钾离子通道蛋白Kir2.1/KCNJ2及多药耐药蛋白MRP1/ABCC1在小细胞肺癌中的表达及相关性

 目的：探讨内向整流钾通道2.1（Kir2.1/KCNJ2）及多药耐药相关蛋白1（MRP1/ABCC1）在小细胞肺癌(SCLC) 中的表达情况及两者的相关性。方法：采用实时定量PCR和蛋白印迹法检测小细胞肺癌多药耐药细胞株H69AR及敏感株H69细胞中Kir2.1/KCNJ2及MRP1/ABCC1 mRNA和蛋白的表达水平,采用免疫组化EnVision两步法检测44 例SCLC组织中Kir2.1/KCNJ2和MRP1蛋白的表达水平;采用蛋白免疫共沉淀实验检测Kir2.1/KCNJ2与MRP1/ABCC1之间的相互作用。
结果：H69AR细胞株中Kir2.1/KCNJ2及MRP1/ABCC1 mRNA和蛋白的表达均显著高于H69细胞株,二者均有显著差异（P<005）;免疫组化结果表明SCLC组织中Kir2.1/KCNJ2和MRP1/ABCC1阳性表达率分别为47.7%(21/44) 和52.3%(23/44),两者表达在SCLC 中呈正相关(r=0853,P<0.01); Kir2.1/KCNJ2与MRP/ABCC1在H69AR细胞内可形成复合物。结论：Kir2.1/KCNJ2与小细胞癌多药耐药有关。Kir2.1/KCNJ2和MRP1/ABCC1之间可能存在共同作用通路。Kir2.1/KCNJ2可能通过调控MRP1/ABCC1的表达促进SCLC多药耐药的发生。     

Identification of DJ‐1 as a contributor to multidrug resistance in human small‐cell lung cancer using proteomic analysis

Proteomic approaches have been proven to provide an important tool in identifying drug resistance‐associated proteins. The aim of this study was to investigate the protein profiling of drug resistance‐related proteins in small‐cell lung cancer (SCLC) by proteomic analysis. The proteomic profiling was performed by two‐dimensional fluorescence difference gel electrophoresis (2D‐DIGE) coupled with MALDI‐TOF‐TOF of SCLC in the multidrug‐resistant cell line H69AR and its parental cell line H69. A total of 11 proteins were identified to be >2‐fold up‐or downregulated between the two cell lines. DJ‐1, one of the differently expressed proteins identified by proteomics, was further examined by immunohistochemistry staining in 116 cases of SCLC tissues. Immunohistochemical results demonstrated that DJ‐1 was expressed in 51.7% (60/116) of SCLC. DJ‐1 expression was correlated significantly with survival time of SCLC patients (P < 0.05), but not with other clinical parameters such as gender, age and clinical stage (P > 0.05). Downregulation of DJ‐1 using DJ‐1‐siRNA in H69AR cells sensitized cancer cells to chemotherapeutic drugs through increasing drug‐induced cell apoptosis accompanied with G0‐G1 phase arrest. These findings suggest DJ‐1 may serve as a potential biomarker for chemoresistance and prognostic factor for patients with SCLC.     

MicroRNA-299-3p promotes the sensibility of lung cancer to doxorubicin through directly targeting ABCE1

MicroRNAs (miRNAs) are a class of endogenous, small non-coding RNAs which play important roles in various biological and cellular processes, including chemoresistance. The expression level of miR-299-3p was dysregulated in doxorubicin-resistance lung cancer cell lines. However, the exact role of miR-299-3p in doxorubicin-resistance is still unknown. In the present study, miR-299-3p was down-expressed in doxorubicin-resistant or -sensitive lung cancer samples and it was identified to directly targeted adenosine triphosphate binding cassette E1 (ABCE1) 3’-untranslated region (UTR) in lung cancer H69 cells by luciferase assay. After transfection of miR-299-3p mimics or ABCE1-siRNA, MTT assay confirmed that the H69/ADR cell proliferation was inhibited, as well as the enhanced cell inhibitory rate in the presence of doxorubicin. H69/ADR cell apoptosis rate was promoted after miR-299-3p or ABCE1-siRNA transfection. The results indicated that miR-299-3p promotes the sensibility of lung cancer to doxorubicin through suppression of ABCE1, at least partly. Therefore, the disordered decreased of miR-299-3p and resulting ABCE1 up-expression may contribute to chemoresistance of lung cancer, and miR-299-3p-ABCE1 may represent a new potential therapeutic target for the treatment of chemoresistance of lung cancer.     

