Characterization of the human NDRG gene family: a newly identified member, NDRG4, is specifically expressed in brain and heart

RTP/Drg1/Cap43/rit42/TDD5/Ndr1/NDRG1 (referred to as NDRG1 hereafter) is a cytoplasmic protein involved in stress responses, hormone responses, cell growth, and differentiation. Recently, the mutation of this gene was reported to be causative for hereditary motor and sensory neuropathy-Lom. Here, we cloned two human cDNAs encoding NDRG3 and NDRG4, which are homologous to NDRG1. These two genes, together with NDRG1 and a previously deposited cDNA (designated NDRG2), constitute the NDRG gene family. The four members share 57-65% amino acid identity. NDRG4 was further characterized because its mRNA expression was quite specific in brain and heart, in contrast to the relatively ubiquitous expression of the other three members. NDRG4 mRNA consists of three isoforms, NDRG4-B, NDRG4-B(var), and NDRG4-H. Northern and Western blot analyses showed that NDRG4-B was expressed only in the brain, whereas NDRG4-H was expressed in both brain and heart. NDRG4-B(var) was a minor product. NDRG4 expression was more abundant in adult than fetal brain and heart and was markedly decreased in the Alzheimer's diseased brain. In situ hybridization showed that NDRG4 was localized in neurons of the brain and spinal cord. The NDRG4 gene contains 17 exons. mRNA expression of the three NDRG4 isoforms is regulated by alternative splicing and possibly by alternative promoter usage. The finely tuned expression of the NDRG gene family members suggests that they have different specific functions.     

Characterization and expression of three novel differentiation-related genes belong to the human NDRG gene family

NDRG1(N-Myc downstream regulated) is upregulated during cell differentiation, repressed by N-myc and c-myc in embryonic cells, and suppressed in several tumor cells. A nonsense mutation in the NDRG1 gene has been reported to be causative for hereditary motor and sensory neuropathy-Lom (HMSNL), indicating that NDRG1 functions in the peripheral nervous system necessary for axonal survival. Here, we cloned three human cDNAs encoding NDRG2 (371aa), NDRG3 (375aa) and NDRG4 (339aa), which are homologous to NDRG1. These three genes, together with NDRG1, constitute the NDRG gene family. The phylogenetic analysis of the family demonstrated that human NDRG1 and NDRG3 belong to a subfamily, and NDRG2 and NDRG4 to another. At amino acid (aa) level, the four members share 53–65% identity. Each of the four proteins contains an / hydrolase fold as in human lysosomal acid lipase. Expression of the fusion proteins NDRG2/GFP, NDRG3/GFP and NDRG4/GFP in COS-7 cells showed that all of them are cytosolic proteins. Based on UniGene cluster analysis, the genes NDRG2, NDRG3 and NDRG4 are located at chromosome 14q11.1–11.2, 20q12–11.23 and 16q21–22.1, respectively. Northern and dot blot analysis shows that all of the three genes are highly expressed in adult brain and almost not detected in the eight human cancer lines. In addition, in contrast to the relatively ubiquitous expression of NDRG1, NDRG2 is highly expressed in adult skeletal muscle and brain, NDRG3 highly expressed in brain and testis, and NDRG4 specifically expressed in brain and heart, suggesting that they might display different specific functions in distinct tissues.     

NDRG4 protein-deficient mice exhibit spatial learning deficits and vulnerabilities to cerebral ischemia

