Streptococcus pneumoniae surface-exposed glutamyl tRNA synthetase, a putative adhesin, is able to induce a partially protective immune response in mice

Glutamyl tRNA synthetase (GtS) has been found to be among the Streptococcus pneumoniae cell wall-derived proteins that have age-dependent immunogenicity in children. Here, GtS was cloned, expressed, and purified and then was used to immunize 7-week-old BALB/c OlaHsd mice. Serum obtained from mice immunized with recombinant (r) GtS cross-reacted with a 55.9-kDa protein, identified as GtS, in the cell wall fraction derived from genetically and capsularly unrelated strains of S. pneumoniae. Surface localization of GtS was further confirmed using flow cytometry analysis. The rGtS and anti-rGtS antiserum significantly inhibited the adhesion of 3 pairs of encapsulated and unencapsulated strains of S. pneumoniae to A549 cells. Thirty-nine percent of rGtS-immunized mice survived a lethal bacterial challenge, whereas no control mice survived. These results suggest that GtS, an age-dependent S. pneumoniae antigen, is a surface-located adhesin that is capable of inducing a partially protective immune response against S. pneumoniae in mice.     

Phagocytosis and killing of common bacterial pathogens of the lung by human alveolar macrophages

To investigate factors that determine susceptibility of the lungs to infection with common respiratory pathogens, we studied phagocytosis and killing of nontypable Haemophilus influenzae, H. influenzae type b, Streptococcus pneumoniae types III, VI, and XIV, an unencapsulated variant of S. pneumoniae type III, and Staphylococcus aureus Cowan I, by using human alveolar macrophages obtained by bronchoalveolar lavage of healthy nonsmokers. After opsonization with 10% pooled human serum, mean uptake (+/- standard deviation) of nontypable H. influenzae (67.5% +/- 15.0%), unencapsulated S. pneumoniae type III (71.2% +/- 4.8%) and S. aureus (79.1% +/- 10.2%) was significantly greater (P less than .01) than that of H. influenzae type b (40.1% +/- 15.0%), and S. pneumoniae types III (4.4% +/- 3.1%), VI (11.8% +/- 9.6%), or XIV (8.7% +/- 7.0%). Nontypable H. influenzae was ingested after opsonization with much less pooled human serum than was H. influenzae type b, and uptake of encapsulated S. pneumoniae was not enhanced by as much as 80% pooled human serum. Intracellular killing of unencapsulated S. pneumoniae type III and nontypable H. influenzae was rapid and complete and corresponded to the degree of phagocytosis, but despite a high uptake, S. aureus were killed slowly and incompletely. The virulence of S. pneumoniae and H. influenzae as lung pathogens is thus determined jointly by encapsulation and the inadequate opsonizing effect of normal human serum, whereas that of S. aureus may be related to the organism's relative resistance to intracellular killing by alveolar macrophages.     

The contribution of pneumococcal cell wall to the pathogenesis of experimental otitis media

We studied the contribution of pneumococcal cell wall to the pathogenesis of otitis media in chinchillas after middle ear inoculation of killed, encapsulated type 7F Streptococcus pneumoniae; killed, unencapsulated R6 S. pneumoniae; and isolated R6 pneumococcal cell wall. Ears inoculated with encapsulated and unencapsulated pneumococci had significantly higher concentrations of polymorphonuclear and mononuclear leukocytes and lysozyme in middle ear fluid and developed more epithelial metaplasia and granulation tissue than did saline-inoculated ears. The mean concentration of lysozyme in middle ear fluid was higher in ears inoculated with killed, unencapsulated than encapsulated pneumococci. The middle ear mucoperiosteum of ears inoculated with pneumococcal cell wall showed significantly more polymorphonuclear leukocytes, epithelial metaplasia, subepithelial congestion, and granulation tissue than did control ears. Because nonviable, unencapsulated pneumococci and pneumococcal cell wall caused middle ear inflammation in the chinchilla model of otitis media, it is possible that cell envelope and cell wall components released during bacterial lysis may contribute to chronic otitis media with effusion in humans.     

