辣椒碱对乳腺癌MDA-MB-231细胞裸鼠移植瘤生长的抑制作用

目的：观察辣椒碱对乳腺癌MDA-MB-231细胞裸鼠移植瘤生长的抑制作用及其机制。方法：通过皮下注射MDA-MB-231细胞的方法建立乳腺癌裸鼠移植瘤模型，待肿瘤体积达到约100 mm³，将裸鼠随机分为模型组和辣椒碱低、中、高剂量（5，10，20 mg·kg^-1）组，每组5只。辣椒碱低、中、高剂量（5，10，20 mg·kg^-1）组裸鼠分别腹腔注射相应剂量的辣椒碱，模型组注射等体积的磷酸缓冲盐溶液（PBS）溶剂，3 d/次，连续给药8次。每次给药前先检测裸鼠体质重和肿瘤体积，末次给药24 h后处死各组裸鼠，计算肿瘤体积，称肿瘤质量，并计算抑瘤率。应用免疫组化法和蛋白免疫印迹法（Western blot）检测辣椒碱治疗后各组肿瘤组织中高迁移率族蛋白B1（HMGB1）和Toll样受体4（TLR4）蛋白表达水平。结果：与模型组比较，辣椒碱低、中、高剂量（5，10，20 mg·kg^-1）组裸鼠体质量无明显变化，但肿瘤体积显著缩小（P<0.01），肿瘤质量显著减小（P<0.01），抑瘤率显著增大（P<0.01），且呈剂量依赖性；与模型组比较，辣椒碱低、中、高剂量（5，10，20 mg·kg^-1）组肿瘤组织HMGB1和TLR4蛋白表达明显降低，且呈剂量依赖性。结论：辣椒碱对乳腺癌MDA-MB-231细胞裸鼠移植瘤生长具有明显的抑制作用，其机制可能与下调HMGB1和TLR4蛋白表达有关。

Inhibitory Effect of Capsaicin on Growth of Breast Cancer MDA-MB-231 Cells Transplanted Tumor in Nude Mice

Objective: To investigate the inhibitory effect of capsaicin on the growth of breast cancer MDA-MB-231 cells transplanted tumour in nude mice and its possible molecular mechanism. Method: Transplanted tumor model of breast cancer MDA-MB-231 cells in nude mice were established. Then the tumor-bearing mice were randomly divided into 4 groups:model group, and low, medium and high-dose capsaicin groups (5, 10, 20 mg·kg^-1). Mice of low, medium and high-dose capsaicin groups (5, 10, 20 mg·kg^-1) were intraperitoneally injected with the corresponding dose of capsaicin, and the model group was injected with the same volume of phosphate buffer saline (PBS), once every 3 days, for a total of 8 times in succession. Body weight of mice and transplantation tumor volume were measured before each injection of capsaicin. Mice of each group were put to death 24 h after the last administration, and then the tumor volume, mass and the tumor inhibitory rate were calculated. The protein expression levels of high mobility group box 1 (HMGB1) and Toll-like receptors 4(TLR4) were measured by immunohistochemistry and Western blot. Result: No significant difference was observed between each group in body weight. However, compared with the model group, capsaicin (5, 10, 20 mg·kg^-1) remarkably inhibited the tumor volume and mass (P<0.05,P<0.01), and increased the tumor inhibitory rate (P<0.01) in a dose-dependent manner. Capsaicin (5, 10, 20 mg·kg^-1) also markedly inhibited the protein expression levels of HMGB1 and TLR4 (P<0.01). Conclusion: Capsaicin remarkably inhibits the growth of breast cancer MDA-MB-231 cells transplanted tumour in nude mice, and the possible mechanism may be related to the down-regulation of HMGB1 and TLR4 at the protein level.