阿司匹林通过抑制EphA4通路保护缺血造成的脑白质损伤

目的:我们前期研究发现阿司匹林具有脑白质保护作用,但其机制尚不清楚。有研究报道Eph信号与白质损伤密切相关,为此本研究拟探讨大鼠脑白质损伤后阿司匹林对Eph受体表达变化的影响。方法:成年雄性SD大鼠利用双侧永久性颈总动脉结扎模型造成脑白质损伤(WML)。随机分为正常组、WML组和阿司匹林处理组(每日100 mg/kg,ip,30d),每组15只。采用Real-time PCR法检测正常组胼胝体内8种Eph受体的表达情况;免疫荧光染色检测Eph受体是否表达在少突胶质细胞中;Western Blot检测各组Eph受体和髓鞘碱性蛋白(myelin basic protein,MBP)的表达变化及相互关系。结果:Real-time PCR结果:8种Eph受体中,EphA4的mRNA表达水平最高。EphA4与CNPase的免疫荧光染色示:EphA4表达于胼胝体内的少突胶质细胞。与正常组相比,WML组中EphA4~+细胞数量增多(P0.05),阿司匹林处理后EphA4~+细胞数量减少(P0.05)。Western Blot结果显示:与正常组比较,WML组胼胝体部EphA4表达升高(P0.05),但MBP蛋白表达下降(P0.05);阿司匹林处理后,可下调EphA4(P0.05)、上调MBP的表达水平(P0.05),二者呈显著负相关。结论:阿司匹林可能通过抑制EphA4通路保护缺血造成的脑白质损伤。     

促红细胞生成素肝细胞激酶受体与ephrin配体及其信号转导在肿瘤中的研究进展

促红细胞生成素肝细胞激酶(erythropoietin producing hepatocyte kinase,Eph)受体及其膜结合配体ephrin是最大的受体酪氨酸激酶(receptor tyrosine kinases,RTKs)家族,其不仅调节生物体的多种生理功能,而且参与多种疾病的发生发展过程.近年来,已有越来越多的证据表明肿瘤的发生发展与Eph家族成员异常表达密切相关.     

Eph-ephrin双向信号功能的研究进展

产生促红细胞生成素的肝细胞(erythropoietinproducing hepatocyte,Eph)受体是众多的细胞表面型酪氨酸蛋白激体酶受体中的一种,是酪氨酸蛋白激酶受体家族中的最大成员.其配体主要表达于细胞表面,被命名为ephrin.Eph受体及其配体ephrin统称为Eph家族蛋白.Eph受体属跨膜蛋白,存在胞外配体结合区、跨膜区和胞内区.Eph胞内近细胞膜区域相对保守,包含1个具有酪氨酸残基的高度保守的近膜区结构域,紧接1个具酪氨酸激酶活性的结构域、SAM(sterile alpha motif)结构域和C端的PDZ结合序列.Eph的胞外结构包含1个球形的配体结合域(ligand binding domain,LBD)、1个临近的半胱氨酸富集区(cysteine-rich domain,CRD)以及2个Ⅲ型纤维连接蛋白重复区.其中CRD在Eph-ephrin信号复合体的形成过程中起到关键作用[1].所有ephrin均包含1个保守的胞外受体结合区.除此之外,ephrinA通过一个糖基磷脂酰肌醇(glycosylphosphatidylinositol,GPI)锚定于细胞膜上;ephrinB的结构包括跨膜区和胞质区,其中胞质区包含一小段高度保守的区域以及羧基端PDZ结构域的结合基序,这一PDZ结构域结合基序对于细胞定位及逆向信号起到重要作用.     

屋尘螨提取物激活气道上皮细胞EphA2-STAT3/p38 MAPK信号通路介导气道炎症

目的 探讨受体酪氨酸激酶肝配蛋白A型受体2(EphA2)对屋尘螨提取物(HDM)诱导气道上皮细胞表达炎症细胞因子的作用及其机制.方法 用EphA2小干扰RNA(siRNA)转染气道上皮细胞株16HBE细胞建立EphA2敲减的细胞模型,HDM刺激16HBE细胞后,采用实时定量PCR检测EphA2、白细胞介素6(IL-6)...     

