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Updated: May 15, 2026
Gene Regulation and Targeted Therapy in Gastric Cancer Peritoneal Metastasis: Radiological Findings from Dual Energy CT and PET/CT
Published on: January 22, 2018
rG17PE38, a novel immunotoxin target to gastric cancer with overexpressed CCK-2R
Jie Song1, Honglin Ren, Yansong Li
1Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, PR China.
Background:
Gastrin/cholecystokinin subtype 2 receptor (CCK2R) is overexpressed in several types of tumors. Gastrin-17 (G17) peptide has a high affinity with CCK2R. These characters suggest that G17 may be useful for target cancer therapy.
Purpose:
Construct a new immunotoxin (IT) targeting of CCK2R overexpressed gastric cancer.
Methods:
Two ITs were generated using forward and reverse G17 peptides fused with PE38. To get a high yield, codon optimized gene and optimized fermentation parameters were used in large-scale protein expression. An immunoaffinity technique was introduced into pseudomonas exotoxin (PE)-derived IT purification procedure. G17 competition, GST pull-down and indirect immunoflourescence assays were carried out to confirm the interaction between rG17 and CCK2R. Then, several cytotoxic assays were carried out on 18 cell lines, and an in vivo antitumor activity experiment was tested in nude mice.
Results:
The rG17PE38 showed specific cytotoxicity on three gastric cancer cells, while G17PE38 did not. After optimization, the expression level reached about 40% in medium deprived of NaCl. Next, 15-27.5 mg of pure rG17PE38 per 1 L of cultures was obtained. Results of G17 competition, GST pull-down and indirect immunoflourescence assays demonstrated that rG17 have a specific interact with CCK2R. Purified rG17PE38 showed high cytotoxicity on gastric cancer cell lines with the IC50 value of 0.6-4 ng·mL(-1). Treatment of nude mice inoculated with BGC-823 tumor xenografts with rG17PE38 efficiently inhibited tumor size.
Conclusions And Discussion:
The present study demonstrates that reversed G17 could be used as target moiety of PE-derived IT and the rG17PE38 could be developed as a new immunotherapy agent. Codon optimized gene could increase the rG17PE38 expression level in E. coli and furthermore NaCl inhibits the rG17PE38 expression in large scale. Meanwhile, our present study inducts an immunoaffinity method in the IT purification procedure, which could purify the PE-derived ITs in native form.
Insights
A novel immunotoxin, rG17PE38, targeting gastrin-17 receptor (CCK2R) effectively eradicated gastric cancer cells and inhibited tumor growth. This reversed G17 peptide-based immunotoxin shows promise as a new immunotherapy agent.
Area of Science:
- Biochemistry
- Molecular Biology
- Immunology
Background:
- Gastrin/cholecystokinin subtype 2 receptor (CCK2R) is overexpressed in various tumors.
- Gastrin-17 (G17) peptide exhibits high affinity for CCK2R, suggesting its potential in targeted cancer therapy.
Purpose of the Study:
- To construct a novel immunotoxin (IT) specifically targeting CCK2R-overexpressed gastric cancer.
- To evaluate the efficacy of the constructed immunotoxin in vitro and in vivo.
Main Methods:
- Two immunotoxins were generated by fusing forward and reverse G17 peptides with PE38.
- Codon-optimized genes and fermentation parameters were employed for large-scale protein expression.
- Immunoaffinity techniques were utilized for purification of Pseudomonas exotoxin (PE)-derived ITs.
- Interaction and cytotoxicity assays were performed on 18 cell lines, along with in vivo antitumor experiments in nude mice.
Main Results:
- The rG17PE38 immunotoxin demonstrated specific cytotoxicity against three gastric cancer cell lines, unlike the G17PE38 construct.
- Optimized expression yielded approximately 40% rG17PE38 in NaCl-deprived medium, with 15-27.5 mg of pure protein obtained per liter of culture.
- G17 competition, GST pull-down, and immunofluorescence assays confirmed the specific interaction of rG17 with CCK2R.
- rG17PE38 exhibited potent cytotoxicity against gastric cancer cell lines (IC50: 0.6-4 ng·mL⁻¹).
- In vivo studies showed efficient inhibition of tumor xenograft growth (BGC-823) in nude mice treated with rG17PE38.
Conclusions:
- Reversed G17 peptide can serve as a targeting moiety for PE-derived immunotoxins, with rG17PE38 emerging as a potential immunotherapy agent.
- Codon optimization enhances rG17PE38 expression in E. coli, while NaCl inhibits large-scale production.
- An immunoaffinity method was successfully applied for purifying PE-derived immunotoxins in their native form.
