ARHI在肿瘤发生和发展中的作用与机制研究进展

ARHI是1999年发现的母源性印迹基因,属于小G蛋白Ras超家族,是该家族第1个被报道的抑癌基因。ARHI的功能包括抑制小鼠生长和生殖发育,抑制细胞增殖、迁移,参与周期调控和凋亡,近年来研究发现ARHI还具有调控肿瘤细胞自噬、抑制肿瘤转移的作用。ARHI蛋白在人体卵巢、乳腺等多种组织中表达,在卵巢癌、乳腺癌、甲状腺癌、胰腺癌、肝癌组织中表达下调,ARHI基因高表达可提示卵巢癌、胰腺癌的预后良好。ARHI表达调控机制包括杂合性丢失、DNA甲基化、组蛋白去乙酰化、转录因子调节、miRNA和突变,应用表观遗传学技术调节ARHI表达可能在一些肿瘤中具有抗肿瘤临床应用价值。ARHI基因参与调节肿瘤细胞休眠过程,有望成为诱导肿瘤细胞休眠、抗肿瘤转移复发的关键点。     

ARHI基因对人胰腺癌组织血管生成的影响

目的 探讨ARHI基因与胰腺癌组织血管密度和临床病理的相关性.方法 收集23例胰腺癌石蜡标本作为实验组,27例正常胰腺石蜡标本作为对照组.然后采用免疫组化方法检测两组标本ARHI、CD34蛋白表达情况;分析ARHI、CD34蛋白表达与胰腺癌的关系;分析ARHI与MVD的相关性.结果 对照组和实验组标本中ARHI阳性率分别为88.9%(24/27)、21.7%(5/23),实验组标本中ARHI基因表达下降,两组比较差异具有统计学意义(P<0.05);对照组MVD值显著低于实验组,差异具有统计学意义(P<0.05);ARHI表达与胰腺癌分化程度呈负相关(P<0.05),其中肿瘤分化程度越低,ARHI表达缺失概率越大;实验组标本中CD34阳性表达较高,多数具有管腔结构,且MVD值明显高于对照组标本,差异具有统计学意义(P<0.001);胰腺癌组织中,MVD与ARHI的表达无相关性(P>0.05);而所有统计病例中,ARHI阴性者比阳性者的MVD值高,且MVD与ARHI的表达呈负相关(P<0.001).结论 ARHI可能通过抑制胰腺癌微血管的生成进而抑制胰腺癌生长.     

抑癌基因ARHI研究进展

ARHI（aplasia ras homologue member I）/NOEY2是1999年新发现的一个母源性抑癌印迹基因,位于人染色体1p31,编码一个相对分子量为26kD的小GTP结合蛋白。ARHI属ras/rap超家族成员,与该家族成员有50%～60%的同源性并且两者具有相似的GTP/GDP结合域,但与该家族其它成员不同,ARHI发挥抑癌基因作用,是该家族第一个被报道的肿瘤抑制基因。ARHI基因编码的蛋白在人类多种组织表达,而该基因在人卵巢癌、乳腺癌、胰腺癌、肝癌等多种肿瘤中表达下调或缺失,提示其与上述肿瘤的发生、发展密切相关。ARHI可能通过作用于cyclin D1,使其不能与CDK结合形成活性激酶,从而使细胞停止于G1期来参与细胞周期调控;可能通过依赖caspase和calpain两条途径参与信号通路传导诱发细胞凋亡;另外,该基因可通过抑制STAT3的激活而发挥抑癌基因功能,也可以调节自体吞噬和肿瘤细胞休眠。目前研究显示,ARHI基因的表达缺失主要通过遗传事件和表观遗传学机制发生,包括DNA甲基化异常、杂合性丢失,乙酰化组蛋白的低水平表达及基因突变有关,但有待进一步深入研究。可以预见,ARHI基因的深入研究必将为早期肿瘤的基因诊治提供新的思路和理论依据。      

肿瘤抑制基因ARHI的生物学功能及研究进展

肿瘤是一种基因病,抑癌基因在抵御肿瘤发生、发展中起着重要作用。ARHI(aplysia ras hom olog I)/NOEY2 是一个新发现的抑癌基因,是 ras/rap超家族成员之一,与 ras家族有50%~60%的同源性,位于人染色体1p31,属小GTP结合蛋白,是该家族第1个被报道的肿瘤抑制基因。ARHI基因编码的蛋白在人类多种组织表达,其中正常卵巢的ARHI表达最高。ARHI是一个印迹基因,印迹机制可能与其CpG岛的差异甲基化有关。ARHI 参与细胞周期调控可能作用于cyclin D1 ,使其不能与 CDK结合形成活性激酶,从而使细胞停止于 G1 期。AR HI可能通过依赖caspase和 calpain两条途径参与信号通路传导诱发细胞凋亡。该基因的异常表达跟多种肿瘤的发生、发展有关。ARHI基因参与了乳腺癌的发生和发展,该基因的表达缺失可能与乳腺癌的转移机制有关。卵巢癌、乳腺癌存在广泛的1p31缺失,其中 ARHI 基因是最常见的一个缺失区域。ARHI基因和蛋白在胰腺癌组织中有较高比例的缺失,提示该基因和蛋白在胰腺癌的发生中起一定作用。ARHI基因在膀胱癌、肝癌、前列腺癌等其他肿瘤中也有不同程度的表达异常。     

