Shen Zhongying, Shen Jian, Cai Weijia, Chen Minghua, Wu Xianying, Zheng Ruiming, Zeng Yi
Department of Tumor Pathology, Shantou University Medical College, Shantou 515031, China.
Zhonghua Bing Li Xue Za Zhi. 2002 Aug;31(4):327-30.
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(6)E(7) genes.
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.
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.
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 cytotoxicity 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.
基于人乳头瘤病毒（HPV）18E（6）E（7）基因诱导人胎儿食管上皮永生化，研究高剂量和低剂量丁酸钠对致癌过程的启动作用。
将永生化食管上皮细胞SHEE分别用高浓度丁酸钠（80 mmol/L）处理8周，然后用低浓度丁酸钠（5 mmol/L）处理8周。细胞在无丁酸钠的情况下连续培养14周。通过相差显微镜、免疫组织化学和流式细胞术研究细胞的形态、增殖和凋亡。用Hoechst 33342和碘化丙啶染色，通过荧光显微镜检测死细胞和活细胞。通过软琼脂集落形成以及将细胞移植到裸鼠和重症联合免疫缺陷（SCID）小鼠体内来评估细胞的致瘤性。
当细胞暴露于高浓度丁酸钠时，细胞死亡增加，存活细胞很少。当细胞在含有低浓度丁酸钠的培养基中培养时，出现了第一个增殖阶段。去除丁酸钠导致细胞进入危机期，倍增时间延长，类似于衰老细胞。危机期过后，细胞进入第二个增殖阶段，持续复制并出现非典型增生。在第二个增殖阶段结束时，细胞发生癌变，在软琼脂中形成大菌落，并在移植的SCID小鼠和裸鼠体内形成肿瘤。
丁酸钠作用导致永生化上皮细胞发生恶性变化是两阶段死亡机制的结果：丁酸钠细胞毒性导致细胞死亡，去除丁酸钠导致细胞危机。这些数据表明，高剂量丁酸钠诱导细胞死亡，低剂量丁酸钠诱导细胞增殖，这强调了丁酸钠作为致癌启动剂的重要性。
