DNA結(jié)合抑制因子在腫瘤靶向治療中的展望

郭 品 綜述 邱永明 審校

(上海交通大學(xué)醫(yī)學(xué)院附屬仁濟(jì)醫(yī)院神經(jīng)外科,上海 200127)

DNA結(jié)合抑制因子(inhibitor of DNA binding,Id)蛋白屬于螺旋 -環(huán) -螺旋(helix-loop-helix,HLH)蛋白超家族,為負(fù)性調(diào)節(jié)因子,缺少基本的 DNA結(jié)合域,無(wú) DNA結(jié)合活性,主要通過(guò)螯合廣泛表達(dá),見(jiàn)圖 1。人類的 Id家族包括四名成員,即 Id-1,Id-2,Id-3,Id-4[1],所有的 Id蛋白擁有高度同源的螺旋環(huán)螺旋區(qū)域。經(jīng)過(guò)近 20年的研究,它們的細(xì)胞和生物學(xué)特性已逐漸明了。在細(xì)胞分化、凋亡、細(xì)胞周期的調(diào)節(jié)、腫瘤生成、浸潤(rùn)和轉(zhuǎn)移等不同細(xì)胞生物學(xué)過(guò)程中,Id家族各自發(fā)揮不同的生物學(xué)作用[1-3]。Id基因或蛋白的表達(dá)異常,在腫瘤的發(fā)生和發(fā)展過(guò)程中起著重要作用。因此,人為調(diào)控 Id基因和蛋白有望成為腫瘤的治療靶點(diǎn)。本文總結(jié)了 Id基因和蛋白在腫瘤發(fā)生發(fā)展以及預(yù)后中的作用,來(lái)探討 Id作為腫瘤治療有效治療靶點(diǎn)的可行性。

圖1 Id在 bhlh轉(zhuǎn)錄作用的模型[1]

1 Id在原發(fā)性腫瘤細(xì)胞中的表達(dá)

正常情況下,Id在成熟的成年正常組織中微量表達(dá),而在多個(gè)系統(tǒng)的腫瘤中發(fā)現(xiàn) Id的異常表達(dá)[4]。2003年,Lee等[5]在研究肝細(xì)胞癌時(shí)發(fā)現(xiàn) Id-1可通過(guò) p16INK4a/RB途徑來(lái)影響腫瘤的發(fā)生和發(fā)展。之后,在消化系統(tǒng)的其他腫瘤的研究中也發(fā)現(xiàn)了 Id的異常。如肝細(xì)胞型肝癌中,Id-1在 RNA水平和蛋白水平均存在高表達(dá)[5];在原發(fā)性結(jié)腸癌的研究中,Id-1的表達(dá)水平較正常黏膜相比有所升高[6];另外,Shuno等[7]發(fā)現(xiàn),Id-1和 Id-3的異常表達(dá)與胰腺癌細(xì)胞的轉(zhuǎn)移有關(guān)。

同樣,在生殖系統(tǒng)腫瘤的研究中也發(fā)現(xiàn) Id基因和蛋白的異常。Id-1在卵巢腫瘤、宮頸癌、乳腺癌、子宮內(nèi)膜癌以及前列腺癌中的表達(dá)異常,并且 Id-1的表達(dá)水平與低分化類型、高度的惡性潛能及不良的臨床結(jié)果有關(guān)[8-12];Sablizky等[13]發(fā)現(xiàn)在精原細(xì)胞癌中,Id家族均高表達(dá)。

Id基因和蛋白在中樞神經(jīng)系統(tǒng)腫瘤的研究較少,但也有發(fā)現(xiàn) Id基因和蛋白表達(dá)含量與神經(jīng)系統(tǒng)腫瘤惡性程度的關(guān)系。如在星型細(xì)胞腫瘤中,高級(jí)別的腫瘤中 Id1-3的表達(dá)水平高于低級(jí)別的腫瘤[14]。目前 Id基因和蛋白表達(dá)含量與神經(jīng)系統(tǒng)腫瘤患者預(yù)后的關(guān)系尚未明確。

