TGF-α和EGFR在Barrett食管和食管腺癌的表达

摘要

目的: 研究Barrett食管和食管腺癌中TGF-α和EGFR的表达意义.

方法: 采用免疫组化SABC法检测反流性食管炎13例、Barrett食管17例和食管腺癌11例中TGF-α和EGFR的表达, 并以30例正常食管黏膜为对照, 运用免疫组化图像分析加以定量, 进行统计学的分析和比较.

结果: TGF-α和EGFR在正常食管黏膜、反流性食管炎、Barrett食管和食管腺癌的表达逐渐增高, 二者呈明显的正相关(r= 0.951, P<0.01); TGF-α主要表达于细胞质, EGFR在正常食管黏膜和反流性食管炎表达于细胞膜, 而在Barrett食管非典型增生和食管腺癌, 则可见细胞质和细胞核的明显表达.

结论: TGF-α和EGFR在反流性食管炎、Barrett食管和食管腺癌中表达逐渐增高并且相互作用, 可能对Barrett食管和食管腺癌的发生、发展起一定的作用.

关键词: 转化生长因子α; 表皮生长因子受体; Barrett食管; 食管腺癌

Expression of transforming growth factor alpha and epidermal growth factor receptor in Barrett's esophagus and esophageal adenocarcinoma

Chuang-Ying Hu, Cai-Feng He

Chuang-Ying Hu, Cai-Feng He, Department of Gastroenterology, the Second Affiliated Hospital of Suzhou University, Suzhou 215004, Jiangsu Province, China

Correspondence to: Dr. Chuang-Ying Hu, Department of Gastroenterology, the Second Affiliated Hospital of Suzhou University, 1055 Sanxiang Avenue, Suzhou 215004, Jiangsu Province, China. huchuangying@163.com

Received: February 14, 2006
Revised: February 24, 2006
Accepted: March 6, 2006
Published online: March 28, 2006

Abstract

AIM: To investigate the expression of transform-ing growth factor alpha (TGF-α) and epidermal growth factor receptor (EGFR) in Barrett's esophagus and esophageal adenocarcinoma.

METHODS: Immunohistochemistry (SABC assay) was used to detect the expression of TGF-α and EGFR protein in patients with reflux esophagitis (n = 13), Barrett's esophagus (n = 17), esophageal adenocarcinoma (n = 11) and normal esophageal mucosa (n = 30).

RESULTS: In the development of reflux esophagitis, Barrett's esophagus and esophageal adenocarcinoma, the expression of TGF-α and EGFR protein increased gradually and closely correlated with each other (r = 0.951, P < 0.01). TGF-α protein was mainly expressed in the cytoplasm. EGFR was expressed in the cellular membrane in the normal esophageal mucosa and reflux esophagitis, but strongly positively expression was also observed in the cytoplasm and nucleus of cells in Barrett's esophagus with dysplasia and esophageal adenocarcinoma.

CONCLUSION: TGF-α and EGFR expression increase and may play synergic roles in the development of Barrett's esophagus and esophageal adenocarcinoma.

Key Words: TGF-α; EGFR; Barrett's esophagus; Esophageal adenocarcinoma

0 引言

Barrett食管是反流性食管炎的主要并发症之一, 他是由于长期胃食管反流导致柱状上皮化生替代正常食管鳞状上皮的一种病理现象, 被认为是食管腺癌的癌前病变[1-2]. 在过去30 a里, 食管腺癌的发病增长速度远远超出其他肿瘤, 严重威胁着人类健康, 而大多数食管腺癌可能来源于Barrett上皮化生[3-7]. 但是, 在胃食管反流者中只有少数发生了Barrett食管, 而Barrett食管发展为食管腺癌的年发生率估计约为0.2%-2%[8-10]. 目前研究表明, 源于Barrett上皮化生的食管腺癌的形成是一个由多因素参与的多步骤的过程, 在这一过程中, 转化生长因子(transforming growth factor alpha, TGF-α)和其受体表皮生长因子受体(epidermal growth factor receptor, EGFR)可能起一定作用[11-12]. 我们通过免疫组化法及图像分析, 探讨TGF-α和EGFR在反流性食管炎、Barrett食管和食管腺癌中的表达变化及其意义, 初步阐述二者在其发生、发展中的作用, 为Barrett食管和食管腺癌的发病机制提供可能的理论依据.