The N-myc downstream-regulated gene (NDRG) family consists of four related proteins, NDRG1-NDRG4, in mammals. We previously generated NDRG1-deficient mice that were unable to maintain myelin sheaths in peripheral nerves. This condition was consistent with human hereditary motor and sensory neuropathy, Charcot-Marie-Tooth disease type 4D, caused by a nonsense mutation of NDRG1. In contrast, the effects of genetic defects of the other NDRG members remain unknown. In this study, we focused on NDRG4, which is specifically expressed in the brain and heart. In situ mRNA hybridization on the brain revealed that NDRG4 was expressed in neurons of various areas. We generated NDRG4-deficient mice that were born normally with the expected Mendelian frequency. Immunochemical analysis demonstrated that the cortex of the NDRG4-deficient mice contained decreased levels of brain-derived neurotrophic factor (BDNF) and normal levels of glial cell line-derived neurotrophic factor, NGF, neurotrophin-3, and TGF-β1. Consistent with BDNF reduction, NDRG4-deficient mice had impaired spatial learning and memory but normal motor function in the Morris water maze test. When temporary focal ischemia of the brain was induced, the sizes of the infarct lesions were larger, and the neurological deficits were more severe in NDRG4-deficient mice compared with the control mice. These findings indicate that NDRG4 contributes to the maintenance of intracerebral BDNF levels within the normal range, which is necessary for the preservation of spatial learning and the resistance to neuronal cell death caused by ischemic stress.     

Identification of NDRG1-regulated genes associated with invasive potential in cervical and ovarian cancer cells

N-myc downstream regulated gene 1 (NDRG1) is an important gene regulating tumor invasion. In this study, shRNA technology was used to suppress NDRG1 expression in CaSki (a cervical cancer cell line) and HO-8910PM (an ovarian cancer cell line). In vitro assays showed that NDRG1 knockdown enhanced tumor cell adhesion, migration and invasion activities without affecting cell proliferation. cDNA microarray analysis revealed 96 deregulated genes with more than 2-fold changes in both cell lines after NDRG1 knockdown. Ten common upregulated genes (LPXN, DDR2, COL6A1, IL6, IL8, FYN, PTP4A3, PAPPA, ETV5 and CYGB) and one common downregulated gene (CLCA2) were considered to enhance tumor cell invasive activity. BisoGenet network analysis indicated that NDRG1 regulated these invasion effector genes/proteins in an indirect manner. Moreover, NDRG1 knockdown also reduced pro-invasion genes expression such as MMP7, TMPRSS4 and CTSK. These results suggest that regulation of invasion and metastasis by NDRG1 is a highly complicated process.     

NDRG1 is important to maintain the integrity of airway epithelial barrier through claudin‐9 expression

Impairment of epithelial barrier integrity caused by environmental triggers is associated with the pathogenesis of airway inflammation. Using human airway epithelial cells, we attempted to identify molecule(s) that promote airway epithelial barrier integrity. Microarray analyses were conducted using the Affimetrix human whole genome gene chip, and we identified the N‐myc downstream‐regulated gene 1 (NDRG1) gene, which was induced during the development of the epithelial cell barrier. Immunohistochemical analysis revealed strong NDRG1 expression in ciliated epithelial cells in nasal tissues sampled from patients with chronic rhinosinusitis (CRS), and the low expression of NDRG1 was observed in goblet cells or damaged epithelial cells. NDRG1 gene knockdown with its specific siRNA decreased the transepithelial electrical resistance and increased the dextran permeability. Immunocytochemistry revealed that NDRG1 knockdown disrupted tight junctions of airway epithelial cells. Next, we analyzed the effects of NDRG1 knockdown on the expression of tight and adhesion junction molecules. NDRG1 knockdown significantly decreased only claudin‐9 expression, but did not decrease other claudin family molecules, such as E‐cadherin, and ZO‐1, ‐2, or ‐3. Knockdown of claudin‐9 markedly impaired the barrier function in airway epithelial cells. These results suggest that NDRG1 is important for the barrier integrity in airway epithelial cells.     

