20.500.12556/RUL-179010 In vitro proučevanje pomena proteasoma v trombocitih in njegove vloge pri oblikovanju tumorskega mikrookolja Elucidating the significance of platelet proteasome function and its role in shaping the tumour microenvironment in vitro Trombociti imajo ključno vlogo pri regulaciji hemostaze, a so danes prepoznani tudi kot aktivni regulatorji imunosti, vnetja in napredovanja tumorjev. Kljub njihovim številnim biološkim vlogam pa ostajajo molekularni mehanizmi, ki uravnavajo aktivacijo trombocitov in njihovo sekretorno vedenje, pomanjkljivo opredeljeni. Nedavne raziskave so pokazale, da trombociti vsebujejo tako konstitutivni proteasom kot tudi imunoproteasom, ki ju običajno povezujemo predvsem z jedrnimi in imunskimi celicami. Ta doktorska disertacija preučuje, kako ti proteolitični sistemi oblikujejo biologijo trombocitov in vplivajo na trombocitno posredovane imunske in tumorske interakcije. Klinično pomembnost delovanja proteasoma v trombocitih smo definirali s kvantifikacijo trombocitopenije pri bolnikih z diseminiranim plazmocitomom, zdravljenih z zaviralci proteasoma. Zaviranje proteasoma je pomembno povečalo pojavnost trombocitopenije, pri čemer je bilo tveganje odvisno od uporabljenega zaviralca in njegovega odmerka. V okviru mehanističnih raziskav smo zato okarakterizirali aktivnost proteasoma in imunoproteasoma v človeških trombocitih ter zaznali pomembne inter-individualne razlike v proteasomskih profilih, kar nakazuje, da sestava proteasoma prispeva k specifičnim razlikam med donorji v odzivnosti trombocitov. Za razliko od jedrnih celic trombociti ob izpostavitvi vnetnim citokinom ne povišajo proteinskega nivoja katalitičnih podenot imunoproteasoma, kar nakazuje, da je njihova proteasomska sestava določena že med megakariopoezo. Selektivno zaviranje katalitičnih podenot okrepi izločanje gostih granul, a ne vpliva na proces agregacije, kar dokazuje, da imunoproteasom natančno uravnava sekretorne odzive trombocitov, ne da bi pri tem ogrozil njihovo osnovno hemostatsko funkcijo. Proteomske analize so pokazale spremenjeno izločanje proteinov iz trombocitov, povezanih s presnovnimi in mitohondrijskimi potmi, kar kaže na vlogo imunoproteasoma pri uravnavanju trombocitne bioenergetike in medcelične komunikacije. Selektivno zaviranje izbranih podenot proteasomov v trombocitih vodi v sproščanje dejavnikov, ki izrazito modulirajo vedenje celic raka dojk. Zlasti zaviranje podenote β1i sproži sekretorni profil, ki okrepi migracijo celic trojno negativnega raka dojk, poveča angiogeno signaliziranje ter zviša izražanje označevalcev značilnih za epitelijsko-mezenhimski prehod. Ti izsledki kažejo, da imunoproteasom trombocitov neposredno oblikuje tumorsko relevantne parakrine signale in lahko vpliva na metastatsko napredovanje. Platelets, traditionally recognized for their role in haemostasis, are now understood to actively regulate immune responses, inflammation, and tumour progression. Despite their broad functional repertoire, the molecular mechanisms governing platelet activation and secretion remain incompletely defined. Recent evidence has revealed that platelets contain both the constitutive proteasome and the immunoproteasome, proteolytic complexes previously thought to function primarily in nucleated immune cells. This dissertation investigates how these systems regulate platelet biology and influence platelet-driven immune and tumour interactions. The clinical relevance of platelet proteasome function was assessed through a meta-analysis of thrombocytopenia in multiple myeloma patients treated with proteasome inhibitors. Proteasome inhibition significantly increased thrombocytopenia incidence, with risk dependent on inhibitor type and dosage, underscoring the hematologic consequences of targeting proteasomal pathways. Mechanistic studies in human platelets revealed substantial interindividual variability in proteasome and immunoproteasome activity, suggesting that proteasomal composition contributes to donor-specific differences in platelet responsiveness. Unlike nucleated