Gab2-Mediated Signaling Promotes Melanoma Metastasis

Metastatic melanoma is a disease with a poor prognosis that currently lacks effective treatments. Critical biological features of metastasis include acquisition of migratory competence, growth factor independence, and invasive potential. In an attempt to identify genes that contribute to melanoma pathogenesis, a genome-wide search using bacterial artificial chromosome array comparative genomic hybridization and single nucleotide polymorphism arrays in a series of 64 metastatic melanoma samples and 20 melanoma cell lines identified increased copy numbers of Gab2 located on 11q14.1. Gab2 is an adaptor protein that potentiates the activation of the Ras-Erk and PI3K-Akt pathways and has recently been implicated in human cancer; however, its role in melanoma has not been explored. In this study, we found that Gab2 was either amplified (∼11%) and/or overexpressed (∼50%) in melanoma. Gab2 protein expression correlated with clinical melanoma progression, and higher levels of expression were seen in metastatic melanomas compared with primary melanoma and melanocytic nevi. We found that overexpression of Gab2 potentiates, whereas silencing of Gab2 reduces, migration and invasion of melanoma cells. Gab2 mediated the hyperactivation of Akt signaling in the absence of growth factors, whereas inhibition of the PI3K-Akt pathway decreased Gab2-mediated tumor cell migration and invasive potential. Gab2 overexpression resulted in enhanced tumor growth and metastatic potential in vivo. These studies demonstrate a previously undefined role for Gab2 in melanoma tumor progression and metastasis.Melanoma is the fifth most common cancer in the US, accounting for more than 60,000 new cases each year.¹ If diagnosed in the early stages, melanoma can be cured by surgery; however metastatic disease has a poor prognosis with a median survival of 6 to 9 months.² There is no therapy for thicker or metastatic melanomas proven to have a significant impact on survival. Therefore, gaining mechanistic insight into melanoma metastasis and identifying therapeutic targets are critical for improved patient care.The gab genes, encoding mammalian Gab1, Gab2, and Gab3, represent a family of scaffolding or docking adaptor proteins.³ Gab proteins are recruited to activated receptors by direct or indirect mechanisms, mostly indirectly via Grb2. They contain several functional motifs that mediate interactions with multiple signal relay molecules and can assemble multimeric signaling complexes. On stimulation, Gab2 (Grb2-associated binding protein 2) undergoes tyrosine phosphorylation, creating a number of docking sites to mediate interactions with SH2 domain-containing proteins such as the tyrosine phosphatase Shp2 and the p85 subunit of PI3K. The interaction of Gab2 with Shp2 activates Ras-Erk signaling, whereas its association with the p85 subunit of PI3K is crucial in mediating the PI3K-Akt signaling.^3,4Recent studies provide evidence that Gab2 plays a critical role in human cancer. Gab2 is overexpressed in a subset of breast cancers.⁵ Its overexpression increases the proliferative capacity of mammary epithelial cells and alters growth factor dependence.⁶ Gab2 cooperates with receptor tyrosine kinases such as erbB2 or the Src family and promotes an invasive phenotype in breast tumorigenesis.^6,7 In the Her2/Neu-induced Gab2 knockout mouse model, Gab2-deficient cells exhibit decreased migration and mice show reduced lung metastasis, suggesting its role in promoting mammary tumor metastasis.⁸ Gab2 maps to a region commonly amplified in several human malignancies and is amplified in a subset of Gab2-overexpressing breast tumors. In addition to breast tumorigenesis, Gab2-mediated signaling has been implicated in hematological malignancies. The Grb2-Gab2 pathway is critical for leukemic transformation by Bcr-Abl.⁹ Gab2 can be activated downstream of tyrosine kinases in hematopoietic cells and propagates signals for the transforming activity of those kinases. Although these studies suggest the importance of Gab2-mediated signaling in breast tumorigenesis and leukemia, its role in melanoma is unexplored.In this study, we identified increased copy numbers of Gab2 in metastatic melanomas through a genome-wide search using bacterial artificial chromosome (BAC) array comparative genomic hybridization (CGH) and single nucleotide polymorphism (SNP) arrays that led us to analyze its role in melanoma. We found that metastatic melanomas express significantly higher levels of Gab2 than primary melanomas and melanocytic nevi, identifying Gab2 as a molecular marker for neoplastic progression. Moreover, we show that Gab2 promotes tumor cell migration and invasion by activating Akt signaling, and enhances tumor growth and metastasis in vivo, suggesting a role for Gab2-mediated signaling in promoting metastatic capability in melanoma.     