Zinc finger E-box-binding homeobox 2 (ZEB2) regulated by miR-200b contributes to multi-drug resistance of small cell lung cancer

Zinc finger E-box-binding homeobox 2 (ZEB2) was closely related to the oncogenesis, development and response to chemotherapy of cancer. However, its biological functions in small cell lung cancer (SCLC) remain unknown. The aim of this study is to investigate the roles of ZEB2 in chemoresistance of SCLC and its possible molecular mechanism. Expression of ZEB2 was examined in sixty-eight cases of SCLC tissues by immunohistochemistry. Knockdown of ZEB2 was carried out in SCLC multidrug resistant cells (H69AR) to assess its influence on chemoresistance. The results showed that ZEB2 was expressed in 23.5% (16/68) of SCLC. Overexpression of ZEB2 was associated with the poor pathologic stage of SCLC (P < 0.001 by the Fisher's Exact Test) and the shorter survival time (by the Kaplan–Meier method). Inhibition of ZEB2 expression using small interfering RNA in H69AR cells sensitized cancer cells to chemotherapeutic drugs through increasing drug-induced cell apoptosis accompanied with S phase arrest. In silico analysis demonstrated that there are complementary binding sites between miR-200b and ZEB2 3′-UTR, and identified miR-200b as a potential regulator of ZEB2. We found that miR-200b was down-regulated in the resistant cells and enforced expression of miR-200b by miRNA mimics increased cell sensitivity. Overexpression of miR-200b led to the downregulation of ZEB2 at protein level. Luciferase reporter gene assay showed that 3′UTR ZEB2 activity was regulated by miR-200b. Our results suggest that ZEB2 modulates drug resistance and is regulated by miR-200b. All findings provide insight into the ZEB2 signaling mechanism and ZEB2 may be a potentially novel target for multi-drug resistance in SCLC.     

MIR‐137 Suppresses Growth and Invasion,is Downregulated in Oligodendroglial Tumors and Targets CSE1L

MicroRNA‐137 (miR‐137) expression has been reported to be decreased in astrocytic tumors in two expression profiling studies but its role in the pathogenesis of oligodendroglial tumors is still limited. In this study, we demonstrate that miR‐137 expression is significantly downregulated in a cohort of 35 oligodendroglial tumors and nine glioma cell lines compared with normal brains. Lower miR‐137 expression is associated with shorter progressive‐free survival and overall survival. Restoration of miR‐137 expression in an oligodendroglial cells TC620, and also glioblastoma cells of U87 and U373 significantly suppressed cell growth, anchorage‐independent growth, as well as invasion. Demethylation and deacetylation treatments resulted in upregulation of miR‐137 expression in TC620 cells. In silico analysis showed that CSE1 chromosome segregation 1‐like (yeast) (CSE1L) is a potential target gene of miR‐137. Luciferase reporter assay demonstrated that miR‐137 negatively regulates CSE1L by interaction between miR‐137 and complementary sequences in the 3′ UTR of CSE1L. Immunohistochemistry revealed that CSE1L is upregulated in oligodendroglial tumors. Knockdown of CSE1L resulted in similar outcomes as overexpressing miR‐137 in oligodendroglioma cells and glioblastoma cells. Overall, our data suggest that miR‐137 regulates growth of glioma cells and targets CSE1L, providing further understanding in the tumorigenesis of gliomas.     

Caveolin‐1 is an Important Factor for the Metastasis and Proliferation of Human Small Cell Lung Cancer NCI‐H446 Cell

Caveolin‐1 (CAV‐1) has been reported to play an important role in the development of a variety of human cancers. CAV‐1 expression is revealed to be reduced or absent in the malignant tumor cells of small cell lung cancers (SCLC). This study was performed to investigate the influences of the stable expression of CAV‐1 on the metastasis and proliferation of SCLC in vitro. The wild‐type CAV‐1 gene was successfully transfected into the NCI‐H446 cells and was stably expressed in the NCI‐H446 cells. The effects of CAV‐1 on the morphology, proliferation, and metastasis potential for NCI‐H446 cell were evaluated by crystal violet staining, MTT analysis, transwell assay, and scratch wound assay, respectively. Western blot and gelatin zymography were used to examine the expression changes of the metastasis‐related MMP‐3 and E‐cadherin. Stable expression of CVA‐1 was observed in the H446‐CAV‐1 cells, which enlarged the cell shape with filopodia. The proliferation of H446‐CAV‐1 was inhibited, while its migration and invasion abilities were promoted in vitro. The re‐expression of CAV‐1 reduced the expression of E‐cadherin, while it increased the protein expression and enzyme activity of MMP‐3. Taken together, the cellular proliferation of the NCI‐H446 could be inhibited by the re‐expression of CAV‐1. CAV‐1 might increase the cell metastasis potential through the interaction with E‐cadherin and MMP‐3 genes. These in vitro findings confirm the involvement of CAV‐1 in the proliferation and metastasis of SCLC. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.     