2 Id參與腫瘤的發(fā)生發(fā)展

2.1 參與腫瘤血管的生成 血管的生成是腫瘤發(fā)生的關(guān)節(jié)環(huán)節(jié)之一。已證實(shí),Id-1、Id-3和 Id-4在血管生成方面有促進(jìn)作用[15,16]。Si等[17,18]在對(duì)胃癌的研究中發(fā)現(xiàn),Id-1的過(guò)表達(dá)可使腫瘤血管的密度增加。另外,在口腔鱗狀上皮細(xì)胞癌、卵巢癌、子宮頸癌中,也同樣發(fā)現(xiàn) Id-1的過(guò)表達(dá)可能與腫瘤血管的生成有關(guān)[8,19,20],其機(jī)制尚未明確,有研究者推斷可能與 Id-1激活 VEGF有關(guān)。在前列腺癌中,Id-1的過(guò)表達(dá)可激活 VEGF,以提供促進(jìn)腫瘤血管生成的自分泌信號(hào)[21],從而促進(jìn)腫瘤的發(fā)生發(fā)展。所以作用于 Id-1,以降低 VEGF的活性,干擾腫瘤血管的生成,達(dá)到治療腫瘤的目的。另外,Volpert等[22]發(fā)現(xiàn),Id-1可通過(guò)轉(zhuǎn)錄抑制血小板凝血酶敏感蛋白 -1(thrombospondin-1,TSP-1),來(lái)調(diào)節(jié)血管的生成。這無(wú)疑又證實(shí)了,Id-1可作為腫瘤治療的靶點(diǎn)。

2.2 抑制腫瘤細(xì)胞的凋亡

腫瘤的發(fā)生與細(xì)胞凋亡的調(diào)節(jié)紊亂有密切的關(guān)系。大量的研究證明,Id家族可影響腫瘤細(xì)胞的凋亡。卵巢癌中,Id-1、Id-3蛋白的過(guò)表達(dá)可激活 E-box,并且可增加細(xì)胞周期蛋白依賴性激酶抑制劑(Cyclin-dependent kinase inhibitor,CDKI)的表達(dá)水平,抑制抑癌基因的活性,從而抑制細(xì)胞的凋亡[23];在乳腺癌細(xì)胞中,Id-1可通過(guò) P53和NF-kappaB通路來(lái)干預(yù)細(xì)胞的凋亡[24];在頭頸鱗狀細(xì)胞癌的研究中,Id-1可通過(guò) NF-kappaB/survivin和 phosphoinositIde 3-kinase/Akt信號(hào)途徑阻止腫瘤細(xì)胞的凋亡[25];在腸上皮細(xì)胞中,敲除 Id-1和 Id-2可誘導(dǎo)細(xì)胞的凋亡,而且 Id-2的過(guò)表達(dá)可阻止 TGFbeta誘導(dǎo)的凋亡[26];在食管癌中,Id-1可激活 PI3K/Akt/NfkappaB信號(hào)通路,抑制細(xì)胞的凋亡,還可抑制 TNF-alpha誘導(dǎo)的細(xì)胞凋亡[27];Koyama等[28]研究稱,在肉瘤細(xì)胞系中,Id-3可增強(qiáng) cddp誘導(dǎo)的細(xì)胞凋亡。

另外,Id-1可降低腫瘤細(xì)胞對(duì)化療藥物的敏感性,從而對(duì)抗藥物誘導(dǎo)的凋亡。如在膀胱癌中,Id-1的下調(diào)可增強(qiáng)腫瘤細(xì)胞對(duì)表柔比星的敏感性,誘導(dǎo)細(xì)胞凋亡[29];Wong等研究稱,在前列腺癌細(xì)胞系DU145、PC3中,利用 siRNA技術(shù)檢測(cè)到 Id-1的下調(diào),可增加癌細(xì)胞對(duì)紫杉醇的敏感性,從而促進(jìn)細(xì)胞凋亡[30],其抗藥性可能通過(guò) AkT途徑來(lái)發(fā)揮作用[31];鼻咽癌細(xì)胞中,Id-1可通過(guò) Raf/MEK通路阻止紫杉醇誘導(dǎo)的細(xì)胞凋亡[32]。

