整合蛋白α5,β1亚基的过表达对肝癌细胞粘附和迁移的影响

目的：研究整合蛋白α5,β1亚基的过表达与肝癌细胞粘附能力、迁移能力、集落形成能力、以及与肝癌细胞凋亡的关系。方法：用已建立的单独转染α5,β1整合蛋白亚基的细胞株α5/3-7721,β1/6-7721和共转α5和β1整合蛋白亚基的细胞株α5β1/6-7721;采用结晶紫染色法测定细胞的粘附能力、细胞的迁移能力;应用荧光染色法和流式细胞仪法测定细胞凋亡速度。结果：转染后细胞与主要胞外基质蛋白-纤连蛋白的粘附分别为对照细胞的1.39,1.34,1.7倍;与层粘连蛋白（Ln)的粘附为对细胞的1.3、2.6、1.98倍;α5,β1整合蛋白转移株细胞在Fn上的迁移能力分别增加1.22、0.78、1.38倍。集落形成能力分别下降38%,35%和52%。在无血清培养时,α5,β1整合蛋白转染株细胞的凋亡百分率分别提高2.4、0.53、1.79倍。结论：将α5β1整合蛋白导入人肝癌细胞引起α5β1整合蛋白表达,可显著改变细胞的生长,粘附和迁移能力,从而导致体外集落形成能力明显下降,细胞凋亡增加。     

Constitutive activation of integrin αvβ3 contributes to anoikis resistance of ovarian cancer cells

Epithelial ovarian cancer involves the shedding of single tumor cells or spheroids from the primary tumor into ascites, followed by their survival, and transit to the sites of metastatic colonization within the peritoneal cavity. During their flotation, anchorage‐dependent epithelial‐type tumor cells gain anoikis resistance, implicating integrins, including αvß3. In this study, we explored anoikis escape, cisplatin resistance, and prosurvival signaling as a function of the αvß3 transmembrane conformational activation state in cells suspended in ascites. A high‐affinity and constitutively signaling‐competent αvß3 variant, which harbored unclasped transmembrane domains, was found to confer delayed anoikis onset, enhanced cisplatin resistance, and reduced cell proliferation in ascites or 3D‐hydrogels, involving p27^kip upregulation. Moreover, it promoted EGF‐R expression and activation, prosurvival signaling, implicating FAK, src, and PKB/Akt. This led to the induction of the anti‐apoptotic factors Bcl‐2 and survivin suppressing caspase activation, compared to a signaling‐incapable αvß3 variant displaying firmly associated transmembrane domains. Dissecting the mechanistic players for αvß3‐dependent survival and peritoneal metastasis of ascitic ovarian cancer spheroids is of paramount importance to target their anchorage independence by reversing anoikis resistance and blocking αvß3‐triggered prosurvival signaling.

Abbreviations

CLSM

confocal laser scanning microscopy

ECM

extracellular matrix

EGF‐R

epidermal growth factor receptor

EOC

epithelial ovarian cancer

FAK

focal adhesion kinase

FIGO

Fédération Internationale de Gynécologie et d''Obstétrique

GAPDH

glyceraldehyde 3‐phosphate dehydrogenase)

GpA

glycophorin A

IMD

integrin‐mediated death

MAPK

mitogen‐activated protein kinases

PI

propidium iodide

RGD

Arg‐Gly‐Asp

TMD

transmembrane domain

     

MYO10 contributes to the malignant phenotypes of colorectal cancer via RACK1 by activating integrin/Src/FAK signaling

Liver metastases still remain a major cause of colorectal cancer (CRC) patient death. MYO10 is upregulated in several tumor types; however, its significance and the underlying mechanism in CRC are not entirely clear. Here, we found that MYO10 was highly expressed in CRC tumor tissues, especially in liver metastasis tissues. MYO10 knockout reduced CRC cell proliferation, invasion, and migration in vitro and CRC metastasis in vivo. We identified RACK1 by LC‐MS/MS and demonstrated that MYO10 interacts with and stabilizes RACK1. Mechanistically, MYO10 promotes CRC cell progression and metastasis via ubiquitination‐mediated RACK1 degradation and integrin/Src/FAK signaling activation. Therefore, the MYO10/RACK1/integrin/Src/FAK axis may play an important role in CRC progression and metastasis.     

