independent Cloning (SLIC) and Uracil-Specific Excision Reagent (USER) was obvious. The mechanism can be applied to many other LIC strategies. Finally, the NEases based LIC (NE-LIC) was successfully applied to assemble a pathway of six gene fragments responsible for synthesizing microbial poly-3-hydroxybutyrate (PHB).
Background: Stroke volume variation (SVV) has been shown to be a reliable predictor of fluid responsiveness. However, the predictive role of SVV measured by FloTrac/Vigileo system in prediction of fluid responsiveness was unproven in patients undergoing ventilation with low tidal volume. Methods: Fifty patients undergoing elective gastrointestinal surgery were randomly divided into two groups: Group C [n1=20, tidal volume (Vt) = 8 ml/kg, frequency (F) = 12/min] and Group L [n2=30, Vt= 6 ml/kg, F=16/min]. After anesthesia induction, 6% hydroxyethyl starch130/0.4 solution (7 ml/kg) was intravenously transfused. Besides standard haemodynamic monitoring, SVV, cardiac output, cardiac index (CI), stroke volume (SV), stroke volume index (SVI), systemic vascular resistance (SVR) and systemic vascular resistance index (SVRI) were determined with the FloTrac/Vigileo system before and after fluid loading. Results: After fluid loading, the MAP, CVP, SVI and CI increased significantly, whereas the SVV and SVR decreased markedly in both groups. SVI was significantly correlated to the SVV, CVP but not the HR, MAP and SVR. SVI was significantly correlated to the SVV before fluid loading (Group C: r = 0.909; Group L: r = 0.758) but not the HR, MAP, CVP and SVR before fluid loading. The largest area under the ROC curve (AUC) was found for SVV (Group C, 0.852; Group L, 0.814), and the AUC for other preloading indices in two groups ranged from 0.324 to 0.460. Conclusion: SVV measured by FloTrac/Vigileo system can predict fluid responsiveness in patients undergoing ventilation with low tidal volumes during gastrointestinal surgery.
Stroke volume variation; tidal volume; Functional haemodynamic; Fluid balance; Gastrointestinal surgery.
Aims: To investigate the reasonable dose of Voluven for rapid plasma volume expansion during the anaesthesia induction patients receiving gastrointestinal surgery. Methods: Sixty patients were randomly divided into three groups (n=20): Group A (5 ml/kg), Group B (7 ml/kg) and Group C (9 ml/kg). HES 130/0.4 was intravenously transfused at a rate of 0.3 ml/kg/min) at 30 min before anaesthesia induction. Besides standard haemodynamic monitoring, cardiac index (CI), systemic vascular resistance index (SVRI) and stroke volume variation (SVV) was continuously detected with the FloTrac/Vigileo system. Haemodynamic variables were recorded immediately before fluid transfusion (T0), immediately before induction (T1), immediately before intubation (T2), immediately after intubation (T3) and 5 min, 10 min, 20 min and 60 min after intubation (T4-T7). Arterial and venous blood was collected for blood gas analysis, Hb and Hct before volume expansion (t0), immediately after volume expansion (t1) and at 1 h after volume expansion (t2). Oxygen delivery (DO2), oxygen extraction ratio (ERO2) and volume expansion rate were calculated. Results: 1) MAP and CI decreased in Group A in T2~T7 and remained changed in Group B and C. 2) CVP increased in three groups after fluid infusion without significant difference. 3) The decrease in SVRI was more obvious in Group B and C than that in Group A after induction and more obvious in Group C than in Group B in T2-T4 and T6~T7. 4) SVV was lower in Group B and C than that in Group A after intubation, and lower in Group C than that in Group B in T3-T6. 5) Hb and Hct decreased after fluid infusion, and the decrease in Hb and Hct was in the order of C>B>A. 6) Volume expansion rate was in the order of C>B>A. 7) ScvO2, PaO2 and DO2 increased in three groups after fluid infusion and the increase in DO2 was in the order of C>B>A. Conclusions: Rapid plasma volume expansion with Voluven at 7-9 ml/kg can prevent haemodynamic fluctuation during anaesthesia induction, maintain the balance between oxygen supply and oxygen consumption during gastrointestinal surgery, and Voluven at 9 ml/kg can improve the oxygen delivery.
Hydroxyethyl starch; General anaethesia; Haemodynamics; Oxygen balance; Gastrointestinal surgery.
To explore the effect of tumor suppressor in lung cancer 1 (TSLC1) on proliferation and apoptosis in esophageal cancer Eca109 cells.
Material and methods
Eca109 cells were divided into three groups: TSLC1 transfected group (TTG), mock group (MG) and untransfected group (UTG). The TTG and MG were transfected transiently with the pIRES2-EGFP-TSLC1 eukaryotic expression vector and pIRES2-EGFP vector respectively. The UTG was a blank control. The TSLC1 expression in TTG was analyzed with the fluorogram and RT-PCR method. Cell proliferation was measured with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Cell cycle was measured by flow cytometry (FCM). Cell apoptosis was detected by Annexin-V/PI double staining FCM.
