赖氨酰氧化酶样蛋白-2的研究进展

赖氨酰氧化酶家族发挥着多种重要的生物学功能,并参与肿瘤的发生、发展,赖氨酰氧化酶样蛋白-2(Lysyl Oxidase-Like 2 protein,LOXL2)就是该家族的成员之一。本文对LOXL2的基因结构,组织表达的特异性及其与肿瘤发生发展的关系作一综述,以期加深对肿瘤侵袭转移机制的认识,并为肿瘤侵袭转移的干预提供新靶标。     

长链非编码RNA LOXL1-AS1在人类恶性肿瘤中的作用及其分子调控机制

长链非编码RNA(lncRNA)广泛参与生物体的各种生理与病理过程。lncRNA作为肿瘤致癌因子或抑癌因子参与恶性肿瘤的多种生物过程，与恶性肿瘤的发生、发展密切相关。赖氨酰氧化酶样蛋白1-反义RNA1(LOXL1-AS1)是近年来发现的一种lncRNA,其在多种恶性肿瘤中表达上调，并与肿瘤大小、TNM分期、淋巴结转移、患者预后等病理特征相关。LOXL1-AS1通过与多种微小RNA竞争性结合，调节下游靶基因的表达及调控相关信号通路发挥促癌作用。该文通过总结LOXL1-AS1参与多种人类恶性肿瘤的生物学过程，不同的分子调控机制影响肿瘤细胞增殖、转移、侵袭和凋亡等恶性生物学行为，探讨潜在的临床意义和应用前景，以期为恶性肿瘤的临床诊断、治疗和筛选预后标志物提供理论基础和参考依据。     

RNA干扰LOXL2基因对头颈部鳞状细胞癌凋亡及PD-L1表达的影响

目的:探讨抑制赖氨酰氧化酶样蛋白2(LOXL2)基因表达对头颈部鳞状细胞癌(HNSCC)增殖凋亡及PD-L1表达的影响研究。方法:通过Western blot检测人HNSCC细胞YCU-H891、YCU-N861和KB中LOXL2的蛋白表达。以Lipo-fectamineTM2000为载体,参照其说明将合成的LOXL2 siRNA转染KB细胞,转染48 h后,Western blot检测LOXL2、PD-L1、STAT3、p-STAT3、PCNA和Bax的蛋白表达; CCK8及流式细胞仪分别检测细胞活力及凋亡率。结果:LOXL2在YCU-H891、YCU-N861和KB中表达均升高。转染LOXL2 siRNA的KB细胞LOXL2的蛋白表达明显降低,与空白组和NC组比较差异均具有统计学意义(P0. 05)。转染LOXL2 siRNA的KB细胞活力明显降低,凋亡率明显升高,PD-L1、p-STAT3和PCNA的蛋白表达均明显降低,Bax的蛋白表达明显升高,与NC组比较,差异均具有统计学意义(P0. 05)。结论:RNA干扰抑制LOXL2基因可降低HNSCC细胞活力和诱导凋亡,下调PD-L1表达,机制可能与抑制STAT3信号通路有关。     

肝细胞肝癌中LOXL2过表达与转移及预后的相关性

目的检测LOXL2和上皮-间质转化(epithelial-mesenchymal transition,EMT)相关基因在肝细胞肝癌组织中的表达,揭示LOXL2和EMT之间的关系,从而阐明LOXL2对肝细胞肝癌转移及预后的影响。方法采用免疫组化法检测106例肝细胞肝癌组织中LOXL2、Snail、E-cadherin和vimentin的表达,采用CD31/PAS双染法检测肝细胞肝癌中血管生成拟态(vasculogenic mimicry,VM)的情况,并分析LOXL2与EMT分子之间的相关性。采用χ~2和Spearman相关分析来分析其与VM形成和临床病理资料之间的关系。采用Kaplan-Meier法评估LOXL2对肝细胞肝癌患者生存时间的影响。采用Cox比例风险模型分析LOXL2对肝细胞肝癌预后的价值。结果 LOXL2表达与Snail、vimentin和E-cadherin的表达密切相关,LOXL2表达与肿瘤分级和VM形成相关。LOXL2阳性表达或VM形成的患者其总体生存期和无病生存期比LOXL2阴性表达和无VM形成的患者短(P0.05);同时具有LOXL2阳性表达和VM形成的患者预后最差。结论 LOXL2表达与EMT标记蛋白相关,并与肝细胞肝癌分级和VM形成密切相关,且对预后有一定的影响。     

肺癌中赖氨酰氧化酶样蛋白2的研究进展

赖氨酰氧化酶样蛋白2(lysyl oxidase-like protein-2,LOXL2)是一种铜依赖性胺氧化酶,其过表达可导致肿瘤细胞的增殖、侵袭和转移.大量研究表明LOXL2在肺癌中的高表达与上皮-间质转化、转移、肿瘤进展和预后不良有关.该文主要对LOXL2蛋白的结构、生物学作用、在肺癌中的表达与预后价值进行综述...     

