【摘要】 目的　在人乳头状瘤病毒 (HPV) 18E6E7基因诱导人胚食管上皮细胞永生化的基础上 ,观察高、低剂量丁酸钠在细胞恶性转化过程中的促癌作用。方法　永生化食管上皮细胞SHEE先用高剂量丁酸钠 (80mmol/L) ,后用低剂量丁酸钠 (5mmol/L)各处理 8周 ,再经无丁酸钠条件继续培养 14周。用相差显微镜、免疫组织化学SABC法和流式细胞仪检查细胞形态、增殖和凋亡状况 ;用Hoechst33342和碘化丙啶检查活细胞和死细胞 ;细胞软琼脂集落形成及移植裸小鼠和严重联合免疫缺陷小鼠检查成瘤性。结果　当细胞暴露在 80mmol/L丁酸钠 ,细胞死亡 ,只剩少量活细胞。在含 5mmol/L丁酸钠培养基中细胞出现第一增殖期 ;撤去丁酸钠 ,细胞进入危象期 ,细胞倍增时间延长 ,如老化细胞。度过危象期 ,细胞进入第二增殖期 ,细胞继续增生和异型增生。在第二增殖期末细胞出现恶变 ,软琼脂培养有大集落形成 ,移植裸小鼠和SCID小鼠成瘤。结论　SHEE永生化上皮由丁酸钠诱导的恶性变通过了两个阶段的死亡威胁 :高浓度丁酸钠引起细胞死亡 ,缺乏丁酸钠引起细胞危象。高剂量丁酸钠引起永生化细胞死亡 ,低剂量引起细胞增殖 ,说明丁酸钠对体外培养细胞有促恶变作用更多还原

【Abstract】 Objective Study on the promoter effects of sodium butyrate in high or low dosages on carcinogenesis process, based on the immortalization of human fetal esophageal epithelium induced by human papillomavirus (HPV) 18E 6E 7 genes Methods The immortalized esophageal epithelium SHEE was treated with high concentration of the sodium butyrate (80 mmol/L) and then with low concentration (5 mmol/L) for 8 weeks respectively The cells were cultured continuously without sodium butyrate for 14 weeks The morphology, proliferation and apoptosis of the cells were studied by phase contrast microscopy, immunohistochemistry and flow cytometry The dead and the viable cells were assayed by fluorescent microscopy with Hoechst 33342 and Propidium iodide staining Tumorigenesis of the cells was assessed by soft agar colony formation and by transplantation of cells into nude mice and SCID mice Results When cells were exposed to high concentration of sodium butyrate, cell death was increased leaving few live cells When cells were cultured in the medium with low concentration of sodium butyrate, the first proliferative stage appeared Removal of the butyrate caused the cell to enter a crisis stage with a long doubling time resembling senescent cells After the crisis stage, the cells progressed to the second proliferation stage with continuous replication and atypical hyperplasia At the end of the second proliferative stage, carcinogenesis of the cells appeared with large colonies in soft agar and tumor formation in transplanted SCID mice and nude mice Conclusions The malignant change of the immortalized epithelium by the effects of sodium butyrate is the consequence of a two stage mortality mechanism: cells death by butyrate cytotoxity and cell crisis by abrogation of sodium butyrate These data reveal that in high dosage, sodium butyrate induces cell death and in low dosage, it induces cell proliferation, which emphasizes the importance of butyrate as a promotor of carcinogenesis更多还原