NDRG4基因的表达调控及生物学效应研究进展

NDRG是近年来发现的新的基因家族,被认为与细胞分化和肿瘤形成有关。其中NDRG4基因在心脑组织中特异性高表达,并且参与正常心脑功能的维持。此外,NDRG4基因的异常表达与某些肿瘤的发生发展关系密切,因此备受关注。就NDRG4基因的调控机制、生物学效应以及与肿瘤的关系作一综述,为人们对其进一步探索提供帮助。     

NDRG2在人胚胎呼吸系统的表达特点

目的该实验通过对16-28周人胚胎呼吸系统NDRG2表达的研究,旨在阐明NDRG2在16-28周人胚胎呼吸系统中的表达规律,为进一步明确新的发育相关基因ndrg2的功能提供依据。方法搜集16-28周胎儿呼吸系统的肺和气管组织,制成石蜡切片,用抗NDRG2单克隆抗体,行免疫组化染色(ABC法),从蛋白质水平观察NDRG2表达情况。统计阳性细胞数,利用统计学方法,判断不同胎龄的肺和气管间NDRG2表达有无差别。结果免疫组化染色表明,NDRG2在16-28周胚胎呼吸系统中有广泛的表达,阳性产物主要位于上皮细胞的胞浆中,但是不同胎龄之间NDRG2的表达未见显著差别。结论NDRG2在16-28周胚胎呼吸系统中有广泛的表达,提示NDRG2在早期胚胎的呼吸系统上皮细胞的生长与发育过程中起一定作用。而阳性产物主要表达在上皮细胞的胞浆中,说明NDRG2可能是一种胞浆蛋白。     

NDRG2在人胚胎组织中的表达分布特点

本文旨在研究NDRG2在不同胎龄人胚胎组织中的表达水平及细胞定位。利用RT-PCR和Western blot研究NDRG2 mRNA和蛋白在胎心、肺、肝和肾中的表达水平,免疫组织化学分析NDRG2蛋白在多种胚胎组织中的分布特点。结果表明,NDRG2在胚胎组织中的表达随胚龄的延长而增加。NDRG2 mRNA和蛋白在胎心和肺中的变化一致;在胎肝中mRNA表达低而蛋白表达高,在胎肾中则相反。NDRG2蛋白阳性反应产物存在于细胞胞浆,见于小肠绒毛上皮细胞、结肠上皮细胞、皮肤表层细胞及毛囊、肺内小气道内衬上皮细胞、肝细胞、心肌细胞、胸腺小体、肾小管上皮细胞。结果提示,NDRG2蛋白可能不是一个组织特异性蛋白,并在组织和器官的形成中起作用。     

NDRG1 的功能及其与癌症的关系

细胞生长、分化和多种应激的情况都可以影响NDRG1(N-myc downstream-regulated gene 1)蛋白的表达水平。NDRG1在许多细胞的正常生理功能中起着重要作用,NDRG1的缺乏可能导致多种疾病,如4D型CMTD(夏-马-图三氏病进行性神经性肌萎缩,Charcot-Marie-Tooth disease)的发生与施万细胞中NDRG1的缺失有关。在多种癌细胞系中,NDRG1的转录和翻译与肿瘤的分化和转移有关。在缺氧环境中,NDRG1的表达水平上调,而且在许多肿瘤细胞中都存在缺氧的现象,这使得NDRG1与缺氧和癌症之间存在着复杂的关系。NDRG1与癌症的关系使得NDRG1可能作为肿瘤演进的标识和癌症诊断的辅助工具。     

Hypermethylation-mediated silencing of NDRG4 promotes pancreatic ductal adenocarcinoma by regulating mitochondrial function

The N-myc downstream regulated gene (NDRG) family members are dysregulated in several tumors. Functionally, NDRGs play an important role in the malignant progression of cancer cells. However, little is known about the potential implications of NDRG4 in pancreatic ductal adenocarcinoma (PDAC). The aim of the current study was to elucidate the expression pattern of NDRG4 in PDAC and evaluate its potential cellular biological effects. Here, we firstly report that epigenetic-mediated silencing of NDRG4 promotes PDAC by regulating mitochondrial function. Data mining demonstrated that NDRG4 was significantly down-regulated in PDAC tissues and cells. PDAC patients with low NDRG4 expression showed poor prognosis. Epigenetic regulation by DNA methylation was closely associated with NDRG4 down-regulation. NDRG4 overexpression dramatically suppressed PDAC cell growth and metastasis. Further functional analysis demonstrated that up-regulated NDRG4 in SW1990 and Canpan1 cells resulted in attenuated mitochondrial function, including reduced ATP production, decreased mitochondrial membrane potential, and increased fragmented mitochondria. However, opposite results were obtained for HPNE cells with NDRG4 knockdown. These results indicate that hypermethylation-driven silencing of NDRG4 can promote PDAC by regulating mitochondrial function and that NDRG4 could be as a potential biomarker for PDAC patients.     

