胃癌组织PLK1的表达及其意义
张庆, 刘南植,洪玮, 倪志,李秀梅,华中科技大学同济医学院附属同济医院消化内科 湖北省武汉市 430030
通讯作者:刘南植,430030, 湖北省武汉市汉口解放大道1095号,华中科技大学同济医学院附属同济医院消化内科.www95@126.com
电话: 027-83663595
收稿日期:2005-04-26 接受日期:2005-05-14
Expression of Polo-like kinase 1 and itssignificance in gastric carcinoma
Qing Zhang, Nan-Zhi Liu, Wei Hong, Zhi Ni, Xiu-Mei Li
Qing Zhang, Nan-ZhiLiu, Wei Hong, Zhi Ni, Xiu-Mei Li, Department of Gastroenterology,Tongji Hospital, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan 430030, Hubei Province, China
Correspondence to: Nan-Zhi Liu, Department of Gastroenterology,Tongji Hospital, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan 430030, Hubei Province, China. www95@126.com
Received: 2005-04-26 Accepted:2005-05-14
Abstract
AIM: To investigate the expression of Polo-like kinase 1 (PLK1)and its relationship with clinicopathological characteristics, anti-oncogeneand tumor proliferation in human gastric carcinoma, and to explore therole of PLK1 in the carcinogenesis and progression of tumor and itsclinical significance.
METHODS: The expression of PLK1, P53 and Ki67 was detected intissues of gastric carcinoma (n = 54), atypical hyperplasia (n= 10)and normal gastric mucosa (n = 15) by immunohistochemicalmethod.
RESULTS: PLK1 was negatively expressed in normal mucosa. Weaklypositive staining for PLK1 was observed in 4 out of 11 Atypicalhyperplasia tissues. The expression of PLK1 was elevated in 88.9%(48/54)of the gastric carcinoma. There were no significant associations betweenPLK1 and clinicopathological characteristics such as histologicaldifferentiation, distant metastasis and lymph node metastasis (P>0.05).PLK1 expression was significantly related to the depth of invasion (c2= 6.775, P<0.01) and TMN staging (c2= 9.009, P<0.01). In gastric cancer,positive staining for P53 was detected in 38 of 54 cases (70.4%). P53expression was significantly associated with PLK1 (c2 = 6.664, P<0.05). The mean value of Ki67 labelling index(Ki67 LI) was 34.7±13.4%,with a range of 10.3-60.1%. PLK1 expression was positively associated withKi67 level (r = 0.720, P<0.01).
CONCLUSION: PLK1 is over-expressed in gastric cancer, andassociated with tumor proliferation and anti-oncogene. PLK1 plays animportant role in the carcinogenesis and development of gastric carcinoma.
Key Words: Polo-like kinase 1; Gastric carcinoma; P53; Ki67
Zhang Q, Liu NZ, Hong W, Ni Z, Li XM. Expression of Polo-like kinase 1 andits significance in gastric carcinoma. Shijie Huaren Xiaohua Zazhi 2005;13(13):1499-1502
摘要目的:研究Polo样激酶1(Polo-likekinase 1，PLK1)在胃癌中的表达与各临床病理特征、抑癌基因和肿瘤增殖活性的关系，探讨PLK1在胃癌发生发展中的作用以及其临床意义.
方法:运用免疫组织化学的方法检测正常胃组织15例，非典型增生组织11例，胃癌54例中PLK1，Ki67，P53的表达.
结果:PLK1在正常胃组织中表达均为阴性;11例非典型增生组织有4例弱阳性;胃癌中有48例阳性(88.9%)，其表达与组织分化程度、远处转移和淋巴结转移无关(P>0.05),与浸润深度(c2= 6.775, P <0.01)和临床分期(c2= 9.009, P<0.01)相关.在胃癌中，P53阳性38例(70.4%)，PLK1的表达与P53蛋白积聚相关(c2= 6.664, P<0.05).胃癌中Ki67标记指数均值为34.7±13.4%，范围为10.3-60.1%，PLK1的表达与Ki67呈正相关(r =0.720, P<0.01).