Effect of Mycoplasma pneumoniae lysate on interleukin-8 gene expression in human respiratory epithelial cells

STUDY OBJECTIVES: Mycoplasma pneumoniae is a common cause of lower respiratory disease. Several studies have suggested that respiratory infection by M pneumoniae is associated with reactive airway disease and asthma. Interleukin (IL)-8 has been suggested to have a role in the pathogenesis of the allergic inflammation of bronchial asthma, and is well known to be expressed in bronchial epithelial cells. MEASUREMENTS: An examination was carried out into the effect of M pneumoniae lysate (MPL) and the role of mitogen-activated protein kinases (MAPKs) and extracellular signal-regulated kinase (ERK) on IL-8 expression in human lung epithelial cells. A549 cells were seeded at a density of 5 x 10(4) cells per well and incubated in basal medium for a further 24 h. IL-8 levels were determined by an enzyme-linked immunosorbent assay. MAPK phosphorylation was assessed by Western blotting. RESULTS: In A549 cells, MPL induced IL-8 release in a time- and dose-dependent manner. Pretreatment with PD 98059, which blocks the activation of MAPK/ERK kinase 1, inhibited MPL-induced IL-8 production by 64.4% at 25 micromol/L. Stimulation of A549 cells by MPL also caused an increase in the activity of ERK, compared with the nonstimulated cells. The MPL stimulation had no effect on the activities of p38. CONCLUSION: These observations suggest that activation of ERK by MPL may be one of the mechanisms that result in an increase of the production of IL-8.     

The effect of type-specific polysaccharide capsule on the clearance of group B streptococci from the lungs of infant and adult rats.

To study the importance of the type-specific polysaccharide capsule of group B streptococci (GBS) in the pathogenesis of lung infections, bacterial clearance rates and lung cellular responses to encapsulated and unencapsulated variants of types III and Ia GBS strains were investigated in rats. Bacteria were instilled by direct intratracheal inoculation to simulate aspiration during parturition. Neonates failed to eliminate encapsulated or unencapsulated GBS strains within 6 h of inoculation, whereas adults cleared greater than 90% of each strain within 6 h. Neutrophils accumulated rapidly in the lungs of neonates and adults in response to all GBS strains. Immediately after inoculation, neonatal alveolar macrophages contained fewer encapsulated GBS than did adult alveolar macrophages and fewer encapsulated than unencapsulated GBS, suggesting that the capsule impairs the initial phagocytosis of GBS in the lungs of neonates. Animal age was a more important determinant of bacterial elimination from the lung than the type-specific GBS capsule. However, both age and the bacterial capsule were important determinants of systemic dissemination.     

Streptococcus pneumoniae-associated human macrophage apoptosis after bacterial internalization via complement and Fcgamma receptors correlates with intracellular bacterial load

Opsonization enhances Streptococcus pneumoniae-induced human monocyte-derived macrophage (MDM) apoptosis. Both depletion of complement and immunoglobulin from opsonizing serum and blockade of the macrophages CR1, CR3, FcgammaRII, and FcgammaRIII partially decreased MDM apoptosis after S. pneumoniae phagocytosis, and these effects correlated with reduced numbers of internalized bacteria. Chloramphenicol inhibition of protein synthesis by opsonized S. pneumoniae down-regulated subsequent MDM apoptosis. Phagocytosis of an unencapsulated mutant of S. pneumoniae resulted in increased MDM apoptosis, in association with enhanced internalization. Caspase inhibition was associated with decreased killing of bacteria. Enhanced induction of apoptosis by opsonized S. pneumoniae is the result of increased intracellular burden of bacteria, rather than of a specific pattern of engagement of complement receptor or FcgammaR. A dynamic interaction between live intracellular bacteria and the host cell is necessary for induction of apoptosis in MDMs, and induction of apoptosis contributes to the host defense against S. pneumoniae.     