cells, platelets do not upregulate immunoproteasome subunits in response to inflammatory stimuli, indicating that their proteasomal profile is established during megakaryopoiesis. Selective inhibition of immunoproteasome catalytic subunits modulated platelet secretion in a subunit-specific manner, enhancing dense-granule release without impairing aggregation. Proteomic analysis of activated platelet supernatants demonstrated altered secretion of proteins linked to metabolic and mitochondrial pathways, implicating the immunoproteasome in the regulation of platelet bioenergetics and intercellular communication. Importantly, platelets with selectively inhibited immunoproteasome subunits released factors that markedly influenced breast cancer cell behaviour. Inhibition of the β1i subunit promoted migration of triple-negative breast cancer cells, increased angiogenic signalling, and induced markers associated with epithelial-mesenchymal transition. Collectively, this work establishes the platelet immunoproteasome as regulator of platelet secretion and signalling, with implications for immune regulation and tumour progression. degranulacija trombocitov imunoproteasom imunska regulacija metastaziranje proteasom rak dojke trombociti breast cancer immune regulation immunoproteasome metastasis platelets platelet degranulation proteasome true false false Slovenski jezik Angleški jezik Neznano 2026-02-03 09:20:04 2026-02-05 09:13:10 2026-03-23 14:25:12 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 2027-03-31 README.docx README.docx README 1 8DE1CDC2F4C3F569A07090E189858F9E ac7e2cbae2fda9676d64faeb65e182945cbaa138db00151bbb4d718a3fc34094 006c90d7-032d-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=227355 1_A_systematic_review_and_meta-analysis_of_carfilzomib-associated_thrombocytopenia_as_an_adverse_event_in_patients_with_MM.zip 1_A_systematic_review_and_meta-analysis_of_carfilzomib-associated_thrombocytopenia_as_an_adverse_event_in_patients_with_MM.zip 1 A systematic review and meta-analysis of carfilzomib-associated thrombocytopenia as an adverse event in patients with MM 1 69AEFD2602EFB30CEBDA2E77E684DA15 f6ea0ae203e975863ab1550b1f76f7d2708d77ad09917b1cd05bc61b3b54ceaa 79756f57-026c-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=227239 2_1_Catalytic_proteasome_subunits_are_heterogeneously_active_in_human_platelets_with_β1i_playing_a_role_in_signaling_and_granule_release.zip 2_1_Catalytic_proteasome_subunits_are_heterogeneously_active_in_human_platelets_with_β1i_playing_a_role_in_signaling_and_granule_release.zip 2 1 Catalytic proteasome subunits are heterogeneously active in human platelets with β1i playing a role in signaling and granule release 1 C586EEABC6213C9EBA9ABB9893E31A01 941920e506572da3789636bc1be9d1fa574cda94e91744c0065f448c78eb37a8 63312c91-026e-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=227240 2_2_Catalytic_proteasome_subunits_are_heterogeneously_active_in_human_platelets_with_β1i_playing_a_role_in_signaling_and_granule_release.zip 2_2_Catalytic_proteasome_subunits_are_heterogeneously_active_in_human_platelets_with_β1i_playing_a_role_in_signaling_and_granule_release.zip 2 2 Catalytic proteasome subunits are heterogeneously active in human platelets with β1i playing a role in signaling and granule release 1 7A30C024E5A8B83183A9684B63D92830 4541166ac4296bff5e99d4edb831b26c22027de8096ddaad53edf484ce9b88c9 e7e6278b-026f-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=227242 3_PAR-1-mediated_platelet_activation_alters_platelet_secretome_composition_and_influences_monocyte-macrophage_polarisation.zip 3_PAR-1-mediated_platelet_activation_alters_platelet_secretome_composition_and_influences_monocyte-macrophage_polarisation.zip 3 PAR-1-mediated platelet activation alters platelet secretome composition and influences monocyte-macrophage polarisation 1 E7C4433439C5EAC8C277E82CDDA5A354 b00f958453aff2f449e35d64ced80ce622dcb01c66901bbe0d5318044bc3070c 98abcce6-0270-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=227244 Fakulteta za farmacijo Poskus: Laboratorij 0 0 0