NDRG1的功能及其与癌症的关系

细胞生长、分化和多种应激的情况都可以影响NDRGI（N-myc downstream-rvgulatcd gene 1）蛋白的表达水平。NDRG1在许多细胞的正常生理功能中起着重要作用。NDRG1的缺乏可能导致多种疾病,如．碡D型CMTD（夏-马-图三氏病进行性神经性肌萎缩,Charcot-Marie-Toothdisease）的发生与施万细胞中NDRG1的缺失有关。在多种癌细胞系中。NDRG1的转录和翻译与肿瘤的分化和转移有关。在缺氧环境中。NDRG1的表达水平上调,而且在许多肿瘤细胞中都存在缺氧的现象,这使得NDRG1与缺氧和癌症之间存在着复杂的关系。NDRGI与癌症的关系使得NDRG1可能作为肿瘤演进的标识和癌症诊断的辅助工具。     

NDRG2 通过影响CD24 调控乳腺癌细胞的粘附能力

目的:阐明NDRG2(N-Myc downstream-regulated gene 2)在乳腺癌细胞中对CD24的调控及其对乳腺癌细胞粘附能力的影响。方法:RT-PCR和Western blot方法检测乳腺癌细胞MCF-7及Bcap-37中NDRG2和CD24的表达;通过腺病毒上调MCF-7细胞中NDRG2的表达,或利用siRNA下调Bcap-37细胞中NDRG2的表达,检测CD24基因和蛋白的变化。粘附实验检测改变NDRG2表达水平后对MCF-7及Bcap-37细胞粘附能力的影响。结果:MCF-7细胞中NDRG2基因和蛋白的表达水平低于Bcap-37细胞,而CD24的表达水平高于Bcap-37细胞;在MCF-7细胞中通过腺病毒载体上调NDRG2可以抑制CD24的表达并抑制其粘附能力,而在Bcap-37细胞中利用siRNA下调NDRG2的表达可以提高CD24的水平及细胞的粘附能力;结论:NDRG2通过影响CD24参与调控乳腺癌细胞的粘附能力。     

Cellular distribution of NDRG1 protein in the rat kidney and brain during normal postnatal development.

N-myc downregulated gene 1 (NDRG1) is a 43-kD protein whose mRNA is induced by DNA damage, hypoxia, or prolonged elevation of intracellular calcium. Although NDRG1 is also upregulated during cell differentiation, there are few studies on NDRG1 expression during postnatal development. Here we investigated the expression and cellular distribution of NDRG1 protein in rat kidney and brain during postnatal development. Immunohistochemical analysis revealed that the cellular localization of NDRG1 protein in the kidney changed from the proximal convoluted tubules to the collecting ducts between postnatal days 10 and 20. In the brain, a change in cellular expression was also found from the hippocampal pyramidal neurons to the astrocytes in the gray matter during the same postnatal period. These alterations in the cellular distribution of NDRG1 were associated with shifts in the molecular assembly on Western blots. Under non-reduced conditions, the main NDRG1 band was found only around 215 kD in both kidney and brain during the early postnatal stage. After postnatal day 10, the immunoreactive bands shifted to 43 kD in the kidney and 129 kD in the brain. These changes in the cellular distribution and state of assembly may correlate with the functional maturation of both organs.     

