Gene-expression profiling in desmoplastic small round cell tumors

The study provides evidence that DSRCTs are characterised by a high degree of plasticity governed by the MErT/hybrid-partial EMT/EMT process and that, within this three-way switching, the hybrid/partial and MErT classes are also enriched in stemness. The expression of miRNA-21 in all three classes indicates pluripotency as an additional trait of DSRCT cells. These findings are consistent with either the broad histological spectrum of DSRCTs or their poor response to treatments, including tailored treatments against AR-positive DSRCTs. The study also demonstrates that DSRCTs carry a PD-L1 signature corresponding to “immunological ignorance” and highlights the fact that this signature is closely histotype-related and immuno-context-dependent. Finally, the results show that ISLR/Meflin, a further marker of pluripotency, is co-expressed with PDGFRα in DSRCT cells, albeit at a low level and that, in line with the first report concerning PDGFRα, their expression correlates with desmoplasia. We interrogated the database of the Department of Pathology at our Institution and identified seven primary DSRCTs surgically removed after combined chemotherapy between 2000 and 2016. The study was approved by the Independent Ethics Committee of the Fondazione IRCCS Istituto Nazionale dei Tumori di Milano (INT-MI). All of the patients whose biological samples were included in the study gave their signed consent to donate the tissue remaining after the diagnostic procedure had been completed to INT-MI.