Radiation-enhanced hepatocellular carcinoma cell invasion with MMP-9 expression through PI3K/Akt/NF-kappaB signal transduction pathway

This study is to investigate the molecular mechanism of radiation-enhanced cell invasiveness of hepatocellular carcinoma (HCC) correlating with clinical patients undergoing radiotherapy and subsequently developing metastasis. Three HCC cell lines (HepG2, Hep3B and Huh7) and normal hepatocyte cell line (CL-48) were irradiated with different doses. The effect of radiation on cell invasiveness was determined using the Boyden chamber assay. Radiation-enhanced invasion capability was evident in HCC cells but not in normal hepatocytes. Invasion was observed in gelatin-coated but not fibronectin-coated or type I collagen-coated membranes. Radiation upregulated matrix metalloproteinase-9 (MMP-9) mRNA level, MMP-9 protein level and MMP-9 activity. MMP-9 antisense oligonucleotides inhibited radiation-induced MMP-9 expression and thereby significantly inhibited radiation-induced HCC invasion. Furthermore, phosphatidylinositol 3-kinase (PI3K)/Akt chemical inhibitors LY294002 and wortmannin suppressed radiation-induced MMP-9 mRNA expression. Transient transfection with dominant-negative Akt plasmid also showed that the PI3K/Akt-signaling pathway was involved in this radiation-induced MMP-9 expression. Moreover, nuclear factor-kappaB (NF-kappaB) decoy oligodeoxynucleotide suppressed radiation enhanced MMP-9 promoter activity completely. PI3K/Akt chemical inhibitors inhibited radiation-induced NF-kappaB-driven luciferase promoter activity. Taken together, our results indicated that sublethal dose of radiation could enhance HCC cell invasiveness by MMP-9 expression through the PI3K/Akt/NF-kappaB signal transduction pathway.     

Activation of PI3K-Akt signaling pathway promotes prostate cancer cell invasion

Activated phosphoinositide 3-kinase (PI3K) and its downstream target Akt/PKB are important signaling molecules and key survival factors involved in the control of cell proliferation, apoptosis and oncogenesis. We investigated the role of the PI3K-Akt signaling pathway in the invasion of prostate cancer cell lines and activation of this pathway in primary human prostate tumors. Treatment of human prostate cancer cells viz. LNCaP, PC-3 and DU145 with PI3K pharmacological inhibitor, LY294002, potentially suppressed the invasive properties in each of these cell lines. Restoration of the PTEN gene to highly invasive prostate cancer PC-3 cells or expression of a dominant negative version of the PI3K target, Akt also significantly inhibited invasion and downregulated protein expression of urokinase-type plasminogen activator (uPA) and matrix metalloproteinase (MMP)-9, markers for cell invasion, indicating a central role of the PI3K-Akt pathway in this process. Immunoblot analysis of PI3K and total/activated levels of Akt showed increased protein levels of catalytic (p110alpha/beta) and regulatory (p85) subunits of PI3K and constitutive Akt activation in high-grade tumors compared to low-grade tumor and benign tissue. Immunohistochemical analyses further confirmed a progressive increase in p-Akt (p-Ser473) levels but not of total-Akt (Akt1/2) in cancer tissues compared to benign specimens. A successive increase in p-Akt expression was further noted in specimens serially obtained from individuals with time-course disease progression. Taken together, these results suggest that aberrant activation of PI3K-Akt pathway may contribute to increased cell invasiveness and facilitate prostate cancer progression.     

