| Colorectal cancer(CRC)is the third cause of cancer deaths in the world.This disease continues to carry high cancer-related mortality.At present,surgical treatment is the most common method used and adjuvant-based chemotherapy with fluoropyrimidines is recommended after surgical treatment due to a demonstrated improved overall survival rate of 20% to 33% after 5 years.However,cytostatic agents and ionising radiation used in cancer therapy exert strong damaging effects on normal tissues and induce a complex response at the cellular level.Targeting drug offers tantalizing opportunities for therapeutic intervention for the treatment of human diseases.Cholecystokinin(CCK)is a peptide hormone which mediates its actions regulating secretion of digestive enzymes via two G-protein coupled receptors,CCKAR and CCKBR,respectively active in the central nervous system and peripheral organs.Among them,the cholecystokinin type B/gastrin receptor(CCKBR)has been shown to be widespread expressed in CRC and been reported to be involved in human tumorigensis playing a important role in tumor cell proliferation[a].However,the correlation of expression levels of CCKBR with clinicopathological parameters of CRC was not very clear.Previous studies reported that rCCK8PE38,a novel recombinant protein drug,could target CCKBR and produce specific cytotoxic activity againist HCT-116 cells with over-expressed CCKBR in CRC.And an in vivo antitumor activity experiment showed rCCK8PE38 can efficiently inhibit tumor size.At present,we are working on the production process and preclinical study of rCCK8PE38 recombinant toxin.The selection of targeted cases for colorectal cancer or the establishment of a target diagnosis method should be established before entering the clinical study.Since rCCK8PE38 is a target toxin for CCKBR,we used fluorescence quantitative PCR and Western-blot to establish molecular diagnostic methods for CCKBR at the gene level and protein level,respectively.The cell killing assay was used to verify the relationship between the expression of CCKBR and the killing activity of rCCK8PE38Cell-level results showed that CCKBR was highly expressed in multiple CRC cell lines and gastric cancer cell lines,and the results of gene and protein levels were basically the same.rCCK8PE38 targeted recombinant toxin specifically could target colorectal cancer cell lines with high expression of CCKBR,however,it is not sensitive to gastric cancer cell lines with high expression of CCKBR.By correlating the expression level with the cell line background,CCKBR expression levels may be related to gender,P53 levels,and keratin levels.Although the number of experiments at the cell level does not completely replace the actual sample analysis from sample size to reflect type,the results provide an indication of the direction of clinical analysis.The screening method of rCCK8PE38 was verified and optimized through case specimen detection.Clinical case results show that the positive rate of CCKBR in the cancer tissues of 70 cases of CRC patients is approximately 48.2%,and CCKBR overexpression is likely to occur in male,mucinous and CRC cases with P53 levels higher than 70%.Both the cellular level and the primary isolation of the tissue can be demonstrated that rCCK8PE38 can effectively target CCKBR-positive CRC cells and produce a significant killing effect.In addition,analysis of rCCK8PE38 plasma minimally invasive diagnostic methods,the results show that the detection of plasma than tissue detection sensitivity is low,but the positive accuracy is high,can become an auxiliary diagnostic tool for tissue detection..In conclusion,the rCCK8PE38-targeting toxin specifically binds to and kills CCKBR-expressing colon cancer tumor cells and tissues.The suitable case screening of the target toxin can be performed by analyzing the sex of the CRC patients,histological classification of cancer and P53 histochemical screening,and combined with plasma detection to jointly diagnose the applicable cases of rCCK8PE38. |
PDF Full Text Request