Sialic acid differential expression in non-melanoma skin cancer biopsies

Altered sialylation has been observed during oncogenic transformation and has been implicated in tumor progression and metastases. This pattern may aid the biological behavior of many tumors. Skin cancer is the most common cancer worldwide and their diagnosis becomes difficult, in some cases, due to variety of factors that affect the accuracy of the nowadays exams, such as huge spectrum of tumors and their variants. So, this study investigates the changes in expression and distribution of α2,3 and α2,6-linked sialic acid in non-melanomas skin cancer to identify the sialylation pattern which may be useful in the differential diagnosis of this tumor. Lectin histochemistry was used to examine the expression and distribution of sialic acid in different types of non-melanoma skin cancers. We applied Maackia amurensis lectin, which interacts with α2,3-linked sialic acid and Sambucus nigra lectin specific for α2,6-linked sialic acid. The histochemical analysis showed that α2,3 and α2,6-linked sialic acid vary their expression according with the tumor type analyzed. The distribution of α2,3-linked sialic was differentially expressed in between basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) (p < 0.0001), BCC and actinic keratosis (p = 0.0033) and BCC and keratoacanthoma (p < 0.0001). In the case of α2,6-linked sialic acid its expression was also different between BCC and SCC (p < 0.0001), BCC and actinic keratosis (p = 0.0002) and BCC and keratoacanthoma (p < 0.0362). Lectin histochemistry showed a different expression of both sialic acid linkages types between pre-malign and malign tumors and between malign tumors. Although preliminary, these findings are promising for the development of diagnostic techniques to help in the differential diagnosis of non-melanoma skin tumors using lectin histochemistry as an auxiliary tool.