| Objective:Cancer is a serious threat to human health. Early diagnosis and radical surgery are the keys to avoid metastasis, prolong survival time and improve the five years survival rate of patients. Regular screening high-risk groups is an important guarantee to achieve early diagnosis of the patients. The effective serological screening methods of lung cancer and colorectal cancer is lack currently, then explore of early screening method in lung cancer and colorectal cancer are particularly important.Methods:(1) From 22 selected individual phage clones, clones with higher reactivity with 30 cases of lung cancer sera were selected by ELISA reaction, and their diagnosis capacity were validated by 90 cases of lung cancer serum and 90 cases control serum. A group of serum markers to early screening lung cancer patients were established. A displayed peptide was matched with protein OLFM1, whose expression was analysed by immunohistochemical method. (2) To construct Chinese CRC phage display peptide library and screen molecular markers can be used for early detect CRC. A total of 30 tissues of CRC were used to build T7 phage display peptide library. With protein-A/G agarose beads the CRC specific peptides were enriched by 5 rounds affinity antibody screening.2000 phage clones randomly picked. CRC associated clones were screening using ELISA method, which had different reactivity with the mixture of CRC patients sera and the mixture of sera of controls. CRC associated clones were screened again using ELISA method, which could distinguish the 30 CRC patients'sera and 30 controls'sera. Finally, the 60 CRC patients'sera and 60 controls'sera applied to verify the screening ability of these CRC associated clones. Meanwhile, the clones were analysis by genetic sequence, and blasted into genes and proteins. The genes function mined by Bioinformatics as Chilibot. A blasted protein were analysed by immunohistochemistry in a CRC tissue microarray for verifing the diagnostic significance of the protein.Results:(1) Six phage clones were found with higher reactivity with lung cancer sera, and formed a panel to detected lung cancer patients. The detection ability was analysed by logistic regression, and the area under the curve of ROC (AUC) was up to 0.956, which also could achieve 0.888 for early stage lung cancer patients. The blasted protein OLFM1 was highly expressed in lung adenocarcinoma cells. (2) The titer of CRC phage display peptide library was 3.0×106pfu, the recombinant rate was 60%, and the storage capacity was 1.8 x 106pfu by PCR identification. A total of 19 phage clones were screened by sera pools of CRC patients and the controls. After sequencing and bibliographic search,12 clones were associated with tumorigenesis, and 7 with unknown function. (3) Five CRC associated clones were screened due to distinguish serum of CRC patient from serum of control. The area under the ROC curve (AUC) of logistic regression analysis the five phages combination was up to 0.981, and it could achieve 0.962 in independent verification group. (4) By immunohistochemistry COX6B1 protein was higher expressed in rectum adenocarcinoma cells compared with paired adjacent normal tissues, which mainly located in cytoplasm and cell membrane.Conclusion:(1) In this study, a panel was established which can be used for early screenning lung cancer patients. OLFM1 protein was found as an over-expressed antigen in lung adenocarcioma, which in is not expressed in other types of lung cancer tissue and paired normal lung tissue.(2) Colorectal cancer phage display peptide library based on Han people was constructed and a panel was established which may be used for early screenning colorectal cance patients. The higher expression of protein COX6B1 may be closely related to the occurrence of CRC.
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