A pneumococcal protein that elicits interleukin-8 from pulmonary epithelial cells

To understand how neutrophils are recruited to the lung in pneumococcal pneumonia, the ability of pneumococcal components to elicit the chemokine interleukin (IL)-8 from monolayers of cultured human type II cells was assessed. Heat-killed clinical and laboratory strains of Streptococcus pneumoniae and secreted proteins from exponentially growing pneumococci elicited significant quantities of IL-8 from A549 cells. All strains that elicited IL-8 production secreted a protein ( approximately 90 kDa) that comigrated on SDS-PAGE with a C3-binding protein previously identified in S. pneumoniae. As little as 7 pmol of the purified 90-kDa protein readily elicited levels of IL-8 production equivalent to those obtained with 1 U of IL-1alpha. Supernatant proteins and heat-killed cells of an isogenic mutant that failed to produce the C3-binding protein elicited significantly less IL-8 than did supernatant proteins or heat-killed cells of the parent strain. These results implicate the C3-binding protein of S. pneumoniae in a novel pathway of pulmonary inflammation.     

蛴螬提取物对人肺癌A549细胞Bax和p21蛋白表达的影响

目的观察蛴螬提取物对人肺癌A549细胞增殖的影响及诱导凋亡的机制。方法采用MTT法检测蛴螬提取物对人肺癌A549细胞的增殖抑制率;运用免疫细胞化学SP法检测用药前后Bax和p21蛋白表达的变化;运用流式细胞仪检测细胞周期及细胞凋亡率。结果蛴螬提取物对人肺癌A549细胞具有明显的增殖抑制作用,并呈时间依赖性;蛴螬提取物组细胞Bax和p21表达均增强,细胞凋亡率与对照组相比有显著性差异,并被阻滞在细胞周期的S期。结论蛴螬提取物可通过上调Bax和p21使细胞阻滞于S期,从而抑制A549细胞的生长。     

沉默HIF-1α调控MAPK/ERK信号通路抑制NSCLC转移的分析

目的探讨HIF-1α在体内及体外对非小细胞肺癌(NSCLC)细胞转移的影响及其作用机制。 方法采用实时荧光定量PCR(RT-qPCR)检测HIF-1α在癌旁正常组织、肺鳞癌组织(LUSC)、肺腺癌组织(LUAD)、A549细胞和HEB细胞中的表达量。上调HIF-1α表达后,通过MTT、细胞侵袭和Western blot实验检测过表达HIF-1α对A549细胞增殖、侵袭和EMT的影响。下调HIF-1α表达后,Western blot检测A549细胞ERK和p-ERK蛋白的表达量。THBQ激活MAPK/ERK通路后,分析A549细胞增殖、侵袭和EMT能力。将细胞株植入裸鼠体内,构建移植瘤模型,最后测量裸鼠移植瘤的体积和重量。 结果HIF-1α在NSCLC组织的表达水平明显高于癌旁正常组织(P<0.05)。A549细胞中HIF-1α表达水平明显高于HEB细胞(P<0.01),过能够促进A549细胞的增殖和侵袭,N-cadherin蛋白表达量明显上升,E-cadherin蛋白表达量明显下降。下调HIF-1α能够抑制A549细胞内MAPK/ERK通路,且抑制了A549细胞的增殖、侵袭和EMT。下调HIF-1α使裸鼠移植瘤的重量和体积明显减小。 结论沉默HIF-1α通过MAPK/ERK信号通路在体内及体外抑制NSCLC转移。     

Delivery of antisense oligodeoxyribonucleotides against the human epidermal growth factor receptor into cultured KB cells with liposomes conjugated to folate via polyethylene glycol.

