Cyclooxygenase-2 Expression Correlates With Membrane-Type-1 Matrix Metalloproteinase Expression in Colorectal Cancer Tissue

Purpose Elevated expression of cyclooxygenase-2 has been found in colorectal cancer. One of the mechanisms through which cyclooxygenase-2 affects tumorigenesis is through its overexpression, which leads to increased invasiveness of cancer cells. A crucial step in this pathway is thought to be the induction of membrane-type-1 matrix metalloproteinase, which activates matrix metalloproteinase-2. However, to date there have been few clinicopathologic studies concerning cyclooxygenase-2-mediated invasiveness in human colorectal cancer tissues. Methods We performed immunohistochemical analysis of the respective antigens on colorectal cancer specimens obtained by surgical resections from 96 patients with colorectal cancer. Results Cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression was positive exclusively in cancer cells in 88 cases (92 percent) and 23 cases (24 percent), respectively. All 23 cases expressing membrane-type-1 matrix metalloproteinase also expressed cyclooxygenase-2. Matrix metalloproteinase-2 expression was positive in cancer cells in 20 cases (21 percent) and stromal cells in 52 cases (54 percent). Expression of matrix metalloproteinase-2 in cancer cells correlated with lymphatic invasion and local recurrence. Statistically, a significant correlation was found between cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression, and membrane-type-1 matrix metalloproteinase and matrix metalloproteinase-2 expression in cancer cells. There was no association between cyclooxygenase-2 expression and matrix metalloproteinase-2 expression. However, immunostaining of serial sections revealed that in the majority of cases examined, nearly 100 percent of cancer cells expressing matrix metalloproteinase-2 also coexpressed cyclooxygenase-2. Conclusions This study indicates strong association between both cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression, and membrane-type-1 matrix metalloproteinase and matrix metalloproteinase-2 in colorectal cancer. These results support our thesis of a direct correlation between cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression—with consequent association between cyclooxygenase-2 and matrix metalloproteinase-2 activation, and tumor invasiveness andrecurrence in certain cases of colorectal cancer. Presented at the meeting of the American Gastroenterological Association, Digestive Diseases Week, May 14 to 19, 2005, Chicago, Illinois. Reprints are not available.     

PPIs抑制P13K/Akt／mTOR信号通路逆转胃癌细胞的化疗多药耐药

背景：前期实验显示质子泵抑制剂（PPIs）可抑制空泡型质子泵（V-H＋-ATPases）和多药耐药蛋白P—gP、MRP1表达,增强胃癌细胞的化疗敏感性。目的：探讨PPIs抑制空泡型质子泵逆转胃癌细胞化疗多药耐药与P13K／Akt／mTOR信号通路的关系。方法：应用不同浓度埃索美拉唑或泮托拉唑预处理人胃腺癌细胞敏感株SGC7901和多药耐药株SGC7901／MDR,或以V—H＋-ATPasessiRNA干扰SGC7901／MDR细胞内的V-H＋-ATPases表达,或以雷帕霉素阻断mTOR表达,以蛋白质印迹法检测经不同方式处理的细胞内V—H＋ATPases、P—SP、MRPl蛋白表达以及P13K／Akt/mT0R／HIF—1α信号通路及其信号旁路TSCl／2-Rheb中的相关蛋白表达;以免疫荧光法检测经埃索美拉唑预处理的SGC7901／MDR细胞内的V-H＋ATPases、P—gP蛋白表达和定位。结果：PPIs可呈浓度依赖性地抑制SGC7901／MDR细胞内的V—H＋ATPases、P13K、Akt、roTOR、HIF-1仅、TSCI、TSC2、Rheb、P—gP、MRP1表达以及Akt底物和TSC2磷酸化,改变V-H＋ATPases、P—gP的胞内定位,对SGC7901细胞则无上述影响。以V—H＋-ATPasessiRNA抑制SGC7901／MDR细胞内的V—H＋-ATPases表达,作用与PPIs预处理相似。以雷帕霉素阻断mTOR可呈浓度依赖性地抑制SGC7901／MDR细胞内的HIF-1α、P—gP表达。结论：PPIs抑制空泡型质子泵逆转胃癌细胞化疗多药耐药的机制与抑制P13K／Akt／mTOR信号通路有关。     