NRSN2 promotes non-small cell lung cancer cell growth through PI3K/Akt/mTOR pathway

Neurensin-2 (NRSN2), a small neural membrane protein which localized in small vesicles in neural cells. Recent report suggested that Neurensin-2 might play a suppressive role in tumor. While the biological functions and molecular mechanisms in cancer progression remain unknown. We retrieved Oncomine Database and found that NRSN2 is commonly highly expressed in non-small cell lung cancer (NSCLC). We examined the levels of NRSN2 in 18 pairs of NSCLC and adjacent tissues and found that NRSN2 was overexpressed in malignant tissues. Both loss and gain of function experiments in NSCLC cell lines suggest that NRSN2 promotes cell growth, but no effects in cell invasion. Further investigation show that NRSN2 could affect phosphatidylinositol 3 kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling. Taken together, our findings suggest that NRSN2 promotes non-small cell lung cancer cell growth through PI3K/Akt/mTOR pathway.     

Luteolin Reduces Aqueous Extract PM2.5-induced Metastatic Activity in H460 Lung Cancer Cells

Fine particulate matter (PM2.5) is the critical cause of lung cancer and can further promote tumor cell migration and invasion. This study investigated the effects of luteolin, an antiangiogenic flavonoid agent, on blocking aqueous extract PM2.5-prompted cancer progression. We observed that luteolin reduced cell migration and the expression of pro-metastatic factors pro-matrix metalloproteinase (MMP)-2 and intercellular adhesion molecule (ICAM)-1 in PM2.5-exposed H460 lung cancer cells. Luteolin treatment also reduced the transduction of PM2.5-induced epidermal growth factor receptor (EGFR)-phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT) cascade signaling. Furthermore, the reduction of MMP-2 expression and ICAM-1 production by luteolin in PM2.5-stimulated H460 cells is EGFR-PI3K-AKT pathway dependent. These results suggest that luteolin exhibits antitumor progression by inhibiting EGFR-PI3K-AKT pathway.     

Gab2在人骨肉瘤细胞U2-OS中的表达及意义

目的:探讨Grb2协同结合蛋白2(Gab2)在人骨肉瘤细胞系中的表达及其与人骨肉瘤细胞侵袭转移的关系。方法:应用小RNA干扰技术,将合成的小RNA干扰质粒转染给人骨肉瘤U2-OS细胞,采用Western blotting和RT-PCR法检测转染后Gab2的蛋白和mRNA表达水平;体外细胞趋化运动实验和侵袭实验检测细胞的迁移和侵袭能力。结果:Gab2在人骨肉瘤U2-OS细胞系中高表达,且转染Gab2 siRNA后的细胞(Si Gab2/U2-OS)中Gab2蛋白及mRNA的表达水平低于转染scramble siRNA细胞(Scr/U2-OS)和U2-OS;趋化运动实验发现在10μg/L表皮生长因子(EGF)的诱导下Si Gab2/U2-OS细胞的迁移能力较U2-OS和Scr/U2-OS细胞明显下降,差异有统计学意义(P0.01);Si Gab2/U2-OS细胞侵袭并穿透Matrigel膜基质的细胞数量均比Scr/U2-OS细胞和U2-OS细胞少,Si Gab2/U2-OS细胞的体外侵袭能力显著降低(P0.01)。结论:利用siRNA干扰技术降低Gab2的表达对人骨肉瘤U2-OS细胞的迁移和侵袭能力有明显的抑制作用。     

