A novel HER2 protein identification methodology in breast cancer cells using Raman spectroscopy and Raman imaging: an analytical validation study

BackgroundConventional assays such as immunohistochemistry (IHC) and in situ hybridization (ISH) used in clinical procedures for quantification of the human epidermal growth factor receptor-2 (HER2) status in breast cancer have many limitations. Our results suggest that a new Raman method may improve specificity that will result in better patients selection for HER2 targeted therapy. In the current study, we have used HER2 expression in a broad range of breast cancer phenotypes to explore the potential utility of a novel immunodetection technique, using Raman spectroscopy and Raman imaging combined with artificial intelligence models. MethodsThe expression of HER2 protein in different cancer subtypes was evaluated using Raman methodology to test correlations with currently used quantitative protein analysis for a broad range of cancer subtypes based on the expression levels of estrogen and progesterone receptors (ER and PR), HER2, cytokeratins and claudins. In the current study, five breast cancer cell lines: MCF-10A, MCF-7, MDA-MB-231, HTB-30 (SK-BR-3) and AU-565 were tested. ResultsThe correlations between Raman method and conventional HER2 testing methodologies (IHC and ISH) have been tested. Raman measurements showed a strong linear correlation (p= 0.05, R2=0,9816) with IHC analysis in the studied breast cell lines: MCF-10A, MCF-7, MDA-MB- 231, HTB-30 (SK-BR-3) and AU-565 representing normal, non-tumorigenic epithelial cells, triple-positive breast carcinoma and triple-negative breast cancer cell lines. ConclusionsAnalytic testing of Raman spectroscopy and Raman imaging demonstrated that this method may offer advantages over currently used diagnostic methodologies. The broad range of HER2 expression on the surface of human breast normal and cancer cells from triple negative to triple positive cell lines were studied. Our data demonstrate that Raman based methods for HER2 quantitation of HER2 may offer significant progress in patient selection for HER2 targeted therapy over conventional HER2 identification. Further studies of HER2 determination by Raman methods with in vivo cells and ex vivo tissue are warranted.