Peroxynitrite modified DNA may be an antigenic trigger for antibodies in various cancers of gynecologic origin

Area of Science:

• Oncology
• Immunology
• Biochemistry

Background:

• Nitrosative stress, indicated by peroxynitrite (ONOO(-)) formation, is implicated in various diseases.
• Oxidative and nitrosative DNA damage can lead to the formation of neo-epitopes.
• Autoantibodies against modified DNA may serve as biomarkers in cancer.

Purpose of the Study:

• To investigate the role of peroxynitrite-damaged DNA (ONOO(-)-DNA) in inducing circulating antibodies in gynecologic cancers.
• To compare the binding specificity of ONOO(-)-DNA with DNA from cancer patients.
• To evaluate the potential of anti-ONOO(-)-DNA antibodies as probes for oxidative DNA damage in cancer.

Main Methods:

• Human placental DNA was modified with peroxynitrite (ONOO(-)) and characterized using spectroscopy and electrophoresis.
• Antibodies against ONOO(-)-DNA were generated in experimental animals.
• Enzyme-linked immunosorbent assay (ELISA) and band shift assays were used to assess antibody binding specificity and epitope recognition.

Main Results:

• Antibodies generated against ONOO(-)-DNA showed specific binding to the modified DNA.
• Competitive-inhibition ELISA revealed that cancer patient IgG significantly inhibited antibody binding to ONOO(-)-DNA, indicating epitope sharing.
• Neo-epitopes generated on DNA by ONOO(-) modification were recognized by cancer-associated IgG.

Conclusions:

• The study demonstrates the generation of neo-epitopes on DNA due to peroxynitrite modification.
• Epitope sharing exists between in-vitro ONOO(-)-DNA and DNA isolated from gynecologic cancer patients.
• These findings suggest a potential role for nitrosative stress and associated autoantibodies in gynecologic oncology.