Objective To develop a specific trans-splicing intron ribozyme type Ⅰ-mediated dual reporter gene system (Rib53-Fluc-tk) for targeting CEA.Methods The novel CEA-targeting trans-splicing ribozyme with the downstream reporter system (Rib53-Fluc-tk) was constructed by genetic engineering technology.The trans-splicing reaction product was evaluated using the 131I-5-iodo-2'-fluro-l-beta-D-arabinofuranosy-luracil (FIAU) cellular uptake rates and the bioluminescence.Two-sample t test,the analysis of variance and the least significant difference (LSD) t test was performed for data analysis.Results The sequence of Rib53-Fluc-tk was proved by gene-sequencing test.Human MCF-7 breast cancer cells showed a high ratio of firefly luciferase/renilla luciferase (0.64±0.10,n =4).A 520 bp band of product existed,which matched with the predicted size using RNA from cells transfected with Rib53-Fluc-tk in MCF-7.Signals were detected by bioluminescence in human embryonic kidney 293T cells co-transfected with Rib53-Fluc-tk and pCDNA3.1-CEA.The labelling rate of 131I-FIAU was (64.02±4.79)％ (n =3).The radiochemical purity was (95.96± 1.07)％ (n=3),and the stability of the radiocompound remained high in human serum at least for 24 h.The uptake of 131I-FIAU in 293T cells transfected with Rib53-Fluc-tk was (0.31±0.01)％ (n=4),while it increased with the incubation time in 293T cells co-transfected with pCDNA3.1-CEA and Rib53-Fluc-tk and reached (1.40±0.06)％ at 4.5 h (F=1 007.29,t=136.34,both P＜0.01).Conelusions A novel and specific reporter gene in the cellular level was established.Taking advantage of trans-splicing reaction of the ribozyme,it could improve the specificity of the reporter gene imaging.

Objective    To explore the diagnostic value of circulating tumor cells (CTC) measured by magnetic nanoparticle method in lung cancer. Methods    (1) We measured binding capability of A549 or NCI-H1965 cell lines with recognition peptide and capture efficiency by adding tumor cells into the whole blood of healthy human. (2) We measured CTC of 34 patients suspected with lung cancer, and the counting results of CTC were compared with the following pathological results. Results    (1) The binding capability was 80.0%±6.0% for A549 and 70.1%±4.8% for H1957, while the capture efficiency was 57.3%±7.0% for A549 and 37.3%±6.1% for H1975. (2) CTCs were identified in 71.9% of patients with lung cancer. The specificity was 83.3%, and area under receiver operating characteristic (ROC) curve was 0.792 (P=0.003). Conclusion    CTC measured by magnetic nanoparticle method has promising application in the diagnosis of lung cancer.