肿瘤抑制基因ARHI的生物学功能及研究进展

肿瘤是一种基因病，抑癌基因在抵御肿瘤发生、发展中起着重要作用。ARHI(aplysia ras homolog I)／NOEY2是一个新发现的抑癌基因．是ras/rap超家族成员之一．与ras家族有50％～60％的同源性．位于人染色体1p31，属小GTP结合蛋白，是该家族第1个被报道的肿瘤抑制基因。ARHI基因编码的蛋白在人类多种组织表达，其中正常卵巢的ARHI表达最高。ARHI是一个印迹基因．印迹机制可能与其CpG岛的差异甲基化有关。ARHI参与细胞周期调控可能作用于cyclin D1，使其不能与CDK结合形成活性激酶，从而使细胞停止于G1期。ARHI可能通过依赖caspase和calpain两条途径参与信号通路传导诱发细胞凋亡。该基因的异常表达跟多种肿瘤的发生、发展有关。ARHI基因参与了乳腺癌的发生和发展，该基因的表达缺失可能与乳腺癌的转移机制有关。卵巢癌、乳腺癌存在广泛的1p31缺失，其中ARHI基因是最常见的一个缺失区域。ARHI基因和蛋白在胰腺癌组织中有较高比例的缺失，提示该基因和蛋白在胰腺癌的发生中起一定作用。ARHI基因在膀胱癌、肝癌、前列腺癌等其他肿瘤中也有不同程度的表达异常。     

ARHⅠ和E钙粘蛋白在乳头状甲状腺癌中的表达及意义

[目的]探讨ARHI蛋白及E钙粘蛋白在乳头状甲状腺癌中的表达及意义。[方法]56例经病理确诊的乳头状甲状腺癌患者人组,并取其距癌组织边缘〉2cm的正常甲状腺组织作为对照。采用免疫组化方法检测ARHI蛋白及E钙粘蛋白的表达。[结果]ARHI及E钙粘蛋白在乳头状甲状腺癌中的表达均显著低于正常甲状腺组织（48．2％V,q80．4％,51．8％VS91．1％．P均〈0．05）。ARHI、E钙粘蛋白在乳头状甲状腺癌中的表达与肿瘤大小、TNM分期、淋巴结转移情况有关（P〈0．05）。ARHI与E钙粘蛋白在乳头状甲状腺癌中的表达无明显相关性（Kappa=0．287,P=0．023）。[结论]ARHI、E钙粘蛋白在乳头状甲状腺癌中表达降低,提示其在乳头状甲状腺癌的发生发展、侵袭中可能发挥重要作用。     

PDCD5与肿瘤的临床相关性

程序性细胞死亡因子5（PDCD5）是一种新的程序性细胞死亡调控基因。PDCD5表达广泛,进化保守,具有促进肺癌、肝癌等多种肿瘤细胞凋亡和抑制细胞增殖的效应。PDCD5在疾病情况下,特别是在肿瘤细胞中的表达明显下调,与肿瘤有着密不可分的临床相关性,对肿瘤的发现、诊断和治疗有很大的临床检验价值。     

植物生物碱的抗肿瘤机制

植物中的生物碱具有抗肿瘤功效,近年来发现其抗肿瘤机制与干扰肿瘤细胞周期、诱导肿瘤细胞凋亡、抑制肿瘤新生血管生成和多药耐药性等有关,另外最近还发现植物生物碱可抑制端粒酶活性和诱导自噬.因此,植物生物碱可能是一类具有潜力的抗肿瘤药物.     

CD47在肿瘤中的表达及治疗应用

近年来研究发现,CD47通过上调在肿瘤细胞表面的表达来影响肿瘤的生长与转移,同时,其表达上调预示临床预后较差;而CD47单抗可通过激活适应性免疫及直接介导细胞凋亡等机制抑制肿瘤生长.此外,CD47还具有调节血液系统和胃肠道系统正常组织细胞的放射性损伤修复作用,有望成为肿瘤治疗的新靶点.     

