大肠上皮恶性转化不同阶段中Fas,p53表达及其与凋亡的关系

Expression of Fas and p53 in different stages of large intestinal malignant transformation and their association with apoptosis

目的:研究大肠腺癌、腺瘤恶变、管状绒毛状腺瘤、管状腺瘤中Fas及p53的表达,探讨Fas在大肠癌发生发展中的作用. 方法:收集石蜡包埋的大肠腺癌组织37例,腺瘤恶变组织26例,管状绒毛状腺瘤30例,管状腺瘤24例,以6例非肿瘤大肠黏膜作为对照.通过原位杂交,免疫组化及TUNEL 等技术,原位观察不同病变组织大肠上皮中的Fas mRNA 和p53蛋白表达及细胞凋亡的状况及相互关系. 结果:Fas mRNA阳性细胞密度:非肿瘤黏膜39.60±6.51, 管状腺瘤50.93±21.64,管状绒毛状腺瘤45.91±24.15, 腺瘤非恶变区25.47±14.76,腺瘤恶变区11.92±9.47, 腺癌5.88±5.10;Fas mRNA在腺瘤中有较高表达,而在恶性病变中表达明显下降(P<0.001).大肠非肿瘤黏膜、管状腺瘤、管状绒毛状腺瘤、腺瘤非恶变区、腺瘤恶变区和腺癌中,p53蛋白阳性细胞密度分别为8.40±2.67, 13.19±8.95,13.50±7.29,12.24±7.16,73.31±28.57 和80.99±44.54;p53蛋白在非肿瘤黏膜中表达最低,腺瘤中略增加,在恶性病变中明显增加(P<0.001).上皮凋亡细胞密度:非肿瘤黏膜15.02±11.14,管状腺瘤46.31±18.86,管状绒毛状腺瘤29.43±16.66,腺瘤非恶变区68.42±19.61,腺瘤恶变区22.01±12.07,腺癌18.64±12.88;上皮凋亡细胞密度在腺瘤中明显升高,在恶性病变中较低(P<0.001).p53蛋白阳性表达细胞密度与上皮凋亡细胞密度呈负相关(r=0.389,P<0.001),Fas mRNA阳性表达细胞密度与上皮凋亡细胞密度呈正相关(r=0.190, P<0.05). 结论:本文证实大肠腺癌可通过下调Fas表达,上调p53表达,抑制细胞凋亡,形成“Fas抵抗”.

AIM: To explore the expression of Fas and p53 in the large intestinal adenocarcinoma, malignantly transformed adenoma, tubulo-villous adenoma, and tubular adenoma, and to assess their influence on the pathogenesis of large intestinal carcinoma. METHODS: Using in-situ hybridization, immunohistochem-istry and TUNEL techniques, we examined a number of paraffin-embedded tissues including 37 cases of large intestinal adenocarcinomas, 26 cases of malignantly transformed adenomas, 30 cases of tubulo-villous adenomas, and 24 cases of tubular adenomas for Fas mRNA, p53 protein and DNA fregment. 6 cases of non-tumor mucosa were used as control group. RESULTS: Fas mRNA positive cell density was: 39.60 ± 6.51 in non-tumor mucosa, 50.93 ± 21.64 in tubular adenoma, 45.91 ± 24.15 in tubulo-villous adenoma, 25.47 ± 14.76 in non-malignantly transformed area of adenoma, 11.92 ± 9.47 in malignantly transformed area of adenoma, and 5.88 ± 5.10 in adenocarcinoma, which was significantly lower in the malignant lesions than in adenomas (P <0.001). p53 protein positive cell density was: 8.40 ± 2.67 in non-tumor mucosa, tubular adenoma 13.19 ± 8.95, tubulo-villous adenoma 13.50 ± 7.29, non-malignantly transformed area of adenoma 12.24 ± 7.16, malignantly transformed area of adenoma 73.31 ± 28.57, adenocarcinoma 80.99 ±44.54, among which it was the lowest in the non-tumor mucosa, slightly increased in adenoma, and significantly increased in malignant lesions (P<0.001). Apoptotic cell density was: non-tumor mucosa 15.02 ± 11.14, tubular adenoma 46.31 ± 18.86, tubulo-villous adenoma 29.43 ± 16.66, non-malignantly transformed area of adenoma 68.42 ± 19.61, malignantly transformed area of adenoma 22.01 ± 12.07, adenocardnoma 18.64 ± 12.88, which was higher in adenomas, but lower in malignant lesions (P<0.001). The positively expressed cell density of p53 protein was reversely related with that of the apoptotic epithelial cells (r =-0.389, P <0.001). The positively expressed cell density of Fas mRNA was related with that of the apoptotic epithelial cells (r=0.190, P<0.05). CONCLUSION: The apoptotic cell death is inhibited via downregulation of Fas expression and upregulation of p53 expression in large intestinal adenocarcinoma, and a so-called 'Fas resistance' mechanism is induced.