Antisense oligodeoxyribonucleotides targeted to the epidermal growth factor (EGF) receptor were encapsulated into liposomes linked to folate via a polyethylene glycol spacer (folate-PEG-liposomes) and efficiently delivered into cultured KB cells via folate receptor-mediated endocytosis. The oligonucleotides were a phosphodiester 15-mer antisense to the EGF receptor (EGFR) gene stop codon (AEGFR2), the same sequence with three phosphorothioate linkages at each terminus (AEGFR2S), a randomized 15-mer control of similar base composition to AEGFR2 (RC15), a 14-mer control derived from a symmetrized Escherichia coli lac operator (LACM), and the 5'-fluorescein-labeled homologs of several of the above. Cellular uptake of AEGFR2 encapsulated in folate-PEG-liposomes was nine times higher than AEGFR2 encapsulated in nontargeted liposomes and 16 times higher than unencapsulated AEGFR2. Treatment of KB cells with AEGFR2 in folate-PEG-liposomes resulted in growth inhibition and significant morphological changes. Curiously, AEGFR2 and AEGFR2S encapsulated in folate-PEG-liposomes exhibited virtually identical growth inhibitory effects, reducing KB cell proliferation by > 90% 48 hr after the cells were treated for 4 hr with 3 microM oligonucleotide. Free AEGFR2 caused almost no growth inhibition, whereas free AEGFR2S was only one-fifth as potent as the folate-PEG-liposome-encapsulated oligonucleotide. Growth inhibition of the oligonucleotide-treated cells was probably due to reduced EGFR expression because indirect immunofluorescence staining of the cells with a monoclonal antibody against the EGFR showed an almost quantitative reduction of the EGFR in cells treated with folate-PEG-liposome-entrapped AEGFR2. These results suggest that antisense oligonucleotide encapsulation in folate-PEG-liposomes promise efficient and tumor-specific delivery and that phosphorothioate oligonucleotides appear to offer no major advantage over native phosphodiester DNA when delivered by this route.     

Antibodies against PsrP, a novel Streptococcus pneumoniae adhesin, block adhesion and protect mice against pneumococcal challenge

Pneumococcal serine-rich repeat protein (PsrP) is a putative adhesin encoded in the Streptococcus pneumoniae pathogenicity island psrP-secY2A2. Challenge of mice with serotype 4, strain TIGR4, and the isogenic mutants T4DeltapsrP and T4DeltapsrP-secY2A2 determined that PsrP was required for bacterial persistence in the lungs but not for colonization in the nasopharynx or replication in the bloodstream during sepsis. In vitro experiments corroborated this anatomical site-specific role; psrP mutants failed to bind to A549 and LA-4 lung cells, yet adhered normally to human nasopharyngeal epithelial cells and to cells from human and rodent capillary endothelial cell lines. We determined that the amino terminus of PsrP mediated adhesion. Microspheres coated with recombinant PsrP(SRR1-BR) (rPsrP(SRR1-BR)) adhered to A549 cells, and moreover, preincubation of cells with rPsrP(SRR1-BR) inhibited TIGR4 adhesion in vitro. Antibodies against rPsrP(SRR1-BR) also neutralized PsrP function; antiserum against rPsrP(SRR1-BR) blocked TIGR4 adhesion in vitro and, following passive immunization, it protected mice against challenge. We conclude that PsrP is an adhesin required for bacterial persistence in the lungs and that rPsrP(SRR1-BR) is a protective antigen.     

