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目的探讨维甲酸(RA)对结直肠癌组织维甲酸受体(RAR)和增殖细胞核抗原(PCNA)表达的影响。方法选Wistar大鼠160只,随机分4组。第1、2组注射二甲基肼,第3、4组注射生理盐水。于第7周开始,第2、3组每天给大鼠灌服维甲酸50mg/kg,至第14周,然后分批处死。用受体放射性配基结合分析法测定正常结直肠组织和癌组织的RAR含量和用免疫组织化学法计算PCNA指数。结果第1、2组结直肠癌发生率100%和15%,差异有非常显著性意义(P<0.01)。注射RA前后正常结直肠组织和结直肠癌组织RAR水平分别为2.64、2.11、1.16和1.78fmol/μgDNA,RA可使癌组织RAR水平升高(P<0.01)。注射RA治疗前后正常结直肠组织和癌组织PCNA分别为33、33、168、98,RA能明显降低结直肠癌组织PCNA指数(P<0.01)。结论RA可以减少二甲基肼诱发结直肠癌的发生;并可使结直肠癌组织的RAR水平上升和PCNA水平下降。
Objective To investigate the effect of retinoic acid (RA) on the expression of retinoid receptor (RAR) and proliferating cell nuclear antigen (PCNA) in colorectal cancer tissue. Methods 160 Wistar rats were randomly divided into 4 groups. Dimethylhydrazine was injected into groups 1 and 2, and saline was injected into groups 3 and 4. At the 7th week, rats in groups 2 and 3 were given retinoic acid 50 mg/kg every day until the 14th week and then sacrificed in batches. RAR levels in normal colorectal and cancer tissues were determined by receptor radioligand binding assays and PCNA index was calculated by immunohistochemistry. Results The incidence of colorectal cancer was 100% and 15% in the 1st and 2nd groups, and the difference was significant (P<0.01). The RAR levels in normal colorectal tissue and colorectal cancer tissue before and after RA injection were 2.64, 2.11, 1.16, and 1.78 fmol/μg DNA, respectively, and RA increased the RAR level in cancer tissue (P<0.01). The PCNA of normal colorectal tissues and cancer tissues before and after RA injection was 33, 33, 168, 98, respectively. RA significantly decreased the PCNA index of colorectal cancer tissues (P<0.01). Conclusion RA can reduce the incidence of colorectal cancer induced by dimethyl hydrazine, and can increase the RAR level and PCNA level in colorectal cancer tissue.