芹菜素通过 PI3K/Akt 信号通路诱导 Hela 细胞凋亡

目的：初探芹菜素（Apigenin）对人宫颈癌细胞 Hela 的抑制机制。方法：MTT 法检测 Apigenin 对 Hela细胞的增殖抑制作用,实时无标记细胞分析技术测量 Apigenin 对 Hela 细胞生长曲线的影响。Western blot 检测 Apigenin 对 Hela 细胞中 PI3K/ Akt 信号通路的影响。结果：与阴性对照组相比,Apigenin 能显著抑制 Hela细胞的增殖（P <0.01）,当药物浓度为20μmol/ L 时抑制率达到（80.5±5.3）%,IC50值为（6.8±0.8）μmol/ L。细胞生长曲线反映,Apigenin 减缓了 Hela 细胞的增殖,对数期细胞经20μmol/ L Apigenin 处理后,细胞数量迅速下降。Western blot 结果显示,Apigenin 能显著抵抗 IGF -1引起的 Akt 激活但并不能降低 PI3K 的磷酸化水平。同时 Apigenin 还能降低 Bcl -2/ Bax 比例,提高 Caspase -3活性,启动细胞线粒体凋亡。结论：Apigenin可以通过 PI3K/ Akt 信号通路促进 Hela 细胞的凋亡。     

ＰＩ３Ｋ／Ａｋｔ信号传导通路及其在结直肠癌中的研究进展

结直肠癌是常见的恶性肿瘤之一,近十年来,结直肠癌在我国的发病率呈逐年上升的趋势。已有研究表明,ＰＩ３Ｋ／Ａｋｔ信号传导通路是与细胞增殖和细胞凋亡关系最密切的信号传导通路之一。随着ＰＩ３Ｋ／ＡＫｔ信号通路在结直肠癌发生、发展中的研究不断深入,该通路对结直肠癌发生、发展及治疗药物的研发具有十分重要的价值。本文就ＰＩ３Ｋ／Ａｋｔ信号传导通路在结直肠癌发生、发展和治疗中的作用以及机制的研究进展作一综述。     

Effects of AFP-activated PI3K/Akt signaling pathway on cell proliferation of liver cancer

This study aims to investigate effects of alpha-fetoprotein (AFP)-activated phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway on hepatocellular carcinoma cell proliferation. Active cirrhosis patients after hepatitis B infection (n?=?20) and viral hepatitis patients with hepatocellular carcinoma (HCC) (n?=?20) were selected as the subjects of the present study. Another 20 healthy subjects were selected as the control group. The serum AFP expression and liver tissue PI3K and Akt gene mRNA expression were detected. The hepatoma cell model HepG2 which had a stable expression of AFP gene was used. Real-time quantitative PCR and Western blot and other methods were used to analyze the intracellular PI3K and Akt protein levels. Compared with control group and cirrhosis group, the serum AFP levels in HCC group significantly increased, and the tissue PI3K and Akt mRNA expression also significantly increased. HepG2 cells were intervened using AFP, in which the PIK and Akt protein expression significantly increased. After intervention by use of AFP monoclonal antibodies or LY294002 inhibitor, the PIK and Akt protein expression in HepG2 cell was significantly decreased (P?<?0.05). AFP can promote the proliferation of hepatoma cells via activation of PI3K/Akt signaling pathway.     

PI3K/Akt signalling pathway and cancer

Phosphatidylinositol-3 kinases, PI3Ks, constitute a lipid kinase family characterized by their ability to phosphorylate inositol ring 3'-OH group in inositol phospholipids to generate the second messenger phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P(3)). RPTK activation results in PI(3,4,5)P(3) and PI(3,4)P(2) production by PI3K at the inner side of the plasma membrane. Akt interacts with these phospholipids, causing its translocation to the inner membrane, where it is phosphorylated and activated by PDK1 and PDK2. Activated Akt modulates the function of numerous substrates involved in the regulation of cell survival, cell cycle progression and cellular growth. In recent years, it has been shown that PI3K/Akt signalling pathway components are frequently altered in human cancers. Cancer treatment by chemotherapy and gamma-irradiation kills target cells primarily by the induction of apoptosis. However, the development of resistance to therapy is an important clinical problem. Failure to activate the apoptotic programme represents an important mode of drug resistance in tumor cells. Survival signals induced by several receptors are mediated mainly by PI3K/Akt, hence this pathway may decisively contribute to the resistant phenotype. Many of the signalling pathways involved in cellular transformation have been elucidated and efforts are underway to develop treatment strategies that target these specific signalling molecules or their downstream effectors. The PI3K/Akt pathway is involved in many of the mechanisms targeted by these new drugs, thus a better understanding of this crossroad can help to fully exploit the potential benefits of these new agents.     