结论:PLK1在胃癌中高表达，与肿瘤的增殖活性和抑癌基因相关，在胃癌发生发展中起重要作用.
关键词:Polo样激酶1;胃癌; P53; Ki67
张庆, 刘南植,洪玮, 倪志,李秀梅.胃癌组织PLK1的表达及其意义.世界华人消化杂志 2005;13(13):1499-1502
:正常组织未见明显表达(×100，DAB显色);B: 非典型增生组织中可见少数弱阳性(×100，DAB显色);C: 胃癌组织PLK1可见明显表达(×200，DAB显色).
表1 PLK1分别在正常、非典型增生组织和胃癌组织中的表达
2.2 PLK1表达与胃癌临床病理特征的关系PLK1在胃癌中的表达与组织分化程度、远处转移和淋巴结转移均无关(P>0.05)，而随着临床分期的进展，PLK1的表达增高，各期间的表达率有显著性差异(c2= 9.009，P<0.01，表2)，还与肿瘤的浸润深度相关(c2= 6.775，P<0.01，表2).
2.3 PLK1表达与P53，Ki67 LI的关系在胃癌中P53和Ki67均为核表达(图2).P53阳性38例(70.4%)，其中PLK1(+)/P53(+)37例，PLK1(+)/P53(-)11例，PLK1(-)/P53(+)1例，PLK1(-)/P53(-)5例，在胃癌中PLK1的表达与P53蛋白积聚显著相关(c2= 6.664，P<0.05，表2).胃癌中Ki67LI均值为34.7±13.4%(mean±SD)，范围为10.3-60.1%，通过相关分析PLK1的表达与Ki67LI呈正相关(r =0.720，P<0.01).
图2 胃癌组织中P53和Ki67的表达. A:P53阳性表达(×100，AEC显色);B: Ki67阳性表达(×200，DAB显色).
表2 PLK1在胃癌中的表达与各临床病理特征和P53的关系
bP<0.01vs 阴性.
3 讨论肿瘤的发生和发展是在多种因素的作用下，包括癌基因激活以及抑癌基因失活的结果，而癌基因和抑癌基因作用的归结均在于对细胞周期的调控，细胞周期的调控失常是肿瘤发生的主要原因[5].PLK1在G2晚期M初期参与CDC25C的激活、继而促成CyclinB/Cdc2的激活，协助中心体的功能成熟以及纺锤体的形成，从而促进M期的起始和染色体正常分离分配[6-8];通过调节APC(anaphase-promotingcomplex)来决定细胞能否按期离开M期;他在细胞自我保护中也起到着重要作用，当DNA受损时可引起PLK1苏氨酸残基磷酸化而使其活性受抑，从而使细胞阻滞于G2/M期[9-11];在分裂活跃的组织器官或肿瘤细胞中PLK1活性较高.PLK1在许多人类肿瘤和细胞系中提示高表达，如非小细胞肺癌[12]、头颈部鳞癌[13]、食管癌、胃癌[14]、结肠癌[15]、乳腺癌[16]、卵巢癌[17]、子宫内膜癌[18]、黑色素瘤[19]、前列腺癌[20]、非霍奇金淋巴瘤[21]等.此外Smithet al[22]报道PLK1的过多表达能使NIH3T3细胞癌基因聚集，这些细胞能在裸鼠上形成肿瘤.这些研究表明PLK1可能参与人类肿瘤发生发展.Tokumitsuet al[14]曾从mRNA水平上对75例胃癌PLK1的表达进行分析，高表达为55例(73%).我们从蛋白水平对PLK1在正常、非典型增生和胃癌组织进行分析，正常组织均未见明显表达;非典型增生组织中有4例弱阳性(36.4%)，均为低表达;54例胃癌中48例阳性(88.9%).在胃癌中PLK1高表达，明显高于正常和非典型增生性组织;并且PLK1的表达在各临床分期中有着显著性差异，随临床分期的进展，表达增高，还与肿瘤浸润深度相关，而与组织分化程度、远处转移和淋巴结转移无关.由此从mRNA水平和蛋白水平都反映了PLK1在胃癌中高表达，说明PLK1在胃癌发生发展上可能起着重要的作用，在诊断上可作为一个新的肿瘤标志物.