Melittin suppresses growth and induces apoptosis of non-small-cell lung cancer cells via down-regulation of TGF-β-mediated ERK signal pathway

The purpose of this study was to investigate the anti-cancer effect of melittin on growth, migration, invasion, and apoptosis of non-small-cell lung cancer (NSCLC) cells. This study also explored the potential anti-cancer mechanism of melittin in NSCLC cells. The results demonstrated that melittin suppressed growth, migration, and invasion, and induced apoptosis of NSCLC cells in vitro. Melittin increased pro-apoptotic caspase-3 and Apaf-1 gene expression. Melittin inhibited tumor growth factor (TGF)-β expression and phosphorylated ERK/total ERK (pERK/tERK) in NSCLC cells. However, TGF-β overexpression (pTGF-β) abolished melittin-decreased TGF-β expression and pERK/tERK in NSCLC cells. Treatment with melittin suppressed tumor growth and prolonged mouse survival during the 120-day observation in vivo. Treatment with melittin increased TUNEL-positive cells and decreased expression levels of TGF-β and ERK in tumor tissue compared to the control group. In conclusion, the findings of this study indicated that melittin inhibited growth, migration, and invasion, and induced apoptosis of NSCLC cells through down-regulation of TGF-β-mediated ERK signaling pathway, suggesting melittin may be a promising anti-cancer agent for NSCLC therapy.     

溶质载体家族6成员1通过调节PI3K/Akt信号通路磷酸化促进乳腺癌细胞的迁移和侵袭

目的 探讨溶质载体家族6成员1（SLC6A1）对乳腺癌细胞迁移和侵袭的影响及分子机制。 方法 下载并综合分析数据集GSE125989和GSE100534,筛选差异基因;通过STRING数据库和Cytoscape 3.6.1 软件构建差异基因的蛋白相互作用网络,并筛选hub基因;通过Ualcan和GEPIA数据库检测hub基因SLC6A1在乳腺癌中的表达及其对预后的影响;转染SLC6A1-siRNA干扰乳腺癌细胞MDA-MB-231中SLC6A1的表达;细胞划痕实验和Transwell实验检测乳腺癌细胞迁移和侵袭能力的变化;基因集富集分析和Western blotting检测SLC6A1在乳腺癌中发挥作用的机制;采用SC79激活Akt通路并检测细胞迁移和侵袭能力的变化。 结果 共筛选出92个乳腺癌原位癌与转移瘤的差异基因,并确定Ⅰ型胶原蛋白α1（COL1A1）、血管内皮生长因子A（VEGFA）、SLC6A1等20个hub基因;SLC6A1在乳腺癌组织中高表达（P＜0.001）,且与患者预后相关（P=0.01）;SLC6A1表达被干扰后,乳腺癌细胞迁移和侵袭能力显著下降（P＜0.05）;SLC6A1表达降低可抑制PI3K/Akt信号通路的磷酸化（P＜0.05）;激活PI3K/Akt通路后 SLC6A1-siRNA对乳腺癌细胞迁移和侵袭的抑制作用消失（P＜0.05）。 结论 SLC6A1通过调节PI3K/Akt信号通路促进乳腺癌的侵袭和转移。     

E3 ubiquitin-protein ligase 2 inhibits cell proliferation,migration, and invasion of non-small cell lung cancer through ubiquitination of Notch1

This study aimed to explore the role of MIB2 in non-small cell lung cancer (NSCLC) and the underlying mechanism. Quantitative real-time PCR (QRT-PCR) and western blot were first performed to detect MIB2 expression in tumor tissues obtained from NSCLC patients (n = 30) and NSCLC cells, respectively. 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) and transwell assays were then used to examine the effect of MIB2 on the proliferation, migration and invasion of NSCLC cells. Western blot was further performed to examine the effect of Mind bomb 2 (MIB2), an E3 ligase on Notch1 protein and its ubiquitination. MIB2 was significantly down-regulated in NSCLC tissues and cells, both in mRNA and protein level. MIB2 also note worthily inhibited the proliferation, migration, and invasion of NSCLC cells. Furthermore, MIB2 only down-regulated Notch1 protein level, while facilitated the ubiquitination of Notch1. Additionally, Notch1 significantly relieved the repressed proliferation, migration and invasion of NSCLC cells induced by MIB2. Conclusively, MIB2 inhibited cell proliferation, migration and invasion via inducing Notch1 ubiquitination and degradation in NSCLC.     

