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HER—4在结直肠癌中的表达及其临床意义

2017-06-01刘传渊夏来阳刘金秀王建

中国现代医生 2016年34期
关键词:靶点直肠癌染色

刘传渊 夏来阳 刘金秀 王建

[摘要] 目的 研究HER-4蛋白在结直肠癌中的表达,并探讨其临床意义。 方法 采用免疫組织化学Envision二步法检测100例患者结直肠癌组织、20例正常癌旁组织中HER-4蛋白的表达,分析HER-4蛋白表达水平与临床病理因素间的关系。 结果 HER-4蛋白在正常癌旁组织、结直肠癌中的表达率分别为0%、44%,差异有统计学意义(P=0.000),结直肠癌组织中HER-4蛋白表达与淋巴结转移、TNM分期密切相关(P<0.05),而与性别、年龄、肿瘤部位、肿瘤大体、病理类型、浸润深度、脉管癌栓、术前癌胚抗原(CEA)等无关。 结论 HER-4蛋白在结直肠正常癌旁组织中未见阳性表达,而在结直肠癌病灶中呈现高表达,且与淋巴结转移、TNM分期密切相关,高表达者预示病程较晚,预后较差。HER-4不仅是一个有价值的生物标志物,而且是一个潜在的抗癌治疗靶点。

[关键词] 基因;HER-4;肿瘤;结直肠;免疫组织化学;病理学

[中图分类号] R735.3 [文献标识码] A [文章编号] 1673-9701(2016)34-0013-04

Expressions and clinical significance of HER-4 in colorectal cancer

LIU Chuanyuan1 XIA Laiyang1 LIU Jinxiu2 WANG Jian3

1.Department of No.1 General Surgery, Ganzhou People's Hospital in Jiangxi Province, Ganzhou 341000, China; 2.The Second Affiliated Hospital of Gannan Medical College,Ganzhou 341600, China; 3.Department of Pathology, Ganzhou People's Hospital in Jiangxi Province, Ganzhou 341000, China

[Abstract] Objective To evaluate the HER-4 expression and its correlation with clinical pathological parameters in colorectal cancer patients. Methods The expressions of HER-4 protein in 100 cases of colorectal carcinoma and 20 cases of normal colorectal tissues were detected by immunohistochemistry method, and the association between the expression and the clinicopathological parameter of colorectal carcinoma was analyzed. Results Positive staining of HER-4 was observed in 44% colorectal cancer tissues compared with 0% in normal colorectal epithelia(P=0.000). HER-4 expression was associated with lymph node metastasis and TNM stage(P<0.05), and was not correlated with age, gender, tumor location, tumor gross, pathological type, tumor depth, invasion of vessel and preoperative serum carcinoembryonic antigen(CEA). Conclusion HER-4 protein expression in colorectal normal tissue was negative, but in colorectal cancer lesions showed high, which was closely related to lymph node metastasis and TNM stage. High expression indicates a late course of disease, and a poor prognosis. HER-4 is not only a valuable biomarker, but also a potential therapeutic target in colorectal cancer.

[Key words] Gene; HER-4; NeopIasms; Colorectum; Immunohistochemistry; Pathology

过去的几十年中,结直肠癌的发病率和死亡率在许多地区已显著增加[1,2]。在美国,2014年新发结直肠癌病约为136 830例,近50 310的患者死于该疾病[3]。根治手术后5年生存率约为60%[4-6]。为了改善结直肠癌的预后,随着精准医疗的推进,寻找有效的治疗靶点具有重要的意义。人表皮生长因子受体(HER)家族包括EGFR(HER-1)、HER-2、HER-3和 HER-4,它们是具有典型的胞外受体结合位点的酪氨酸激酶受体。HER激活多条信号传导通路并且通过此环节影响大量的信号传导过程,这些受体的异常激活与不同的病理过程密切相关,影响肿瘤的增殖、分化和转移。HER-1过度表达在许多癌症中提示预后不良[7,8],HER-2在乳腺癌和胃癌诊疗中已经成为重要的生物标志物和治疗靶点[9,10]。HER-3的表达与实体肿瘤预后差明显相关[11]。HER-4对肿瘤的作用仍存在争议,有报道认为在宫颈癌中与更好的预后有关[12],同时也有报道认为在口腔鳞状细胞癌中HER-4蛋白的过表达提示远处转移和更差的生存预后[13]。HER-4在结直肠癌中的研究甚少,HER-4在结直肠癌中的作用如何,能否作为一个潜在的治疗靶点?本研究就HER-4在结直肠癌中的表达进行研究,并分析其与临床病理间的关系。

1 资料与方法

1.1 一般资料

选取2014年7月~2015年7月我院胃肠外科行根治性手术的结直肠癌患者标本100例,术前均未行新辅助放、化疗。其中男52例,女48例;年龄26~81岁,中位年龄62岁;结肠癌49例、直肠癌51例。依据患者年龄、性别、肿瘤部位、肿瘤大小、淋巴结转移、TNM分期等进行分组(表1)。另取20例癌旁正常组织作为对照组。

