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目的探讨裸鼠低位直肠癌淋巴结转移模型血清及移植瘤组织中E-钙黏蛋白(E-cad)的表达情况,分析其在直肠癌淋巴结转移过程中的作用。方法取对数生长期的人大肠癌细胞株SW480接种于裸鼠直肠黏膜下,建立裸鼠低位直肠癌淋巴结转移模型。120只裸鼠随机分为3组,每组40只,A组(直肠癌模型组)采用二甲基肼注射+SW480种植,B组(二甲基肼对照组)采用二甲基肼注射,C组(空白对照组)不作任何处理。采用ELISA检测血清E-cad的含量,采用Western blot法、RT-PCR法检测种植瘤组织中E-cad蛋白及mRNA表达水平。结果A组裸鼠的血清E-Cad含量为(19.48±1.25)mg/L,明显高于B组裸鼠和C组裸鼠的血清E-Cad含量(2.36±0.18mg/L和2.15±0.12 mg/L)(t=8.28,9.01,P<0.05)。发现侧方淋巴结转移的裸鼠血清E-Cad含量,明显高于未发现侧方淋巴结转移的裸鼠,差异有显著性(t=10.28,P<0.05)。A组裸鼠移植瘤组织中E-Cad蛋白的表达强度弱于B组和C组(t=9.81,7.69,P<0.05)。A组中,有侧方淋巴结转移发生的裸鼠移植瘤组织中E-Cad蛋白表达强度较未有侧方淋巴结转移发生的裸鼠移植瘤组织中表达明显减弱,差异有显著性(t=9.36,P<0.05)。A组裸鼠移植瘤组织中E-Cad mRNA表达明显下调,与B组和C组比较,有明显的差异(P<0.05)。A组中发现侧方淋巴结转移的裸鼠移植瘤组织中E-Cad mRNA表达强度明显下调,与未发现侧方淋巴结转移的裸鼠比较,差异有显著性(t=7.85,P<0.05)。结论血清E-cad的表达水平可能与直肠癌淋巴转移密切相关,同时直肠癌组织中E-Cad蛋白和mRNA表达减弱或缺失,导致癌细胞间粘附性降低,促进癌细胞获得侵袭和转移的能力。
Objective To investigate the expression of E-cadherin (E-cad) in the serum and xenograft tissues of lymph node metastasis of low rectal cancer in nude mice and to analyze the role of E-cadherin in lymph node metastasis of rectal cancer. Methods The logarithmic growth phase human colorectal cancer cell line SW480 was inoculated into the rectal mucosa of nude mice to establish a lymph node metastasis model of low rectal cancer in nude mice. 120 nude mice were randomly divided into 3 groups (n = 40). A group (rectal cancer model group) was treated with dimethyl hydrazine injection + SW480. Group B (dimethylhydrazine control group) Group C (blank control group) did not make any treatment. The content of E-cad in serum was detected by ELISA. The expression of E-cad protein and mRNA in tumor tissue was detected by Western blot and RT-PCR. Results The level of serum E-Cad in group A was (19.48 ± 1.25) mg / L, which was significantly higher than that in group B and 2. (2.15 ± 0.12 mg / L) (t = 8.28, 9.01, P <0.05). The serum E-Cad level in nude mice with lateral lymph node metastases was significantly higher than that in nude mice without lateral lymph node metastases (t = 10.28, P <0.05). The expression of E-cad protein in the nude mice transplanted tumor in group A was weaker than that in group B and C (t = 9.81, 7.69, P <0.05). In group A, the expression of E-Cad protein in nude mice transplanted with lateral lymph node metastasis was significantly lower than that in non-transplanted tumor without lateral lymph node metastasis (t = 9.36 , P <0.05). The expression of E-Cad mRNA was significantly down-regulated in the transplanted tumor of nude mice in group A, which was significantly different from that in group B and C (P <0.05). The intensity of E-Cad mRNA expression in the nude mice xenografts with lateral lymph node metastasis in group A was significantly lower than that in the nude mice without lateral lymph node metastasis (t = 7.85, P <0.05). Conclusions The expression level of E-cadherin may be closely related to the lymphatic metastasis of rectal cancer. Meanwhile, the expression of E-Cad protein and mRNA in rectal cancer is decreased or absent, which leads to the decrease of adhesion between cancer cells and the invasion and metastasis of cancer cells ability.