P53是一种抑癌基因，对细胞周期的调控和肿瘤的转归起着重要作用[23].据研究表明，PLK1能抑制P53的转录，从而影响诱导细胞凋亡的活性，P53可能是PLK1的一个作用靶点[24].Liuet al[25]在PLK1基因敲除细胞中发现P53大量聚集，提示PLK1对P53的活性有调节作用.我们在通过突变型P53抗体对胃癌的检测发现，PLK1(+)/P53(+)37例，PLK1(+)/P53(-)11例，PLK1(-)/P53(+)1例，PLK1(-)/P53(-)5例，在胃癌中PLK1的表达与P53蛋白积聚明显相关(P<0.05).从而表明，PLK1除了对肿瘤细胞的细胞周期调控外，可能还通过对抑癌基因调节参与胃癌的发生发展.
在肿瘤诊断中，肿瘤增殖活性是一个评价肿瘤进展的重要参数.Ki67是一种细胞增殖核抗原，存在于G0期以外的所有细胞周期中，在有丝分裂后迅速降解或失去抗原决定簇，因此，被认为是反映细胞增殖状态的理想标记物，并且还与肿瘤预后密切相关[26-27].在我们的实验中，胃癌PLK1的表达与Ki67LI呈正相关(r =0.720，P<0.01)，表明PLK1可反映胃癌的增殖活性，可能对预后判定也有作用.临床分期和组织分级系统最重要的功能是评价预后和指导治疗，而在我们的实验中PLK1的表达与胃癌临床分期相关.此外许多关于肿瘤PLK1的表达与预后的研究发现[12-14，20-21]:PLK1的表达与预后相关，PLK1表达越高预后越差.因此PLK1不仅可反映胃癌的增殖活性，而且可能象非小细胞肺癌、头颈鳞状细胞癌、食管癌、前列腺癌和非霍奇金淋巴瘤等一样对预后判定有着重要意义.
根据PLK1在许多肿瘤中高表达，与肿瘤细胞增殖和致癌性转化密切相关，目前已经建立了针对PLK1mRNA的反义寡核苷酸和小干扰RNA(smallinterference RNA，siRNA)，他们能特异性的对PLK1mRNA及其蛋白产物表现为剂量依赖性的抑制作用，由此也抑制了PLK1的丝氨酸/苏氨酸激酶的活性，能有效抑制培养细胞系或裸鼠肿瘤模型中肿瘤细胞的增殖[28].说明了PLK1可以作为肿瘤治疗的一个靶点，在临床治疗中有着重要的指导作用.综合以上，我们的研究表明PLK1在胃癌中表达明显高于正常和非典型增生组织，其表达与临床分期、浸润深度和肿瘤增殖活性密切相关，与抑癌基因(P53)相互作用，在胃癌的发生发展中可能起着重要作用，在胃癌诊断中可作为一种新的肿瘤标志物，在临床治疗和预后判定中有一定的指导意义.
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编辑 潘伯荣 审读 张海宁, http://www.100md.com( 张 庆, 刘南植, 洪 玮, 倪 志, 李秀梅)
通讯作者:刘南植,430030, 湖北省武汉市汉口解放大道1095号,华中科技大学同济医学院附属同济医院消化内科.www95@126.com
电话: 027-83663595
收稿日期:2005-04-26 接受日期:2005-05-14
Expression of Polo-like kinase 1 and itssignificance in gastric carcinoma
Qing Zhang, Nan-Zhi Liu, Wei Hong, Zhi Ni, Xiu-Mei Li
Qing Zhang, Nan-ZhiLiu, Wei Hong, Zhi Ni, Xiu-Mei Li, Department of Gastroenterology,Tongji Hospital, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan 430030, Hubei Province, China
Correspondence to: Nan-Zhi Liu, Department of Gastroenterology,Tongji Hospital, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan 430030, Hubei Province, China. www95@126.com
Received: 2005-04-26 Accepted:2005-05-14
Abstract
AIM: To investigate the expression of Polo-like kinase 1 (PLK1)and its relationship with clinicopathological characteristics, anti-oncogeneand tumor proliferation in human gastric carcinoma, and to explore therole of PLK1 in the carcinogenesis and progression of tumor and itsclinical significance.