由此,我們可以把 Id基因和蛋白作為腫瘤治療靶點(diǎn),促進(jìn)腫瘤細(xì)胞的凋亡,從而達(dá)到治療腫瘤的目的。

2.3 調(diào)節(jié)腫瘤細(xì)胞的分化

細(xì)胞分化是細(xì)胞之間產(chǎn)生差異的過(guò)程,細(xì)胞的非正常分化,常使得正常細(xì)胞瘤變。宮頸癌細(xì)胞中,Id-1的過(guò)表達(dá)可影響細(xì)胞分化,從而加速腫瘤的惡性進(jìn)程[9]。前列腺癌細(xì)胞通過(guò) Id-1調(diào)節(jié)破骨細(xì)胞的分化,間接作用于前列腺癌骨轉(zhuǎn)移[33]。在肝臟腫瘤的研究中,Id-1可調(diào)節(jié)肝細(xì)胞瘤細(xì)胞的分化,從而加速肝細(xì)胞癌變的進(jìn)程[34]。Kebebew等[35]發(fā)現(xiàn),Id-1基因的過(guò)表達(dá)可調(diào)節(jié)甲狀腺癌細(xì)胞的分化。Id-2在腫瘤的研究較少,但也發(fā)現(xiàn),Id-2可調(diào)節(jié)乳腺上皮細(xì)胞的、肝星形細(xì)胞、人類角質(zhì)化細(xì)胞的分化,調(diào)控 Id2的表達(dá)量,可阻止這些細(xì)胞的非正常分化[36-38]。另外,Umetani等[39]發(fā)現(xiàn),Id-4的失活,可與結(jié)直腸癌細(xì)胞的低分化有關(guān)。

可見(jiàn) Id基因和蛋白在細(xì)胞分化中的重要作用,認(rèn)為調(diào)節(jié) Id基因和蛋白的含量,可影響腫瘤細(xì)胞的分化,為腫瘤的治療提供新的思路。

3 Id與腫瘤患者預(yù)后的關(guān)系

Id的表達(dá)的高低,可影響患者的預(yù)后。Ding等[40]發(fā)現(xiàn),在乙肝型肝細(xì)胞癌患者中,Id-1過(guò)表達(dá)患者較 Id-1低者的生存時(shí)間短,其原因可能與 Id-1的過(guò)表達(dá)與腫瘤的級(jí)別高有關(guān),所以 Id-1可能作為乙肝型肝細(xì)胞癌患者預(yù)后預(yù)測(cè)的指標(biāo)。Tang等[41]在對(duì)急性淋巴細(xì)胞性白血病患者的研究中發(fā)現(xiàn),Id-1高表達(dá)的患者的預(yù)后普遍較 Id-1低者差,所以 Tang提出 Id-1可作為急性淋巴細(xì)胞性白血病靶向治療的靶點(diǎn)。在對(duì) Id-2的研究中,也發(fā)現(xiàn) Id-2可影響患者的預(yù)后,如 Stighall等[42]發(fā)現(xiàn)在原發(fā)性乳腺癌患者中,Id-2高表達(dá)患者的預(yù)后較好,并且有研究證實(shí),在食管上皮細(xì)胞癌中,胞漿和胞核均存在 Id-2高表達(dá)的患者生存時(shí)間較長(zhǎng)[43],所以 Id-2也可作為判斷預(yù)后的一個(gè)獨(dú)立指標(biāo)。Umetani等[39]在研究結(jié)直腸癌時(shí)發(fā)現(xiàn),Id-4可作為抑癌基因,從而影響患者的預(yù)后。