Make Yourself at Home: Viral Hijacking of the PI3K/Akt Signaling Pathway

As viruses do not possess genes encoding for proteins required for translation, energy metabolism or membrane biosynthesis, they are classified as obligatory intracellular parasites that depend on a host cell to replicate. This genome limitation forces them to gain control over cellular processes to ensure their successful propagation. A diverse spectrum of virally encoded proteins tackling a broad spectrum of cellular pathways during most steps of the viral life cycle ranging from the host cell entry to viral protein translation has evolved. Since the host cell PI3K/Akt signaling pathway plays a critical regulatory role in many cellular processes including RNA processing, translation, autophagy and apoptosis, many viruses, in widely varying ways, target it. This review focuses on a number of remarkable examples of viral strategies, which exploit the PI3K/Akt signaling pathway for effective viral replication.     

Targeting PI3K/Akt/HSP90 Signaling Sensitizes Gastric Cancer Cells to Deoxycholate-Induced Apoptosis

Background  

The heat shock protein 90 (HSP90) plays a crucial role in the stability of several proteins that are essential for cell survival and for malignant transformation. The binding of HSP90 with pro-survival kinase Akt prevents proteosomal degradation of Akt and contributes to the functional stabilization of PI3K/Akt signaling and cell survival. Akt kinase and HSP90 are therefore highly over-expressed in a large panel of cancer cell lines and are present in multi-chaperoning complexes. In this paper, we investigated whether targeting both Akt and HSP90 would inhibit the survival pathway in AGS cells (human gastric mucosal cells), and how Akt/HSP90 inhibition modulates the deoxycholate (DC)-induced apoptosis.     

内皮祖细胞与PI3K/Akt信号传导通路

内皮祖细胞作为内皮的前体细胞,主要来源于骨髓,在成人受损血管的修复、新生血管发生/生成中起重要作用.多种伴有血管内皮细胞损伤的疾病都可引起外周血循环、内皮祖细胞数量、功能的变化.因此,内皮祖细胞功能的研究,日益为人们所关注.研究显示PI3K/Akt信号传导通路在内皮祖细胞的动员、迁移、归巢、分化、抗凋亡上发挥重要作用.现主要就内皮祖细胞与PI3K/Akt信号传导通路关系作一综述.     

巨噬细胞游走抑制因子通过PI3K／Akt信号通路调控人结肠癌细胞株HT-29增殖和血管生成因子表达

背景：巨噬细胞游走抑制因子（MIF）是-种多功能细胞因子,其在结直肠癌发生、发展中的作用机制尚不明确。目的：探讨MIF是否通过P13K／Akt信号通路调控人结肠癌细胞增殖和血管生成因子表达。方法：人结肠癌细胞株HT-29分为对照组（RPMI-1640）、重组人MIF（rhMIF）组、PI3K抑制剂LY294002组和LY294002预处理联合rhMIF组,并予相应干预。以甲基噻唑基四唑（MTT）法检测HT-29细胞增殖状态,分别以逆转录聚合酶链反应（RT-PCR）和酶联免疫吸附测定（ELISA）检测血管内皮生长因子（VEGF）、白细胞介素-8（IL-8）mRNA表达和蛋白分泌,蛋白质印迹法检测Akt和磷酸化Akt（p—Akt）蛋白表达。结果：rhMIF对HT-29细胞具有促增殖作用,能增加细胞VEGF、IL-8 mRNA表达和蛋白分泌,并促进Akt蛋白磷酸化（P＜0．05）;而先予LY294002预处理可显著抑制rhMIF的上述作用．HT-29细胞增殖显著受抑（P＜0．05）,VEGF、IL-8mRNA表达、蛋白分泌以及p-Akt蛋白水平与对照组相比无明显差异。各组总Akt蛋白水平均无明显差异。结论：MIF诱导人结肠癌细胞增殖和血管生成因子表达可能是通过活化PI3K／Akt信号通路实现的。     

