Dottorato in FARMACOLOGIA E TOSSICOLOGIA

Titolo della tesi: Multifaceted roles of prokineticins and prokineticin receptors

More than two decades of research on the prokineticin system show that prokineticins (PKs) are involved in several physiological processes such as angiogenesis, neurogenesis, nociception, regulation of the circadian cycle, and reproduction by acting as angiogenic, anorectic and proinflammatory cytokines, hormones, and neuropeptides. Therefore, mutations, dysfunctions or dysregulations of PKs and their cognate receptors (PKRs) may be involved in various pathologies and trigger disease progression or promote their cure, depending on the pathological insults. After reviewing the current knowledge on the functions of the PK system in health and disease and evidencing the promising effects of PKR non-peptide ligands in various preclinical models, in the present thesis I have highlighted the multifaceted roles of PK2 and PKRs in diseases with a strong neuroinflammatory component as Parkinson’s disease (PD) and post-COVID-19 olfactory dysfunction (OD) as well as in acquired chemoresistance in cancer suggesting the potential of PK2 and PKRs as biomarkers and/or novel therapeutic targets in humans. We investigated the dynamics of PK2 pathway, at both the mRNA and protein levels, in olfactory neurons of PD patients at different disease stages and determined the relationship between PK2 upregulation and clinicopathological features of PD. In particular, the increase in PK2 levels in early disease stages and in accordance with the severity of motor symptoms and the accumulation of α-synuclein suggests that PK2 serves as both disease biomarker and novel therapeutic target for PD. Furthermore, overexpression of PK2 was also found in olfactory neurons from patients with post-COVID-19 OD compared to healthy controls. We hypothesised that PK2 is neuroprotective in PD, especially at the beginning of the disease course, and that it seems to support recovery of the sense of smell following post-COVID-19 OD. These data highlight for the first time the promising role of PKR agonists as a disease-modifying therapy in both PD and post-COVID-19 OD. In addition, we also examined the expression profile of Substance P (SP), a neurotransmitter whose role in PD and olfaction has been extensively described by previous studies, in olfactory neurons of PD and post-COVID-19 OD patients. We found a correlation between olfactory neuronal SP and gastrointestinal dysfunction in PD, confirming the reliability of olfactory neurons as a model to study PD progression. In post-COVID-19 OD, persistent activation of SP appears to maintain inflammation and contribute to olfactory impairment, counteracting the functions of PK2. Finally, we developed heterocellular spheroid models of human breast and lung cancer that resemble the in vivo tumour response to treatment, to investigate pathways of acquired resistance to Doxorubicin (Dox). We demonstrated that hypoxia-induced HIF-1α plays a role in mediating resistance. This occurs through the increase of CD73, an enzyme responsible for ATP hydrolysis into adenosine. Moreover, hypoxia-induced HIF-1α and the subsequently activation of CD73 promotes the release of PK2, which may be a biomarker for the development of resistance associated with Dox therapy. Despite the promising results here reported, a more detailed characterization of PK2 pathway dynamics in humans is needed to validate its clinical value.