Endocrine Abstracts

Anaplastic thyroid cancer (ATC) is the most aggressive and lethal form of thyroid cancer. ATC rarely develop as ex-novo lesions, but rather evolves from pre-existing well-differentiated thyroid cancer (DTC) through a de-differentiation process that leads cells to acquire an aggressive phenotype. ATC are refractory to radiotherapy, having lost the expression of Sodium-Iodine Symporter, and often also to standard chemotherapy. Moreover, debulking surgery is frequently difficult, thus these patients remain with no effective therapeutic options. Drug Repurposing aims to discover new clinical indications for existing drugs. The application of this approach may represent an alternative and efficient strategy to identify ready-to-use new treatments for rare diseases, such as ATC. We hypothesized that re-programming the ATC cells toward a more differentiated phenotype should mitigate aggressiveness and restore sensitivity to standard therapies, thus we applied a systematic drug repurposing approach based on gene expression. To overcome the rarity of ATCs samples, we collected data from 7 public GEO patient sample datasets and analyzed them to identify a differential Gene Expression Signature (dGES) describing the transition DTC-ATC. Gene Ontology analysis highlighted that Up-regulated genes were enriched in cell migration, motility and mitotic-related processes, while Down-regulated genes were enriched mainly in thyroid hormone generation, cell-cell junctions and adhesion. These observations confirmed the validity of our analysis. Then, this dGES was used to query the Connectivity Map, a database of gene expression signatures induced by hundreds of compounds. To identify a list of drugs virtually able to induce a signature opposite to our query, thus to revert the DTC-ATC transition, we retrieved small molecules with a connectivity score <-90. This score was re-calculated to consider the weight of the most represented Perturbagen Classes, then compounds were re-ranked. The obtained 69 compounds were prioritized through manually curated data mining. 8 candidates emerged and undergo an in-vitro screening, in three different ATC cell lines. Due to early toxicity, 2 molecules were excluded and for the remaining 6 IC50 were calculated, and proliferation/cytotoxicity assays were performed. The results excluded 3 other compounds, and another one was excluded since it had no effects on cell morphology. The 2 remaining drugs, a CDKi and an AURKi, will be further assessed for their biological effects on ATC cells, alone and in combination with standard chemotherapeutics. Results will allow us to identify a drug, able to restrain ATC aggressiveness and refractory, which is also already used in clinical practice, thus providing an effective ready-to-use therapeutic option.