TRAIL及其在血液系统恶性肿瘤中的治疗进展

细胞凋亡（apoptosis）与肿瘤的发生、发展和转移有密切关系,诱导肿瘤细胞凋亡以达到治疗目的是近几年肿瘤治疗的热点之一。肿瘤坏死因子相关的凋亡诱导配体（TNF-related apoptosis-inducing ligand,TRAIL）是新近发现的TNF超家族成员,它能选择性的诱导肿瘤细胞和转化细胞发生凋亡,且与血液系统肿瘤常用的化疗药物具有协同性,还能克服一部分多药耐药现象,而对正常细胞没有显毒性效应,这些特性使TRAIL在血液系统恶性肿瘤的治疗中具有很大的应用前景。本就其结构、功能、作用机制及抗血液病肿瘤研究最新进展作一综述。     

ARHI is the center of allelic deletion on chromosome 1p31 in ovarian and breast cancers

In our previous work, we had characterized ARHI as an imprinted putative tumor-suppressor gene in ovarian and breast cancers. ARHI is expressed in primary breast and ovarian cell lines but largely absent from the corresponding malignant tumors. Moreover, the non-imprinted functional allele is typically deleted in malignant cells. Since ARHI had been mapped to 1p31, a common deletion site in breast and ovarian cancer and male germ-cell tumors, in this study, we set out to define precisely the physical location of ARHI at 1p31 and to determine if this location lies within the smallest common region of deletion in breast and ovarian cancers. To this end, we first carried out radiation hybrid mapping of ARHI and surrounding markers, followed by a high-resolution study of loss of heterozygosity at 1p31 in 49 ovarian and breast cancers. Combining a radiation hybrid map and a physical map of the region encompassing ARHI, 3 discrete regions of minimal deletion were found at 1p31 in breast and ovarian cancers. ARHI is the most common deletion region at 1p31. Two other less common regions of deletion were found centromeric to this gene. One of them centered on D1S207 and the other one included and was proximal to D1S488. We also confirmed the preferential loss of non-imprinted functional allele in 7 of 9 tumor specimens. These data support the possibility that ARHI is a tumor-suppressor gene and suggest that additional tumor-suppressor genes may lie proximal to ARHI at 1p31. The data obtained from our study should aid in the identification and characterization of genes in this novel imprinted region.     

ARHI/NOEY2 inactivation may be important in breast tumor pathogenesis

Allelic loss frequently occurs on the short arm of chromosome 1 in human breast carcinoma, suggesting that the ARHI/NOEY2 gene, an imprinted putative tumor suppressor gene, is involved in the pathogenesis of the tumor entity. To clarify the clinical importance of ARHI/NOEY2 mRNA in breast cancer, we studied whether ARHI/NOEY2 inactivation might contribute to tumors arising in the breast. An ARHI/NOEY2 message was detected by real-time PCR analysis in all noncancerous breast tissues, but was not detected in 2 of 26 breast cancer tissue samples. In 10 of 26 breast cancer tissue samples ARHI/NOEY2 mRNA was substantially reduced. ARHI/NOEY2 expression was lost or markedly reduced in 12 of 26 (46.15%) breast cancer tissue samples. In summary, we conclude that decreased ARHI/NOEY2 mRNA expression may play an important role in the pathogenesis of breast cancer.     

MicroRNAs 221/222 and genistein-mediated regulation of ARHI tumor suppressor gene in prostate cancer

ARHI is an imprinted tumor suppressor gene and is downregulated in various malignancies. However, ARHI expression, function, and mechanisms of action in prostate cancer have not been reported. Here, we report that ARHI mRNA and protein levels were downregulated in prostate cancer tissues compared with adjacent normal tissues. Overexpression of ARHI inhibited cell proliferation, colony formation, invasion, and induced apoptosis. Further studies on a new mechanism of ARHI downregulation showed a significant inverse relationship between ARHI and miR-221 and 222, which were upregulated in prostate cancer cell lines. Transfection of miR-221 and 222 inhibitors into PC-3 cells caused a significant induction of ARHI expression. A direct interaction of miR-221 or 222 with a target site on the 3'UTR of ARHI was confirmed by a dual luciferase pMIR-REPORT assay. Finally, we also found that genistein upregulates ARHI by downregulating miR-221 and 222 in PC-3 cells. In conclusion, ARHI is a tumor suppressor gene downregulated in prostate cancer, and overexpression of ARHI can inhibit cell proliferation, colony formation, and invasion. This study demonstrates for the first time that prostate cancer cells have decreased level of ARHI which could be caused by direct targeting of 3'UTR of ARHI by miR221/222. Genistein, a potential nontoxic chemopreventive agent, restores expression of ARHI and may be an important dietary therapeutic agent for treating prostate cancer.     

Expression of the tumor suppressor gene ARHI in epithelial ovarian cancer is associated with increased expression of p21WAF1/CIP1 and prolonged progression-free survival.

