Subcellular Fractionation and Metaproteogenomic Identification and Validation of Key Differentially Expressed Molecular Targets for Keloid Disease

Keloid disease (KD) is a common connective tissue disorder of unknown aetiopathogenesis with ill-defined treatment. Keloid scars present as exophytic fibroproliferative reticular lesions postcutaneous injury, and even though KD remains neoplastically benign, keloid lesions behave locally aggressive, invasive and expansive. To date, there is limited understanding and validation of biomarkers identified through combined proteomic and genomic evaluation of KD. Therefore, the aim in this study was to identify putative causative candidates in KD by performing a comprehensive proteomics analysis of subcellular fractions as well as the whole cell, coupled with transcriptomics data analysis of normal compared with KD fibroblasts. We then applied novel integrative bioinformatics analysis to demonstrate that NF-kB-p65 (RELA) from the cytosolic fraction and CAPN2 from the whole-cell lysate were statistically significantly upregulated in KD and associated with alterations in relevant key signaling pathways, including apoptosis. Our findings were further confirmed by showing upregulation of both RELA and CAPN2 in KD using flow cytometry and immunohistochemistry. Moreover, functional evaluation using real-time cell analysis and flow cytometry demonstrated that both omeprazole and dexamethasone inhibited the growth of KD fibroblasts by enhancing the rate of apoptosis. In conclusion, subcellular fractionation and metaproteogenomic analyses have identified, to our knowledge, 2 previously unreported biomarkers of significant relevance to keloid diagnostics and therapeutics.