METHODS: The expression of PLK1, P53 and Ki67 was detected intissues of gastric carcinoma (n = 54), atypical hyperplasia (n= 10)and normal gastric mucosa (n = 15) by immunohistochemicalmethod.
RESULTS: PLK1 was negatively expressed in normal mucosa. Weaklypositive staining for PLK1 was observed in 4 out of 11 Atypicalhyperplasia tissues. The expression of PLK1 was elevated in 88.9%(48/54)of the gastric carcinoma. There were no significant associations betweenPLK1 and clinicopathological characteristics such as histologicaldifferentiation, distant metastasis and lymph node metastasis (P>0.05).PLK1 expression was significantly related to the depth of invasion (c2= 6.775, P<0.01) and TMN staging (c2= 9.009, P<0.01). In gastric cancer,positive staining for P53 was detected in 38 of 54 cases (70.4%). P53expression was significantly associated with PLK1 (c2 = 6.664, P<0.05). The mean value of Ki67 labelling index(Ki67 LI) was 34.7±13.4%,with a range of 10.3-60.1%. PLK1 expression was positively associated withKi67 level (r = 0.720, P<0.01).
CONCLUSION: PLK1 is over-expressed in gastric cancer, andassociated with tumor proliferation and anti-oncogene. PLK1 plays animportant role in the carcinogenesis and development of gastric carcinoma.
Key Words: Polo-like kinase 1; Gastric carcinoma; P53; Ki67
Zhang Q, Liu NZ, Hong W, Ni Z, Li XM. Expression of Polo-like kinase 1 andits significance in gastric carcinoma. Shijie Huaren Xiaohua Zazhi 2005;13(13):1499-1502
摘要目的:研究Polo样激酶1(Polo-likekinase 1，PLK1)在胃癌中的表达与各临床病理特征、抑癌基因和肿瘤增殖活性的关系，探讨PLK1在胃癌发生发展中的作用以及其临床意义.
方法:运用免疫组织化学的方法检测正常胃组织15例，非典型增生组织11例，胃癌54例中PLK1，Ki67，P53的表达.
结果:PLK1在正常胃组织中表达均为阴性;11例非典型增生组织有4例弱阳性;胃癌中有48例阳性(88.9%)，其表达与组织分化程度、远处转移和淋巴结转移无关(P>0.05),与浸润深度(c2= 6.775, P <0.01)和临床分期(c2= 9.009, P<0.01)相关.在胃癌中，P53阳性38例(70.4%)，PLK1的表达与P53蛋白积聚相关(c2= 6.664, P<0.05).胃癌中Ki67标记指数均值为34.7±13.4%，范围为10.3-60.1%，PLK1的表达与Ki67呈正相关(r =0.720, P<0.01).
结论:PLK1在胃癌中高表达，与肿瘤的增殖活性和抑癌基因相关，在胃癌发生发展中起重要作用.
关键词:Polo样激酶1;胃癌; P53; Ki67
张庆, 刘南植,洪玮, 倪志,李秀梅.胃癌组织PLK1的表达及其意义.世界华人消化杂志 2005;13(13):1499-1502
:正常组织未见明显表达(×100，DAB显色);B: 非典型增生组织中可见少数弱阳性(×100，DAB显色);C: 胃癌组织PLK1可见明显表达(×200，DAB显色).