1 材料和方法

1.1 材料

反流性食管炎13例经临床、内镜及24 h食管pH检测确诊, 根据我国食管炎内镜诊断标准[13]分级为Ⅱ-Ⅲ级. Barrett食管17例, 其组织标本来源于胃-食管交界处上方3 cm以上的舌形、岛形或环周形病灶黏膜, 均在内镜下取得, 并经病理诊断证实伴有肠化者收入本研究; 在17例Barrett食管中, 7例属非典型增生, 其中6例为中-重度不典型增生. 食管腺癌11例收集于病理科标本. 对照组30例为反流性食管炎和Barrett食管患者自身正常食管黏膜, 均取自胃-食管交界处上方3 cm以上且距病灶缘至少5 cm之外, 并经病理证实为正常食管鳞状上皮. TGF-α和EGFR多克隆抗体、相应二抗IgG和SABC试剂盒均购自武汉博士德生物公司.

1.2 方法

实验采用免疫组织化学链霉亲合素-生物素-过氧化物酶复合法SABC法, 具体操作步骤按说明书进行, 免疫反应阳性物呈淡黄色或棕褐色, 以PBS代替一抗作为阴性对照. 免疫组化图像分析采用北航多功能真彩色病理分析图像-[miad]软件, 每例标本选3个不同视野, 以阳性目标总面积/统计场总面积即面密度为指标, 在光镜下进行定量分析.

统计学处理 计量资料用mean±SD表示, TGF-α和EGFR组内差异分别采用F检验, 二者之间的相关性采用Spearman等级相关分析法, P<0.05为显著性差异.

2 结果

2.1 TGF-α和EGFR的表达

在正常食管黏膜, TGF-α几乎无表达, EGFR弱表达; 在反流性食管炎, TGF-α表达仍很低, 而EGFR的表达明显增加(P<0.05); 在Barrett食管, TGF-α和EGFR表达量均较反流性食管炎明显增加(P<0.05, P<0.05); 在Barrett食管非典型增生, TGF-α和EGFR的表达虽然有所增加, 但与Barrett食管组相比无统计学意义; TGF-α和EGFR在食管腺癌中的表达最高, 与Barrett食管相比, 具有显著性差异(P<0.05, P<0.05)(表1). TGF-α主要表达于细胞质; EGFR则定位于正常食管黏膜和反流性食管炎的细胞膜, 在Barrett食管中-重度非典型增生和食管腺癌中, EGFR除表达于细胞质, 在细胞核也可见明显的表达(图1).

表1 TGF-α和EGFR免疫组化表达量 (面密度, mean±SD).

分组	n	男:女	年龄 (岁)	TGF-α	EGFR
对照组	30	21:9	43 (26-71)	0.036±0.003	0.089±0.005
反流性食管炎	13	9:4	41 (28-67)	0.045±0.009	0.236±0.031
Barrett食管	10	7:3	39 (26-51)	0.469±0.054	0.381±0.029
非典型增生	7	5:2	52 (35-71)	0.590±0.053	0.388±0.033
食管腺癌	11	6:5	60 (37-75)	0.768±0.069	0.426±0.040

图1 食管组织EGFR的表达 (SABC×200). A: 反流性食管炎; B: Barrett食管非典型增生; C: 食管腺癌.

2.2 TGF-α和EGFR的相关性

TGF-α和EGFR在正常食管黏膜、反流性食管炎、Barrett食管、Barrett食管非典型增生和食管腺癌组表达增幅虽不尽一致, 但均呈逐渐增高趋势. 通过绘制散点图发现, TGF-α和EGFR在上述五组中的表达呈非线性关系, 而且为等级资料, 故采用Spearman等级相关分析法, 二者在统计学上呈显著的正相关(r = 0.951, P<0.01)(图2).

图2 TGF-α和EGFR的相关性 (Spearman等级相关分析法).

