Insufficient antibody validation challenges oestrogen receptor beta research.

Area of Science:

• Endocrinology and Molecular Biology
• Cancer Research
• Immunohistochemistry and Antibody Validation

Background:

• The discovery of oestrogen receptor beta (ERβ/ESR2) offered potential for novel endocrine therapies, particularly in breast cancer, due to its homology with ERα (ESR1).
• Despite significant research over two decades, the therapeutic promise of ERβ has not been realized, prompting a re-evaluation of its expression and detection.

Purpose of the Study:

• To rigorously validate the specificity of commercially available anti-ERβ antibodies for reliable protein expression analysis.
• To profile the tissue expression pattern of ERβ protein in normal and malignant human tissues using a validated antibody.

Main Methods:

• Validation of 13 anti-ERβ antibodies using well-characterized controls and multiple validation techniques, including immunohistochemistry.
• Protein expression profiling of ERβ in 44 normal and 21 malignant human tissues using the single validated antibody (PPZ0506).
• Comparison of protein expression data with existing RNA-sequencing data.

Main Results:

• Only one monoclonal antibody (PPZ0506) demonstrated specific targeting of ERβ in immunohistochemistry.
• ERβ protein was detected in testis, ovary, lymphoid cells, granulosa cell tumors, and subsets of malignant melanoma and thyroid cancers.
• No ERβ protein expression was found in normal or cancerous human breast tissue, contradicting numerous previous studies.

Conclusions:

• The majority of anti-ERβ antibodies lack specificity, potentially leading to erroneous conclusions in previous research.
• Validated ERβ protein expression is restricted to specific tissues and tumor types, excluding the human breast.
• This study underscores the critical importance of rigorous antibody validation to ensure the accuracy of scientific findings in molecular biology and cancer research.