CIP2A在高危局限性前列腺癌中的表达及临床意义

2020-04-09 04:38郑克文陈伟
中国现代医生 2020年2期

潘 悦 郑克文 陈伟

[摘要] 目的 探讨蛋白磷酸酶2A的抑制性癌因子(cancerous inhibitor of proteinphosphatase 2A,CIP2A)在高危局限性前列腺癌组织中的表达情况及临床意义。 方法 选取2010年1月~2016年1月于温州医科大学附属第一医院行手术治疗的50例高危局限性前列腺癌患者为实验组,并选取同期在我院手术治疗的良性前列腺增生患者50例为对照组,应用免疫印迹(western blot)的方法对两组术后标本的CIP2A表达情况进行对比分析,并进一步比较两组CIP2A的表达与临床病理因素的关系。 结果 实验组中CIP2A的表达明显高于对照组(P<0.05);并且CIP2A的表达与术后1年肿瘤转移复发、Gleason评分、前列腺特异抗原(prostate specific antigen, PSA)水平密切相关(P<0.05)。 结论 CIP2A在高危局限性前列腺癌中高度表达,有望成为高危局限性前列腺癌早期诊断、术后预测复发转移的一个重要的生物学指标。

[关键词] 高危局限性前列腺癌;CIP2A;Gleason评分;PSA

[中图分类号] R737.2          [文献标识码] B          [文章编号] 1673-9701(2020)02-0049-03

The expression and clinical significance of CIP2A in high risk localized prostate cancer

PAN Yue   ZHENG Kewen   CHEN Wei

Department of Urology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou   325000, China

[Abstract] Objective To explore the expression and clinical significance of cancerous inhibitor of protein phosphatase 2A (CIP2A) in high risk localized prostate cancer. Methods 50 patients with high risk localized prostate cancer who were operated in the First Affiliated Hospital of Wenzhou Medical University from January 2010 to January 2016 were selected as the study group, while 50 patients with benign prostatic hyperplasia who were operated in our hospital at the same period were selected as the control group. The expression of CIP2A after surgery in the two groups was compared by Western blot, and the relationship between CIP2A expression and clinicopathologic factors was analyzed. Results The expression of CIP2A in the study group was significantly higher than the control group(P<0.05), and the expression of CIP2A was closely related to tumor metastasis and recurrence, Gleason score, prostate specific antigen (PSA) level in one year after operation(P<0.05). Conclusion The high expression of CIP2A in high risk localized prostate cancer is expected to be an important biological index for early diagnosis and postoperative prediction of recurrence and metastasis of high risk localized prostate cancer.

[Key words] High risk localized prostate cancer; Cancerous inhibitor of protein phosphatase 2A; Gleason score; Prostate specific antigen

蛋白磷酸酶2A的抑制性癌因子(cancerous inhibitor of proteinphosphatase 2A,CIP2A)能抑制蛋白磷酸酶2A(proteinphosphatase 2A,PP2A),近來被发现是一种致癌因子,可在多种类型的肿瘤中高表达,包括胃癌、乳腺癌、结肠癌等,它通过与PP2A、c-Myc相互作用最终达到抑制c-Myc蛋白水解的作用。CIP2A作为最新被重视的癌蛋白,在前列腺癌的早期诊断中也发挥着重要作用,然而CIP2A在高危局限性前列腺癌发生发展中所起的作用仍不清楚。本次研究通过对比CIP2A蛋白在高危局限性前列腺癌标本及良性前列腺增生标本中的表达情况,并通过远期随访,探讨CIP2A在高危局限性前列腺癌的早期诊断、术后检测及预后判断中的作用,现报道如下。

1 资料与方法

1.1 一般资料

选择在温州医科大学附属第一医院2010年1月~2016年1月期间接受手术治疗患者的前列腺增生标本50例为对照组和高危局限性前列腺癌标本50例为实验组。高危前列腺癌标本中18例通过前列腺活检穿刺术获得,32例通过前列腺癌根治性切除术获得。纳入标准:均为病理证实良性前列腺增生或高危局限性前列腺癌;患者授权同意参与本次研究;患者临床资料齐全。排除标准:患者合并有其他脏器肿瘤;患者术前发现肿瘤远处转移;患者行姑息性手术而非根治术。

1.2 蛋白免疫印迹法

100例前列腺癌标本和良性前列腺增生标本均采用蛋白免疫印迹法进行CIP2A测定。采用匀浆器将前列腺组织研磨成匀浆,加入裂解液,离心后取上清。蛋白上清加入SDS上样缓冲液后水浴变性。取适量样本加入10%的SDS-PAGE凝胶,通过电泳,依据蛋白分子量的大小来分离蛋白。随后將电泳结束后的凝胶转移至PVDF膜,将膜与封闭缓冲液在室温下孵育1 h,在4℃下在含有第一抗体的封闭缓冲液中孵育过夜,然后洗涤3次,之后PVDF膜在室温下与辣根过氧化物酶缀合的第二抗体孵育1 h。使用ECL检测系统检测结合的抗体,以GAPDH为内参。