Involvement of JNK-mediated pathway in EGF-mediated protection against paclitaxel-induced apoptosis in SiHa human cervical cancer cells.

We investigated the signalling pathways by which epidermal growth factor (EGF) modulates paclitaxel-induced apoptosis in SiHa human cervical cancer cells. SiHa cells exposed to paclitaxel underwent apoptosis, which was strongly inhibited by EGF. This inhibition of apoptosis by EGF was not altered by pharmacological blockade of phosphatidylinositol 3'-OH kinase (PI-3K) with the PI-3K specific inhibitor LY294002 or blockade of the mitogen-activated protein kinase (MAPK) kinase (MEK) with the MEK specific inhibitor PD98059, or by transfection of the cells with PI-3K or MEK dominant-negative expression vectors. EGF did not stimulate PI-3K/Akt, MEK/MAPK, or p38 MAPK activity in SiHa cells but did transiently activate the c-Jun NH2-terminal kinase (JNK). Co-exposure of SiHa cells to SB202190 at concentrations that inhibit JNK abolished the protective effect of EGF on SiHa cells against paclitaxel-induced apoptosis. Our findings indicate that the JNK signaling pathway plays an important role in EGF-mediated protection from paclitaxel-induced apoptosis in SiHa cells.     

整合素β1在浸润性乳腺癌中的表达及其意义

目的：探讨浸润性乳腺癌中整合素β1蛋白的表达及其在乳腺癌侵袭转移过程中的作用。方法：应用免疫组化Elisivion法检测62例浸润性乳腺癌组织中整合素β1蛋白的表达水平。结果：腋淋巴结转移者中整合素β1阳性率高于无腋淋巴结转移者（P〈0.05）;组织学分级Ⅲ级者,整合素β1阳性率明显高于组织学分级Ⅰ、Ⅱ级者（P〈0.01）。结论：整合素β1蛋白是乳腺癌浸润和转移过程中的潜在生物学标志,随着整合素β1表达水平的增高,肿瘤细胞的恶性程度增加并且侵袭性增强。     

整合素α5β1在非小细胞肺癌组织中的表达及临床意义

目的研究整合素α5β1在非小细胞肺癌(non-small cell lung cancer,NSCLC)组织中的表达以及与临床病理特征的关系.方法用免疫组化SP法检测53例NSCLC组织及12例正常肺组织的石蜡标本中α5β1的表达情况.结果整合素α5β1在NSCLC组织中的表达(58.49%)明显高于正常肺组织(16.67%),差异有统计学意义,P=0.009;α5β1的表达与病理分级负相关,高、中、低分化NSCLC组织α5β1的阳性率分别是28.57%、68.18%和70.59%,病理分级越低,表达越高,差异有统计学意义,P=0.031;α5β1表达升高与淋巴结转移、临床分期有关,α5β1在淋巴结转移阳性的NSCLC组织中的表达(67.50%)高于淋巴结转移阴性组表达(30.77%),差异有统计学意义,P=0.020,α5β1在Ⅱ、Ⅲ期NSCLC组织中的表达(64.29%、75.00%)高于Ⅰ期(30.77%),差异有统计学意义,P=0.042.结论α5β1高表达可能与NSCLC的恶性生物学特性有关,α5β1在NSCLC的发生、发展中可能起了一定的作用.     

PI3K信号通路在结直肠癌中的作用

结直肠癌(CRC)的早期症状隐匿,多数患者在诊断时已经发生转移.化疗与靶向药物的联合治疗是目前治疗转移性CRC的主要策略,在CRC中高频出现异常激活的磷脂酰肌醇-3-激酶(PI3K)信号通路与CRC的发生发展有着十分密切的关系,对CRC的诊断与治疗具有重要的价值.     