1.2 免疫组织化学染色

鼠抗人单克隆HER-4抗体(克隆号 HFR1-ab 1939,工作浓度1:100)购自Abcam香港有限公司。Envision反应液购自福建迈新公司。采用免疫组织化学Envision二步法检测HER-4在结直肠癌中的表达,组织石蜡切片经脱蜡、水化、自来水冲洗,并对组织行高压抗原修复,实验步骤按照试剂盒进行。实验同时设阳性对照(已知阳性的肾组织切片)和阴性对照(PBS代替一抗)。

1.3评定标准

对结果进行双盲阅片。HER-4定位于细胞膜或细胞核,染色判读及评分参照Lai C、Kountourskis P等[14,18]的研究标准:(0):不染色或<10%肿瘤细胞染色;(1+):>10%的肿瘤细胞微弱或隐约可见染色;(2+):>10%的肿瘤细胞弱到中度染色;(3+):>10%的肿瘤细胞强染色。(0)和(1+)定义为低表达(阴性表达),(2+)和(3+)定义为高表达(阳性表达)。

1.4 统计学处理

使用SPSS 19.0统计学软件对数据进行分析,计数资料采用χ2检验、四格表Fishers确切概率法,P<0.05为差异有统计学意义。

2 结果

2.1 结直肠癌组织、正常结直肠癌旁组织中HER-4表达情况

HER-4蛋白主要表达于癌组织细胞膜或细胞核中(图1、2),HER-4在结直肠癌组织中的阳性表达率为44%(44/100),而在20例正常癌旁组织中未见表达,二者阳性表达率差异有统计学意义(P=0.000)(表1)。

2.2 结直肠癌组织中HER-4表达情况与临床病理因素的关系

HER-4蛋白在结直肠癌组织中的表达程度与淋巴结转移、TNM分期有关(P<0.05),与患者性别、年龄、肿瘤部位、肿瘤大体、病理类型、浸润层次、脉管癌栓、术前癌胚抗原(CEA)、术前糖类抗原199(CA199)等无关(表2)。

3 讨论

HER-4基因是HER癌基因家族的一员,首次被发现是在小鼠神经系统发育的研究中,其在小鼠神经系统发育阶段呈现广泛表达[15],后来发现正常的人体脑组织、骨骼肌、心肌和垂体组织中也有不同的表达,在多种肿瘤组织中存在过度表达[16-18]。本研究中,HER-4蛋白在正常结直肠黏膜组织中未见阳性表达,而在结直肠癌病灶中呈现高表达,此与有关研究的结论类似[14,19-20]。

淋巴结转移是影响结直肠癌术后生存最重要的因素之一,也是肿瘤分期及术后进一步综合治疗的重要依据,淋巴结转移预示着病程较晚,预后较差。本研究结果显示,HER-4在结直肠癌原发灶中的阳性表达率为44%(44/100),存在高表达;与结直肠癌淋巴结转移有关(P=0.039),淋巴结转移者阳性表达率明显高于无淋巴结转移者。这与Kountourskis等[18]的研究结果相同,其对106个结直肠肿瘤组织进行免疫组化,结果发现HER-4表达阳性与患者的淋巴结转移相关(P=0.01),HER-4的高表达与癌细胞的转移能力密切相关。Baiocchi G等[20]认为HER-4表达阳性是淋巴结转移、肿瘤复发的一个独立危险因素。

在国际抗癌联盟(UICC)、美国癌症联合委员会(AJCC)的共同努力推动下,原发肿瘤一区域淋巴结一远处转移(TNM)分期系统不断完善,逐步成为全球肿瘤研究工作者比较各自临床资料、评价治疗效果的共同依据。TNM分期越后,其预后越差。本研究中,TNM分期Ⅰ、Ⅱ、Ⅲ期患者其HER-4表達率分别为9.31%、38.82%、51.87%,差异具统计学意义(P=0.042),提示HER-4的表达与TNM分期密切相关,分期越后,原发肿瘤病灶中其HER-4表达越高。这与一些学者的研究结果类似。Lee JC等[19]发现结直肠癌TNM分期Ⅰ或Ⅱ期肿瘤病灶HER-4阳性表达明显低于Ⅲ或Ⅳ期肿瘤病灶,He XX等[21]发现HER-4在胃癌中的表达与肿瘤的TNM分期密切相关。肿瘤是多基因、多因素长期共同作用的结果,HER-4阳性表达率越高,预示分期越晚。有学者报道,在人肺癌细胞 H1299中转染入HER-4,与对照组相比,HER-4明显促进了肺癌细胞的生长,而使用抗HER-4的抗体Mab-3之后,发现表达HER-4的肺癌细胞不仅生长速度明显受到抑制,而且凋亡速度显著加快[22]。通过敲除、下调HER-4的表达,能抑制肿瘤细胞的增值与生长[23]。

综上所述,HER-4蛋白在正常结直肠组织中未见阳性表达,而在结直肠癌病灶中呈现高表达,且与淋巴结转移、TNM分期密切相关,高表达者预示着病程较晚,预后较差。HER-4不仅是一个有价值的生物标志物,而且是一个潜在的抗癌治疗靶点。

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(收稿日期:2016-08-02)

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