血管内皮生长因子、Eph受体酪氨酸激酶A2、基质金属蛋白酶-2和-9在卵巢癌血管生成拟态中的作用

目的 探讨血管内皮生长因子(VEGF)、Eph受体酪氨酸激酶A2 (EphA2)、基质金属蛋白酶(MMP)-2和MMP-9在卵巢癌血管生成拟态中的作用.方法 收集临床和预后资料完整的卵巢癌组织标本84例,切片经明确诊断后进行CD31和过碘酸-雪夫 (PAS) 双重染色,证实肿瘤组织中存在血管生成拟态,行VEGF、EphA2、MMP-2和MMP-9 免疫组织化学染色,根据染色指数统计免疫组织化学染色结果.结果 有血管生成拟态组(36/84)和无血管生成拟态组卵巢癌组织(48/84)的VEGF、EphA2、MMP-9表达差异有统计学意义,有血管生成拟态组的卵巢癌细胞VEGF、EphA2、MMP-9表达明显高于无血管生成拟态组.但有血管生成拟态组和无血管生成拟态组患者的MMP-2表达差异无统计学意义.结论 在卵巢癌中血管生成拟态和内皮依赖性血管并存,VEGF、EphA2和MMP-9等参与了卵巢癌血管生成拟态的形成.检测VEGF、EphA2和MMP-9可作为预测卵巢癌预后的间接指标.     

DDRs对免疫细胞调控机制的研究进展

盘状结构域受体(DDRs)是受体酪氨酸激酶(RTKs)超家族的重要成员,由DDR1和DDR2组成.胶原蛋白与DDRs特异性结合可诱导其酪氨酸磷酸化,从而引起下游细胞信号的转导.目前,研究表明DDRs在树突状细胞、巨噬细胞、小胶质细胞、中性粒细胞、T淋巴细胞中均有表达,并通过NF-κB、p38 MAPK、JNK、ERK等...     

受体酪氨酸激酶EphA7在乳腺癌中的表达及其临床意义

目的观察受体酪氨酸激酶EphA7在乳腺癌和正常乳腺组织中的表达,探讨EphA7蛋白表达的临床意义。方法应用免疫组化En Vision法染色检测乳腺正常细胞系、乳腺癌肿瘤细胞系和150例浸润性导管癌组织中EphA7的表达,分析其表达与临床病理特征的相关性。结果 EphA7蛋白在乳腺癌细胞系和浸润性导管癌中表达丢失,其表达水平与患者年龄(r_s=-0.157,P=0.055)、肿瘤分级(r_s=-0.331,P0.001)呈负相关;与淋巴结转移(r_s=0.245,P=0.002)、TNM分期(r_s=0.217,P=0.008)、HER-2表达(r_s=0.179,P=0.028)呈正相关。结论 EphA7在多数乳腺癌细胞中表达丢失,可能在乳腺癌发生和转移中发挥重要作用。     

外周神经损伤大鼠背根神经节中Ephrin B1及RYK 受体表达的变化

目的研究外周神经损伤后背根神经节细胞中Ephrin B1及其相关受体的表达变化。方法建立一侧坐骨神经夹伤的大鼠动物模型,通过免疫荧光组织化学方法检测受损侧背根神经节细胞中Ephrin B1及其相关受体Eph B1、Eph B2、Eph B3和Eph A4、RYK等的表达,并分析阳性细胞数和不同大小阳性细胞的构成比例。结果外周坐骨神经受损侧背根神经节细胞中Ephrin B1的表达明显减弱,而Eph B1、Eph B2、Eph B3和Eph A4受体的表达无明显变化,但RYK受体的表达则明显加强。结论Ephrin B1和RYK受体在一侧外周坐骨神经夹伤后的大鼠背根神经节细胞中表达的变化,说明它很有可能参与了损伤后的功能活动。     

