林蕤+顾卫+黄慧

[摘要]目的 探讨特异乳酸杆菌（Lb-f）对人直肠癌裸鼠异种移植瘤模型癌细胞增殖的抑制作用。方法 采用小鼠背部皮下接种人直肠癌系（Colo320）细胞的方法建立裸鼠异种移植瘤模型，并随机分为五组，Ⅰ组作为模型对照组；Ⅱ～Ⅳ组分别以180、360、720 mg/kg的Lb-f灌胃，1次/d，灌胃2周。Ⅴ组腹腔注射化疗剂环磷酰胺100 mg/kg，1次/d，共计2周。利用MTT比色法和台盼蓝计数法测定各组的细胞增殖相对抑制率及生长抑制率，并取肿瘤组织，计算瘤重抑制率以及肿瘤生长抑制率，采用ELISA试剂盒测定Bax、Bcl-2、Caspase-3含量。结果 随着干预时间的延长，Colo 320瘤块体积有明显变化（P<0.01），且在开始的48 h内，体积增大不明显，48 h之后，体积增大情况较为明显。体外实验结果显示，各组的细胞增殖相对抑制率和生长抑制率比较，差异有统计学意义（P<0.01）；空白对照组和溶媒对照组的细胞增殖相对抑制率和生长抑制率比较，差异无统计学意义；其他组均较前两组高，且阳性药对照组为最高，其次是Lb-f 90组、Lb-f 60组、Lb-f 30组，各组之间的差异均有统计学意义（P<0.01或P<0.05）。在体实验结果显示，各组的细胞瘤重抑制率、肿瘤生长抑制率、肿瘤组织Bax含量、Bcl-2含量、Bcl-2/Bax、Caspase-3比较，差异有统计学意义（P<0.01或P<0.05）；细胞瘤重抑制率、肿瘤生长抑制率、肿瘤组织Bax含量按顺序由低到高分别是Ⅰ组、Ⅱ组、Ⅲ组、Ⅳ组、Ⅴ组，Bcl-2含量、Bcl-2/Bax、Caspase-3按顺序由低到高分别是Ⅴ组、Ⅳ组、Ⅲ组、Ⅱ组、Ⅰ组。结论 Lb-f可调节Bcl-2/Bax平衡，从而起到抑制肿瘤生长的作用，且呈剂量依赖性。

[关键词]直肠癌；裸鼠；异种移植瘤；特异乳酸菌

[中图分类号] R735.3+7 [文献标识码] A [文章编号] 1674-4721（2016）07（b）-0007-04

[Abstract]Oobjective To explore the inhibiting effect of Lactobacillus fermentum （Lb-f） to cancer cells proliferation of human colorectal cancer in nude mouse of xenograft tumor models.Methods The xenograft tumor models of human colorectal cancer in nude mouse were prepared by back subcutaneous injecting Colo320 in mice，and all the models were randomly divided into 5 group，Group Ⅰ was the control group，Group Ⅱ-Ⅳ were gavaged with Lb-f of 180，360，720 mg/kg respectively，one time every day for two weeks，and Group Ⅴ was given intraperitoneal chemotherapy cyclophosphamide of 100 mg/kg，one time every day for two weeks.Cell proliferation inhibition rate and growth inhibition rate among each group were detected using MTT colorimetry and trypan blue counting method.Further more，tumor tissues were extracted to calculate tumor inhibition rate and growth inhibition rate，and the content of Bax，Bcl-2，Caspase-3 was detected by ELISA kit.Results With the extension of intervention time，the volume of Colo320 tumor block was significantly changed （P<0.01），and in the beginning of 48 hours，the volume increase was not obvious，after 48 hours，the volume increase was more obvious.In vitro experimental results showed that the relative cell proliferation inhibition rate and the growth inhibition rate in each group was compared，and the difference was statistically significant （P<0.01）.There was no statistical difference between the blank control group and the solvent control group，and the other groups were all higher than that the control group and the solvent group，in which the positive control group was the highest，followed by Lb-f 90 group，Lb–f 60 group，Lb-f 30 group，the difference between erery group was statistically significant （P<0.01 or P<0.05）.In vivo experiment results showed that there was significant difference in the cell tumor inhibition rate，tumor growth inhibition rate，tumor tissue Bax content，Bcl-2 content，Bcl-2/Bax，Caspase-3 between every group （P<0.01 or P<0.05）.The tumor inhibition rate，tumor growth inhibition rate，tumor tissue Bax content in order from low to high respectively was groupⅠ，Ⅱ，Ⅲ，Ⅳ，Ⅴ，and the Bcl-2 level，the Bcl-2/Bax，Caspase-3 in order from low to high respectively was groupⅤ，Ⅳ，Ⅲ，Ⅱ，Ⅰ.Conclusion Lb-f is able to adjust colorectal antiapoptotic/apoptosis factors （Bcl-2 / Bax） balance，which contributes to the inhibiting of tumor growth，and inhibitory effect was dose-dependent.

[Key words]Colorectal cancer；Nude mice；Xenograft tumor；Lactobacillus fermentum

直肠癌（carcinoma of rectum）是消化道最常见的恶性肿瘤之一，由于位置低，易被直肠指诊及乙状结肠镜诊断[1-3]。本病具有位置深入盆腔、解剖关系复杂、手术不易彻底、术后复发率高等特点和难点，近年来发病率逐年增高，且青年人发病率有升高的趋势。目前，临床主要采用手术、放化疗以及免疫治疗等综合治疗手段进行治疗，常用的化疗药物存在选择性低、疗效欠佳、毒性较大和易产生耐药性等缺点[4-5]，因此寻找选择性较高、对正常细胞毒性较低的药物已经成为新的发展方向。特异乳酸杆菌（Lactobacillus fermentum，Lb-f）是乳酸杆菌中的一种，有文献表明其对机体有免疫调节作用，这可能与其治疗某些疾病存在相关性，而且Lb-f对人结肠癌存在抑制功能。本研究根据人直肠癌裸鼠异种移植瘤模型治疗实验对Lb-f抗人直肠癌的作用进行评价，得到了一些有效数据和结论。……