赖氨酰氧化酶样蛋白2在Col4α3/Alport小鼠中导致肾纤维化

正赖氨酰氧化酶样蛋白2(lysyl oxidase like-2,LOXL2)是一种胺氧化酶,在细胞内和细胞外均具有重要功能。在细胞外,LOXL2促进胶原蛋白和弹性蛋白交联;而在细胞内,已报道LOXL2可修饰组蛋白H3,稳定SNAIL,并降低细胞极性。尽管     

类赖氨酰氧化酶2与肿瘤转移和发生

类赖氨酰氧化酶2(lysyl oxidase-like 2,LOXL2)是赖氨酰氧化酶(lysyl oxidase,LOX)基因家族的成员之一,其表达产物能促进胶原沉积.LOXL2的过表达能促进纤维化,并与肿瘤侵袭、转移及不良预后有关.目前大部分学者认为LOXL2是一种转移促进基因,也有实验支持其是一种肿瘤抑制基因.研究发现LOXL2可以通过激活Snail/Ecadherin通路或Src/FAK通路促进转移.LOXL2有望作为肿瘤生物标志物,用于预后判断,成为一个新的治疗靶点.     

外泌体介导LOXL4通过PI3K/AKT信号通路调控口腔鳞癌的免疫逃逸相关因子表达

目的探讨外泌体(EXO)介导的赖氨酰氧化酶样蛋白4(LOXL4)对口腔鳞癌细胞(OSCC)免疫逃逸相关因子表达的影响和调控机制。方法 q RT-PCR检测口腔鳞癌细胞SCC9以及人口腔上皮细胞HOEC培养上清液中LOXL4的mRNA水平。差速离心法提取SCC9的外泌体,进行表征分析。Western blot检测外泌体标志物CD63、CD9以及目标基因LOXL4的表达量。使用荧光蛋白标记外泌体、SCC9细胞以及细胞核,利用共聚焦显微镜观察SCC9细胞对LOXL4-EXO的摄取。SCC9细胞和CD8+T细胞共培养,共培养体系分为空白对照组、LOXL4-EXO处理组、LOXL4-EXO联合PI3K/AKT的阻断剂Wortmannin处理组(LOXL4-EXO+WOR组)。CCK-8法检测细胞增殖率,ELISA法检测细胞培养液中IL-2、INF-γ、TNF-α的水平,Western blot检测PI3K、Akt、p-Akt、PD-L1的表达变化。结果与HOEC相比,LOXL4的m RNA水平在SCC9培养上清液中上调(P0.05),并且成功分离和鉴定LOXL4-EXO,而且SCC9可摄取LOXL4-EXO。与空白对照组相比、LOXL4-EXO组的细胞增殖率上调(P0.05),IL-2、INF-γ、TNF-α的水平下调(P0.05),PI3K、Akt、p-Akt、PD-L1的表达量上调(P0.05)。与LOXL4-EXO组相比,LOXL4-EXO+WOR组的细胞增殖率下调(P0.05),IL-2、INF-γ、TNF-α的水平上调(P0.05),PI3K、Akt、p-Akt、PD-L1的表达量下调(P0.05)。结论外泌体介导LOXL4通过PI3K/AKT信号通路调节口腔鳞癌的免疫逃逸相关因子IL-2、INF-γ、TNF-α、PD-L1的表达。     

Ezrin与肿瘤发生及发展关系的研究进展

Ezrin是一种膜－细胞骨架连接蛋白,在多种肿瘤中表达上调或亚细胞定位改变,通过与细胞粘附分子相互作用、参与Rho信号传导以及受体酪氨酸激酶信号传导途径等多种机制,参与肿瘤的发生及发展。     

几种值得深入研究的肿瘤相关干(祖)细胞

越来越多证据表明,肿瘤是一类多因素致病、多步骤发生、异质性演进的遗传性疾病,是特殊的"难愈性创伤",并与慢性炎性过程密切相关.肿瘤还被认为属于分化异常性干细胞疾病[1].不仅肿瘤的发生与干细胞(stem cells)和(或)祖细胞(progenitor cells)密切相关,而且多种具有干细胞或祖细胞特性的细胞也参与肿瘤的生长和演进[2-3].存在于肿瘤内并参与肿瘤发生发展的干(祖)细胞可统称为肿瘤相关干(祖)细胞(tumor associated stem/progenitor cells).这些细胞包括来源于骨髓经血液进入肿瘤组织的一些干(祖)细胞和肿瘤组织固有的肿瘤干细胞(cancer stem cells)及其衍生的干细胞样细胞.深入研究肿瘤相关干(祖)细胞的病理生物学特性和作用,对于进一步揭示肿瘤发病机制、寻找防治新方法,具有重要意义.     