整合素β1在浸润性乳腺癌中的表达及其意义

目的:探讨浸润性乳腺癌中整合素β1蛋白的表达及其在乳腺癌侵袭转移过程中的作用.方法: 应用免疫组化Elisivion法检测62例浸润性乳腺癌组织中整合素β1蛋白的表达水平.结果: 腋淋巴结转移者中整合素β1阳性率高于无腋淋巴结转移者(P<0.05);组织学分级Ⅲ级者,整合素β1阳性率明显高于组织学分级Ⅰ、Ⅱ级者(P<0.01).结论: 整合素β1蛋白是乳腺癌浸润和转移过程中的潜在生物学标志,随着整合素β1表达水平的增高,肿瘤细胞的恶性程度增加并且侵袭性增强.     

IFN-gamma withdrawal after immunotherapy potentiates B16 melanoma invasion and metastasis by intensifying tumor integrin alphavbeta3 signaling

Immunotherapy can effectively suppress tumor, yet complete tumor eradication occurs infrequently. The metastatic potential of remnant tumor cells after immunotherapy and the underlying mechanisms have not been fully elucidated. Here, we report that the termination of immunotherapy strikingly increases the metastatic potential of remnant melanoma. This is mainly due to the withdrawal of IFN-gamma after immunotherapy. The relief of IFN-gamma stress led to the increase of alphavbeta3 integrin expression in B16 cells, which increased the adhesion of B16 cells to fibrinogen, fibronectin and laminin. Through alphavbeta3 signaling, the activation of FAK, upregulation of cdc2, production of active MMP-2 and MMP-9 and actin polymerization were intensified in B16 cells stimulated with ECM molecules 24 h after the withdrawal of IFN-gamma. The i.v. injection of such tumor cells into mice resulted in more metastatic tumor nodes in lung and shortened the survival of mice. The pitfall of immunotherapy termination can be remedied by the administration of recombinant CBD-HepII polypeptide of fibronectin, which effectively inhibits alphavbeta3 signaling. These findings suggest that the risk of tumor metastasis can be increased after the termination of immunotherapy, due to the withdrawal of IFN-gamma and that targeting alphavbeta3 signaling pathway can improve the therapeutic effect of immunotherapeutic approaches by reducing such metastatic risk.     

SMYD3 promotes implant metastasis of ovarian cancer via H3K4 trimethylation of integrin promoters

Detachment of cancer cells from the primary tumor and formation of spheroids in ascites is required for implantation metastasis in epithelial ovarian cancer (EOC), but the underlying mechanism of this process has not been thoroughly elucidated. To mimic this process, ovarian cancer cells were grown in 3D and 2D culture. Hey and OVCA433 spheroids exhibited decreased cell proliferation and enhanced adhesion and invasion. SMYD3 expression was elevated in ovarian carcinoma spheroids in association with increased H3K4 methylation. Depletion of SMYD3 by transient siRNA, stable shRNA knockdown and the SMYD3 inhibitor BCI-121 all decreased spheroid invasion and adhesion. Gene expression arrays revealed downregulation of integrin family members. Inhibition assays confirmed that invasion and adhesion of spheroids are mediated by ITGB6 and ITGAM. SMYD3-deficient cells regained the ability to invade and adhere after forced overexpression of SMYD3, ITGB6 and ITGAM. However, this biological ability was not restored by forced overexpression of SMYD3 in ITGB6- and/or ITGAM-deficient cancer cells. SMYD3 and H3K4me3 binding at the ITGB6 and ITGAM promoters was increased in spheroids compared to that in monolayer cells, and the binding was decreased when SMYD3 expression was inhibited, consistent with the expression changes in integrins. SMYD3 expression and integrin-mediated adhesion were also activated in an intraperitoneal xenograft model and in EOC patient spheroids. In vivo, SMYD3 knockdown inhibited tumor metastasis and reduced ascites volume in both the intraperitoneal xenograft model and a PDX model. Overall, our results suggest that the SMYD3-H3K4me3-integrin pathway plays a crucial role in ovarian cancer metastasis to the peritoneal surface.     