表1 PLK1分别在正常、非典型增生组织和胃癌组织中的表达
| 诊断 | n | - | + | ++ | +++ | 阳性数 |
| 正常胃组织 | 15 | 15 | 0 | 0 | 0 | 0(0%) |
| 非典型增生 | 11 | 7 | 4 | 0 | 0 | 4(36.4%) |
| 胃癌 | 54 | 6 | 6 | 30 | 12 | 48(88.9%) |
2.2 PLK1表达与胃癌临床病理特征的关系PLK1在胃癌中的表达与组织分化程度、远处转移和淋巴结转移均无关(P>0.05)，而随着临床分期的进展，PLK1的表达增高，各期间的表达率有显著性差异(c2= 9.009，P<0.01，表2)，还与肿瘤的浸润深度相关(c2= 6.775，P<0.01，表2).
2.3 PLK1表达与P53，Ki67 LI的关系在胃癌中P53和Ki67均为核表达(图2).P53阳性38例(70.4%)，其中PLK1(+)/P53(+)37例，PLK1(+)/P53(-)11例，PLK1(-)/P53(+)1例，PLK1(-)/P53(-)5例，在胃癌中PLK1的表达与P53蛋白积聚显著相关(c2= 6.664，P<0.05，表2).胃癌中Ki67LI均值为34.7±13.4%(mean±SD)，范围为10.3-60.1%，通过相关分析PLK1的表达与Ki67LI呈正相关(r =0.720，P<0.01).
图2 胃癌组织中P53和Ki67的表达. A:P53阳性表达(×100，AEC显色);B: Ki67阳性表达(×200，DAB显色).
表2 PLK1在胃癌中的表达与各临床病理特征和P53的关系
| 临床特征 | n | PLK1 | ||
| 阴性 | 阳性 | |||
| 分化程度 | 高 | 5 | 0 | 5 |
| 中 | 10 | 0 | 10 | |
| 低 | 39 | 6 | 33 | |
| 临床分期 | I | 10 | 4 | 6b |
| II | 17 | 2 | 15 | |
| III | 11 | 0 | 11 | |
| IV | 16 | 0 | 16 | |
| 浸润深度 | T1 | 11 | 4 | 7b |
| T2 | 6 | 0 | 6 | |
| T3 | 24 | 2 | 22 | |
| T4 | 13 | 0 | 13 | |
| 淋巴结转移 | 有 | 34 | 2 | 30 |
| 无 | 20 | 4 | 18 | |
| 远处转移 | 有 | 15 | 1 | 14 |
| 无 | 39 | 5 | 34 | |
| P53 | 阳性 | 38 | 1 | 37b |
| 阴性 | 16 | 5 | 11 | |
| 总计 | 54 | 6 | 48 |
bP<0.01vs 阴性.
3 讨论肿瘤的发生和发展是在多种因素的作用下，包括癌基因激活以及抑癌基因失活的结果，而癌基因和抑癌基因作用的归结均在于对细胞周期的调控，细胞周期的调控失常是肿瘤发生的主要原因[5].PLK1在G2晚期M初期参与CDC25C的激活、继而促成CyclinB/Cdc2的激活，协助中心体的功能成熟以及纺锤体的形成，从而促进M期的起始和染色体正常分离分配[6-8];通过调节APC(anaphase-promotingcomplex)来决定细胞能否按期离开M期;他在细胞自我保护中也起到着重要作用，当DNA受损时可引起PLK1苏氨酸残基磷酸化而使其活性受抑，从而使细胞阻滞于G2/M期[9-11];在分裂活跃的组织器官或肿瘤细胞中PLK1活性较高.PLK1在许多人类肿瘤和细胞系中提示高表达，如非小细胞肺癌[12]、头颈部鳞癌[13]、食管癌、胃癌[14]、结肠癌[15]、乳腺癌[16]、卵巢癌[17]、子宫内膜癌[18]、黑色素瘤[19]、前列腺癌[20]、非霍奇金淋巴瘤[21]等.此外Smithet al[22]报道PLK1的过多表达能使NIH3T3细胞癌基因聚集，这些细胞能在裸鼠上形成肿瘤.这些研究表明PLK1可能参与人类肿瘤发生发展.Tokumitsuet al[14]曾从mRNA水平上对75例胃癌PLK1的表达进行分析，高表达为55例(73%).我们从蛋白水平对PLK1在正常、非典型增生和胃癌组织进行分析，正常组织均未见明显表达;非典型增生组织中有4例弱阳性(36.4%)，均为低表达;54例胃癌中48例阳性(88.9%).在胃癌中PLK1高表达，明显高于正常和非典型增生性组织;并且PLK1的表达在各临床分期中有着显著性差异，随临床分期的进展，表达增高，还与肿瘤浸润深度相关，而与组织分化程度、远处转移和淋巴结转移无关.由此从mRNA水平和蛋白水平都反映了PLK1在胃癌中高表达，说明PLK1在胃癌发生发展上可能起着重要的作用，在诊断上可作为一个新的肿瘤标志物.