Valproic acid inhibits the invasion of PC3 prostate cancer cells by upregulating the metastasis suppressor protein NDRG1

Valproic acid (VPA) is a clinically available histone deacetylase inhibitor with promising anticancer attributes. Recent studies have demonstrated the anticancer effects of VPA on prostate cancer cells. However, little is known about the differential effects of VPA between metastatic and non-metastatic prostate cancer cells and the relationship between the expression of metastasis suppressor proteins and VPA. In the present study, we demonstrate that inhibition of cell viability and invasion by VPA was more effective in the metastatic prostate cancer cell line PC3 than in the tumorigenic but non-metastatic prostate cell line, RWPE2. Further, we identified that the metastasis suppressor NDRG1 is upregulated in PC3 by VPA treatment. In contrast, NDRG1 was not increased in RWPE2 cells. Also, the suppressed invasion of PC3 cells by VPA treatment was relieved by NDRG1 knockdown. Taken together, we suggest that the anticancer effect of VPA on prostate cancer cells is, in part, mediated through upregulation of NDRG1. We also conclude that VPA has differential effects on the metastasis suppressor gene and invasion ability between non-metastatic and metastatic prostate cancer cells.     

NDRG4 Is Required for Cell Cycle Progression and Survival in Glioblastoma Cells

NDRG4 is a largely unstudied member of the predominantly tumor suppressive N-Myc downstream-regulated gene (NDRG) family. Unlike its family members NDRG1–3, which are ubiquitously expressed, NDRG4 is expressed almost exclusively in the heart and brain. Given this tissue-specific expression pattern and the established tumor suppressive roles of the NDRG family in regulating cellular proliferation, we investigated the cellular and biochemical functions of NDRG4 in the context of astrocytes and glioblastoma multiforme (GBM) cells. We show that, in contrast to NDRG2, NDRG4 expression is elevated in GBM and NDRG4 is required for the viability of primary astrocytes, established GBM cell lines, and both CD133⁺ (cancer stem cell (CSC)-enriched) and CD133⁻ primary GBM xenograft cells. While NDRG4 overexpression has no effect on cell viability, NDRG4 knockdown causes G₁ cell cycle arrest followed by apoptosis. The initial G₁ arrest is associated with a decrease in cyclin D1 expression and an increase in p27^Kip1 expression, and the subsequent apoptosis is associated with a decrease in the expression of XIAP and survivin. As a result of these effects on cell cycle progression and survival, NDRG4 knockdown decreases the tumorigenic capacity of established GBM cell lines and GBM CSC-enriched cells that have been implanted intracranially into immunocompromised mice. Collectively, these data indicate that NDRG4 is required for cell cycle progression and survival, thereby diverging in function from its tumor suppressive family member NDRG2 in astrocytes and GBM cells.The N-Myc downstream-regulated gene (NDRG)⁵ family consists of four genes (NDRG1–4) that can be divided into two subfamilies based on sequence homology: NDRG1 and NDRG3 are in the first subfamily, and NDRG2 and NDRG4 make up the second subfamily. Although the four NDRG family members show distinct spatiotemporal expression patterns during embryonic development and in adult tissues (1–10), all four are highly expressed in the brain (4). To date, however, NDRG2 is the only NDRG family member that has been studied in the context of GBM cells and astrocytes. NDRG2 mRNA and protein levels are lower in GBM than in normal brain tissue, normal glial cells, and low grade astrocytomas (11–14), suggesting a tumor suppressive function. Data from experimental and clinical studies support this hypothesis: NDRG2 overexpression inhibits GBM cell proliferation (15), and decreased NDRG2 expression correlates with decreased GBM patient survival (13).In contrast to its subfamily member NDRG2, NDRG4 has not been studied in GBM cells or astrocytes. Nevertheless, available evidence supports the hypothesis that NDRG4 has an important role in this context that is similar to the role of NDRG2. First, unlike the relatively ubiquitous expression patterns of NDRG1–3, NDRG4 expression is restricted to a small number of tissues including the brain, where it is expressed at particularly high levels (7, 10). This restricted expression pattern suggests that NDRG4 plays an important role within the central nervous system. Second, NDRG4 is more than 60% identical in amino acid sequence to NDRG2. This sequence similarity is likely behind the overlapping functions of these two proteins in certain cell types within the brain. For example, in PC12 neuronal cells, both NDRG4 and NDRG2 promote neurite extension (16–18). In combination with the brain-specific expression pattern of NDRG4, these functional and sequence similarities suggest that NDRG4 may recapitulate the tumor suppressive function of NDRG2 in primary brain neoplasms.To determine if the similarities between NDRG2 and NDRG4 extend to the context of GBM, we investigated the role of NDRG4 in GBM cell lines and primary human astrocytes. In contrast to the established roles of NDRG2 and other NDRG family members, we found that the role of NDRG4 in GBM is not tumor suppressive. On the contrary, both astrocytes and GBM cells require the presence of NDRG4 for cell cycle progression and survival.     

