Introduction:Non-melanoma skin tumours are the most frequent cancers in humans. Specifically two main types, basal cell carcinomas (BCC) and cutaneous squamous cell carcinomas (cSCC). Both types are originated in the epidermis and are very invasive, infiltrating easily in the surrounding dermis. The surgical excision is the main treatment for these cancers, but in many cases, the most infiltrates show recurrences. Intriguingly, infiltrate and recurrent cSCCs can develop metastasis but BCCs very rarely metastasize. The secreted factors and proteins from cancer cells present in Tumour Interstitial Fluid (TIF) are key elements in the regulation of the invasive and metastatic responses. However, for non-melanoma skin tumours little is known about TIF.
Objectives: To characterize and compare the TIF from BCC and cSCC tumours, as well as from normal skin (NS); and to determine,from the differences among them, possible biomarkers and therapeutic targets related to the invasive and metastatic issues.
Methods: We compared the two most used methods, elution and centrifugation, in pieces of the same biopsy samples of cSCC to analysis the protein profile expression of TIF. First, we established for the centrifugation method the 10000g to obtain TIF from cSCC. Secondly, we compared the centrifugation with the elution method in pieces of three different cSCC tumors.
Results: We found that the mean protein intensities based in the number of peptide spectrum matches was significantly higher in the centrifuged samples than in the eluted samples. Regarding the robustness of the methods, we observed higher overlapping between both methods (77-80%) than among samples (50%). These results suggest that exists an elevated consistence of TIF composition independently of the method used. However, we observed a three-fold increase of extracellular proteins in non-overlapped proteome obtained by centrifugation.
Conclusions: The centrifugation is the method of choice to study the proteome of TIF.