P53是一种抑癌基因，对细胞周期的调控和肿瘤的转归起着重要作用[23].据研究表明，PLK1能抑制P53的转录，从而影响诱导细胞凋亡的活性，P53可能是PLK1的一个作用靶点[24].Liuet al[25]在PLK1基因敲除细胞中发现P53大量聚集，提示PLK1对P53的活性有调节作用.我们在通过突变型P53抗体对胃癌的检测发现，PLK1(+)/P53(+)37例，PLK1(+)/P53(-)11例，PLK1(-)/P53(+)1例，PLK1(-)/P53(-)5例，在胃癌中PLK1的表达与P53蛋白积聚明显相关(P<0.05).从而表明，PLK1除了对肿瘤细胞的细胞周期调控外，可能还通过对抑癌基因调节参与胃癌的发生发展.
在肿瘤诊断中，肿瘤增殖活性是一个评价肿瘤进展的重要参数.Ki67是一种细胞增殖核抗原，存在于G0期以外的所有细胞周期中，在有丝分裂后迅速降解或失去抗原决定簇，因此，被认为是反映细胞增殖状态的理想标记物，并且还与肿瘤预后密切相关[26-27].在我们的实验中，胃癌PLK1的表达与Ki67LI呈正相关(r =0.720，P<0.01)，表明PLK1可反映胃癌的增殖活性，可能对预后判定也有作用.临床分期和组织分级系统最重要的功能是评价预后和指导治疗，而在我们的实验中PLK1的表达与胃癌临床分期相关.此外许多关于肿瘤PLK1的表达与预后的研究发现[12-14，20-21]:PLK1的表达与预后相关，PLK1表达越高预后越差.因此PLK1不仅可反映胃癌的增殖活性，而且可能象非小细胞肺癌、头颈鳞状细胞癌、食管癌、前列腺癌和非霍奇金淋巴瘤等一样对预后判定有着重要意义.
根据PLK1在许多肿瘤中高表达，与肿瘤细胞增殖和致癌性转化密切相关，目前已经建立了针对PLK1mRNA的反义寡核苷酸和小干扰RNA(smallinterference RNA，siRNA)，他们能特异性的对PLK1mRNA及其蛋白产物表现为剂量依赖性的抑制作用，由此也抑制了PLK1的丝氨酸/苏氨酸激酶的活性，能有效抑制培养细胞系或裸鼠肿瘤模型中肿瘤细胞的增殖[28].说明了PLK1可以作为肿瘤治疗的一个靶点，在临床治疗中有着重要的指导作用.综合以上，我们的研究表明PLK1在胃癌中表达明显高于正常和非典型增生组织，其表达与临床分期、浸润深度和肿瘤增殖活性密切相关，与抑癌基因(P53)相互作用，在胃癌的发生发展中可能起着重要作用，在胃癌诊断中可作为一种新的肿瘤标志物，在临床治疗和预后判定中有一定的指导意义.
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