Alternatively spliced lysyl oxidase-like 4 isoforms have a pro-metastatic role in cancer

We previously found LOXL4 to be alternatively spliced in an anatomic site-specific manner in tumors involving the serosal cavities. LOXL4 splice variants were predominantly or exclusively expressed in effusion specimens from ovarian and breast carcinoma patients, and were absent in primary carcinomas. In the present study, LOXL4 full-length or splice variants were overexpressed in ES-2 and MDA-MB-231 cells and their invasive and metastatic potential and microRNA expression profile were evaluated. ES-2 cells were further injected into SCID mice ovaries and the extent of tumor progression and metastases formation were compared. We show that both splice variants have a positive effect on the metastatic potential of cells in vitro and on tumor progression in vivo. In contrast, full-length LOXL4 is not pro-metastatic, and may even be considered as a tumor suppressor. In addition, we show that LOXL4 is a possible splicing target of the oncogenic splicing factors SRSF1 and hnRNP A1. In conclusion, our results point to a significant role for LOXL4 alternative splicing in tumor progression.     

Lysyl oxidase-like 2 expression is increased in colon and esophageal tumors and associated with less differentiated colon tumors

Lysyl oxidase-like 2 (LOXL2) belongs to an amine oxidase family whose members have been implicated in crosslink formation in stromal collagens and elastin, cell motility, and tumor development and progression. We previously demonstrated the association between increased LOXL2 expression and invasive/metastatic behavior in human breast cancer cells and mouse squamous and spindle cell carcinomas, interaction between LOXL2 and SNAIL in epithelial-mesenchymal transition, and localization of the LOXL2 gene to 8p21.2-21.3, within a minimally deleted region in several cancers, including colon and esophagus. In the present study, we analyzed LOXL2 expression in colon and esophageal tumors, and explored methylation as a regulator of LOXL2 expression. Immunohistochemistry using normal tissues demonstrated intracellular localization of LOXL2 in colonic enteroendocrine cells and esophageal squamous cells at the luminal surface, but not in mitotically active cells. Tissue array analysis of 52 colon adenocarcinomas and 50 esophageal squamous cell carcinomas revealed presence of LOXL2 expression in 83 and 92% of the samples, respectively, and a significant association between increased number of LOXL2-expressing cells and less-differentiated colon carcinomas. We determined that the methylation status of the 1150 bp 5' CpG island may contribute to the regulation of the gene. Loss of heterozygosity studies, using a microsatellite within intron 4 of the LOXL2 gene, revealed that loss of LOXL2 was unlikely to play a major role in either colon or esophageal tumors. These results suggest that increased LOXL2 expression in colon and esophageal cancer may contribute to tumor progression.     

LOXL4 is downregulated in hepatocellular carcinoma with a favorable prognosis

Lysyl oxidase like 4 (LOXL4), a member of the secreted copper-dependent amine oxidases that contribute to the assemble and maintenance of the extracellular matrix (ECM), was found to be up-regulated or down-regulated in different cancer types, suggesting its paradoxical roles in cancer. The specific role of LOXL4 in hepatocellular carcinoma (HCC), however, is still yet to be defined. Twenty-eight pairs of HCC specimens were used for LOXL4 mRNA expression analysis. The mRNA expression in HCC cell lines was examined, and HepG2 was selected for LOXL4 small interfering RNA (siRNA) interference to investigate the biological function of LOXL4, LOXL4 immunohistochemical staining was performed using a tissue microarray containing 298 HCC patients. The prognostic and diagnostic value of LOXL4 was evaluated using Cox regression and Kaplan-Meier analysis. LOXL4 mRNA or protein expression was significantly lower in HCC tissues than peritumoral tissues (LOXL4 mRNA expression, P = 0.018; LOXL4 protein expression, P < 0.001). Low LOXL4 expression was associated with lower overall survival (OS) rates and higher cumulative recurrence rates. Multivariate analysis indicated that LOXL4 was an independent prognostic indicator for OS and time to recurrence (TTR). Our results revealed that LOXL4 was down-regulated in HCC and correlated with aggressive tumors and a worse clinical outcome. LOXL4 may be a potential biomarker to identify the HCC patients with a higher risk of recurrence.     