Methotrexate stimulates lung epithelial cells to release inflammatory cell chemotactic activities

Methotrexate-induced pneumonitis has been reported as an infrequent but potentially serious complication of therapy in a variety of malignant and benign conditions. Because inflammatory cell infiltration is concerned with the development of methotrexate-induced pneumoinitis, and because airway epithelial cells participate in the orchestration of lung inflammation, the authors determined whether methotrexate might stimulate airway epithelial cells (A549 cells) to release neutrophil, monocyte, and eosinophil chemotactic activities (NCA, MCA, and ECA). A549 cells released NCA, MCA, and ECA in a dose- and time-dependent manner in response to methotrexate. Partial characterization revealed the heterogeneity of NCA, MCA, and ECA. The release of chemotactic activity was blocked by lipoxygenase inhibitors and cycloheximide. NCA was inhibited by leukotriene (LT) B(4) receptor antagonist, and anti-interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) antibodies. MCA was attenuated by LTB(4) receptor antagonist, and anti-monocyte chemoattractant protein (MCP)-1 and granulocyte-macrophage CSF (GM-CSF) antibodies. ECA was attenuated by LTB(4) receptor antagonist, and anti-IL-8 and GM-CSF antibodies. The release of IL-8, G-CSF, MCP-1, GM-CSF, and LTB(4) from A549 cells significantly increased in response to methotrexate. The mRNA expression of IL-8 and MCP-1 was augmented by methotrexate stimulation. These data suggest that type II epithelial cells may modulate inflammatory cell recruitment into the lung by releasing NCA, MCA, and ECA in response to methotrexate.     

Differential alveolar epithelial injury and protein expression in pneumococcal pneumonia

The integrity of the alveolar epithelium is a key factor in the outcome of acute lung injury. Here, we investigate alveolar epithelial injury and the expression of epithelial-selective markers in Streptococcus pneumoniae-induced acute lung injury. S. pneumoniae was instilled into rat lungs and alveolar type I (RTI(40)/podoplanin, MMC6 antigen) and alveolar type II (MMC4 antigen, surfactant protein D, pro-surfactant protein C, RTII(70)) cell markers were quantified in lavage fluid and lung tissue at 24 and 72 hours. The alveolar epithelium was also examined using electron, confocal, and light microscopy. S. pneumoniae induced an acute inflammatory response as assessed by increased total protein, SP-D, and neutrophils in lavage fluid. Biochemical and morphological studies demonstrated morphologic injury to type II cells but not type I cells. In particular, the expression of RTI(40)/podoplanin was dramatically reduced, on the surface of type I cells, in the absence of morphologic injury. These data demonstrate that type II cell damage can occur in the absence of type I cell injury without affecting the ability of the lung to return to a normal morphology. These data also demonstrate that RTI(40)/podoplanin is not a type I cell phenotypic marker in experimental acute lung injury caused by S. pneumoniae. Given that RTI(40)/podoplanin is an endogenous ligand for the C-type lectin receptor and this receptor plays a role in platelet aggregation and neutrophil activation, we hypothesize that the reduction of RTI(40)/podoplanin on type I cells might be important for the regulation of platelet and/or neutrophil function in experimental acute lung injury.     

aKinesin家族成员18A在肺腺癌进展中的作用

目的探讨Kinesin家族成员（Kinesin family member, KIF）18A在肺腺癌中的表达水平及其在肺腺癌进展中的作用。 方法选取2014年4月至2018年5月在连云港第二人民医院进行手术治疗的102例肺腺癌患者,均留取肺腺癌组织及癌旁组织。采用免疫组化方法检测肺腺癌组织及癌旁正常组织中KIF18A的表达水平。并行体外细胞试验观察KIF18A对肺腺癌细胞增殖、迁移、入侵等的影响,以及动物实验观察KIF18A对小鼠肿瘤生长和转移的影响。 结果免疫组化检测：KIF18A主要表达于肺腺癌细胞的细胞质中,而癌旁组织中KIF18A的表达水平明显较低。定量PCR检测：转染KIF18A shRNA质粒后,KIF18A在A549和H1975细胞中的表达均被有效抑制。免疫印迹分析：转染KIF18A shRNA质粒的A549和H1975细胞中KIF18A的表达水平明显降低。菌落测定：KIF18A的消耗明显降低了菌落数目。MTT检测：两种类型的肺腺癌细胞在570 nm处的吸光度值明显降低。伤口愈合试验：KIF18A的耗竭显著抑制了A549和H1975细胞的伤口愈合程度。Transwell实验：KIF18A的耗竭显著阻断了A549和H1975细胞的侵袭,细胞数量显著下降。动物实验：KIF18A基因敲除小鼠的肿瘤体积明显小于对照组,KIF18A的表达水平也明显降低;肿瘤转移8周后,A549细胞的肺转移发生率明显低于对照组。 结论KIF18A参与了肺腺癌的进展和转移,这将为肺腺癌的靶点治疗提供新的可能。     