由此可見(jiàn),Id可作為影響和判斷預(yù)后的潛在的標(biāo)志。這也為我們探討 Id作為腫瘤治療的靶點(diǎn)提供了又一有力的證據(jù)。

綜上所述,Id在腫瘤的發(fā)生、發(fā)展及對(duì)患者預(yù)后發(fā)揮重要作用。腫瘤的治療,可考慮從控制 Id基因和蛋白表達(dá)水平入手,特別是 Id-1。Id作為高效性和選擇性治療癌癥的靶點(diǎn),有以下原因:①I(mǎi)d蛋白已被證明調(diào)解的幾個(gè)重要基因的活性調(diào)控腫瘤的生成和癌癥進(jìn)展[1]。Id蛋白作為調(diào)控血管生成、增殖、分化、遷移、侵襲和細(xì)胞間相互作用的通路的核心之一。因此,以 Id作為目標(biāo)可能會(huì)同時(shí)影響癌癥的發(fā)展幾個(gè)不同的方面,可能實(shí)現(xiàn)高功效;②Id蛋白在大部分成人的成熟組織中尚未表達(dá)[4]。這可能是一種全身治療的優(yōu)勢(shì),因?yàn)榇蠖鄶?shù)正常細(xì)胞的功能不會(huì)受到影響,從而有可能實(shí)現(xiàn)目標(biāo)的選擇性和低毒性。③Id可影響患者預(yù)后,認(rèn)為調(diào)控 Id的含量,可延長(zhǎng)患者的生存期限。

4 展 望

Id的異常表達(dá)可能是一種癌基因的上游或腫瘤抑制基因失調(diào)的結(jié)果,目前的研究只是停留在推測(cè)階段,其在腫瘤發(fā)生發(fā)展及預(yù)后的作用機(jī)制還需要更多的證據(jù)支持。每一種靶點(diǎn)的選擇都有潛在的優(yōu)點(diǎn)或者缺點(diǎn),其可行性和有效性還都需要大量的證據(jù)支持。相信隨著人類對(duì) Id基因和蛋白越來(lái)越多的了解,其作為腫瘤治療靶點(diǎn)的可行性會(huì)得到進(jìn)一步的證實(shí)。接下來(lái),需要的是更深入的研究和更充分的臨床證據(jù)。

[1]Sikder HA,Devlin MK,Dunlap S,et al.Id proteins in cell growth and tumorigenesis[J].Cancer Cell,2003,3:525-530.

[2]Zebedee Z,Hara E.Id proteins in cell cyc le control and cellular senescence[J].Oncogene,2001,20:8317-8325.

[3]Yokota Y,Mori S.Role of Id family proteins in growth control[J].JCell Physiol,2002,190:21-28.

[4]Coppe JP,Smith AP,Desprez PY.Id proteins in epithelial cells[J].Exp Cell Res,2003,285:131-145.

[5]Lee TK,Man K,Ling MT,et al.Over-expression of Id-1 induces cell proliferation in hepatocellular carcinoma through inactivation of p16INK 4a/RB pathway[J].Carcinogenesis,2003,24:1729-1736.

[6]Wilson JW,Deed RW,Inoue T,et al.Expression of Id helix-loophelix proteins in colorectal adenocarcinoma correlates with p53 expression and mitotic index[J].Cancer Res,2001,61:8803-8810.

[7]Shuno Y,Tsuno NH,Okaji Y,et al.Id1/Id3 knockdown inhibits metastatic potential of pancreatic cancer[J].J Surg Res,2010,161:76-82.

[8]Maw MK,Fujimoto J,Tamaya T.Overexpression of inhibitor of DNA-binding(ID)-1 protein related to angiogenesis in tumor advancement of ovarian cancers[J].BMCCancer,2009,9:430.

[9]Li J,Jia H,Xie L,et al.Correlation of inhibitorofdifferentiation 1 expression to tumor progression,poor differentiation and aggressive behaviors in cervical carcinoma[J].Gynecol Oncol,2009,114:89-93.