Genotype-correlated expression of lysyl oxidase-like 1 in ocular tissues of patients with pseudoexfoliation syndrome/glaucoma and normal patients

Pseudoexfoliation (PEX) syndrome is a generalized disease of the extracellular matrix and the most common identifiable cause of open-angle glaucoma. Two single nucleotide polymorphisms in the lysyl oxidase-like 1 (LOXL1) gene (rs1048661 and rs3825942) have been recently identified as strong genetic risk factors for both PEX syndrome and PEX glaucoma. Here we investigated the expression and localization of LOXL1, LOXL2, and lysyl oxidase (LOX) in tissues of PEX syndrome/glaucoma patients and controls in correlation with their individual single nucleotide polymorphism genotypes and stages of disease. LOXL1 ocular expression was reduced by ~20% per risk allele of rs1048661, whereas risk alleles of rs3825942, which were highly overrepresented in PEX cases, did not affect LOXL1 expression levels. Irrespective of the individual genotype, LOXL1 expression was significantly increased in early PEX stages but was decreased in advanced stages both with and without glaucoma compared with controls, whereas LOX and LOXL2 showed no differences between groups. LOXL1 was also found to be a major component of fibrillar PEX aggregates in both intra- and extraocular locations and to co-localize with various elastic fiber components. These findings provide evidence for LOXL1 involvement in the initial stages of abnormal fibrogenesis in PEX tissues. Alterations of LOXL1 activation, processing, and/or substrate specificity may contribute to the abnormal aggregation of elastic fiber components into characteristic PEX fibrils.     

LOXL3 novel mutation causing a rare form of autosomal recessive Stickler syndrome

Stickler syndrome is a collagenopathy that is typically inherited as autosomal dominant disease caused by monoallelic mutations in COL2A1, COL11A2, and COL11A1. Rarely, biallelic mutations in COL9A1, COL9A2, and COL9A3 cause an autosomal recessive Stickler syndrome. One previous report described two siblings with Stickler syndrome and a homozygous mutation in LOXL3, suggesting that biallelic mutations in LOXL3 can also cause autosomal recessive Stickler syndrome. LOXL3 is a member of the lysyl oxidase family of genes which encode enzymes oxidizing the side chain of peptidyl lysine permitting the covalent crosslinking of collagen and elastin chains. Therefore, LOXL3 deficiency is expected to result in collagen defect. Furthermore, Loxl3 deficient mouse model demonstrated features overlapping with Stickler syndrome. In this report, we describe a child and his father who had clinical features consistent with Stickler syndrome and found to have a homozygous novel mutation c.1036C>T (p.Arg346Trp) in LOXL3. This report not only supports that biallelic LOXL3 mutations cause autosomal recessive Stickler syndrome, but also further delineates the phenotype associated with LOXL3 mutations. In addition, the family described here shows an interesting example for pseudodominance, which can be observed in recessive diseases when one parent is affected and the other is heterozygous carrier.     

LOXL null mice demonstrate selective dentate structural changes but maintain dentate granule cell and CA1 pyramidal cell potentiation in the hippocampus

Lysyl oxidase-like protein (LOXL), part of the lysyl oxidase copper-dependent amine oxidase family, is expressed in the extracellular matrix and in the nucleus. It likely plays a role in cross-linking collagen and elastin, possibly modulating cellular functions. Immunohistochemical studies show the presence of LOXL in the pyramidal cell layer of the hippocampus; and in this study, we report that cells in the granule cell layer have significantly smaller somas in LOXL -/- compared to LOXL +/+ mice. In addition we tested the hypothesis that these structural alterations in the dentate granule layer were associated with synaptic efficacy and thus muted long-term potentiation in mice lacking the protein. Electrical recordings were obtained in 300-mum hippocampal slices in dentate and CA1 pyramidal cell layers in age-matched wild type and LOXL null mice. Potentiation in the CA1 cell layer of 10 LOXL -/- and 8 LOXL +/+ mice was 191.0+/-9.3% and 181.6+/-9.1%, respectively (mean+/-S.E.M.). Dentate potentiation was 120.8+/-7.0% and 121.0+/-3.4% in 11 LOXL -/- and 11 LOXL +/+ mice, respectively. No phenotypic difference in potentiation of population spike amplitude (or in EPSP slope) in either layer was observed. Thus, contrary to expectation, structural changes in the hippocampus of LOXL -/- mice did not affect synaptic remodeling in a manner that impaired the establishment of LTP.