Leader: Rosamaria Lappano (UNICAL); Other collaborator(s):
We plan to better understand the molecular mechanisms (membrane and cytoplasmic effectors) through which SASP components including cytokines, chemokines and growth factors, drive cellular senescence. Biological responses triggered by SASP components will be explored in epithelial cells, endothelial cells and macrophages. The multifaceted paracrine liaison among the aforementioned cellular components of the tissue environment toward senescence will be investigated.
Brief description of the activities and of the intermediate results: We have characterized: i) the activity carried out by the receptor for advanced glycation terminal factors (RAGE), as a pro-inflammatory molecule involved in various physiological and pathological processes, including cellular senescence; ii) the transcriptional and phenotypic profile of cells stably silenced (through genome editing with CRSPR/CAS9 technology) for the G protein-coupled membrane estrogen receptor (GPER), known for its involvement in the regulation of inflammatory processes. An important inducer of SASP and cellular senescence is DNA damage caused by chemotherapy. Considering that senescence in non‐transformed cells can lead to toxicity as well as resistance to chemotherapeutics, we’re currently investigating the SASP profile that characterizes senescent endothelial and stromal cells exposed to diverse cyclin-dependent kinases 4 and 6 inhibitors. The results obtained will allow to clarify whether the patient response to these therapeutics can be improved by manipulating cellular senescence and SASP.
Brief description of the activities and of the intermediate results: Given that the SASP (Senescence-Associated Secretory Phenotype) of senescent cells initially inhibits tumor progression but may have deleterious effects in the long-term including acquired therapeutic resistance, we are investigating the SASP profile of endothelial cells (HUVECs) induced by cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors in tumor cells and components of the tumor microenvironment (TME). To this end, we first evaluated the senescence-associated (SA)-β-galactosidase activity and performed viability assays in HUVECs exposed to CDK4/6 inhibitors. Thereafter, in order to corroborate these findings, we performed a telomere-shortening assay in collaboration with Dr. Andreassi's research group (IFC-CNR) on HUVECs treated with CDK4/6 inhibitors. Similar experiments are currently being conducted on fibroblasts (WI38).
Brief description of the activities and of the intermediate results: On the basis of our previous results on the capability of cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors to induce senescence in endothelial cells (HUVEC), we combined transcriptomic and proteomics approaches, followed by bioinformatics analyses, toward a deep comprehension of the molecular alterations occurring in CDK4/6 inhibitors-induced senescence. Ongoing experiments aim to determine whether the CDK4/6 inhibitor-treated HUVECs medium may create a pro-tumorigenic environment, potentially influencing cancer cells and other TME components, such as cancer-associated fibroblasts, towards the development of novel strategies targeting SASP. Particular attention will be focused on elucidating the shared and distinct mechanisms of action among the three CDK4/6 inhibitors abemaciclib, palbociclib and ribociclib.
Brief description of the activities and of the intermediate results: Further analyzing the transcriptomic and proteomic data obtained from RNAsequencing and proteomic studies performed in endothelial cells in which cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors have induced senescence, we found that the three molecules tested can regulate a different senescence-associated expression profile. In particular, bioinformatics analyses revealed that all the CDK4/6 inhibitors prompted a similar marked senescence profile, as revealed by the up-regulation of genes linked to senescence, like those implicated in the regulation of lysosomal activity and extracellular matrix functions. Notably, palbociclib and ribociclib share the ability to stimulate the expression of pro-inflammatory molecules, specifically belonging to the cytokines and TGF-β transduction pathways. While abemaciclib did not show the same property to stimulate some genes belonging to the cytokine transduction pathways, it surprisingly demonstrated the ability to up-regulate the expression of a main pro-inflammatory molecule, as TGF-β, at both mRNA and protein levels. A deep comprehension of the molecular characteristics of the SASP triggered by each inhibitor may provide novel insights into their potential to create a pro-inflammatory milieu affecting cancer progression as well as may offer new targets for therapeutic combination strategies involving SASP inhibition.
Brief description of the activities and of the intermediate results: Transcriptomic and proteomic analyses of endothelial cells treated with CDK4/6 inhibitors, followed by bioinformatics analyses, revealed that among the senescence-associated genes regulated by palbociclib, ribociclib and abemaciclib, TGF-β2 is one of the most induced. Previous studies have ascertained that TGF-β2 may play a dual role in cellular senescence: it contributes to senescence induction by promoting cell cycle arrest through the up-regulation of CDK inhibitors such as p15 and p21; additionally, TGF-β2 is a key component of the senescence-associated secretory phenotype (SASP), influencing extracellular matrix remodeling and modulating the inflammatory microenvironment, with context-dependent effects on tumor suppression or progression. On these bases, we are exploring whether TGF-β2 signaling may have an impact on the promotion of a pro-inflammatory and tumorigenic cellular microenvironment. Simultaneously, the molecular mechanisms underlying TGF-β2 regulation and signaling cascade triggered by CDK4/6 inhibitors in senescent endothelial cells are under investigation.