Apolipoprotein E expression promotes lung adenocarcinoma proliferation and migration and as a potential survival marker in lung cancer

Many human lung cancer cell lines express apolipoprotein E (ApoE), especially cells derived from malignant pleural effusions (MPE) in patients with lung adenocarcinoma. This study aimed to investigate the influence of ApoE expression on lung cancer. In lung cancer tissues, ApoE expression was more frequently found in malignant pleural effusions (MPE)-associated lung adenocarcinoma than in lung adenocarcinoma or squamous cell carcinoma without MPE (P< 0.05), indicating that ApoE is associated with the pathogenesis of MPE in patients with lung adenocarcinoma. Next, we examined the roles of ApoE in an MPE-derived lung adenocarcinoma cell line that endogenously over-expresses ApoE, PC14PE6/AS2 (AS2). In that experiment we inhibited ApoE expression by transfection of a plasmid carrying ApoE siRNAs into AS2 cells to generate AS-S2 and AS-S3 cells. Compared to vector-control cells and parental AS2 cells, AS2-S2 and AS2-S3 cells grew slower (P< 0.05), were more sensitive to cisplatin, and had significantly impaired cellular migration (P< 0.05). Furthermore, over-expression of ApoE was independently associated with poor survival in lung adenocarcinoma patients who had MPE at the time of diagnosis (P< 0.001). Conclusively, ApoE over-expression promotes cancer proliferation and migration and contributes to an aggressive clinical course in patients with lung adenocarcinoma and MPE.