PFKFB3在胃癌中的表达及对胃癌细胞生长和凋亡的影响研究

背景与目的:6-磷酸果糖激酶-2同工酶3(6-phosphofructo-2-kinase 3,PFKFB3)与肿瘤的发生、发展密切相关,且对肿瘤细胞的生物学行为具有重要的调节作用。分析PFKFB3在胃癌组织及癌旁组织中的表达,并观察其对胃癌细胞生长和凋亡的作用及机制。方法:采用TCGA数据库分析72例在南昌大学第二附属医院及第三附属医院经外科手术切除的新鲜胃癌标本及其相应的癌旁组织中PFKFB3的表达,并分析PFKFB3的表达与胃癌预后的关系。进一步通过实时荧光定量聚合酶链反应(real-time fluorescence quantitative polymerase chain reaction,RTFQ-PCR)、蛋白质印迹法(Western blot)及免疫组织化学法分析胃癌组织标本及癌旁组织标本中PFKFB3的表达。shNC及shPFKFB3质粒转染至胃癌细胞中,采用RTFQ-PCR和Western blot验证转染效率。分别通过细胞计数试剂盒-8(cell counting kit-8,CCK-8)实验、EdU实验、流式细胞术和Western blot分析PFKFB3下调后对胃癌细胞的增殖能力、细胞周期变化和细胞凋亡的影响。最后采用Western blot分析PFKFB3影响胃癌细胞生长的机制。结果:TCGA数据库分析显示,胃癌组织中PFKFB3的表达明显高于癌旁组织(P<0.05),且PFKFB3高表达与胃癌患者较差的预后密切相关。另外,RTFQ-PCR、Western blot及免疫组织化学检测也同样证实PFKFB3在胃癌组织中高表达(P<0.01),且PFKFB3的表达升高与淋巴结转移及TNM分期密切相关(P<0.05)。沉默胃癌细胞中PFKFB3的表达后,其生长能力明显减弱(P<0.01),胃癌细胞凋亡比例增加(P<0.01),细胞周期G1期阻滞(P<0.01)。PFKFB3通过激活磷酸化磷脂酰肌醇3-激酶(phosphoinositide 3-kinase,PI3K)/蛋白激酶B(protein kinase B,AKT)信号通路而调控胃癌细胞的生长。结论:PFKFB3在胃癌组织中高表达,且与患者预后密切相关,沉默PFKFB3的表达后抑制胃癌细胞的生长并促进其凋亡,PFKFB3可能是胃癌靶向治疗的潜在生物标志物。     

PI3K/Akt/mdm2信号通路活化对胃癌细胞阿霉素敏感性的影响

目的 研究PI3K/Akt/mdm2信号通路活化对胃癌细胞阿霉素(DOX)敏感性的影响.方法 分别用DOX和PI3K特异性抑制剂wortmannin处理胃癌细胞株SGC7901,采用流式细胞仪检测肿瘤细胞的凋亡,免疫沉淀法检测PI3K活性,Western blot法检测PI3K-p85、phospho-Akt(S473)、phospho-mdm2(S166)、Akt和p53的表达.结果 DOX能诱导胃癌细胞SGC7901凋亡,且凋亡率与作用时间密切相关,联合应用wortmannin后,可促进胃癌细胞凋亡.DOX作用SGC7901细胞3、6、12和24 h后, PI3K活性逐渐增强,分别为(8.4±1.7)%、(12.7±2.1)%、(17.4±3.2)%和(16.8±2.4)%;同时,还促进Akt、mdm2磷酸化和p53表达.wortmannin可以抑制mdm2磷酸化,进一步增强p53的表达.结论 DOX可以诱导PI3K/Akt通路异常激活,并通过促进mdm2磷酸化降低胃癌细胞化疗敏感性.     