Ginkgol C17:1 inhibits tumor growth by blunting the EGF-PI3K/Akt signaling pathway

Ginkgol C17:1 has been shown to inhibit apoptosis and migration of cancer cells, but the underlying mechanisms are not fully elucidated. In this study, we explored whether the inhibitory effects of Ginkgol C17:1 were associated with epidermal growth factor receptor (EGFR) and PI3K/Akt signaling. The results showed that EGF treatment increased the phosphorylation of EGFR, PI3K, Akt, mTOR and NF-kB, and also enhanced the proliferation, migration and invasion of HepG2 cells. Ginkgol C17:1 dose-dependently inhibited EGF-induced phosphorylation/activation of all the key components including EGFR, PI3K, Akt, mTOR and NF-kB, leading to a significant reduction either of proliferation or migration and invasion of HepG2 cells. Notably, treatment with Ginkgol C17:1 in mice suppressed the growth of tumor mass in vivo, and expression of EGFR in the tumor tissue. The results suggest that Ginkgol C17:1 is a potent tumor inhibiting compound that acts on EGF-induced signal transduction of the PI3K/vjjhhAkt signaling pathways, and may represent a clinically interesting candidate for cancer therapy.     

桔皮素对人非小细胞肺癌细胞生长及侵袭的影响

目的:探讨桔皮素(TGN)对非小细胞肺癌(NSCLC)细胞生长和侵袭的影响及其分子机制。方法:体外培养非小细胞肺癌A549细胞,分别用不同浓度的TGN处理,MTT比色法检测细胞活性,Annexin V-FITC/PI染色及流式细胞术检测细胞凋亡率,Transwell检测细胞侵袭,RT-PCR分析MMP-2和MMP-9的mRNA表达水平,Western blotting检测Ki67、Cyt C、caspase-3、cleaved caspase-3、MMP-2、MMP-9、Akt、p-Akt以及p-PI3K表达水平。结果:桔皮素剂量依赖性地抑制A549细胞增殖(P0.05),同时伴随有增殖标记分子Ki67表达水平的下调。分析发现,桔皮素诱导细胞中Cyt C、caspase-3和cleaved caspase-3的表达上调(P0.01),加速A549细胞的凋亡。此外,桔皮素作用后,A549细胞中侵袭相关蛋白MMP-2和MMP-9的表达量下降,且侵袭数目随桔皮素浓度增加而减少。进一步研究表明,桔皮素作用后A549细胞中p-Akt和p-PI3K表达水平降低(P0.05),阻断PI3K/Akt信号通路后,不同浓度TGN对细胞活性影响没有变化。结论:桔皮素能抑制A549细胞生长及侵袭,促进细胞凋亡,可能通过抑制PI3K/Akt信号通路的激活起作用。因此,本研究将为非小细胞肺癌的防治提供新的研究方向。     

Elevated expression of Fn14 in non-small cell lung cancer correlates with activated EGFR and promotes tumor cell migration and invasion

