RESUMEN
BACKGROUND: Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a multifunctional Ig-like cell adhesion molecule that has a wide range of biological functions. According to previous reports, serum CEACAM1 is dysregulated in different malignant tumours and associated with tumour progression. However, the serum CEACAM1 expression in non-small-cell lung carcinomas (NSCLC) is unclear. The different expression ratio of CEACAM1-S and CEACAM1-L isoform has seldom been investigated in NSCLC. This research is intended to study the serum CEACAM1 and the ratio of CEACAM1-S/L isoforms in NSCLC. METHODS: The expression of the serum CEACAM1 was determined by enzyme-linked immunosorbent assay. The protein expression and the location of CEACAM1 in tumours were observed by immunohistochemical staining. The CEACAM1 mRNA levels in tumour and normal adjacent tissues were measured using quantitative real-time PCR, and the expression patterns and the rate of CEACAM1-S and CEACAM1-L were analysed by reverse transcription-PCR. RESULTS: Serum CEACAM1 levels were significantly higher in NSCLC patients compared with that from normal healthy controls (P <0.0001). 17 patients (81%) among 21 showed high expression of CEACAM1 by immunohistochemical staining. Although no significant differences were found between tumour and normal tissues on mRNA expression levels of CEACAM1 (P >0.05), the CEACAM1-S and the CEACAM1-S/L (S: L) ratios were significantly higher in tumour than normal tissues (P <0.05). CONCLUSIONS: Our data indicated that the serum levels of CEACAM1 could discriminate lung cancer patients from health donors and that CEACAM1 might be a useful marker in early diagnosis of NSCLC. Moreover, our results showed that the expression patterns of CEACAM1 isoforms could be changed during oncogenesis, even when total CEACAM1 in tumour tissues did not show significant changes. Our study suggested that the expression ratios of CEACAM1-S/CEACAM1-L might be a better diagnostic indicator in NSCLC than the quantitative changes of CEACAM1.
Asunto(s)
Antígenos CD/biosíntesis , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Moléculas de Adhesión Celular/biosíntesis , Neoplasias Pulmonares/metabolismo , Adulto , Anciano , Antígenos CD/sangre , Área Bajo la Curva , Biomarcadores de Tumor/análisis , Biomarcadores de Tumor/sangre , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico , Moléculas de Adhesión Celular/sangre , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunohistoquímica , Neoplasias Pulmonares/diagnóstico , Masculino , Persona de Mediana Edad , Isoformas de Proteínas/biosíntesis , Isoformas de Proteínas/sangre , Curva ROC , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Ecto-ATP synthase has been considered to be an effective target for cancer recently. As inhibitors of ecto-ATP synthase were found to be cytotoxic for tumor cells, a monoclonal antibody (Mc178-Ab) against ecto-ATP synthase was generated in our previous study that exhibited both anti-angiogenic and anti-tumorigenic effects. However, the mechanism of action of Mc178-Ab and its downstream pathways for anti-tumor effects remain unclear. In this research, we intended to investigate the mechanism of the anti-tumor action of Mc178-Ab. The expressions of cell surface ATP synthase on A549 and CHO cells were confirmed by flow cytometry and confocal microscope. Proliferation and apoptosis were examined after the treatment with Mc178-Ab. In order to examine the activity of ecto-ATP synthase changed by Mc178-Ab, extracellular ATP generation and intracellular pH levels were assessed. The phosphorylation of the signaling molecules, MAPKase and Akt, was analyzed by western blot. Cell proliferation was blocked, and apoptosis was induced in A549 cells treated with Mc178-Ab, as determined by MTT assay and flow cytometry analysis of Annexin-V/PI staining separately. The intracellular pH level and extracellular ATP generation were also decreased after Mc178-Ab treatment. Finally, western blot data revealed that the phosphorylation of JNK and p38 was increased, while the phosphorylation of ERK and Akt was decreased in A549 cells treated with Mc178-Ab. Compared with A549 cells, Mc178-Ab had less effect on CHO cells. The decreased intracellular pH levels and the altered concentration of extracellular ATP may contribute to the mechanisms of the effect of Mc178-Ab on A549 and CHO cells. The results also suggested that the anti-tumor effect of Mc178-Ab was associated with MAPKase and Akt pathways.