1.3 免疫组织化学染色法

本次研究采用过氧化物酶标记的链霉卵蛋白素法(S-P)法。将标本制成石蜡切片后,将切片在二甲苯中脱蜡并在梯度乙醇中水化。为了增强免疫反应性,将切片在3%过氧化氢去离子水中37℃温育10 min,并高压煮沸15 min进行抗原修复。载玻片冷却至室温,加入血清封闭20 min,PBS洗涤3次后,滴加CIP2A,4℃孵育过夜。次日滴加生物素标记的二抗,37℃条件下孵育30 min。随后滴加链霉亲和素-过氧化物酶,在室温下孵育30 min。最后滴加二氨基联苯胺显色,并用苏木素复染细胞核。

1.4 结果判定

CIP2A主要表达于细胞质,免疫组化结果阳性表现为细胞质染色为褐色。采用半定量方式判读免疫组化结果。评分标准如下:无染色为0分,弱染色为1分,中度染色为2分,强染色为3分。

1.5 统计学方法

CIP2A在良性前列腺增生组和前列腺癌组的差异表达情况通过χ2检验来分析,P<0.05为差异有统计学意义。所有统计均在SPSS19.0软件上进行。

2 结果

2.1 CIP2A在两组中的表达情况

本次研究结果发现高危局限性前列腺癌患者组织中,CIP2A的阳性表达率为76%(38/50),良性前列腺增生患者的组织中,CIP2A的阳性表达率为30%(15/50)(封三图3),χ2检验结果提示两组表达的差异有统计学意义(χ2=21.236,P<0.05)。见表1。

2.2 CIP2A与高危局限性前列腺癌患者临床病理特征的关系

高危局限性前列腺癌患者CIP2A的阳性表达与术后1年肿瘤复发转移、术前PSA水平和Gleason评分值密切相关(均P<0.05),与患者年龄无明显相关(P=0.825)。见表2。

3 讨论

前列腺癌是美国男性最常见的癌症,也是导致男性癌症相关死亡的主要原因,占男性癌症诊断的30%。这种高死亡率主要原因是原发肿瘤的转移。目前最常用的判断高危局限性前列腺癌的标准为PSA>20 ng/mL,Gleason评分8~10分,临床分期≥T2c[1]。初诊前列腺癌的患者中有约15%患者为高危局限性前列腺癌,但此类疾病具有明显的临床进展性,且术后有较高的复发和转移风险[2-4]。因此,前列腺癌早期诊断技术的改进及特异性靶点分子治疗对前列腺癌的诊疗将会起到显著的改善作用。

最新的研究表明,蛋白磷酸酶2A的癌性抑制因子(CIP2A)是一种肿瘤蛋白,可在多种恶性肿瘤中高表达,并通过抑制抑癌因子蛋白磷酸酶2A的表达从而诱导肿瘤细胞不断增殖[5]。目前,多项研究均证实CIP2A在多种恶性肿瘤的发生发展中扮演着重要的作用,如胃癌、食管癌、乳腺癌、子宫内膜癌、口腔癌、肾癌等[5-13]。有研究表明CIP2A能通过促进MYC稳定来诱导胃癌细胞的增殖,并且CIP2A的表达水平与胃癌的预后相关[14]。此外高表达的CIP2A可促进乳腺癌异种移植物的生长,并且CIP2A的表达水平与乳腺癌组织中的肿瘤增殖标志物、p53突变水平以及淋巴结阳性率呈正相关[15]。近年来越来越多的研究发现CIP2A在前列腺癌的发生发展中扮演着重要的作用[16-20]。Vaarala等发现CIP2A在良性前列腺增生组织和前列腺癌组织中差异表达,并且该差异具有统计学意义(P<0.01);在接受前列腺癌根治术的患者中,CIP2A的表达与Gleason评分、临床分期和术前危险分级呈正相关(P<0.05),但是CIP2A的表达与PSA水平无显著相关性。

本研究中,高危局限性前列腺癌患者和良性前列腺增生患者的病理组织中,CIP2A的表达具有明显差异,其在两组中表达阳性率分别为76%和30%,差异有统计学意义(P<0.05)。并且CIP2A的表达与术后1年肿瘤转移复发、Gleason评分、PSA水平密切相关(P<0.05),评分越高,PSA水平越高,CIP2A的阳性表达率越高。但CIP2A的表达与年龄无显著相关性。

综上所述,本研究结果提示CIP2A有望成为高危局限性前列腺癌发生发展过程中的一个重要的生物学指标。然而目前国内外关于CIP2A与高危局限性前列腺癌的报道较少,建议继续开展相关研究论证结果,能为前列腺癌患者提供更敏感而特异的诊断工具。

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(收稿日期:2019-09-05)