Screening Of Tumor Mark For The Lung Cancer By Using Peptide Zs6

Objective To select a potential biomarker for early lung cancer diagnosis and targeted therapy by using the cancer specific bounded peptide ZS6 which had already been obtained from the laboratory. Methods the peptideZS6 and fluorescein isothiocyanate(FITC)-conjugated peptideZS6 were synthesized and purified. First, immunofluorescence assay was used to identify the specificity and affinity of peptideZS6^-FITC to lung cancer cells and human lung cancer tissue. The results showed that peptide ZS6^-FITC has high affinity with lung squamous carcinoma cell line NCI-H1299 and lung adenocarcinoma cell line A549, and low affinity with Human hepatoma cell line HPG-2 and Human colon cancer cell line HT-29, but almost no affinity with normal Human normal hepatoma cell line LO-2 and Human normal lung cell line WI-38. Meanwhile, the affiniy of peptideZS6-FITC with human lung cancer tissue was significantly higher than normal tissues. Then, tumor-bearing nude mice experiment was used to observe the distribution of peptideZS6-FITC in vivo. It suggest that peptide zs6 could bind specifically to lung tumor in vivo and there were no distribution in nude mice brain, heart, lung and other normal tissues. But the peptide ZS6^-FITC still can be found in the major metabolic organ, such as liver, kidney.In order to search the binding site of peptide zs6 with lung cancer, Biotin- conjugated peptide ZS6was synthesized and purified. Peptide ZS6Biotin was immobilized on ELISA plate which has coated with avidin. Then, peptide zs6 was panning with human lung cDNA library. After 4 rounds screening, several phage clones were picked and amplified. Plasmid of phage were extracted and amplified by PCR, then the PCR products were purified and sequenced. Bioinformatics analysis results revealed that the peptide-specific lung cancer antigens are.After amplification and purification, then identified those DNA sequences and analyzed with bioinformatics. Results: 18 phage clones were identified to the specific peptide ZS6 and the DNA sequence showed one of them was GSTA1 while the others were already known tumor related gene. Conclusion: A tumor biomarker selected from human lung cancer cDNA library provides a potential tool for early lung cancer diagnosis and therapy.