Applications of novel monoclonal antibodies specific for Ciz1 in evaluating its levels in cancer tissues and plasma from lung cancer patients

Backgrounds: Cip1-interacting zinc-finger protein1 (Ciz1) is a nuclear matrix-associated DNA replication factor which has been found to be overexpressed in several types of cancers. Ciz1 is also negatively correlated with the prognosis of patients with colorectal cancer. However, the relationship between Ciz1 and prognosis of lung cancer patients remains elusive. This study was designated to examine Ciz1 expression pattern and its potential as a biomarker of prognosis in lung cancer. Methods: We generated monoclonal antibodies (mAbs) against Ciz1 using hybridoma fusion technology. With one mAb, we detected the levels of Ciz1 in lung cancer cell lines as well as tissues and plasma from lung cancer patients by Western blot. In addition, we examined Ciz1 levels in the human lung adenocarcinoma tissue microarray by immunohistochemical staining. We also investigated the prognostic value of Ciz1 in lung cancer by Kaplan-Meier method. Results: Six mAbs against Ciz1 were generated. Ciz1 protein levels in plasma from lung cancer patients were found to be higher than those from benign patients (P = 0.0016). Ciz1 was also highly expressed in lung adenocarcinoma compared with its corresponding adjacent tissues (P = 0.0017). Importantly, high expression of Ciz1 was negatively correlated with the prognosis of lung adenocarcinoma patients (P = 0.0298), which was further confirmed by network database analysis. Conclusion: Our results suggested that Ciz1 may be involved in lung cancer progression and could be utilized as a novel prognostic factor for lung adenocarcinoma patients.