PURPOSE: ARHI, an imprinted putative tumor suppressor gene, is expressed in normal ovarian epithelial cells, but its expression is down-regulated or lost in most ovarian cancer cell lines. Reexpression of ARHI in cancer cells induces p21(WAF1/CIP1), down-regulates cyclin D1 promoter activity and inhibits growth in cell culture and in heterografts. To determine the relevance of these observations to clinical cancer, we have now measured ARHI expression in normal, benign and malignant ovarian tissues using immunohistochemistry and in situ hybridization. EXPERIMENTAL DESIGN: Paraffin embedded tissues from 7 normal ovaries, 22 cystadenomas and 42 borderline lesions were analyzed using standard immunoperoxidase and in situ hybridization techniques to assess ARHI expression. In addition, immunohistochemistry against ARHI was performed on a tissue microarray containing 441 consecutive cases of ovarian carcinoma. RESULTS: Strong ARHI expression was found in normal ovarian surface epithelial cells, cysts and follicles using immunohistochemistry and in situ hybridization. Reduced ARHI expression was observed in tumors of low malignant potential as well as in invasive cancers. ARHI expression was down-regulated in 63% of invasive ovarian cancer specimens and could not be detected in 47%. When immunohistochemistry and in situ hybridization were compared, ARHI protein expression could be down-regulated in the presence of ARHI mRNA. ARHI expression was correlated with expression of p21(WAF1/CIP1) (P = 0.0074) but not with cyclin D1 and associated with prolonged disease free survival (P = 0.001). On multivariate analysis, ARHI expression, grade and stage were independent prognostic factors. ARHI expression did not correlate with overall survival. CONCLUSIONS: Persistence of ARHI expression in epithelial ovarian cancers correlated with prolonged disease free survival and expression of the cyclin dependent kinase inhibitor p21(WAF1/CIP1).     

The expression of ARHI in pT2a and pT2b stage gastric cancer and its clinical significance

ARHI is a novel tumor suppressor gene located on chromosome 1p31. Downregulation of ARHI expression has been detected in many types of cancer. However, the effects of ARHI in gastric cancer remain unclear. The aim of this study was to identify the relationship between ARHI expression and gastric cancer clinicopathological features. In this study, 81 pT2 stage gastric cancer specimens were subclassified by pT2a and pT2b stage. ARHI mRNA and protein levels were evaluated by real-time PCR and western blot analysis, respectively. Methylation plays an important role in suppressor gene silencing. We utilized methylation-specific PCR to identify the status of CpG islands in the ARHI gene. We used immunohistochemistry to determine the expression of the protein and analyzed clinicopathological features. The levels of ARHI mRNA in gastric cancer were lower compared to normal tissues (P<0.01). Similarly, the levels of ARHI protein in the cancer specimens were lower (P<0.05). DNA hypermethylation was identified in 79.1% of gastric cancer specimens without ARHI expression. Immunohistochemistry results were significantly correlated with the pT2 category (P<0.05). The cumulative survival rate of patients with ARHI expression was significantly higher compared to those without ARHI expression (P<0.05). ARHI as a suppressor is not only an important factor in the pathogenesis of gastric cancer, but also a potential factor for tumor aggravation. ARHI expression in gastric cancer can be employed to indicate favorable prognosis for the disease.     

Effects of ARHI on breast cancer cell biological behavior regulated by microRNA-221

The aplysia ras homolog member I (ARHI) is a tumor suppressor gene and is downregulated in various cancers. The downregulation of ARHI was regulated by miR-221 in prostate cancer cell lines. However, it has not been reported whether ARHI is regulated by miR-221 in breast cancer. Here, we reported that the ARHI protein level was downregulated in breast cancer tissues and breast cancer cell lines. The overexpression of ARHI could inhibit cell proliferation and invasion and induce cell apoptosis. To address whether ARHI is regulated by miR-221 in breast cancer cell lines, the results in this study showed that a significant inverse correlation existed between ARHI and miR-221. MiR-221 displayed an upregulation in breast cancer tissues and breast cancer cell lines. The inhibition of miR-221 induced a significant upregulation of ARHI in MCF-7 cells. To prove a direct interaction between miR-221 and ARHI mRNA, ARHI 3′UTR, which includes the potential target site for miR-221, was cloned downstream of the luciferase reporter gene of the pMIR-REPORT vector to generate the pMIR-ARHI-3′UTR vector. The results confirmed a direct interaction of miR-221 with a target site on the 3′UTR of ARHI. In conclusion, ARHI is a tumor suppressor gene that is downregulated in breast cancer. The overexpression of ARHI could inhibit breast cancer cell proliferation and invasion and induce cell apoptosis. This study demonstrated for the first time that the downregulation of ARHI in breast cancer cells could be regulated by miR-221.