Green color was found in TTG and MG. The band of TSLC1 mRNA of TTG was located at about 1400 bp by RT-PCR and agarose gel electrophoresis assay. The TSLC1 inhibited cell proliferation significantly in MTT assay, and the cell proliferation was slower in TTG than MG and UTG. After TSLC1 transfection, cell numbers increased in G0/G1 phase and decreased in S phase. Forty-eight hours after transfection, the apoptosis rate and death rate of TTG were higher than MG and UTG. Thus TSLC1 induced Eca109 cells to apoptosis.
The TSLC1 gene had a potent effect on cell proliferation inhibition, G1/S cell cycle arrest and induction of cell apoptosis in Eca109 cells.
esophageal carcinoma; TSLC1 gene; transient transfection; cell cycle; apoptosis
MicroRNAs (miRNAs or miR) have been integrated into tumorigenic programs as either oncogenes or tumor suppressor genes. The miR-124 was reported to be attenuated in several tumors, such as glioma, medulloblastoma and hepatocellular carcinoma. However, its role in cancer remains greatly elusive. In this study, we show that the miR-124 expression is significantly suppressed in human breast cancer specimens, which is reversely correlated to histological grade of the cancer. More intriguingly, ectopic expression of miR-124 in aggressive breast cancer cell lines MDA-MB-231 and BT-549 strongly inhibits cell motility and invasive capacity, as well as the epithelial–mesenchymal transition process. Also, lentivirus-delivered miR-124 endows MDA-MB-231 cells with the ability to suppress cell colony formation in vitro and pulmonary metastasis in vivo. Further studies have identified the E-cadherin transcription repressor Slug as a direct target gene of miR-124; its downregulation by miR-124 increases the expression of E-cadherin, a hallmark of epithelial cells and a repressor of cell invasion and metastasis. Moreover, knockdown of Slug notably impairs the motility of MDA-MB-231 cells, whereas re-expression of Slug abrogates the reduction of motility and invasion ability induced by miR-124 in MDA-MB-231 cells. These findings highlight an important role for miR-124 in the regulation of invasive and metastatic potential of breast cancer and suggest a potential application of miR-124 in cancer treatment.
Microbial polyhydroxyalkanoates (PHA) are biopolyesters consisting of diverse monomers. PHA synthase PhaC2Ps cloned from Pseudomonas stutzeri 1317 is able to polymerize short-chain-length (scl) 3-hydroxybutyrate (3HB) monomers and medium-chain-length (mcl) 3-hydroxyalkanoates (3HA) with carbon chain lengths ranging from C6 to C12. However, the scl and mcl PHA production in Escherichia coli expressing PhaC2Ps is limited with very low PHA yield.
To improve the production of PHA with a wide range of monomer compositions in E. coli, a series of optimization strategies were applied on the PHA synthase PhaC2Ps. Codon optimization of the gene and mRNA stabilization with a hairpin structure were conducted and the function of the optimized PHA synthase was tested in E. coli. The transcript was more stable after the hairpin structure was introduced, and western blot analysis showed that both codon optimization and hairpin introduction increased the protein expression level. Compared with the wild type PhaC2Ps, the optimized PhaC2Ps increased poly-3-hydroxybutyrate (PHB) production by approximately 16-fold to 30% of the cell dry weight. When grown on dodecanoate, the recombinant E. coli harboring the optimized gene phaC2PsO with a hairpin structure in the 5’ untranslated region was able to synthesize 4-fold more PHA consisting of 3HB and medium-chain-length 3HA compared to the recombinant harboring the wild type phaC2Ps.
The levels of both PHB and scl-mcl PHA in E. coli were significantly increased by series of optimization strategies applied on PHA synthase PhaC2Ps. These results indicate that strategies including codon optimization and mRNA stabilization are useful for heterologous PHA synthase expression and therefore enhance PHA production.
PHB; Polyhydroxyalkanoates; PHA synthase; Codon optimization; Hairpin; Escherichia coli
Industrial biotechnology has not developed as fast as expected due to some challenges including the emergences of alternative energy sources, especially shale gas, natural gas hydrate (or gas hydrate) and sand oil et al. The weaknesses of microbial or enzymatic processes compared with the chemical processing also make industrial biotech products less competitive with the chemical ones. However, many opportunities are still there if industrial biotech processes can be as similar as the chemical ones. Taking advantages of the molecular biology and synthetic biology methods as well as changing process patterns, we can develop bioprocesses as competitive as chemical ones, these including the minimized cells, open and continuous fermentation processes et al.
Industrial biotechnology; Shale gas; Oil fields; PHB; Bioplastics; Biofuels; Bulk chemicals