[Establishment of a malignant pleural effusion mouse model with Lewis lung carcinoma cell lines expressing enhanced green fluorescent protein].

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.