Lung cancer is the leading cause of cancer deaths worldwide; approximately 85% of these cancers are non-small cell lung cancer (NSCLC). Patients with NSCLC frequently have tumors harboring somatic mutations in the epidermal growth factor receptor (EGFR) gene that cause constitutive receptor activation. These patients have the best clinical response to EGFR tyrosine kinase inhibitors (TKIs). Herein, we show that fibroblast growth factor-inducible 14 (Fn14; TNFRSF12A) is frequently overexpressed in NSCLC tumors, and Fn14 levels correlate with p-EGFR expression. We also report that NSCLC cell lines that contain EGFR-activating mutations show high levels of Fn14 protein expression. EGFR TKI treatment of EGFR-mutant HCC827 cells decreased Fn14 protein levels, whereas EGF stimulation of EGFR wild-type A549 cells transiently increased Fn14 expression. Furthermore, Fn14 is highly expressed in EGFR-mutant H1975 cells that also contain an EGFR TKI-resistance mutation, and high TKI doses are necessary to reduce Fn14 levels. Constructs encoding EGFRs with activating mutations induced Fn14 expression when expressed in rat lung epithelial cells. We also report that short hairpin RNA-mediated Fn14 knockdown reduced NSCLC cell migration and invasion in vitro. Finally, Fn14 overexpression enhanced NSCLC cell migration and invasion in vitro and increased experimental lung metastases in vivo. Thus, Fn14 may be a novel therapeutic target for patients with NSCLC, in particular for those with EGFR-driven tumors who have either primary or acquired resistance to EGFR TKIs.     

GKN2在胃癌细胞增殖、转移中的作用及机制

目的 探讨胃动蛋白2(gastrokine 2,GKN2)对胃癌细胞的生长增殖、侵袭、转移的影响及分子机制.方法 利用qRT-pCR和Western blot法检测GKN2在胃癌组织中的表达;构建对照细胞株AGS-CON、SGC-7901-CON与GKN2过表达细胞株AGS-GKN2、SGC-7901-GKN2,应用q...     

慢病毒短发夹RNA介导的多形性腺瘤基因样蛋白2沉默对肝癌细胞MHCC97-L增殖、迁移及侵袭的影响

目的 探讨慢病毒短发夹RNA(shRNA)介导的多形性腺瘤基因样蛋白2(PLAGL2)沉默对肝癌细胞恶性行为的影响及其机制.方法 Real-time PCR与Western blotting分别检测肝癌组织及癌旁组织中PLAGL2的表达水平;体外培养肝癌细胞MHCC97-L,构建慢病毒载体质粒PLAGL2-shRNA与...     

下调晚期糖基化终末产物受体对乳腺癌细胞增殖、凋亡、侵袭、迁移能力的影响

目的：研究下调晚期糖基化终末产物受体（RAGE）对乳腺癌细胞增殖、凋亡、侵袭、迁移能力的影响。 方法：培养乳腺癌BT474 细胞,分为对照组（ 不做任何处理的乳腺癌BT474 细胞）、上调组（ 乳腺癌BT474 细 胞+RAGE阴性对照）、下调组（ 乳腺癌BT474 细胞+RAGE siRNA）。用四甲基偶氮唑盐法检测乳腺癌细胞增 殖、凋亡水平;用Transwell 法检测乳腺癌细胞迁移、侵袭水平;用免疫印迹法检测细胞PI3K/Akt 信号通路蛋白 PI3K、p-PI3K、Akt、p-Akt、caspase 3、Bcl-2、Bax 表达量。结果：下调组细胞不同时间点增殖率均显著低于 上调组、对照组。下调组细胞不同时间点凋亡率均显著高于上调组、对照组。下调组细胞迁移、侵袭数均显著 低于上调组、对照组。下调组p-PI3K、PI3K、Akt、p-Akt、Bcl-2 蛋白表达量低于上调组、对照组,caspase 3、 Bax 蛋白表达量高于上调组、对照组。结论：经下调RAGE作用于PI3K/Akt 信号通路,其可抑制p-PI3K、PI3K、 Akt、p-Akt、Bcl-2 表达,促进caspase 3、Bax 表达,致乳腺癌细胞凋亡,抑制乳腺癌细胞增殖、侵袭、迁移。     

Kinase switching in mesenchymal-like non-small cell lung cancer lines contributes to EGFR inhibitor resistance through pathway redundancy

