结直肠癌中EpCAM的表达及与DNA倍体改变的关系

Relationship of EpCAM expression and DNA copy number alteration in colorectal carcinoma cells

目的探讨结直肠癌细胞中EpCAM(CD326)表达的临床病理学意义及与DNA倍体改变的关系。方法应用流式细胞直接免疫荧光法检测55例结直肠癌组织及癌旁正常黏膜组织中EpCAM的表达,用阳性率(percentage of positive cells,PPC)、平均荧光强度(mean fluorescence index,MFI)表示;应用细胞周期分析仪对结直肠癌细胞进行细胞周期分析。用细胞定量术分析EpCAM表达和DNA倍体改变的相关性及其在结直肠癌早期诊断、预后中的价值。结果 55例结直肠癌组织中EpCAM蛋白的PPC为(83.48±7.07)%,明显高于癌旁正常黏膜组织(43.56±5.29)%(t=39.22,P<0.001)。55例结直肠癌组织中EpCAM蛋白MFI值为28.90(19.60~45.89),明显高于癌旁正常黏膜组织的4.89(3.79~6.28)(Z=-6.45,P<0.001)。癌组织:浸润型+溃疡型vs肿块型(包括浸润型vs溃疡型),中+低分化vs高分化(包括低分化vs中分化),Dukes分期C+D vs A+B,p TNM分期Ⅲ+ⅣvsⅠ+Ⅱ,浸润深度pT3+T4 vs pT1+T2,淋巴结转移pN1 vs pN0,差异均有统计学意义,即生物学行为越差,EpCAM蛋白表达MFI值与PPC越高,而与患者年龄、性别无关。DNA含量分析结果显示:55例结直肠癌中39例(70.90%)为多倍体,DNA指数(DNA index,DI)和DNA倍体与肿瘤分化程度、Dukes分期相关,与淋巴结转移无关。同时,在EpCAM阳性病例中,DI随着EpCAM表达增强而升高(r=0.668,P=0.000);而增殖指标S期细胞比率(S-phase fraction,SPF)和增殖指数(proliferation index,PI)也随着EpCAM表达增强而升高(r_1=0.664,P_1=0.000;r_2=0.651,P_2=0.000)。结论EpCAM在结直肠癌中的表达明显上调,与肿瘤细胞侵袭转移、增殖密切相关,同时检测EpCAM表达和DNA含量分析能为结直肠癌早期诊断和预后判断提供参考依据。

Purpose To investigate the clinical pathology significance of epithelial cellular adhesion molecule （ EpCAM, CD326） expression in colorectal carcinoma cells. Methods Flow cytometry and immunofluorescence assay were used to detect EpCAM expression in 55 cases of fresh colorectal cancer tissues and adjacent normal mucosa. The percentage of positive cells （PPC） and mean fluorescence index （MFI） were calculated. Correlation of EpCAM expression with DNA ploidy change and its value were investigated in the early diagnosis of colorectal cancer. Results The values of PPC and MFI were significantly higher in colorectal carcinoma tissue than that in the nominal colorectal tissue [（PPC： （83.48 ± 7.07）% vs （43.56 ± 5.29） %, t = 39. 22, P 〈 0. 001. MFI ： 28.90 （ 19. 60 - 45.89 ） vs 4. 89（3.79 -6.28）, Z = -6.45, P 〈0. 001 ） ]. There were also significant differences （P 〈0. 01 ） in the values of PPC and MFI between invasive type and ulcer types, between well - and moderately-differentiated and poorly-differentiated cancers, between Dukes stages A ＋ B and C ＋ D, （ between pTNM stages I ＋ II and III ＋ IV, between pT1 ＋ T2 and pT3 ＋ T4, and between pN0 and pN1. DNA content analysis showed that I）NA polyploid was detected in 39 of 55 eolorectal carcinoma（70.90% ）. The DNA index （DI） and ploid were correlated with differentiation degree and Dukes stages, but uncorrelatcd with lymph node metastasis. At the same time, in lhe EpCAM positive cases, DI was increased with increased expression of EpCAM （ r = 0. 668, P = 0. 000） and the proliferation index of cells in S phase ratio （ S-phase fraction, SPF） （r1 =0. 664, P1 =0. 000, r2 =0. 651 , P2 =0.000）. Conclusion EpCAM cxprcssiml is obviously up- regulated in colorectal carcinoma, and it is closely correlated with the invasion, metastasis and proliferation of tumor cells. The combination of EpCAM expression and DNA content analysis provides references to the early diagnosis and prognosis evaluation in colorectal carcinoma.