EphA2受体与恶性肿瘤关系的研究进展

<正>促红细胞生成素产生肝细胞受体(erythropoietin producing hepatocyte receptor,Eph)家族是己知最大的受体酪氨酸激酶(receptor tyrosine kinase,RTK)亚家族之一,现有14个成员,其配体名为Ephrin,即Eph家族受体相互作用蛋白,现有8个成员。Eph受体为跨膜Ⅰ型糖蛋白,包括三个结构域,即胞外配体结合区、胞内具有酪氨酸激酶活性的功能区和连接这两个区的由疏水氨基酸组成的跨膜区。Eph与Ephrin可互为受体和配     

EphA2调控结直肠癌细胞耐药的初步研究

目的:探究Eph受体A2(Eph A2)在结直肠癌细胞化疗耐药中的作用及相关机制。方法:Western blot及real-time PCR检测人结肠癌细胞株Lo Vo及结肠癌耐药细胞株Lo Vo/5-FU中Eph A2的表达情况。转染Eph A2 siRNA干扰结肠癌耐药细胞株Lo Vo/5-FU中Eph A2的表达,CCK-8法检测细胞对化疗药物的敏感性,划痕实验及Transwell实验检测细胞迁移及侵袭能力的变化,Western blot检测上皮-间充质转化(EMT)及相关信号通路分子的蛋白水平。结果:耐药细胞株Lo Vo/5-FU中Eph A2的mRNA及蛋白表达水平均明显高于亲本细胞株(P0.05);并且在亲本细胞株Lo Vo中,Eph A2的蛋白表达水平随着5-FU浓度的增加有升高趋势。沉默Eph A2可降低结肠癌耐药细胞株Lo Vo/5-FU的细胞活力,增加其对化疗药物的敏感性,并抑制细胞的侵袭迁移;同时上调细胞中上皮细胞标志物E-cadherin和β-catenin的表达并下调间充质细胞标志物N-cadherin和vimentin的表达,可抑制结肠癌耐药细胞株Lo Vo/5-FU的EMT进程。此外,干扰Eph A2的表达之后,Notch和Snail的表达也明显降低。结论:沉默Eph A2可部分恢复结肠癌耐药细胞株Lo Vo/5-FU对化疗药物的敏感性,其机制可能与抑制细胞侵袭和迁移、同时通过Notch/Snail信号通路影响细胞的EMT进程有关。     

Ternary complex formation of EphA4, FGFR and FRS2α plays an important role in the proliferation of embryonic neural stem/progenitor cells

EphA4 belongs to a superfamily of receptor tyrosine kinases and interacts with several molecules including fibroblast growth factor receptors (FGFRs) as we reported earlier. Several receptor tyrosine kinases, FGFRs, Trks, Alk and Ret, are currently known to transduce a signal through a docking protein, fibroblast growth factor receptor substrate 2α (FRS2α). However, nothing has been reported about the interaction of FRS2α with EphA4. Using the yeast two‐hybrid system and the in vitro binding and kinase assays, we found that the mid‐kinase region of EphA4 directly interacts with the FRS2α PTB domain upon tyrosine phosphorylation of the EphA4 juxtamembrane (JM) domain and EphA4 directly phosphorylates FRS2α. We also found that the FRS2α PTB domain and the amino‐terminal region of EphA4 bind to the amino‐ and carboxy‐terminal regions of the FGFR JM domain, respectively, suggesting that FRS2α and EphA4 interact with FGFR simultaneously. Furthermore, a kinase‐dead EphA4 mutant that constitutively binds to FGFR functions as a dominant‐negative molecule for signaling through both EphA4 and FGFR, and so does the truncated FRS2α lacking multiple tyrosine phosphorylation sites. These dominant‐negative mutants similarly inhibit the ligand‐dependent proliferation of the mouse embryonic neural stem/progenitor cells. These results suggest the formation of a ternary complex comprising EphA4, FGFR and FRS2α. The signaling complex appears to integrate the input from FGFR and EphA4, and release the output signal through FRS2α.     

Overexpression and functional alterations of the EphA2 tyrosine kinase in cancer

Cancer is a disease of aberrant signal transduction. The expression and function of intracellular signaling pathways are frequently subverted as cells progress towards a metastatic phenotype. In particular, tyrosine kinases initiate powerful signals that govern many different aspects of cell behavior. In Recent studies have demonstrated that the EphA2 receptor tyrosine kinase is frequently overexpressed and functionally altered in aggressive tumor cells, and that these changes promote metastatic character. Herein, we provide an overview of our current understanding of EphA2, with emphasis upon the differential regulation of EphA2 expression and function. We also show that differential EphA2 expression and function may provide a unique opportunity for selective therapeutic targeting of EphA2 in metastatic disease.     