NDRG2通过调控CD24影响肝癌细胞侵袭能力的研究

目的：阐明NDRG2（N-Myc downstream-regulated gene2）在肝癌细胞中对CD24的调控及其对乳腺癌细胞侵袭能力的影响。方法：Western blot检测低转移性的肝癌细胞Huh7、高转移性的肝癌细胞系MHCC97h及正常人肝细胞系L-02中NDRG2和CD24的表达;通过腺病毒载体上调MHCC97h细胞中NDRG2的水平,或利用siRNA下调Huh7细胞中NDRG2的表达,检测CD24的变化以及细胞侵袭能力的改变。结果：MHCC97h细胞中NDRG2基因和蛋白的表达水平低于Huh7细胞,而CD24的表达水平高于Huh7细胞;在MHCC97h细胞中上调NDRG2可以抑制CD24的表达并抑制其侵袭能力,而在Huh7细胞中下调NDRG2的表达可以提高CD24的水平及细胞的侵袭能力。结论：NDRG2可能通过影响CD24参与调控肝癌细胞的侵袭能力。     

N-myc downstream-regulated gene 2 controls astrocyte morphology via Rho-GTPase signaling

Astrocyte undergoes morphology changes that are closely associated with the signaling communications at synapses. N-myc downstream-regulated gene 2 (NDRG2) is specifically expressed in astrocytes and is associated with several important astrocyte functions, but its potential role(s) relating to astrocyte morphological changes remain unknown. Here, primary astrocytes were prepared from neonatal Ndrg2^+/+ and Ndrg2^−/− pups, and the drug Y27632 was used to induce stellation. We then used a variety of methods to measure the levels of NDRG2, α-Actinin4, and glial fibrillary acidic protein (GFAP), and the activity of RhoA, Rac1, and Cdc42 in Y27632-treated astrocytes as well as in Ndrg2^+/+, Ndrg2^−/−, or Ndrg2^−/− + lentivirus (restore NDRG2 expression) astrocytes. We also conducted live-imaging and proteomics studies of the cultured astrocytes. We found that induction of astrocytes stellation (characterized by cytoplasmic retraction and process outgrowth) resulted in increased NDRG2 protein expression and Rac1 activity and in reduced α-Actinin4 protein expression and RhoA activity. Ndrg2 deletion induced astrocyte flattening, whereas the restoration of NDRG2 expression induced stellation. Ndrg2 deletion also significantly increased α-Actinin4 protein expression and RhoA activity yet reduced GFAP protein expression and Rac1 activity, and these trends were reversed by restoration of NDRG2 expression. Collectively, our results showed that Ndrg2 deletion promoted cell proliferation, interrupted stellation capability, and extensively altered the protein expression profiles of proteins that function in Rho-GTPase signaling. These findings suggest that NDRG2 functions to regulate astrocytes morphology via altering the accumulation of the Rho-GTPase signaling pathway components, thereby supporting that NDRG2 should be understood as a regulator of synaptic plasticity and thus neuronal communications.     

