摘要
目的观察表皮生长因子受体（EGFR）单克隆抗体西妥昔单抗（C225）对裸鼠胃癌移植瘤生长的影响，并探索其分子机制。方法筛选出高表达EGFR的胃癌细胞株SGC-7901，建立裸鼠胃癌移植瘤模型，成瘤后分为治疗组（注射C225）和对照组（注射PBS），绘制肿瘤生长曲线。采用免疫组织化学染色法，评价C225对肿瘤细胞增殖和微血管密度的影响。采用原位末端标记染色（TUNEL）技术，检测肿瘤细胞凋亡。采用免疫组化染色和Western blot技术，检测C225对转录因子Spl及EGFR表达的影响。结果经C225处理后，裸鼠胃癌移植瘤的生长、细胞的增殖能力明显受抑，治疗组和对照组肿瘤细胞的凋亡指数分别为16．4％±0．3％和3．1％±0．9％，差异有统计学意义（P〈0．001）；而治疗组和对照组肿瘤组织的微血管密度并无明显差异。免疫组化染色和Western blot结果均显示，C225处理后，肿瘤细胞表面EGFR及肿瘤细胞核内Sp1的表达均明显上调。结论C225可有效抑制裸鼠胃癌皮下移植瘤的生长及细胞增殖，促进细胞凋亡，但可反馈性上调肿瘤细胞核内转录因子Sp1及该药物靶点EGFR的自身表达。不同信号转导通路间可能通过转录因子Sp1介导的阻断一转录激活一代偿机制，导致单一靶点阻断后的获得性耐药或使肿瘤细胞维持恶性表型。
Objective EGFR-mediated tumor proliferation plays an important role in the development of cancer, and is a key candidate for targeted therapy. The aim of this study is to evaluate the impact of EGFR monoclonal antibody Cetuximab （ C225 ） on the growth, proliferation and apoptsis of gastric cancer xenograft in nude mice, and its possible mechanisms. Methods A gastric cancer cell line SGC-7901 with high EGFR expression level was screened from 7 gastric cancer cell lines. Gastric cancer xenografts in nude mice were established, and randomly divided into C225 treatment group and PBS control group. Tumor growth curves were calculated, the impact of C225 on the tumor growth, proliferation and angiogenesis was evaluated by immunohistochemical （IHC） staining Ki67 and CD34, respectively. The effect of C225 on apoptosis in the gastric cancer cells was evaluated by TUNEL assay. The expression levels of EGFR and its transcription factor Spl were detected by IHC staining and Western blot. Results After C225 treatment, the proliferation and growth of gastric cancer xenograft in nude mice were significantly decreased. In the contrast, the apopotic indexes in C225 treatment group and PBS control group were （ 16.4% ±0.3% ） and （3. 1% ±0.9% ）, respectively, with a significant difference （P 〈0. 001 ）. There was no significant difference of the densities of CD34-positive microvessels between C225 treatment group and control group. Elevated expression of EGFR and Spl after C225 treatment was observed by IHC staining and Western blot assay. Conclusion EGFR monoclonal antibody cetuximab （C225） can effectively inhibit the growth of gastric cancer xenografts in nude mice, and trigger its apoptosis. Yet, C225 treatment may upregnlate the expression of EGFR and its transcription factor Spl. A ＂ block-transcription activationcompensation＂ mechanism may exist to explain the molecular mechanism of acquired resistance of a single target blockade treatment.
出处
《中华肿瘤杂志》
CAS
CSCD
北大核心
2009年第2期85-89,共5页
Chinese Journal of Oncology
基金
国家自然科学基金（30801371）
上海市教委科研专项基金（06BZ039）