Kinase-Dependent and -Independent Roles of EphA2 in the Regulation of Prostate Cancer Invasion and Metastasis

Ligand-activated Eph tyrosine kinases regulate cellular repulsion, morphology, adhesion, and motility. EphA2 kinase is frequently up-regulated in several different types of cancers, including prostate, breast, colon, and lung carcinomas, as well as in melanoma. The existing data do not clarify whether EphA2 receptor phosphorylation or its simple overexpression, which likely leads to Eph kinase-independent responses, plays a role in the progression of malignant prostate cancer. In this study, we address the role of EphA2 tyrosine phosphorylation in prostate carcinoma cell adhesion, motility, invasion, and formation of metastases. Tumor cells expressing kinase-deficient EphA2 mutants, as well as an EphA2 variant lacking the cytoplasmic domain, are defective in ephrinA1-mediated cell rounding, retraction fiber formation, de-adhesion from the extracellular matrix, RhoA and Rac1 GTPase regulation, three-dimensional matrix invasion, and in vivo metastasis, suggesting a key role for EphA2 kinase activity. Nevertheless, EphA2 regulation of cell motility and invasion, as well as the formation of bone and visceral tumor colonies, reveals a component of both EphA2 kinase-dependent and -independent features. These results uncover a differential requirement for EphA2 kinase activity in the regulation of prostate carcinoma metastasis outcome, suggesting that although the kinase activity of EphA2 is required for the regulation of cell adhesion and cytoskeletal rearrangement, some distinct kinase-dependent and -independent pathways likely cooperate to drive cancer cell migration, invasion, and metastasis outcome.Eph receptors, the largest subfamily of receptor tyrosine kinases (RTKs), are involved in many biological processes including angiogenesis, tissue-border formation, cell migration, axon guidance, and synaptic plasticity. Ephs\ephrins are important mediators of cell-cell communication regulating cell attachment to extracellular matrix, cell shape, and motility.¹ Their frequent overexpression in human cancers and the correlation with poor prognosis and high vascularity in cancer tissues emphasize emerging roles in tumor progression.² EphA2 has been implicated in carcinogenesis of several cancers including melanomas and prostate, breast, colon, lung, and esophageal carcinomas.³ These studies showed high levels of EphA2 in both tissue and cell explants of these diseases and especially in the more aggressive stages of progression.⁴ In particular, ectopic overexpression of EphA2 gives untransformed epithelial cells both tumorigenic and metastatic potential.⁵ Certain Ephs and their ligands are expressed and up-regulated at sites of dynamic neovascularization, eg, in endothelial cells during tumor invasion.⁶ EphA2-deficient mice displayed decreased tumor volume, microvasculature density, and lung metastasis.⁷ Actually, the role of EphA2 in the regulation of malignant transformation/progression is far from clear. Indeed recent results unveil some antitumorigenic functions of EphA2: EphA2 is localized on chromosome 1p36.13, a region frequently deleted in a number of human cancers, including prostate and brain tumor and disruption of EphA2 kinase in mice leads to increased susceptibility to skin carcinogenesis, suggesting EphA2 as a potential tumor suppressor gene in mammalian skin.⁸Beside being implicated in tumor aggressiveness and vasculogenesis, class A ephrin/Eph interactions have recently been implicated in the organization of cell migration during several physiological and pathophysiological processes, including development, tissue morphogenesis, and cancer cell migration.¹ As for other receptor tyrosine kinases, ligand binding of EphA receptors induces receptor clustering, activation of kinase activity, and subsequent trans-phosphorylation of the cytoplasmic domains, creating docking sites for a number of signaling proteins.^9,10 The role of class A Eph receptors in regulating endothelial cell migration and assembly is strongly supported by several studies in angiogenic remodeling.¹¹ On the contrary, a clear role of EphA2 kinase in the regulation of cancer cell motility has not been delineated. We recently reported that in prostate carcinoma cells, ephrinA1 elicits a motility response by activating a Rho- and focal adhesion kinase (FAK)-dependent cytoskeleton rearrangement, finally driving the retraction of the cell body and the inhibition of directional cell migration.¹² In addition, activation of EphA2 is able to redirect motility and inhibit invasion of adenocarcinoma cells, again through a FAK-mediated pathway.¹³Ephrin/Eph interaction gives rise to complex cell-cell signaling culminating in a bidirectional pathway. Cells bearing the ephrin ligand engage in reverse signaling, and cells carrying the Eph receptors undergo forward signaling.^10,14,15 Although the reverse signaling of ephrin As is recognized as kinase-independent, attributable to their lack of enzymatic activity, the forward response elicited by the Eph kinase receptors is puzzling, because both kinase-dependent and -independent components have been reported. Indeed, several lines of evidence describe EphA2 signaling as mainly kinase-dependent. First, mutations of the kinase domain of EphA2 affect vascular endothelial cell growth and vascular endothelial growth factor-dependent angiogenesis.¹⁶ Second, recent data showed that EphA2 receptor phosphorylation may be vital in granting oncogenic potential.¹⁷ In agreement, the block of EphA2 receptor activation through EphA2-Fc results in a decrease in phosphorylation that was concurrent with decreased tumor volume.¹⁸ In keeping with these data, emerging evidence suggests that protein tyrosine phosphatases (PTPs) are involved in regulating Eph-mediated responses,^19,20 strongly supporting a role for Eph kinase activity.Nevertheless Eph receptors are nonclassical receptor tyrosine kinases because, beside kinase-dependent signaling, ligation of certain members of the Eph family can also trigger kinase-independent responses.^21,22,23,24 First, the presence of kinase-inactive together with wild-type EphA7 within the same cell changes its ligand-induced response from repulsion to adhesion,²⁵ indicating different functions of Ephs owing to their phosphorylation and degree of clustering. Second, EphA8 receptor localizes p110γ phosphatidylinositol 3-kinase to the plasma membrane in a tyrosine kinase-independent manner, thereby allowing access to lipid substrates to enable the signals required for integrin-mediated cell adhesion.²⁶ Third, the simple removal of membrane-associated EphA2 through ligand-independent endocytosis reduces malignant behavior of the cells and tumor growth.¹³ Finally, Miao and colleagues²⁷ recently reported that EphB3 catalytic activity is required for inhibition of integrin-mediated cell adhesion but is dispensable for directional cell migration.In the context of this controversial literature, we investigated the role of tyrosine phosphorylation of EphA2 kinase in the regulation of prostate carcinoma cell motility and invasion. On the whole, our findings point to a kinase-dependent role of EphA2 receptor for the regulation of cell motility, adhesion, cytoskeleton rearrangements, as well as for invasion and metastasis formation in nude mice, although the invasive and prometastatic effect of EphA2 show a kinase-independent component.     