LRRC3B对食管癌细胞Eca109迁移、侵袭及PI3K/Akt信号通路的影响

背景与目的:先前的研究已经证实富含亮氨酸重复序列3B蛋白(leucine-rich repeat-containing 3B,LRRC3B)在多种癌症中低表达,并且与癌细胞的迁移侵袭密切相关.该研究旨在探讨LRRC3B在食管癌发展中的作用机制.方法:免疫组织化学染色检测LRRC3B在60例食管癌组织及60例癌旁组织中的表达情况,采用实时荧光定量聚合酶链反应(real-time fluorescent quantitative polymerase chain reaction,RTFQ-PCR)和蛋白[质]印迹法(Western blot)分别检测食管癌细胞Eca109和食管正常上皮细胞系HEEC中LRRC3B的mRNA和蛋白表达.处理食管癌细胞Eca109并分3组:正常对照组、阴性对照组(转染对照空pCMV6质粒)和过表达LRRC3B组(转染pCMV6-LRRC3B过表达质粒).采用Transwell法检测各组Eca109细胞迁移和侵袭的变化.采用Western blot检测各组细胞中上皮间质转化(epithelial-mesenchymal transition,EMT)相关蛋白E-cadherin、N-cadherin和Vimentin表达以及p-Akt蛋白水平.结果:LRRC3B在食管癌组织和细胞中的表达明显低于癌旁组织和食管正常上皮细胞.过表达LRRC3B明显抑制Eca109细胞的迁移和侵袭能力,上调上皮因子E-cadherin表达,抑制间质标志物N-cadherin和Vimentin表达,同时降低细胞内p-Akt水平.结论:LRRC3B在食管癌中低表达,上调LRRC3B能够抑制食管癌细胞的EMT过程,可能与抑制PI3K/Akt信号通路有关.     

PI3K/Akt/mTOR信号通路抑制剂在乳腺癌中的研究进展

目的:总结PI3K/Akt/mTOR信号通路靶向治疗在乳腺癌中的研究进展.方法:以“PI3K/Akt/mTOR、信号通路和乳腺癌”等为关键词,检索2000-01-2011-06 PubMed、Ovid和Springer等数据库的相关文献.纳入标准:1)关于PI3K/Akt/mTOR信号通路的组成、功能特点;2)PI3K/Akt/mTOR信号通路与乳腺癌的关系研究;3)以PI3K/Akt/mTOR信号通路中关键分子为靶点的乳腺癌治疗.根据纳入标准,符合分析的文献40篇.结果:信号转导通路的异常是肿瘤发生、发展的重要步骤,PI3K/Akt/mTOR信号通路与人类多种肿瘤密切相关,其在肿瘤细胞的增殖、存活、抵抗凋亡、血管发生和转移以及对放化疗抵抗中发挥了重要作用.乳腺癌中常见PI3K/Akt/mTOR信号通路的异常激活,以此通路为靶点的药物已成为乳腺癌治疗的研究热点.结论:靶向PI3K/Akt/mTOR通路中关键分子的众多药物在乳腺癌开展了一系列相关的临床试验研究,一部分显示出较好的安全性和有效性.随着对PI3K/Akt/mTOR通路的分子生物学机制的深入研究,期待靶向此通路的抑制剂将会在乳腺癌治疗中发挥巨大的作用,进一步提高乳腺癌患者的疗效和改善预后.     

ADAM17 targets MMP-2 and MMP-9 via EGFR-MEK-ERK pathway activation to promote prostate cancer cell invasion