PI3K/Akt/mTOR信号通路对大鼠肾小球系膜细胞增殖的调控作用探讨

目的:探讨磷脂酰肌醇-3(PI3K)/蛋白激酶(Akt)/哺乳动物雷帕霉素靶蛋白(m TOR)信号通路对大鼠肾小球系膜细胞(MC)增殖的调控作用。方法:体外培养大鼠MC,随机分为正常对照组、表皮生长因子(EGF)(10ng/m L)组、PI3K抑制剂LY294002组(2μg/m L)、EGF联合LY294002组。采用四甲基偶氮唑蓝(MTT)法检测4组MC的增殖,流式细胞术检测MC周期,免疫荧光法检测系膜细胞m TOR的表达。结果:与正常对照组相比,EGF组能显著促进大鼠MC增殖,G0/G1期细胞减少,S期及G2/M期细胞增加,且m TOR表达增加;LY294002组大鼠MC增殖受抑制,G0/G1期细胞增加,S期及G2/M期细胞减少,且m TOR表达降低;与EGF组比较,EGF联合LY294002干预组MC增殖受抑制,G0/G1期细胞增多,S期及G2/M期细胞减少,且m TOR表达降低。结论:m TOR信号通路参与了大鼠肾小球MC增殖的调控,抑制该信号通路的活化可显著抑制MC的增殖和MC周期的进程。     

MiR-325 Promotes Oxaliplatin-Induced Cytotoxicity Against Colorectal Cancer Through the HSPA12B/PI3K/AKT/Bcl-2 Pathway

Background

Oxaliplatin is one of the most effective chemotherapeutic drugs used for the treatment of colorectal cancer (CRC). However, intervention that attenuates the resistance of oxaliplatin is still required in the treatment of CRC.

Aims

To investigate the role of miR-325 in changing the oxaliplatin sensitivity to CRC cells.

Methods

Expression of miR-325 in colorectal cancer tissues and cell lines was measured by using qRT-PCR analysis. Cytotoxicity of oxaliplatin to control or miR-325-overexpressed HT29 and SW480 cells was evaluated by CCK-8 assays. Luciferase reporter assay was used to confirm the regulation of miR-325 on HSPA12B. Flow cytometry was performed to detect the mitochondrial membrane potential and cell apoptosis.

Results

Expression of miR-325 was decreased in colorectal cancer tissues and cell lines. However, overexpression of miR-325 can decrease the 50% inhibiting concentration of oxaliplatin to colorectal cancer cell lines HT29 and SW480. Mechanically, we confirmed that miR-325 targeted HSPA12B in colorectal cancer. Therefore, overexpression of miR-325 inhibited the phosphorylation of PI3K and AKT and decreased the expression of Bcl-2 to promote the oxaliplatin-induced mitochondrial apoptosis in colorectal cancer.

Conclusions

MiR-325 sensitizes the colorectal cancer cells to oxaliplatin-induced cytotoxicity through the HSPA12B/PI3K/AKT/Bcl-2 pathway.

     