Diosgenin targets Akt‐mediated prosurvival signaling in human breast cancer cells

In recent years, Akt signaling has gained recognition for its functional role in more aggressive, therapy‐resistant malignancies. As it is frequently constitutively active in cancer cells, several drugs are being investigated for their ability to inhibit Akt signaling. The purpose of this study is to determine effect of diosgenin (fenugreek), a dietary compound on Akt signaling and its downstream targets on estrogen receptor positive (ER⁺) and estrogen receptor negative (ER^?) breast cancer (BCa) cells. Diosgenin inhibits pAkt expression and Akt kinase activity without affecting PI3 kinase levels, resulting in the inhibition of its downstream targets, NF‐κB, Bcl‐2, survivin and XIAP. The Raf/MEK/ERK pathway, another functional downstream target of Akt, was inhibited by diosgenin in ER⁺ but not in ER^? BCa cells. Additionally, we found that diosgenin caused G1 cell cycle arrest by downregulating cyclin D1, cdk‐2 and cdk‐4 expression in both ER⁺ and ER^? BCa cells resulting in the inhibition of cell proliferation and induction of apoptosis. Interestingly, no significant toxicity was seen in the normal breast epithelial cells (MCF‐10A) following treatment with diosgenin. Additionally, in vivo tumor studies indicate diosgenin significantly inhibits tumor growth in both MCF‐7 and MDA‐231 xenografts in nude mice. Thus, these results suggest that diosgenin might prove to be a potential chemotherapeutic agent for the treatment of BCa. © 2009 UICC     

PTEN gene and integrin signaling in cancer.

Integrins are major adhesion- and signaling-receptor proteins that mediate cell migration and invasion. They also trigger a variety of signal transduction pathways and regulate cytoskeletal organization, specific gene expression, growth control, and apoptosis (programmed cell death). Consequently, integrins are thought to play important roles in embryonic development and in the biology of cancers. The functions of integrins can be negatively regulated by the recently discovered tumor suppressor PTEN, a protein with homology to protein tyrosine phosphatases and tensin. The PTEN gene is mutated in a wide range of human cancers. PTEN inhibits cell migration and invasion by directly dephosphorylating two key tyrosine-phosphorylated proteins, thereby antagonizing interactions of integrins with the extracellular matrix and integrin-triggered signaling pathways. Other studies demonstrate important roles for PTEN in dephosphorylating a key signal transduction lipid. In the absence of PTEN, this lipid signal transduction pathway can protect tumor cells from apoptosis. Thus, PTEN appears to be a unique tumor suppressor-with both lipid phosphatase and protein tyrosine phosphatase activities-that negatively regulates cell interactions with the extracellular matrix and that maintains cell sensitivity to apoptosis, e.g., after loss of cell contact with the extracellular matrix. The complex signal transduction pathways regulated by PTEN are described in this review. PTEN and the signaling pathways it regulates may provide novel targets for potential therapy.     

Curcumin inhibits the mammalian target of rapamycin-mediated signaling pathways in cancer cells

Curcumin (diferuloylmethane), a polyphenol natural product of the plant Curcuma longa, is undergoing early clinical trials as a novel anticancer agent. However, the anticancer mechanism of curcumin remains to be elucidated. Here we show that curcumin inhibited growth of rhabdomyosarcoma cells (Rh1 and Rh30) (IC50 = 2-5 microM) and arrested cells in G1 phase of the cell cycle. Curcumin also induced apoptosis and inhibited the basal or type I insulin-like growth factor-induced motility of the cells. At physiological concentrations (2.5 microM), curcumin rapidly inhibited phosphorylation of the mammalian target of rapamycin (mTOR) and its downstream effector molecules, p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), in a panel of cell lines (Rh1, Rh30, DU145, MCF-7 and Hela). Curcumin also inhibited phosphorylation of Akt in the cells, but only at high concentrations (>40 microM). The data suggest that curcumin may execute its anticancer activity primarily by blocking mTOR-mediated signaling pathways in the tumor cells.     