Loss of polymeric immunoglobulin receptor expression is associated with lung tumourigenesis

Polymeric immunoglobulin receptor (pIgR) expression is downregulated in lung cancer, but its implications in lung tumourigenesis remain unknown. We hypothesised that loss of pIgR expression occurs early, and is associated with cell proliferation and poor prognosis. pIgR expression was evaluated by immunohistochemistry in airways of patients with normal mucosa, pre-invasive lesions and invasive lesions, and correlated with clinical outcomes. 16-HBE and A549 cells stably transfected with pIgR were tested for proliferation, apoptosis and cell cycle progression. Immunostaining was strong in normal epithelium, but severely reduced in pre-invasive lesions and most lung cancers. Persistent expression was associated with younger age and adenocarcinoma subtype but not survival. pIgR overexpression significantly reduced A549 and 16-HBE proliferation. Growth inhibition was not due to cell cycle arrest, increased apoptosis or endoplasmic reticulum stress, but we observed altered expression of genes encoding for membrane proteins, including NOTCH3. Interestingly, NOTCH3 expression was inversely correlated with pIgR expression in cell lines and tissues. pIgR expression was lost in most lung cancers and pre-invasive bronchial lesions, suggesting that pIgR downregulation is an early event in lung tumourigenesis. pIgR overexpression in A549 and 16-HBE cells inhibited proliferation. Future investigations are required to determine the mechanisms by which pIgR contributes to cell proliferation.     

姜黄素对肺癌A549细胞迁移和侵袭的影响

目的探讨姜黄素对肺癌A549细胞侵袭迁移力的影响及其机制。 方法利用不同浓度姜黄素处理正常肺上皮细胞,台盼蓝法检测药物细胞毒性;不同浓度的姜黄素作用于A549细胞,MTT法测定A549细胞增殖水平;细胞划痕实验和Transwell实验分别测定药物处理后A549细胞的迁移和侵袭能力变化情况;Werstern blot测定A549细胞中于侵袭迁移有关的表皮生长因子受本(EGFR)、E-型钙黏蛋白(E-cadherin)、N-型钙黏蛋白(N-cadherin)蛋白的表达。 结果姜黄素浓度在0～40 μg/ml时正常肺上皮病死率低,差异无明显统计学差异(P>0.05),表明姜黄素对正常肺上皮细胞的不良反应小;MTT实验结果显示姜黄素以浓度依赖的方式抑制A549细胞的增殖,各组与对照组相比均具有统计学意义(P<0.01);细胞划痕实验显示姜黄素以浓度依赖的方式抑制A549细胞的迁移能力,各组与对照组相比均具有统计学意义(P<0.01);Transwell实验显示姜黄素以浓度依赖的方式抑制A549细胞的侵袭能力,各组与对照组相比均具有统计学意义(P<0.01);Western blot显示姜黄素处理A549细胞后EGFR蛋白(P<0.01)和N-cadherin蛋白表达降低(P<0.01),E-cadherin蛋白表达升高(P<0.01)。 结论一定浓度内姜黄素细胞毒性低,姜黄素能够抑制A549的增殖、迁移和侵袭,可能是通过调节EGFR、N-cadherin、E-cadherin蛋白从而逆转上皮间质转化过程。     

