Giuseppe Ercolano

Background: Lung cancer (LC), including both non-small (NSCLC) and small (SCLC) subtypes, is currently treated with a combination of chemo- and immunotherapy. However, predictive biomarkers to identify high-risk patients are needed. Here, we explore the role of peripheral blood mononuclear cells (PBMCs) as a tool for novel biomarkers searching. Methods: We analyzed the expression of the cGAS-STING pathway, a key DNA sensor that activates during chemotherapy, in PBMCs from LC patients divided into best responders (BR), responders (R) and non-responders (NR). The PBMCs were whole exome sequenced (WES). Results: PBMCs from BR and R patients of LC cohorts showed the highest levels of STING (p < 0.0001) and CXCL10 (p < 0.0001). From WES, each subject had at least 1 germline/somatic alteration in a DDR gene and the presence of more DDR gene mutations correlated with clinical responses, suggesting novel biomarker implications. Thus, we tested the effect of the pharmacological DDR inhibitor (DDRi) in PBMCs and in three-dimensional spheroid co-culture of PBMCs and LC cell lines; we found that DDRi strongly increased cGAS-STING expression and tumor infiltration ability of immune cells in NR and R patients. Furthermore, we performed FACS analysis of PBMCs derived from LC patients from the BR, R and NR cohorts and we found that cytotoxic T cell subpopulations displayed the highest STING expression. Conclusions: cGAS-STING signaling activation in PBMCs may be a novel potential predictive biomarker for the response to immunotherapy and high levels are correlated with a better response to treatment along with an overall increased antitumor immune injury.

Marine compounds represent a varied source of new drugs with potential anticancer effects. Among these, sponges, including those belonging to the Irciniidae family, have been demonstrated to exert cytotoxic effects on different human cancer cells. Here, we investigated, for the first time, the therapeutic effect of an extract (referred as iSP) from the sponge, Ircinia ramosa (Porifera, Dictyoceratida, and Irciniidae), on A375 human melanoma cells. We found that iSP impaired A375 melanoma cells proliferation, induced cell death through caspase-dependent apoptosis and arrested cells in the G1 phase of the cell cycle, as demonstrated via both flow cytometry and qPCR analysis. The proapoptotic effect of iSP is associated with increased ROS production and mitochondrial modulation, as observed by using DCF-DHA and mitochondrial probes. In addition, we performed wound healing, invasion and clonogenic assays and found that iSP was able to restrain A375 migration, invasion and clonogenicity. Importantly, we observed that an iSP treatment modulated the expression of the EMT-associated epithelial markers, E-CAD and N-CAD, unveiling the mechanism underlying the effect of iSP in modulating A375 migration and invasion. Collectively, this study provides the first evidence to support the role of Ircinia ramosa sponge extracts as a potential therapeutic resource for the treatment of human melanoma.