抑制PI3K/Akt/mTOR信号通路对兔原代巨噬细胞自体吞噬的影响及机制

目的 探讨抑制PI3K/Akt/mTOR信号通路对兔原代巨噬细胞自体吞噬中的影响。方法 分离培养纯种新西兰兔腹腔原代巨噬细胞并分为4组,加入磷脂酰肌醇3激酶（PI3K）抑制剂LY294002（10 μmol/L）组、哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂雷帕霉素（10 nmol/L）组、蛋白激酶B（Akt）抑制剂曲西立滨组（20 μmol/L）以及空白对照组。共培养4 h、12 h后分别收集细胞,运用透射电镜观察巨噬细胞自噬体的变化,细胞免疫荧光法检测微管相关蛋白轻链3Ⅱ（LC3Ⅱ）分子的表达,Western blot检测 Akt、mTOR、磷酸化Akt（p-Akt）、磷酸化mTOR（p-mTOR）及自噬相关蛋白Beclin-1和自噬蛋白Atg5-Atg12连接体的表达,单丹酰尸胺（MDC）染色法观察自噬溶酶体的变化。结果 与空白对照组相比,透射电镜下LY294002组自噬体、自噬空泡、髓磷脂图像等自噬标记物明显减少,雷帕霉素组、曲西立滨组明显增多;激光共聚焦显微镜下LY294002组LC3Ⅱ表达显著减少,雷帕霉素组、曲西立滨组表达显著增多;Western blot结果显示LY294002组Beclin-1及Atg5-Atg12蛋白表达水平显著下降,p-mTOR、p-Akt蛋白表达显著减少;雷帕霉素组、曲西立滨组Beclin-1及Atg5-Atg12蛋白表达水平明显上调,共培养4 h后p-Akt表达增多,雷帕霉素组p-mTOR表达增多,曲西立滨组减少;共培养12 h后雷帕霉素组、曲西立滨组p-mTOR表达显著减少,雷帕霉素组p-Akt表达显著增多,曲西立滨组显著减少;MDC染色显示LY294002组自噬溶酶体明显减少,雷帕霉素组、曲西立滨组明显增多。结论 抑制PI3K/Akt/mTOR信号通路能促进兔原代巨噬细胞自体吞噬,抑制PI3K能减少兔原代巨噬细胞自体吞噬,可能是不同类型的PI3K分子通过其他通路起作用。     

HB-EGF enhances restitution after intestinal ischemia/reperfusion via PI3K/Akt and MEK/ERK1/2 activation

BACKGROUND & AIMS: Early recovery of intestinal function after injury occurs by restitution, a complex process with a poorly understood molecular basis. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a potent chemotactic factor that is induced during ischemia/reperfusion in vivo and intestinal wounding in vitro. The role of HB-EGF in intestinal restitution and the underlying intracellular signaling pathways involved were investigated. METHODS: Adult rats were subjected to intestinal ischemia, with histologic and biochemical damage assessed during the first 3 hours of reperfusion. The effect of recombinant HB-EGF (rHB-EGF) on structural and functional recovery of the intestine by restitution was evaluated in vivo. Scrape wounding of intestinal epithelial cell monolayers was used to elucidate the mechanisms of intrinsic and rHB-EGF-induced restitution. RESULTS: Early structural recovery occurred within 3 hours of reperfusion and was attributed to restitution rather than proliferation. HB-EGF treatment significantly improved structural recovery and accelerated functional recovery of the gut barrier. In vivo restitution was preceded by activation of Akt and extracellular signal-regulated kinase (ERK) 1/2, which were accelerated and enhanced by HB-EGF treatment. Blocking of ErbB-1, phosphatidylinositol 3-kinase (PI3K)/Akt, or mitogen-activated protein kinase/ERK kinase (MEK)/ERK activity resulted in significant reduction in intrinsic and HB-EGF-induced restitution in vitro. Endogenous HB-EGF was shown to play an essential role in wound-induced ErbB-1 and ERK1/2 activation and in intrinsic restitution. CONCLUSIONS: Endogenous HB-EGF, ErbB-1, PI3K/Akt, and MEK/ERK are involved in intrinsic restitution. rHB-EGF enhances restitution in vivo and in vitro in a PI3K/Akt- and MEK/ERK1/2-dependent fashion.     