Gene expression profiling of ABC transporters in dermal fibroblasts of pseudoxanthoma elasticum patients identifies new candidates involved in PXE pathogenesis

Mutations in the ABCC6 gene, encoding the multidrug resistance-associated protein 6 (MRP6), cause pseudoxanthoma elasticum (PXE). This heritable disorder leads to pathological alterations in connective tissues. The implication of MRP6 deficiency in PXE is still unknown. Moreover, nothing is known about a possible compensatory expression of other ATP binding-cassette (ABC) transporter proteins in MRP6-deficient cells. We investigated the gene expression profile of 47 ABC transporters in human dermal fibroblasts of healthy controls (n=2) and PXE patients (n=4) by TaqMan low-density array. The analysis revealed the expression of 37 ABC transporter genes in dermal fibroblasts. ABCC6 gene expression was not quantifiable in fibroblasts derived from PXE patients. Seven genes (ABCA6, ABCA9, ABCA10, ABCB5, ABCC2, ABCC9 and ABCD2) were induced, whereas the gene expression of one gene (ABCA3) was decreased, comparing controls and PXE patients (with at least twofold changes). We reanalyzed the gene expression of selected ABC transporters in a larger set of dermal fibroblasts from controls and PXE patients (n=6, each). Reanalysis showed high interindividual variability between samples, but confirmed the results obtained in the array analysis. The gene expression of ABC transporter genes, as well as lineage markers of PXE, was further examined after inhibition of ABCC6 gene expression by using specific small-interfering RNA. These experiments corroborated the observed gene expression alterations, most notably in the ABCA subclass (up to fourfold, P<0.05). We therefore conclude that MRP6-deficient dermal fibroblasts exhibit a distinct gene expression profile of ABCA transporters, potentially to compensate for MRP6 deficiency. Moreover, our results point to a function for ABCC6/MRP6 in sterol transport, as sterols are preferential regulators of ABCA transporter activity and expression. Further studies are now required to uncover the role of ABCA transporters in PXE.     

MEG3 LncRNA from Exosomes Released from Cancer-Associated Fibroblasts Enhances Cisplatin Chemoresistance in SCLC via a MiR-15a-5p/CCNE1 Axis

PurposeLong non-coding RNAs (lncRNAs) may act as oncogenes in small-cell lung cancer (SCLC). Exosomes containing lncRNAs released from cancer-associated fibroblasts (CAF) accelerate tumorigenesis and confer chemoresistance. This study aimed to explore the action mechanism of the CAF-derived lncRNA maternally expressed gene 3 (MEG3) on cisplatin (DDP) chemoresistance and cell processes in SCLC.Materials and MethodsQuantitative real-time PCR was conducted to determine the expression levels of MEG3, miR-15a-5p, and CCNE1. Cell viability and metastasis were measured by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-h-tetrazolium bromide and invasion assays, respectively. A xenograft tumor model was developed to confirm the effect of MEG3 overexpression on SCLC progression in vivo. Relationships between miR-15a-5p and MEG3/CCNE1 were predicted using StarBase software and validated by dual luciferase reporter assay. Western blotting was used to determine protein levels. A co-culture model was established to explore the effects of exosomes on MEG3 expression in SCLC cell lines.ResultsMEG3 was overexpressed in SCLC tissues and cells. MEG3 silencing significantly repressed cell viability and metastasis in SCLC. High expression of MEG3 was observed in CAF-derived conditioned medium (CM) and exosomes, and promoted chemoresistance and cancer progression. Additionally, MEG3 was found to serve as a sponge of miR-15a-5p to mediate CCNE1 expression. Overexpression of miR-15a-5p and knockout of CCNE1 reversed the effects of MEG3 overexpression on cell viability and metastasis.ConclusionMEG3 lncRNA released from CAF-derived exosomes promotes DDP chemoresistance via regulation of a miR-15a-5p/CCNE1 axis. These findings may provide insight into SCLC therapy.     

Human natural Treg microRNA signature: Role of microRNA‐31 and microRNA‐21 in FOXP3 expression

Treg are the main mediators of dominant tolerance. Their mechanisms of action and applications are subjects of considerable debate currently. However, a human microRNA (miR) Treg signature has not been described yet. We investigated human natural Treg and identified a signature composed of five miR (21, 31, 125a, 181c and 374). Among those, two were considerably under‐expressed (miR‐31 and miR‐125a). We identified a functional target sequence for miR‐31 in the 3′ untranslated region (3′ UTR) of FOXP3 mRNA. Using lentiviral transduction of fresh cord blood T cells, we demonstrated that miR‐31 and miR‐21 had an effect on FOXP3 expression levels. We showed that miR‐31 negatively regulates FOXP3 expression by binding directly to its potential target site in the 3′ UTR of FOXP3 mRNA. We next demonstrated that miR‐21 acted as a positive, though indirect, regulator of FOXP3 expression. Transduction of the remaining three miR had no direct effect on FOXP3 expression or on the phenotype and will remain the subject of future investigations. In conclusion, not only have we identified and validated a miR signature for human natural Treg, but also unveiled some of the mechanisms by which this signature was related to the control of FOXP3 expression in these cells.