Genetic variants in the integrin signaling pathway genes predict cutaneous melanoma survival

To identify genetic variants involved in prognosis of cutaneous melanoma (CM), we investigated associations of single nucleotide polymorphisms (SNPs) of genes in the integrin signaling pathway with CM survival by re‐analyzing a published genome‐wide association study (GWAS) from The University of Texas M.D. Anderson Cancer Center (MDACC) and then validated significant SNPs in another GWAS from Harvard University. In the MDACC study, 1,148 SNPs were significantly associated with CM‐specific survival (CMSS) (p ≤ 0.050 and false‐positive report probability ≤ 0.20), and nine SNPs were validated in the Harvard study (p ≤ 0.050). Among these, three independent SNPs (i.e., DOCK1 rs11018104 T > A, rs35748949 C > T and PAK2 rs1718404 C > T) showed a predictive role in CMSS, with an effect‐allele attributed adjusted hazards ratio [adjHR of 1.50 (95% confidence interval (CI) = 1.18‐1.90, p = 7.46E‐04), 1.53 (1.18‐1.97, 1.18E‐03) and 0.58 (0.45‐0.76, 5.60E‐05), respectively]. Haplotype analysis revealed that a haplotype carrying two risk alleles A‐T in DOCK1 was associated with the poorest survival in both MDACC (adjHR = 1.73, 95% CI = 1.19‐2.50, p = 0.004) and Harvard (adjHR = 1.95, 95% CI = 1.14‐3.33, p = 0.010) studies. In addition, patients with an increasing number of unfavorable genotypes (NUGs) for these three SNPs had a poorer survival. Incorporating NUGs with clinical variables showed a significantly improved ability to classify CMSS (AUC increased from 86.8% to 88.6%, p = 0.031). Genetic variants in the integrin signaling pathway may independently or jointly modulate the survival of CM patients. Further large, prospective studies are needed to validate these findings.     

Suppression of integrin alphaupsilonbeta6 by RNA interference in colon cancer cells inhibits extracellular matrix degradation through the MAPK pathway

Integrin alphaupsilonbeta6 plays a very important role in the progression of colon cancer cells and is now defined as a novel, independent prognostic indicator for aggressive colon cancer in humans. Herein, we use the RNA interfering technology to downregulate the expression of alphaupsilonbeta6 in colon cancer cells. Our data demonstrate that plasmid vector based shRNA can effectively down-regulate alphaupsilonbeta6 expression in protein and mRNA levels. Supression of integrin alphaupsilonbeta6 inhibits the phosphorylation and nonphosphorylation level of ERK1/2, the secretion of uPA, pro-MMP-9 and pro-MMP-2 in tumor conditioned medium, and more important, inhibits MAPK-dependent [(3)H] labeled collagen IV degradation via the plasminogen activation cascade. Our study demonstrates in vitro that supression of integrin alphaupsilonbeta6 inhibits extracellular matrix degradation through the MAPK pathway.     

Diagnostic value of integrin alpha3, beta4, and beta5 gene expression levels for the clinical outcome of tongue squamous cell carcinoma

BACKGROUND: The objective of the current study was to identify biomarkers that reflect the clinical course of squamous cell carcinoma of the tongue (TSCC). METHODS: TSCC tissue samples from 66 patients were subjected to gene expression analysis by real-time polymerase chain reaction. Eleven integrin family genes and 14 genes used for normalization, including housekeeping genes and genes that encode desmosomal, cytoskeletal, and extracellular matrix molecules, were considered. Multivariate statistical analysis was performed on 154 expression ratios of integrin genes with clinical parameters. RESULTS: In principal-component analysis, the first principal component was related to the outcome of death, and the second principal component mainly reflected the tendency for cervical lymph node (LN) metastasis. The former axis consisted of the variance of the integrin beta4 gene (ITGB4) and ITGB5 expression levels, and the latter axis agreed with the expression level of the integrin alpha3 gene (ITGA3). Multivariate logistic regression analysis with cervical LN metastasis as the response variable concordantly identified ITGA3/junction plakoglobin gene (JUP) expression (P=.02) and ITGB5/paxillin gene (PXN) expression (P=.04) as significant factors. Only ITGB4/JUP expression was identified as a significant factor in terms of the outcome of death (P<.00049) by a Cox proportional hazards model. The group with high ITGB4/JUP levels exhibited a significantly high death rate on a Kaplan-Meier curve (P<.0001; Wilcoxon and log-rank tests). CONCLUSIONS: The expression levels of ITGA3, ITGB4, and ITGB5 with functional normalization by desmosomal or cytoskeletal molecule genes were selected as candidate biomarkers for cervical LN metastasis or for the outcome of death in TSCC.