ADAM17, also known as tumor necrosis factor-α converting enzyme (TACE), is involved in proteolytic ectodomain shedding of cell surface molecules and cytokines. Although aberrant expression of ADAM17 has been shown in various malignancies, the function of ADAM17 in prostate cancer has not been clarified. In the present study, we sought to elucidate whether ADAM17 contributes to prostate cancer cell invasion, as well as the mechanism involved in the process. The expression pattern of ADAM17 was investigated in human prostate cancer cells. The results showed that ADAM17 expression levels are correlated with the invasive ability of androgen-independent prostate cancer cell lines. Further, ADAM17 was overexpressed in cells showing high invasion characteristics, activation of the EGFR-MEK-ERK pathway, up-regulation of MMP-2, MMP-9, and an increased TGF-α release into the supernatant. However, AG1478, PD98059 and antibody against TGF-α deactivating the EGFR-MEK-ERK signaling pathway, abolished up-regulation of MMP-2, MMP-9 and prevented cell invasion. In addition, cells with knockdown of ADAM17 by siRNA exhibited low invasive ability, deactivated EGFR-MEK-ERK signaling pathway, reduced TGF-α released and down-regulation of MMP-2, MMP-9. However, these effects could be reversed by simultaneous addition of TGF-α. These data demonstrated that ADAM17 contributes to androgen-independent prostate cancer cell invasion by shedding of EGFR ligand TGF-α, which subsequently activates the EGFR-MEK-ERK signaling pathway, leading finally to overexpression of MMP-2 and MMP-9. This study suggests that the ADAM17 expression level may be a new predictive biomarker of invasion and metastasis of prostate cancer, and ADAM17 could provide a target for treating metastatic PCa.     

ICAM-3-induced cancer cell proliferation through the PI3K/Akt pathway

ICAM-3 interacts with LFA1, and is involved in the intercellular adhesion of leukocytes as well as in the mainenance of cell survival. It has also been suggested to induce cancer cell proliferation but the precise signaling pathway is unclear. The aim of this study was to determine the ICAM-3-activated downstream pathway in H1299 lung cancer cells. The level of ICAM-3-induced cell growth was examined using BrdU incorporation, which is a colony-forming assay, FACS analysis, and cell counting. The results showed that ICAM-3 expression induces cancer cell proliferation. In addition, FAK, Akt, PDK1, GSK-3beta, BAD, and PTEN were phosphorylated by ICAM-3-overexpression, resulting in enhanced cell proliferation. In conclusion, ICAM-3 expression induces cancer cell proliferation, and an increase in ICAM-3 expression can contribute to cancer progression.     

Baicalin induces apoptosis in leukemia HL-60/ADR cells via possible down-regulation of the PI3K/Akt signaling pathway

Background: The effect and possible mechanism of traditional Chinese medicine, baicalin, on the PI3K/Akt signaling pathway in drug-resistant human myeloid leukemia HL-60/ADR cells have been investigated inthis current study. Methods: HL-60/ADR cells were treated by 20, 40, 80 μmol/L baicalin followed by cell cycleanalysis at 24h. The mRNA expression level of the apoptosis related gene, Bcl-2 and bad, were measured byRT-PCR on cells treated with 80 μmol/L baicalin at 12, 24 and 48hr. Western blot was performed to detect thechanges in the expression of the proteins related to HL-60/ADR cell apoptosis and the signaling pathway beforeand after baicalin treatment, including Bcl-2, PARP, Bad, Caspase 3, Akt, p-Akt, NF-κB, p-NF-κB, mTOR andp-mTOR. Results: Sub-G1 peak of HL-60/ADR cells appeared 24 h after 20 μmol/L baicalin treatment, andthe ratio increased as baicalin concentration increased. Cell cycle analysis showed 44.9% G0/G1 phase cells24 h after baicalin treatment compared to 39.6% in the control group. Cells treated with 80 μmol/L baicalindisplayed a trend in decreasing of Bcl-2 mRNA expression over time. Expression level of the Bcl-2 and PARPproteins decreased significantly while that of the PARP, Caspase-3, and Bad proteins gradually increased. Nosignificant difference in Akt expression was observed between treated and the control groups. However, theexpression levels of p-Akt, NF-κB, p-NF-κB, mTOR and p-mTOR decreased significantly in a time-dependentmanner. Conclusions: We conclude that baicalin may induce HL-60/ADR cell apoptosis through the PI3K/AKTsignaling pathway.     

