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Promising fusion protein design to target the U87 MG glioma cell line
Chen Jing1, Lin Yuan, Pan Xingguo
1Department of Cadre ward, The General Hospital of Chengdu Military Area, Chengdu, China. chenjing_cd@126.com
Abstract:
Gliomas, with a poor clinical course, account for 30% to 40% of all intracranial tumors. Immunotherapy with monoclonal antibodies has emerged as a promising area of investigation and recently it has been shown that antibodies utilize complementarity-determining regions (CDRs) of their variable domains to bind to antigens with high affinity and specificity. Here, we designed an antibody mimetic fused with diphtheria toxin to target the U87 MG glioma cell line. VHCDR1 and VLCDR3, together with 5 amino acid residues on both side of the CDRs, through a cognate framework region (VHFR2) yielded a mimetic of BT32/A6 (United States Patent number: 5639863). We fused the mimetic with the first 388 amino acid residues of diphtheria toxin and E. coli strain BL21 (ED3) was used to express the soluble immunotoxin DT-MG. The immunotoxin DT-MG alone did not kill Raji up to the maximal concentration tested (10-6M) in vitro. By contrast, concentrations ≥ 10-9M, of the fused DT-MG killed more than 95% of U-87 MG cells. It is suggested that the mimetic maintained the synergic interactions and high-affinity associated with the parent antibody. This construct holds promise for targeting specific cancer epitopes and may be useful when incorporated into diagnostic and therapeutic regimens.
Insights
Researchers developed a novel immunotoxin targeting glioma cells. This antibody mimetic fused with diphtheria toxin effectively killed U87 MG cells, showing promise for cancer therapy.
Area of Science:
- Oncology
- Biotechnology
- Immunology
Background:
- Gliomas are aggressive intracranial tumors accounting for 30-40% of all brain tumors.
- Monoclonal antibody immunotherapy is a promising cancer treatment strategy.
- Antibodies bind antigens via complementarity-determining regions (CDRs) in their variable domains.
Purpose of the Study:
- To design and express an antibody mimetic fused with diphtheria toxin.
- To target the U87 MG human glioblastoma-astrocytoma cell line.
- To evaluate the efficacy of the immunotoxin DT-MG against glioma cells.
Main Methods:
- An antibody mimetic was designed using VHCDR1 and VLCDR3 sequences from BT32/A6.
- The mimetic was fused with diphtheria toxin (residues 1-388).
- The immunotoxin DT-MG was expressed in E. coli BL21 (DE3) and tested in vitro.
Main Results:
- DT-MG demonstrated potent cytotoxicity against U87 MG cells at concentrations ≥ 10-9M, killing over 95%.
- DT-MG showed no significant toxicity against Raji cells at concentrations up to 10-6M.
- The mimetic likely retained the high-affinity binding of the parent antibody.
Conclusions:
- The novel immunotoxin DT-MG effectively targets and kills U87 MG glioma cells.
- This antibody mimetic-diphtheria toxin construct shows potential for cancer therapy.
- The targeted approach may be valuable for diagnostic and therapeutic regimens in oncology.