Expression of the EphA1 protein is associated with Fuhrman nuclear grade in clear cell renal cell carcinomas

Aberrant expression of receptor tyrosine kinase EphA1 in malignant tissues has been reported. However, the expression profile of EphA1 in renal cell carcinoma (RCC) and its association with clinicopathological parameters remain unknown. The aim of this study was to determine the cancerous value of the EphA1 protein expression in patients with renal cell carcinomas. This study included 144 patients with clear cell RCC (ccRCC), 18 patients with chromophobe RCC and 6 patients with papillary RCC. The EphA1 protein was detected in RCC tissue samples by an immunohistochemical staining with a specific polycolonal antibody. The correlation of the expression of the EphA1 protein with clinicopathological parameters was evaluated. High level of the expression of EphA1 was observed in all normal renal tubes. The EphA1 protein was negatively or weakly expressed in 93 out of 144 ccRCC (64.6%) and positively expressed in 51 out of 144 ccRCC (35.4%). The high level expression of the EphA1 protein was significantly associated with younger patients (P<0.001), sex (P=0.016) and lower nuclear grade (P<0.001). No significant relation between the expression of EphA1 and tumor diameter was found (P=0.316). Positive expression of EphA1 was observed in all samples of chromophobe RCC and papillary RCC. Our data indicated that the EphA1 protein may be a new marker for the prognosis of ccRCC.     