A new protoapigenone analog RY10-4 induces apoptosis and suppresses invasion through the PI3K/Akt pathway in human breast cancer

RY10-4, a novel protoapigenone analog, shows potent cytotoxicity against a broad spectrum of human cancer cells. Here we investigate its anti-tumor activity on breast cancer. The results indicated that RY10-4 suppressed proliferation, arrested cell cycle, induced apoptosis and inhibited invasion in MDA-MB-231, MCF-7 and SKBR3 breast cancer cells. Western blot analysis showed that RY10-4 down-regulated the PI3K/Akt signaling pathway and inhibited doxorubicin-induced p-Akt. Moreover, it effectively suppressed tumor growth in mice without major side effects. Therefore, RY10-4 had potential anti-tumor activity, and could be used as a lead to design more potent derivatives.     

Notch1 activation promotes renal cell carcinoma growth via PI3K/Akt signaling

Both the Notch1 and PI3K/Akt pathways are aberrantly activated in clear cell renal cell carcinoma (CCRCC) and involved in the tumorigenesis. The aim of this study was to test our hypothesis that elevated Notch1 signaling activity exerts its growth‐promoting effects via the PI3K/Akt pathway in CCRCC. To investigate the relationship between the two pathways, we enhanced and suppressed the Notch1 activity respectively in a CCRCC cell line through diverse means, and then evaluated ensuing phosphorylated Akt (pAkt) levels. To further study their collaboration in promoting tumor growth, cell proliferation assay, colony formation assay and cell cycle analysis were conducted under several different conditions. Immunostaining of the tissue microarrays was used to determine whether the phenomena we observed also existed in vivo. The results showed that Notch1 signaling was activated in CCRCC tissue samples and cell lines. Notch1 activation increased CCRCC cell proliferation, enhanced anchorage‐independent growth, and accelerated G1/S cell cycle progression. Such effects of the Notch1 signaling were, at least in part, mediated by the PI3K/Akt pathway. Correlations between Notch1, pAkt and Ki‐67 protein levels in tissue microarrays reinforced our in vitro findings. Taken together, the current study established a functional link between the Notch1 and PI3K/Akt pathways in CCRCC. (Cancer Sci 2012; 103: 1253–1258)     

CUEDC2通过活化 PI3K／Akt 信号通路促进乳腺癌细胞的生长

目的：探讨 CUE 结构域2（CUE domain －containing 2,CUEDC2）蛋白在人乳腺癌细胞中的生物学作用。方法：人乳腺肿瘤细胞 MCF －7转染的 Myc －CUEDC2真核表达载体,提取转染细胞的总蛋白检测磷酸化 Akt 和总 Akt 的表达变化。利用 CCK －8检测过表达 CUEDC2后 MCF －7细胞的生长。结果：CUEDC2能够活化 Akt,使磷酸化 Akt 表达增加,能够促进人乳腺癌细胞生长。结论：当乳腺癌中 CUEDC2表达增高时,能够引起 PI3K／Akt 信号通路活化,促进肿瘤细胞生长。     

PI3K/Akt信号通路与肿瘤血管新生的研究进展

PI3K/Akt信号通路在多种细胞中活化,参与细胞的增殖、分化、凋亡、血管新生等病理、生理过程。血管的生成需要PI3K/Akt信号通路的激活,PI3K/Akt活化后可以广泛诱导鸡胚尿囊膜血管的生成。PI3K/Akt信号通路与其下游信号分子mTOR及多种促血管新生因子,如VEGF、HIF等相互作用,从而促进肿瘤血管新生。PI3K/Akt信号通路抑制剂能够抑制其血管新生作用,因此靶向PI3K/Akt信号通路为恶性肿瘤靶向治疗提供了新方法。     

PI3K／AKT信号通路在子宫内膜癌中的研究进展

PI3K／Akt信号通路是许多细胞外因子的下游信号传导通路,在细胞生长、增殖、分化和凋亡中起到重要作用,该通路异常广泛存在于许多恶性肿瘤中,与肿瘤发生、发展密切相关。在子宫内膜癌发生发展中,PI3K／Akt信号传导通路异常起到重要的作用,通过对该通路的进一步研究,可能为子宫内膜癌的发生机制、诊断以及为临床靶向治疗提供新的思路。