Transcriptional Analysis Reveals Evidence of Chronically Impeded ECM Turnover and Epithelium-to-Mesenchyme Transition in Scar Tissue Giving Rise to Marjolin’s Ulcer

Abstract

Marjolin's ulcer (MU) is an aggressive malignancy arising within chronic wounds. A major cause is unhealed burn injuries. This results in well-differentiated squamous cell carcinoma (SCC). This study aimed to elucidate transcriptional changes leading to malignancy by investigating differentially expressed genes in squamous cells present in a SCC compared with MU. MU tumor cells were isolated from histologically confirmed biopsy of SCC within an unhealed burn scar. Epithelial cells (ECs) adjacent to the tumor were co-isolated and a SCC cell line was commercially purchased. mRNA from all three samples was isolated and its expression was quantified using RNASeq. A threshold of log2fold change >2-fold in either direction was considered "differentially expressed." Gene expression analysis revealed distinct differences in gene expression in MU cells compared with EC (665 genes), EC and SCC (1673 genes). Enrichment analysis confirmed that pathways most affected included 1) elevation of genes associated with extracellular matrix organization/degradation, 2) activation of DNA damage, and 3) activation of cytokine signaling. Our analysis revealed two key insights about chronic wound microenvironment conducive to ulceration. First, in EC vs. MU comparison, downregulation of Collagen and Matrix metalloproteinase families suggests chronically impaired extracellular matrix turnover giving rise to a fibrotic microenvironment. Second, in SCC vs. MU comparison, dysregulation of cadherin-mediated cell-cell adhesions is suggestive of epithelial-to-mesenchymal transitions, similar to those during development. Acquisition of epithelial-to-mesenchymal transition may underlie the high metastatic rate in MU tumors. Taken together, this sheds light on mechanisms that underlie the divergent clinical features of these cutaneous cancers.

Epidermolysis Bullosa-Associated Squamous Cell Carcinoma: From Pathogenesis to Therapeutic Perspectives

“…Of note, MU-SCCs are more aggressive than skin SCCs of different etiology, and metastasize in more than 27% of cases [13]. Though a number of theories have been proposed to explain the relation between skin damage and MU development [13], a common denominator is the complex series of events determined by the derailed/prolonged wound healing process at the lesional area [14,15]. Indeed, the aberrant activation of wound healing pathways is a relevant, well-known event able to establish an inflamed, fibrotic stroma which represents the scaffold for tumor initiation and progression [14,16].…”

Marjolin’s ulcer in chronic wounds – review of available literature

“…The loss of epithelial function (inhibition of claudins, cadherin proteins) with a concomitant increase in the mesenchymal markers (fibronectin, vimentin, laminin-4) was also observed. Clear differences in gene expression in squamous cancer cells (SCC) and Marjolin’s ulcers compared to physiological cells confirm the genetic diversity of these histologically similar neoplasms [ 16 ]. No specific factor has been identified.…”

Distribution pattern of invasion‑related bio‑markers in head Marjolin's ulcer

“…In the present, we disclosed the expression levels of several different invasion-associated biomarkers were assessed at different sites of MU, including cell adhesion-associated molecules, TME-associated molecules and certain molecules which involved in invasion-associated cell signaling pathways (8). Sinha et al reported that acquisition of epithelial-to-mesenchymal transition (EMT) may underlie the high metastatic rate in MU tumors (15). The abnormal expression of cell adhesion molecules is in accordance with the invasion of SCC, including claudin-1, E-cadherin and desmoglein (DSG), which represents the tumor progression ability (16).…”