Patterns of EphA2 protein expression in primary and metastatic pancreatic carcinoma and correlation with genetic status

EphA2 is a transmembrane receptor tyrosine kinase that functions in the regulation of cell growth, survival, angiogenesis, and migration and EphA2 targeting has been proposed as a novel therapeutic strategy for neoplasms that overexpress this protein. EphA2 overexpression has been correlated with increased invasive and metastatic ability in pancreatic cancer cell lines. However, the patterns of EphA2 expression in human pancreatic cancers and associated metastases is unknown, as are the genetics of EphA2 in this tumor type. We collected clinicopathologic data and paraffin-embedded materials from 98 patients with primary and/or metastatic pancreatic cancer and performed immunohistochemical labeling for EphA2 protein. EphA2 protein immunolabeling was found in 207 of 219 samples (95%). The expression was predominantly cytoplasmic, although predominant membranous staining was observed in a minority of cases. When evaluated specifically for labeling intensity, primary and metastatic carcinomas were more strongly positive compared to benign ducts and PanIN lesions (P < 0.00001 and P < 0.01, respectively) and poorly differentiated carcinomas were more strongly positive for EphA2 than well and moderately differentiated tumors (P < 0.005). When primary carcinomas without metastatic disease were specifically compared to carcinomas with associated metastatic disease, the advanced carcinomas showed relatively less strong positive labeling for EphA2 (P < 0.008). Moreover, decreased EphA2 labeling was more commonly found in liver (P < 0.002), lung (P < 0.004) or peritoneal metastases (P < 0.01) as compared to distant lymph node metastases (P < 0.01). Genetic sequencing of the tyrosine kinase domain of EPHA2 in 22 samples of xenograft enriched pancreatic cancer did not reveal any inactivating mutations. However, EPHA2 amplification was found in 1 of 33 pancreatic cancers corresponding to a lymph node metastasis, indicating EPHA2 genomic amplification may underlie EphA2 overexpression in a minority of patients. Our data confirms that EphA2 is overexpressed in pancreatic cancer, but suggests a relative loss of EphA2 in co-existent pancreatic cancer metastases as well as a role for EPHA2 in organ specific metastasis. Shiyama V. Mudali and Baojin Fu contributed equally to this work.     

乳腺癌EphA2和EphrinAl的表达及与临床病理因素的关系

目的　研究云南白族地区乳腺癌EphA2和EphrinAl的表达及其与临床病理因素的关系。 方法　用免疫组织化学(IHC)检测乳腺癌组织中EphA2、EphrinAl的表达,比较各自表达情况与临床病理因素的关系及二者间的相关性。 结果　EphA2、EphrinAl主要表达于肿瘤细胞和血管内皮细胞的胞浆和胞膜,呈棕黄色或棕褐色。150 例乳腺癌组织中,EphA2、EphrinAl阳性表达分别为123例、129例,阳性率分别为82%、86%。二者的阳性率与患者年龄无相关性(P>0.05),而与病理类型、肿瘤大小、淋巴结转移、临床分期和组织学分级有相关性(P<0.05)。浸润性导管癌EphA2和EphrinAl阳性率较导管内癌的高;肿瘤较大组、淋巴结转移组、临床分期较晚者、组织学分级较高组EphA2和EphrinAl的阳性率分别高于肿瘤较小组、无淋巴结转移组、临床分期较早者、组织学分级较低组EphA2和EphrinAl的阳性率。EphA2和EphrinAl阳性染色共同定位于大致相同的肿瘤区域和血管内皮细胞,二者的阳性率有相关性(P<0.05)。 结论　EphA2、EphrinAl在乳腺癌高表达,并与其发生发展、侵袭转移及恶性程度有关,有望成为乳腺癌预后评估标志物,为早期诊断和靶向治疗提供新思路。     

High-level expression of EphA2 receptor tyrosine kinase in prostatic intraepithelial neoplasia