[10]Mern DS,Hoppe-Seyler K,Hoppe-Seyler F,et al.Targeting Id1 and Id3 bya specific peptide aptamer induces E-box promoter activity,cell cycle arrest,and apoptosis in breast cancer cells[J].Breast Cancer Res Treat,2010,124:623-633.

[11]Takai N,Miyazaki T,Fujisawa K,et al.Id1 expression is associated with histological grade and invasivebehavior in endometrial carcinoma[J].Cancer Lett,2001,165:185-193.

[12]Coppe JP,Itahana Y,Moore DH,et al.Id-1 and Id-2 proteins as molecularmarkers for human prostate cancer progression[J].Clin Cancer Res,2004,10:2044-2051.

[13]Sablitzky F,Moore A,Brom ley M,et al.Stage-and subcellularspecific expression of Id proteins in male germ and Sertoli cells implicates distinctive regulatory roles for Id proteins during meiosis,spermatogenesis,and Sertoli cell function[J].Cell Growth Differ,1998,9:1015-1024.

[14]Vandeputte DA,TroostD,Leenstra S,et al.Expression and distribution of id helix-loop-helix proteins in human astrocytic tumors[J].G lia,2002,38:329-338.

[15]Fontemaggi G,Dell'Orso S,Trisciuoglio D,et al.The execution of the transcriptional axismutant p53,E 2F1 and ID4 promotes tumor neo-angiogenesis[J].Nat Struct Mol Biol,2009,16:1086-1093.

[16]Lyden D,Young AZ,Zagzag D,et al.Id1 and Id3 are required for neurogenesis,angiogenesis and vascularization of tumour xenografts[J].Nature,1999,401:670-677.

[17]Si CF,Guo JQ,Yang YM,et al.Nuclear and cytoplasmic Id-1 expression patterns play different roles in angiogenesis and lymphangiogenesis in gastric carcinoma[J].Ann Diagn Pathol,2010.[Epub ahead of print]

[18]Lee KT,Lee YW,Lee JK,et al.Overexpression of Id-1 issignificantly associated with tumour angiogenesis in human pancreas cancers[J].Br JCancer,2004,90:1198-1203.

[19]Dong Z,Liu S,Zhou C,et al.Overexpression of Id-1 is associated with tumor angiogenesisand poor clinical outcome in oral squamous cell carcinoma[J].Oral Oncol,2010,46:154-157.

[20]Maw MK,Fujimoto J,Tamaya T.Expression of the inhibitor of DNA-binding(ID)-1 protein as an angiogenic mediator in tumour advancement of uterine cervical cancers[J].Br J Cancer,2008,99:1557-1563.

[21]Ling MT,Lau TC,Zhou C,etal.Overexpression of Id-1 in prostate cancer cells promotes angiogenesis through the activation of vascular endothelial growth factor(VEGF)[J].Carcinogenesis,2005,26:1668-1676.

[22]Volpert OV,Pili R,Sikder HA,et al.Id1 regulates angiogenesis through transcriptional repression of thrombospondin-1[J].Cancer Cell,2002,2:473-483.

[23]Mern DS,Hasskarl J,Burwinkel B.Inhibition of Id proteins by a peptide aptamer induces cell-cycle arrest and apoptosis in ovarian cancer cells[J].Br JCancer,2010,103:1237-1244.

[24]Kim H,Chung H,K im HJ,et al.Id-1 regulates Bcl-2 and Bax expression through p53 and NF-kappaB in MCF-7 breast cancer cells[J].Breast Cancer Res Treat,2008,112:287-296.

[25]Lin J,Guan Z,Wang C,et al.Inhibitor of differentiation 1 contributes to head and neck squamous cell carcinoma survival via the NF-kappaB/survivin and phosphoinositide 3-kinase/Akt signaling pathways[J].Clin Cancer Res,2010,16:77-87.

[26]Cao Y,Liu X,ZhangW,etal.TGF-beta repression of Id2 induces apoptosis in gut epithelial cells[J].Oncogene,2009,28:1089-1098.