ghrelin通过PI3K/Akt信号通路促进RAW264.7源性泡沫细胞迁移

目的探讨ghrelin对RAW264.7源性泡沫细胞迁移的影响及相关机制。方法油红O检测泡沫细胞模型的构建,胆固醇氧化酶法检测泡沫细胞内总胆固醇(TC)、游离胆固醇(FC)和胆固醇酯(CE)含量,transwell小室实验检测ghrelin对RAW264.7源性泡沫细胞迁移的影响,Western blot检测Akt、p-Akt和cleaved Caspase-3蛋白的表达,免疫荧光检测p-Akt和cleaved Caspase-3的表达,细胞骨架荧光探针检测细胞骨架的变化。观察PI3K特异性抑制剂LY294002是否影响RAW264.7源性泡沫细胞的迁移能力及相关蛋白的表达。结果 10-7mol/L ghrelin处理RAW264.7源性泡沫细胞可以促进泡沫细胞迁移,此过程可以被LY294002逆转。Western blot结果显示10-7mol/L ghrelin可显著升高RAW264.7源性泡沫细胞p-Akt的表达,降低cleaved Caspase-3的表达(P0.05),并明显改善RAW264.7源性泡沫细胞的迁移能力(P0.05),LY294002可逆转以上变化。免疫荧光检测显示Akt在RAW264.7细胞明显表达,ghrelin组表达增多,LY294002组明显降低。结论 ghrelin可促进RAW264.7源性泡沫细胞迁移,其分子机制可能与激活PI3K/Akt信号通路有关。     

Stem Cell Factor/c-<Emphasis Type="Italic">kit</Emphasis> Receptor Signaling Enhances the Proliferation and Invasion of Colorectal Cancer Cells Through the PI3K/Akt Pathway

In this study, we examined the role of c-kit receptor (KIT) signal transduction on the proliferation and invasion of colorectal cancer cells. We found that c-kit was expressed in 2 colorectal cancer cell lines as determined by RT-PCR, Western blot, and flow cytometry. In KIT-positive lines, KIT was activated by stem cell factor (SCF). SCF enhanced cellular proliferation of positive lines as demonstrated by the WST-1 proliferation assay. Furthermore, SCF enhanced the invasive ability of KIT-positive cell lines. SCF stimulation upregulated p44/42 mitogen-activated protein kinase (MAPK) and Akt as shown by Western blot. We examined the roles played by p44/42 MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways in proliferation and invasion. PI3K/Akt activity strongly correlated with proliferation and invasion and p44/42 MAPK was correlated with only invasion. In conclusion, the SCF-enhanced proliferation and invasion of KIT-positive colorectal cancer cells is achieved mainly through the PI3K/Akt pathway.     

miR-182 and miR-135b Mediate the Tumorigenesis and Invasiveness of Colorectal Cancer Cells via Targeting ST6GALNAC2 and PI3K/AKT Pathway

Digestive Diseases and Sciences - Metastasis is a leading cause of cancer-related death including colorectal cancer (CRC). MicroRNAs are known to regulate cancer pathways and to be expressed...     

Facilitation of Myocardial PI3K/Akt/nNOS Signaling Contributes to Ethanol-Evoked Hypotension in Female Rats

Background: The mechanism by which ethanol reduces cardiac output (CO) and blood pressure (BP) in female rats remains unclear. We tested the hypothesis that enhancement of myocardial phosphatidylinositol 3‐kinase (PI3K)/Akt signaling and related neuronal nitric oxide synthase (nNOS) and/or endothelial nitric oxide synthase (eNOS) activity constitutes a cellular mechanism for the hemodynamic effects of ethanol. Methods: We measured the level of phosphorylated eNOS (p‐eNOS) and p‐nNOS in the myocardium of ethanol (1 g/kg intragastric, i.g.) treated female rats along with hemodynamic responses [BP, CO, stroke volume, (SV), total peripheral resistance, (TPR)], and myocardial nitrate/nitrite levels (NOx) levels. Further, we investigated the effect of selective pharmacological inhibition of nNOS with N^ω‐propyl‐l ‐arginine (NPLA) or eNOS with N⁵‐(1‐iminoethyl)‐l ‐ornithine (l ‐NIO) on cellular, hemodynamic, and biochemical effects of ethanol. The effects of PI3K inhibition by wortmannin on the cardiovascular actions of ethanol and myocardial Akt phosphorylation were also investigated. Results: The hemodynamic effects of ethanol (reductions in BP, CO, and SV) were associated with significant increases in myocardial NOx and myocardial p‐nNOS and p‐Akt expressions while myocardial p‐eNOS remained unchanged. Prior nNOS inhibition by NPLA (2.5 or 12.5 μg/kg) attenuated hemodynamic effects of ethanol and abrogated associated increases in myocardial NOx and cardiac p‐nNOS contents. The hemodynamic effects of ethanol and increases in myocardial p‐Akt phosphorylation were reduced by wortmannin (15 μg/kg). On the other hand, although eNOS inhibition by l ‐NIO (4 or 20 mg/kg) in a dose‐dependent manner attenuated ethanol‐evoked hypotension, the concomitant reductions in CO and SV remained unaltered. Also, selective eNOS inhibition uncovered dramatic increases in TPR in response to ethanol, which appeared to have offset the reduction in CO. Neither NPLA nor l ‐NIO altered plasma ethanol levels. Conclusions: These findings implicate the myocardial PI3K/Akt/nNOS signaling in the reductions in BP and CO produced by ethanol in female rats.     