EphA2 is a transmembrane receptor tyrosine kinase that is overexpressed in many carcinomas. Specific targeting of EphA2 with monoclonal antibodies is sufficient to inhibit the growth, migration and invasiveness of aggressive cancers in animal models. Using immunohistochemical analyses, we measured the expression of EphA2 in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostate tissue from ninety-three radical prostatectomy specimens. These results were related to multiple clinical and pathologicalcharacteristics. The fraction of cells staining positively with EphA2 in benign prostatic epithelium (mean, 12%) was significantly lower than that in high-grade prostatic intraepithelial neoplasia (mean, 67%, P < 0.001) and prostatic adenocarcinoma (mean, 85%, P < 0.001). Moreover, the intensity of EphA2 immunoreactivity in prostatic adenocarcinoma was significantly higher than in benign prostatic tissue (P < 0.001) or high-grade prostatic intraepithelial neoplasia (P < 0.001). Benign prostatic epithelium showed weak or no immunoreactivity for EphA2 in all cases examined. Whereas EphA2 immunoreactivity related to neoplastic transformation, it did not correlate with other clinical and pathological parameters examined. Our data suggest that EphA2 levels increase as prostatic epithelial cells progress toward a more aggressive phenotype. Progressively higher levels of EphA2 in high-grade prostatic intraepithelial neoplasia and prostatic carcinoma are consistent with recent evidence that EphA2 functions as a powerful oncogene. Moreover, the presence of high levels of EphA2 in these cells suggests opportunities for prostate cancer prevention and treatment.     

Effects of some growth factors and cytokines on ATP synthesis by plasma-membrane-enriched particles isolated from different human tumors

Plasma-membrane-enriched particles isolated from the tissues of malignant tumors of different sites are shown to accumulate ATP under the influence of polypeptide growth factors and cytokines whose receptors have a tyrosine kinase activity. Polypeptide growth factors, such as EGF, FGF, NGF, TNF, insulin, and the cytokine IL-2, were studied on the accumulation of adenosine-5'-triphosphate (ATP) by the preparations of plasma-membrane-enriched particles isolated from the target tissues of human malignant tumors. The tumor (transformed) cell plasma membranes of the lung, bowel, stomach, pancreas, as well as the cells of neurinoma and a retroperitoneal extra-organ malignant tumor (leiomyosarcoma) are demonstrated to be able to synthesize ATP from inorganic phosphate and ADP under aerobic conditions human with the participation of the cyanide-insensitive proton phoric NADH-bound transversely oriented chain. Signal-stimulated accumulation of plasma membranous ATP was found to increase in the tissues in malignant transformation as compared to that in normal tissues. Experiments using selective inhibitors of tyrosine kinases (tyrphostin-25, quercetin) indicated the involvement of plasma membranous signal-transducing ATP in the activation of receptor tyrosine kinase growth factors.     

Expression of EphA2 protein is positively associated with age,tumor size and Fuhrman nuclear grade in clear cell renal cell carcinomas

The receptor tyrosine kinase of EphA2 has been shown frequently overexpressed in various types of human carcinomas, which implicated that it plays important roles in carcinogenesis. Although EphA2 protein expression has been investigated in many types of human carcinomas, the relationship between the expression of EphA2 protein in clear cell renal cell carcinoma was not well documented. In the present study, using specific anit-EphA2 polyclonal antibody and immunohistochemistry, we evaluated EphA2 protein expression levels in clear cell RCC specimens surgically resected from 90 patients. Our results shows that EphA2 protein was positively expressed in all normal renal tubes of 90 samples (100%, 3+), which was expressed at low levels in renal cortex but high levels in the collecting ducts of the renal medulla and papilla. EphA2 was negatively or weakly expressed in 30 out of 90 samples (33.3%, 0/1+), moderately expressed in 24 samples (26.7%, 2+) and strongly expressed in 36 samples (40%, 3+). Expression of EphA2 was positively associated with age (P=0.029), tumor diameters (P<0.001) and Fuhrman nuclear grade (P<0.001). Our results indicate that EphA2 variably expressed in clear cell renal cell carcinomas. High expression of EphA2 was more often found in big size and high nuclear grade tumors, which indicated EphA2 protein may be used as a new marker for the prognosis of clear cell renal cell carcinoma.