Regulation of inflammation and bacterial clearance by lung collectins

Abstract:   Pulmonary surfactant proteins (SP) A and D play important roles in the innate immune system of the lung. These proteins belong to the collectin subgroup in which lectin domains are associated with collagenous structures. To obtain a better understanding of how lung collectins modulate cellular responses, the authors investigated whether SP-A interacts with the toll-like receptor 2 (TLR2). SP-A bound to TLR2 and inhibited interactions between TLR2 and TLR2-ligands such as peptidoglycan (PGN) and zymosan. NF-κB activation and tumour necrosis factor-α expression induced by PGN or zymosan were significantly inhibited in the presence of SP-A. Lung collectins may act as inhibitors of lung inflammation in respiratory infections. The authors also examined the effects of lung collectins on the phagocytosis of bacteria by alveolar macrophages. Lung collectins enhanced the uptake of S. pneumoniae or M. avium by alveolar macrophages. It was demonstrated that the direct interaction of lung collectins with macrophages resulted in increased cell surface expression of scavenger receptor A or mannose receptor, which are responsible for phagocytosis. This study has emphasized the biological relevance of SP-A and SP-D against various respiratory infections, however, a more complete understanding of the molecular mechanism is required.     

Liposome-encapsulated OK-432 specifically and sustainedly induces hepatic natural killer cells and intermediate T cell receptor cells

BACKGROUND: OK-432 is a biological response modifier used in Japan to augment host immunity and is known to increase the host antitumour response. By using liposomes, which are vesicles made from phospholipids that have a structure resembling the cell membrane, we encapsulated OK-432. METHODS AND RESULTS: Encapsulated OK-432 was injected into the tail veins of mice, and its effect was compared with that of unencapsulated OK-432 given intravenously. In mice that received either form of OK-432, both the number of natural killer (NK) and intermediate T cell receptor (intTCR) cells (intrahepatic T cells generated by extrathymic differentiation) increased markedly in the liver, with the peak level occurring 3 days after administration. Both forms of OK-432 also increased cytotoxic activity against Yac-1 cells. The increase in numbers of cells and in cytotoxic activity in the liver persisted for longer in mice that received encapsulated OK-432 than in animals that received unencapsulated OK-432. CONCLUSIONS: Because it has been shown that both NK and intTCR cells play an important role in tumour immunity, an increase in the number of such cells can be considered likely to have an increased antitumour effect. Encapsulated OK-432 elicited liver-specific augmentation of cytotoxic activity and the effect was more persistent than that produced by OK-432 given in the conventional form; therefore, it may be useful for the treatment of tumours, particularly those arising in the liver.     

miR-577通过介导Notch信号通路抑制肺癌细胞的增殖、侵袭和耐药性

目的研究miR-577通过介导Notch信号通路抑制肺癌细胞的增殖、侵袭和耐药性。方法RT-PCR检测肺癌组织和细胞以及配对的正常组织和细胞中miR-577的表达量;CCK-8测定miR-577对肺癌细胞A549增殖的影响;荧光素酶报告实验验证miR-577和Notch是否结合;Western blot检测A549细胞中Notch、DSL以及耐药蛋白P-gp和MRP1的蛋白表达水平。结果RT-PCR结果显示,miR-577在肺癌组织和细胞中的表达量显著低于正常组织和细胞中的表达量;过表达miR-577能够显著抑制肺癌细胞A549的增殖和侵袭,并降低细胞的耐药性;荧光素酶报告实验结果表明miR-577能够靶向结合Notch的启动子序列;Western blot结果显示miR-577能够抑制Notch和DSL的蛋白表达水平;进一步的机制探究结果表明miR-577可通过下调Notch和DSL的蛋白表达抑制A549细胞增殖、侵袭以及耐药性。结论miR-577能够抑制肺癌细胞A549增殖、侵袭以及耐药性的产生,其作用机制是通过介导Notch信号通路来实现的。