NSCLC cells with a mesenchymal phenotype have shown a marked reduction in sensitivity to EGFR inhibitors, though the molecular rationale has remained obscure. Here we find that in mesenchymal-like tumor cells both tyrosine phosphorylation of EGFR, ErbB2, and ErbB3 signaling networks and expression of EGFR family ligands were decreased. While chronic activation of EGFR can promote an EMT-like transition, once having occurred EGFR family signaling was attenuated. We investigated the mechanisms by which mesenchymal-like cells bypass EGFR signaling and acquire alternative routes of proliferative and survival signaling. Mesenchymal-like NSCLC cells exhibit aberrant PDGFR and FGFR expression and autocrine signaling through these receptors can activate the MEK-ERK and PI3K pathways. Selective pharmacological inhibition of PDGFR or FGFR receptor tyrosine kinases reduced cell proliferation in mesenchymal-like but not epithelial NSCLC cell lines. A metastable, reversible EMT-like transition in the NSCLC line H358 was achieved by exogenous TGFβ, which served as a model EMT system. The H358/TGFβ cells showed many of the attributes of established mesenchymal-like NSCLC cells including a loss of cell-cell junctions, a loss of EGF-family ligand expression, a loss of ErbB3 expression, increased EGFR-independent Mek-Erk pathway activation and reduced sensitivity to EGFR inhibition. Notably an EMT-dependent acquisition of PDGFR, FGFR and TGFβ receptors in H358/TGFbeta cells was also observed. In H358/TGFbeta cells both PDGFR and FGFR showed functional ligand stimulation of their intrinsic tyrosine kinase activities. The findings of kinase switching and acquired PDGFR and FGFR signaling suggest investigation of new inhibitor combinations to target NSCLC metastases.     

Blocking the PI3K/AKT and MEK/ERK signaling pathways can overcome gefitinib-resistance in non-small cell lung cancer cell lines

PurposeTo investigate the effects of gefitinib (EGFR-TKI), LY294002 (PI3K inhibitor) and U0126 (MEK inhibitor) on proliferation and apoptosis in five non-small cell lung cancer (NSCLC) cell lines (PC9, PC9/AB2, H1975, H1299 and A549).MethodsThe inhibitory rates of cells were tested by MTT and apoptosis was detected through flow cytometry when treated with gefitinib, LY294002 and U0126.ResultsThe sensitivity to gefitinib was different in different cell lines, which was associated with EGFR mutation type. The cells with EGFR mutation were more sensitive than those with EGFR wild-type, except PC9/AB2 cells. LY294002 and U0126 can inhibit cell proliferation and promote apoptosis in all five cell lines. The sensitivity to gefitinib was restored partially in the resistant cell lines by combining gefitinib with LY294002 or U0126. The effects on cell proliferation and apoptosis were stronger in cells with EGFR mutation when PI3K/AKT pathway was blocked, however, for cells with EGFR wild-type, the effects were stronger when the MEK pathway was blocked. When the PI3K and MEK pathways were blocked together, proliferation inhibition and apoptosis level in NSCLC cells was similar to that in cells treated with EGFR TKI. There were some differences according to EGFR mutation type, suggesting that EGFR mutations may result in alterations of downstream signaling pathways.ConclusionThe sensitivity of gefitinib resistant cell lines can be restored partially when the two downstream signaling pathways are blocked. However, these cells were still drug resistant, suggesting that the activation of PI3K and MEK pathways is not the only mechanism of EGFR-resistance.     

Inhibition of tissue factor/protease-activated receptor-2 signaling limits proliferation,migration and invasion of malignant glioma cells

