Background and objective: Malignant pleural effusion (MPE) is a poor prognosis factor in patients with advanced lung cancer. The aim of this study is to establish a mouse model of MPE using Lewis lung carcinoma (LLC) cell lines expressing enhanced green fluorescent protein (EGFP).
Methods: The mouse model was created by injecting LLC-EGFP cells directly into the pleural cavity of mice that were sacrificed periodically. The dynamic growth and metastasis of tumor cells were screened using in vivo fluorescence imaging. The remaining mice were subjected to transverse computed tomography (CT) imaging periodically to analyze the formation rate of pleural effusion. The survival rate and tumor metastasis were also observed. Pleural fluid was gently aspirated using a 1 mL syringe and its volume was measured. When two or more mice bore pleural effusion at the same time, we calculated the average volume. The correlation of pleural effusion with the integrated optical density (IOD) were analyzed.
Results: Four days after the inoculation of LLC-EGFP cells, green fluorescence was observed by opening the chest wall. The tumor formation rate was 100%, and the IOD gradually increased after inoculation. The metastasis sites were mediastinal, and the hilar lymph nodes were contralateral pleural as well as pericardial. The metastasis rates were 87%, 73% and 20%, respectively. The CT scan revealed that the formation rates of pleural effusion on days 7, 14 and 21 were 13%, 46% and 53%, respectively. The average volume of pleural effusion increased obviously on day 10 and peaked on day 16 with a value of 0.5 mL. The mean survival time of nude mice was 28.8 days. The volume of pleural effusion and IOD were significantly correlated (r=0.91, P<0.000,1).
Conclusions: A mouse model of lung cancer malignant pleural effusion was successfully established by injecting LLC lines expressing EGFP into the pleural cavity under a microscope. The model can enable dynamic observations of the biological behavior of tumor cells in the pleural cavity. It might be helpful for basic research on advanced lung cancer as well as anti-tumor drug development.
背景与目的: 恶性胸腔积液是晚期肺癌预后差的因素之一。本研究拟用Lewis肺癌细胞构建裸鼠恶性胸腔积液模型，从而建立一个良好的动物实验研究平台。
方法: 经胸膜腔接种表达增强型绿色荧光蛋白的Lewis肺癌细胞，建立裸鼠恶性胸腔积液模型。定期解剖小鼠，经小动物活体荧光成像系统观察肿瘤的生长。剩余小鼠定期行胸部CT检查，计算各时间点的成胸水率，并观察建模后裸鼠的生存期和肿瘤转移情况。所有小鼠在解剖时发现有胸水，抽取并计量，同一时间点内获得多份胸水标本，计算其平均体积。利用相关性检验分析胸水体积与肿瘤积分光密度之间的相关性。
结果: 接种后第4天，荧光体视镜下可发现胸膜上有绿色荧光，成瘤率100%。随接种时间延长，肿瘤体积逐渐增加，肿瘤侵及纵隔和肺门淋巴结、对侧胸膜、心包，转移率分别为87%、73%和20%。第7天、第14天和第21天成胸水率分别为13%、46%和53%。小鼠平均生存时间为28.8天，所有胸水均为血性，胸水平均体积在第10天以后逐渐增加，第16天达到峰值（0.5 mL）。胸水体积与积分光密度之间具有相关性（r=0.91, P < 0.000, 1）。
结论: 本研究将表达增强型绿色荧光蛋白的肺癌细胞在显微镜下经胸膜腔接种成功建立肺癌恶性胸腔积液模型，有助于动态观察肿瘤细胞在胸腔内的生物学行为，该模型可应用于肺癌的基础研究及抗肿瘤药物开发。