非小细胞肺癌中PI3K/Akt信号通路通过Cdh1调控Skp2表达的机制研究

目的探讨非小细胞肺癌（NSCLC）中Cdc20同源蛋白1（Cdh1）参与磷脂酰肌醇三羟基激酶（PI3K）/Akt信号通路对S期激酶相关蛋白2（Skp2）表达调控的机制。方法体外培养NSCLC细胞系A549、LK2和H460,LY294002特异性阻断PI3K/Akt信号通路后,Western blot检测Skp2、Cdh1及p-Akt蛋白表达的变化,免疫荧光（IF）检测Cdh1在NSCLC中的定位变化。结果 LY294002处理后,与对照组相比3种细胞中Skp2蛋白表达和Akt磷酸化水平均降低（P〈0.01）,Cdh1在3种细胞的核内表达均增多。结论 NSCLC中PI3K/Akt信号通路抑制剂LY294002使Skp2蛋白表达下调与Cdh1由细胞质向细胞核转位有关。     

粒细胞集落刺激因子通过PI3K-Akt通路抑制缺血再灌注损伤

目的:研究经冠状动脉(冠脉)内注入粒细胞集落刺激因子(G-CSF)对大鼠心肌缺血再灌注损伤的预防作用,及其与PI3K-Akt信号转导途径的关系。方法:制备大鼠心肌缺血再灌注模型。再灌注同时经冠脉内给予G-CSF或G-CSF+PI3K激酶抑制剂(LY294002),灌注120min后应用TUNEL法检测细胞凋亡,免疫组织化学法观察凋亡相关蛋白Bax及Bcl-2及caspase-3表达情况,免疫印迹检测总-Akt(t-Akt)及磷酸化Akt(p-Akt)表达。结果:缺血再灌注同时给予冠脉内G-CSF治疗能够显著减轻缺血区心肌细胞凋亡,降低Bax、caspase-3的表达,增高心肌细胞内Bcl-2表达,同时p-Akt的蛋白水平显著增高(P<0.01)。LY294002阻断Akt活化后,抑制了G-CSF诱导的抗心肌细胞凋亡作用。结论:缺血再灌注同时冠脉内给予G-CSF可保护梗死区残存的心肌细胞,减少缺血再灌注所诱导的心肌细胞凋亡,其保护机制与PI3K-Akt信号通路有关。     