Tissue factor (TF) is upregulated in several malignant diseases, including gliomas. Here, we demonstrate pronounced differences in the expression of TF and its interactors factor VII and protease-activated receptor 2 (PAR-2) in nine human glioma cell lines (U87, U251, U343, U373, MZ-18, MZ-54, MZ-256, MZ-304, Hs 683) as detected by RT-PCR and Western blot analysis. Inhibition of TF signaling by a neutralizing monoclonal antibody (mAb TF9-10H10) led to significantly reduced proliferation in high-grade astroglial (MZ-18 and MZ-304) and oligodendroglial (Hs 683) cell lines abundantly expressing TF, but not in U373 cells expressing low amounts of TF. Scratch migration assays and Boyden chamber assays indicated that mAb TF9-10H10 and lentiviral knockdown of TF significantly reduced cell migration and invasion of MZ-18, MZ-304 and Hs 683 cells, both under normoxic and hypoxic conditions. Of note, all three cell lines displayed increased cell migration and invasion under hypoxic conditions (1% O₂), which was associated with enhanced expression of TF and increased phosphorylation of p44/42 mitogen-activated protein kinase (ERK1/2). Silencing of TF blocked activation of the ERK pathway, induction of TF expression and the potentiating effect of hypoxia on cell migration and invasion. RNA interference against PAR-2 abrogated the autocrine effects of TF on cell proliferation, migration and invasion, indicating that TF signals via PAR-2 in glioma cells. Our results suggest an important role for the TF/FVIIa/PAR-2/ERK axis in tumor growth and invasion of glioma and suggest that TF may be a suitable target for the development of novel therapies against high-grade glioma.     

BTG2 inhibits the proliferation and metastasis of osteosarcoma cells by suppressing the PI3K/AKT pathway

B cell translocation gene 2 (BTG2) has been reported to be a potential tumor suppressor in many types of tumors. However, the roles and molecular mechanisms of BTG2 in osteosarcoma progression are still unknown. In this study, we investigated the role of BTG2 in proliferation and metastasis of osteosarcoma and the underlying mechanism. BTG2 expression levels were measured in fresh osteosarcoma tissues and cell lines. The effects of BTG2 on cell proliferation, migration and invasion were explored by MTT, transwell assays, western blot, and in vivo tumorigenesis in nude mice. We found that BTG2 was down-regulated in human osteosarcoma tissues and cell lines. Overexpression of BTG2 inhibited the proliferation and migration/invasion of human osteosarcoma cells in vitro, it also markedly inhibited xenograft tumor growth in vivo. Furthermore, BTG2 significantly decreased the expression of phosphorylated PI3K and AKT in osteosarcoma cells. Taken together, our data indicate that BTG2 might suppress the tumor growth and metastasis via PI3K/AKT signaling pathway, implying that BTG2 may serve as a potential molecular target for the treatment of osteosarcoma.     

Long non-coding RNA ncRuPAR regulates gastric cancer cell proliferation and apoptosis via phosphoinositide 3-kinase/protein kinase B signaling

Objective: To determine the effect and mechanism of the long non-coding RNA (lncRNA) ncRuPAR (non-protein coding RNA, upstream of coagulation factor II thrombin receptor [F2R]/protease-activated receptor-1 [PAR-1]) in human gastric cancer.Methods: HGC-27-ncRuPAR overexpression and MGC-803-ncRuPAR-RNAi knockdown gastric cancer cell lines were established. We assessed the effect of ncRuPAR on cell proliferation, apoptosis, migration, and invasion using Cell Counting Kit 8, flow cytometry, scratch and transwell assays, respectively. Differentially expressed genes in HGC-27-ncRuPAR overexpression and HGC-27-empty vector cell lines were identified using Affymetrix GeneChip microarray analysis. Ingenuity Pathway Analysis (IPA) of the microarray results was subsequently conducted to identify ncRuPAR-enriched pathways, followed by validation using real time-quantitative PCR (RT-qPCR). As one of the top enriched pathways, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was further examined by western blotting to determine its role in ncRuPAR-mediated regulation of gastric cancer pathogenesis.Results: ncRuPAR inhibited human gastric cancer cell proliferation and induced G1/S phase arrest and apoptosis, but did not affect migration or invasion in vitro. Overexpression of ncRuPAR in vitro was found to inhibit its known target PAR-1, as well as PI3K/Akt signaling. The downstream targets of PI3K/Akt, cyclin D1 was downregulated, but there was no change in expression level of B-cell lymphoma 2 (Bcl-2).Conclusions: We showed that lncRNA-ncRuPAR could inhibit tumor cell proliferation and promote apoptosis of human gastric cancer cells, potentially by inhibiting PAR-1, PI3K/Akt signaling, and cyclin D1. The results suggest a potential role for lncRNAs as key regulatory hubs in GC progression.