NDRG2 通过调控CD24 影响肝癌细胞侵袭能力的研究

目的：阐明NDRG2（N-Myc downstream-regulated gene 2）在肝癌细胞中对CD24 的调控及其对乳腺癌细胞侵袭能力的影响。 方法：Western blot 检测低转移性的肝癌细胞Huh7、高转移性的肝癌细胞系MHCC97h 及正常人肝细胞系L-02 中NDRG2 和 CD24 的表达;通过腺病毒载体上调MHCC97h 细胞中NDRG2 的水平,或利用siRNA 下调Huh7 细胞中NDRG2 的表达,检测 CD24 的变化以及细胞侵袭能力的改变。结果：MHCC97h 细胞中NDRG2 基因和蛋白的表达水平低于Huh7 细胞,而CD24 的表达 水平高于Huh7 细胞;在MHCC97h 细胞中上调NDRG2 可以抑制CD24 的表达并抑制其侵袭能力,而在Huh7 细胞中下调 NDRG2 的表达可以提高CD24 的水平及细胞的侵袭能力。结论：NDRG2 可能通过影响CD24 参与调控肝癌细胞的侵袭能力。     

NDRG1对人肠癌细胞失巢凋亡的影响

目的:探讨NDRG1对体外培养的人肠癌细胞系失巣凋亡的影响。方法:采用慢病毒系统将NDRG1表达单元转入人肠癌细胞系SW620、HCT8中,建立相应的过表达稳定细胞系;通过siRNA的方法干扰HCT116和LOVO细胞系中NDRG1的表达,分别在非贴壁培养的情况下培养48小时,采用流式细胞术和TUNEL染色检测细胞的凋亡情况。结果:在贴壁培养条件下,NDRG1过表达并没有显著影响肠癌细胞的生长及增殖,而NDRG1特异性siRNA干扰HCT116细胞中NDRG1的表达后,其凋亡率无明显变化(P0.05)。在悬浮培养条件下,NDRG1过表达的肠癌细胞的失巢凋亡率显著低于正常对照组(P0.05),而用三种不同的siRNA干扰HCT116及LOVO细胞中NDRG1的表达后,其失巢凋亡率均显著高于正常对照组(P0.05)。结论:NDRG1在体外可抑制人肠癌细胞的失巢凋亡。     

紫杉醇对人肝癌SMMC7721细胞NDRG1表达及增值的影响

旨在探索紫杉醇对人肝癌SMMC7721细胞NDRG1表达的影响,及紫杉醇对肝癌SMMC7721细胞系增殖的抑制作用。分别提取紫杉醇处理前后SMMC7721细胞的RNA,进行逆转录-聚合酶链反应(RT-PCR),判断紫杉醇处理前后肝癌细胞中NDRG1表达的情况;采用蛋白印迹技术(Western blotting)分析紫杉醇处理前后肝癌细胞中NDRG1蛋白表达的情况;应用不同浓度紫杉醇处理肝癌细胞,以MTT法检测处理前后肝癌细胞的抑制率,流式细胞术(FCM)观察细胞周期变化的况。结果表明紫杉醇处理后的肝癌SMMC7721细胞中NDRG1表达下降,紫杉醇浓度越高,NDRG1表达水平越低,具有浓度依赖性。以MTT法观察紫杉醇对肝癌细胞的抑制作用,试验结果表明不同浓度的紫杉醇处理肝癌SMMC7721细胞后,癌细胞被明显抑制;以流式细胞术观察紫杉醇作用后肝癌SMMC7721细胞周期的变化,结果显示G2-M期细胞比例升高的程度随浓度增高而升高,细胞越来越多地被阻滞在G2-M期,不能继续分裂增殖。分化相关基因NDRG1的表达可能是肝癌的发病机制之一,紫杉醇可抑制肝癌SMMC 7721细胞中NDRG1的表达;同时紫杉醇能使肝癌SMMC7721细胞的生长阻滞在G2-M期,从而显著抑制SMMC7721细胞的增殖,并且具有剂量、时间依赖效应。