人宫颈癌癌基因-2 促进SMMC 7721细胞分裂和增殖的机制

目的 建立稳定转染含人宫颈癌癌基因(HCCR)-2的SMMC 7721细胞株,探讨HCCR-2对肝癌细胞生物学特性的影响与在SMMC 7721细胞中HCCR蛋白表达的分子信号通路机制. 方法通过脂质体将HCCR-2的真核表达质粒稳定转染至SMMC 7721细胞,Western blot 检测转染后SMMC 7721细胞中HCCR及其下游基因bcl-2蛋白的表达;四甲基偶氮唑盐法检测HCCR-2对转染后SMMC 7721细胞生长的影响;流式细胞仪检测转染后SMMC 7721细胞周期和细胞凋亡率的变化.用不同浓度表皮生长因子(EGF)处理SMMC 7721细胞24 h,以及用LY294002预孵育细胞1 h后用EGF(100 ng/m1)处理SMMC 7721细胞24 h,Western blot检测HCCR的表达变化.建立稳定转染缺陷型Akt质粒(DN-Akt-pcDNA3.1)的SMMC 7721细胞,Western blot 检测总Akt、磷酸化Akt、HCCR及其下游基因bcl-2的表达.数据以均数±标准差(-x±s)表示,进行单因素方差分析.结果 转染HCCR-2的SMMC 7721细胞较转染空载体的SMMC 7721细胞及亲本细胞的HCCR表达升高,HCCR下游基因bcl-2的表达也升高;四甲基偶氮唑盐法显示其增殖能力增强,从72 h开始转染组较空载体组增殖速度加快(P＜0.01);流式细胞仪检测其细胞凋亡率下降(7.72%±0.23%与1.28%±0.16%,P＜0.01),处于分裂周期的细胞比例明显增加(15.76%±0.73%与21.62%±1.33%,P＜0.01).EGF可促进SMMC 7721细胞中HCCR的表达,用LY294002处理细胞后EGF对其HCCR表达的促进作用被抑制.转染DN-Akt-pcDNA3.1的SMMC 7721细胞中HCCR的表达下降,其下游基因bcl-2的表达亦下降.结论 EGF可通过磷脂酰肌醇3激酶/蛋白激酶B信号通路诱导人肝癌细胞SMMC 7721中HCCR蛋白的表达,HCCR可影响人肝癌细胞的细胞周期、凋亡和增殖能力.     

Y-box binding protein 1 augments sorafenib resistance via the PI3K/Akt signaling pathway in hepatocellular carcinoma

BACKGROUNDSorafenib is the first-line treatment for patients with advanced hepatocellular carcinoma (HCC). Y-box binding protein 1 (YB-1) is closely correlated with tumors and drug resistance. However, the relationship between YB-1 and sorafenib resistance and the underlying mechanism in HCC remain unknown.AIMTo explore the role and related mechanisms of YB-1 in mediating sorafenib resistance in HCC.METHODSThe protein expression levels of YB-1 were assessed in human HCC tissues and adjacent nontumor tissues. Next, we constructed YB-1 overexpression and knockdown hepatocarcinoma cell lines with lentiviruses and stimulated these cell lines with different concentrations of sorafenib. Then, we detected the proliferation and apoptosis in these cells by terminal deoxynucleotidyl transferase dUTP nick end labeling, flow cytometry and Western blotting assays. We also constructed a xenograft tumor model to explore the effect of YB-1 on the efficacy of sorafenib in vivo. Moreover, we studied and verified the specific molecular mechanism of YB-1 mediating sorafenib resistance in hepatoma cells by digital gene expression sequencing (DGE-seq).RESULTSYB-1 protein levels were found to be higher in HCC tissues than in corresponding nontumor tissues. YB-1 suppressed the effect of sorafenib on cell proliferation and apoptosis. Consistently, the efficacy of sorafenib in vivo was enhanced after YB-1 was knocked down. Furthermore, KEGG pathway enrichment analysis of DGE-seq demonstrated that the phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was essential for the sorafenib resistance induced by YB-1. Subsequently, YB-1 interacted with two key proteins of the PI3K/Akt signaling pathway (Akt1 and PIK3R1) as shown by searching the BioGRID and HitPredict websites. Finally, YB-1 suppressed the inactivation of the PI3K/Akt signaling pathway induced by sorafenib, and the blockade of the PI3K/Akt signaling pathway by LY294002 mitigated YB-1-induced sorafenib resistance.CONCLUSIONOverall, we concluded that YB-1 augments sorafenib resistance through the PI3K/Akt signaling pathway in HCC and suggest that YB-1 is a key drug resistance-related gene, which is of great significance for the application of sorafenib in advanced-stage HCC.