[27]Li B,Cheung PY,Wang X,et al.Id-1 activation of PI3K/Akt/NFkappaB signaling pathway and its significance in promoting survival of esophageal cancer cells[J].Carcinogenesis,2007,28:2313-2320.

[28]Koyama T,Suzuki H,Imakiire A,et al.Id3-mediated enhancement of cisplatin-induced apoptosis in a sarcoma cell line MG-63[J].Anticancer Res,2004,24:1519-1524.

[29]Hu H,Han HY,Wang YL,et al.The role of Id-1 in chemosensitivity and epirubicin-induced apoptosis in bladder cancer cells[J].Oncol Rep,2009,21:1053-1059.

[30]Wong YC,Zhang XM,Ling MT,et al.Inactivation of ID-1 gene induces sensitivity of prostate cancer cells to chemotherapeutic drugs[J].Adv Exp Med Biol,2008,617:565-572.

[31]Zhang X,Ling MT,Wang Q,et al.Identification of a novel inhibitor of differentiation-1(ID-1)binding partner,caveolin-1,and its role in epithelial-mesenchymal transition and resistance to apoptosis in prostate cancer cells[J].JBiol Chem,2007,282:33284-33294.

[32]Cheung HW,Ling MT,Tsao SW,et al.Id-1-induced Raf/MEK pathway activation is essential for its protective role against taxolinduced apoptosis in nasopharyngeal carcinoma cells[J].Carcinogenesis,2004,25:881-887.

[33]Yuen HF,Chiu YT,Chan KK,et al.Prostate cancer cellsmodulate osteoblast m ineralisation and osteoc last differentiation through Id-1[J].Br JCancer,2010,102:332-341.

[34]Damdinsuren B,Nagano H,Kondo M,et al.TGF-beta1-induced cell growth arrest and partial differentiation is related to the suppression of Id1 in human hepatoma cells[J].Oncol Rep,2006,15:401-408.

[35]Kebebew E,Peng M,Treseler PA,etal.Id1 geneexpression isupregulated in hyperplastic and neoplastic thyroid tissue and regulates growth and differentiation in thyroid cancer cells[J].JClin Endocrinol Metab,2004,89:6105-6111.

[36]JankiewiczM,Groner B,Desrivieres S.Mammalian target of rapamycin regulates the growth of mammary epithelial cells through the inhibitor of deoxyribonucleic acid binding Id1 and their functional differentiation through Id2[J].MolEndocrinol,2006,20:2369-2381.

[37]Tajima K,TeraiS,Takami T,etal.Importanceof inhibitor ofDNA binding/differentiation 2 in hepatic stellate cell differentiation and proliferation[J].Hepatol Res,2007,37:647-655.

[38]Simbulan-Rosenthal CM,Trabosh V,Velarde A,et al.Id2protein is selectively upregulated by UVB in primary,but not in immortalized human keratinocytesand inhibitsdifferentiation[J].Oncogene,2005,24:5443-5458.

[39]Umetani N,TakeuchiH,Fujimoto A,etal.Epigenetic inactivation of ID 4 in colorectal carcinomas correlates with poor differentiation and unfavorable prognosis[J].Clin Cancer Res,2004,10:7475-7483.

[40]Ding R,Han S,Lu Y,et al.Overexpressed Id-1 isassociated with patient prognosis and HBx expression in hepatitis B virus-related hepatocellular carcinoma[J].Cancer Biol Ther,2010,10:299-307.

[41]Tang R,Hirsch P,Fava F,et al.High Id1 expression is associated with poorprognosis in 237patientswith acutemyeloid leukem ia[J].Blood,2009,114:2993-3000.

[42]Stighall M,Manetopoulos C,Axelson H,et al.High ID 2 protein expression correlates with a favourable prognosis in patientswith primary breast cancer and reduces cellular invasivenessofbreast cancer cells[J].Int JCancer,2005,115:403-411.

[43]Yuen HF,Chan YP,Chan KK,etal.Id-1 and Id-2 aremarkers for metastasis and prognosis in oesophageal squamous cell carcinoma[J].Br JCancer,2007,97:1409-1415.