Tape Stripped Stratum Corneum Samples Prove to be Suitable for Comprehensive Proteomic Investigation of Actinic Keratosis

PURPOSE: Actinic keratoses (AK) are premalignant tumors that can be clinically difficult to differentiate from skin cancer. An easy, quick, and reliable noninvasive alternative to biopsy is needed to definitively confirm the clinical diagnoses. This study evaluates Tape Stripping (TS) of stratum corneum (SC) for noninvasive biomarker analysis of AK. METHOD: Lesional and nonlesional human SC samples are obtained by application of stripping tapes on the skin of five AK patients. Following sample preparation, protein digests are analyzed by LC-MS/MS. Bioinformatics analyses are performed using Funrich, Ingenuity Pathway Analysis (IPA), and Oncomine bioinformatics and analytical tools. RESULTS: Of the total 613 unique proteins identified, 477 overlap with proteins identified in the proteomic analysis of formalin-fixed and paraffin-embedded (FFPE) AK samples. Additionally, 32 proteins are significantly increased and four proteins decreased in AK samples compared to the normal skin (p < 0.05). In line with proteomic analysis of FFPE samples, IPA and Funrich analysis show that differentially abundant proteins in the TS AK samples are implicated in PI3K/AKT and EGF signaling pathways. These findings are confirmed at the transcript level. CONCLUSION: Tape stripped AK sample is suitable for biomarker analysis. The application of this technique further could revolutionize management of keratinocytic skin tumors by reducing the need for traditional invasive biopsy.