3 讨论

生长因子是一类能与细胞膜特异受体呈高亲和力结合而刺激细胞增殖的多肽. 肿瘤细胞自分泌的生长因子可不断地刺激自身细胞的生长, 是肿瘤发生和发展的重要因素之一[14-16]. TGF-α最早发现于病毒感染细胞, 此后证实多种肿瘤细胞可分泌TGF-α并促进自身的生长. EGFR是TGF-α和表皮生长因子EGF的共同受体, 与TGF-α和EGF的亲和力相同, 但EGF的活性远远低于TGF-α. 表达异常的TGF-α如果与过量表达或结构改变的EGFR结合并相互作用, 则可使细胞获得恶性增殖优势[17-18]. 在食管炎、Barrett食管和食管腺癌也分别有TGF-α和EGFR表达异常的报道[19-23]. 我们采用免疫组化法和图像分析定量, 检测了包括反流性食管炎、Barrett食管和食管腺癌以及正常食管黏膜TGF-α和EGFR的表达变化, 以期从肿瘤细胞自分泌生长因子方面解释部分反流性食管炎发展为Barrett食管, 并在此基础上恶变为食管腺癌的可能机制. 结果显示: 从正常食管黏膜、反流性食管炎、Barrett食管和非典型增生到食管腺癌, TGF-α和EGFR的表达呈现逐渐增高的趋势, 但增幅并不一致, TGF-α主要定位于细胞质, EGFR则表达广泛. 在正常食管黏膜, TGF-α几乎无表达, 提示正常食管鳞状上皮可能缺乏生成和分泌TGF-α的能力, EGFR则少量表达于细胞膜. 在反流性食管炎, TGF-α表达仍很低, 提示TGF-α在反流性食管炎炎性反应中不起重要作用, 而EGFR表达增高可能是机体保护反应所致, 其机制可能与其他因素有关[24-25]. 当Barrett食管形成后, 肠化型柱状细胞可大量合成和分泌TGF-α及EGFR, 二者结合可促进细胞的分化和增殖, 而且细胞异型性增生程度越高, 这种能力越强, 最终导致部分细胞发生癌变. 在Barrett食管非典型增生和食管腺癌, TGF-α和EGFR的表达明显增高, 而且EGFR分布广泛, 他不仅表达于细胞质, 细胞核也可见明显的表达. EGFR的高表达特别是细胞核的高表达可能是细胞核过度增殖和细胞异型的表现, 是细胞恶性程度的标志之一[26-27]. EGFR从细胞膜转位至细胞核是否参与了Barrett食管和食管腺癌的发生、发展过程, 尚有待进一步证实.

我们试用Spearman等级相关分析法探讨了TGF-α和EGFR从正常食管黏膜、反流性食管炎、Barrett食管和非典型增生到食管腺癌过程中表达的相关性, 统计学显示二者存在明显的正相关, 提示TGF-α和EGFR同时参与并可能共同作用于Barrett食管和食管腺癌的发生、发展, 其内在机制可能在于二者系受体配体间相互作用的关系[28-30]. 综上所述, TGF-α和EGFR在反流性食管炎、Barrett食管和食管腺癌中表达逐渐增高及其相互作用, 可能对Barrett食管和食管腺癌的发生、发展起一定的作用. TGF-α和EGFR在反流性食管炎、Barrett食管和食管腺癌的表达并不一致, 联合检测TGF-α和EGFR可能更有助于准确地判断病情和预测疾病的进展.

评论

背景资料

胃食管反流病是消化系统的常见病. 慢性胃食管反流一个常见和潜在的严重后果是食管原有的鳞状上皮被化生的柱状上皮增殖所替代, 这一状况被称为Barrett食管. 这种化生上皮可能进展至食管腺癌. 本文研究了Barrett食管和食管腺癌中TGF-α和EGFR的表达意义.

研发前沿

源于Barrett上皮化生的食管腺癌的形成是一个由多因素参与的多步骤的过程, 包括有癌基因与抑癌基因、生长因子、黏附分子、细胞增殖与凋亡及其调控失衡等的参与和作用.

创新盘点

本实验系统地研究了转化生长因子TGF-α及其受体EGFR在反流性食管炎-Barrett食管-食管腺癌这一序贯过程中的表达, 结果发现二者呈逐渐增高的趋势, 并且具有明显的相关性, 提示TGF-α和EGFR可能在Barrett食管和食管腺癌的发生、发展中起一定的作用.

同行评价

本文探讨了Barre-tt食管和食管腺癌中TGF-α和EGFR的表达情况, 对认识Barrett食管和食管腺癌中分子生物学的改变有一定意义. 立题新颖, 设计合理.

备注

电编:张敏 编辑:潘伯荣

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