Detecting Receptor Tyrosine Kinase ROR1 Using a Developed Anti-ROR1 Polyclonal Antibody

Receptor tyrosine kinase ROR1 has been introduced as an interesting prognostic cancer marker in histopathology. The aim of this study was to produce a polyclonal antibody (PAb) against recombinant human ROR1 protein to be used as a tool for investigation of ROR1 expression in human cancer tissue blocks. The extracellular part of human ROR1 recombinant protein was expressed using pET-28b(+) plasmid in Escherichia coli Bl21(DE3) host. The recombinant ROR1, as a candidate immunogen, was purified and injected to a New Zealand rabbit. Followed by raising the titration of antibody, polyclonal anti-ROR1 antibody was purified through affinity chromatography column. After determining the purity of PAb anti-ROR1, its specific reactivity was assessed through various assessments. Flow cytometry analysis showed that PAb anti-ROR1 specifically recognizes ROR1 molecule in a number of positive and negative cell lines. Results obtained from detection of ROR1 in paraffin-embedded breast adenocarcinoma tissue blocks (n = 11) also demonstrated that PAb anti-ROR1 can effectively be used in immunohistochemistry. In conclusion, the developed anti-ROR1 PAb can be used as a tool for determining the prognostic value of ROR1 in histopathology of cancer tissues.

Antibody response to HER2 extracellular domain and subdomains in mouse following DNA immunization

Human epidermal growth factor receptor 2 (HER2) is overexpressed in 15-20 % of breast cancer patients and is an appropriate target for immunotherapy in these patients. Monoclonal antibodies (mAbs) specific to HER2 are currently applied to treat breast cancer patients with HER2 overexpression. Active immunization with HER2 DNA or protein has been considered as a suitable alternative. The aim of this study is to evaluate anti-HER2 antibody response in serum of mice immunized with DNA constructs containing full extracellular domain (fECD) or subdomains of human HER2. Four extracellular subdomains and also fECD of HER2 were cloned into pCMV6-Neo vector. Different groups of Balb/C mice were immunized with HER2 DNA constructs and boosted with HER2 recombinant protein. The anti-HER2 antibody was subsequently determined by ELISA, flow cytometry, and immunohistochemistry. Anti-HER2 antibody was detected only in serum of mice immunized with fECD DNA. None of HER2 extracellular subdomains induced appreciable levels of anti-HER2 antibody. However, boosting with fECD or extracellular subdomain III (DIII) recombinant protein resulted in enhanced anti-HER2 fECD as well as anti-HER2 subdomain antibody responses. In this regard, almost all (99 %) of HER2-overexpressing BT474 cells could be detected by serum antibody from mice immunized with HER2 subdomain DNA and boosted with recombinant HER2 protein by flow cytometry. Similarly, serum of mice immunized with DIII DNA construct and boosted with recombinant DIII protein could also recognize these cells, but to a lesser extent (50 %). Our findings suggest that combination of HER2 DNA and protein immunization could effectively induce anti-HER2 antibody response in Balb/C mice.