Research Margarida Florindo Espadinha

Abstract

Dipeptidyl-peptidase 9 (DPP9) is a proline-selective serine protease that belongs to the peptidase S9 family. During recent years, DPP9 inhibition has shown to cause pyroptosis, selectively in acute myeloid leukemia cells. Pyroptosis is a lytic form of programmed cell death, that has mainly been observed in immune cells. The process typically recruits and activates other immune cells and inflammatory mediators, causing a localized activation of the innate immune system. This is particularly appealing for leukemia treatment, because the immune-response to leukemic cells is typically severely subdued. Recent mechanistic insight suggests that native DPP9 suppresses pyroptosis through a stabilizing protein-protein interaction (PPI) with the NLRP1 inflammasome sensor. Furthermore, DPP9 inhibition with small molecules only has a mildly destabilizing effect on the [DPP9-NLRP1] PPI. This proposal suggests the targeted clearance of DPP9 from the cytoplasm in acute myeloid leukemia cells to cause pyroptosis through enhanced NLRP1 activation. PROTACs and AUTACs are heterobifunctional molecules that mediate the degradation of a protein of interest (POI) by hijacking cell's own proteasome and autophagic system, respectively. The implementation of PROTAC and AUTAC technologies for targeted clearance of DPP9 and consequent pyroptosis induction in acute myeloid leukemia cell lines is proposed in this project. PROTAC and AUTAC molecules will be designed and synthesized, followed by in vitro evaluation of their cell permeability, DPP9-engagement, DPP9 clearance potency and selectivity, and dose/time dependence of DPP9 clearance. Furthermore, a comparison of the pyroptosissignatures of PROTACs, AUTACs and DPP9 inhibitors will be performed. Overall, this proposal can provide a superior therapeutic strategy to AML and other cancer types.

Researcher(s)

• Promoter: Van Der Veken Pieter
• Co-promoter: Martinet Wim
• Fellow: Florindo Espadinha Margarida

Research team(s)

• Medicinal Chemistry (UAMC)

Project type(s)

• Research Project

Abstract

Dipeptidyl-peptidase 9 (DPP9) is a post-proline cleaving serine protease. It occurs in the cytosol of many different cell types. Lately, the enzyme captured the attention of immunology and oncology researchers, after it was shown that DPP9 inhibition causes a pro-inflammatory type of cell death (pyroptosis), selectively in myeloid leukemia cells. Pyroptosis is a lytic form of programmed cell death, that has mainly been observed in immune cells. The process typically recruits and activates other immune cells and inflammatory mediators, causing a localized activation of the innate immune system. This is particularly appealing for leukemia treatment, because the immune-response to leukemic cells is typically severely subdued. As an illustration, highly promising results of DPP9 inhibition were shown in animal models of Acute Myeloid Leukemia (AML). Furthermore, pyroptosis capability has been demonstrated recently in many other cancer cell types, offering opportunities to also study DPP9-mediated pyroptosis in other domains of oncology. Recent mechanistic insight on the enzyme's role in pyroptosis suggests that native DPP9 suppresses pyroptosis through a stabilizing protein-protein interaction (PPI) with the NLRP1 inflammasome sensor. Conversely, inhibition of DPP9 by small molecules was shown to disrupt the [DPP9-NLRP1] complex, setting off NLRP1 activation. This leads to caspase-1 activation, cytokine maturation and pyroptosis. Of note, this finding supports the main hypothesis of this proposal, namely: targeted clearance of DPP9 from the cytoplasm causes pyroptosis in Acute Myeloid Leukemia cells through enhanced NLRP1 activation. Furthermore, DPP9 clearance could be particularly efficient at pyroptosis induction compared to DPP9 inhibition: the latter only has a mildly destabilizing effect on the [DPP9-NLRP1] PPI according to current insights.

Researcher(s)

• Promoter: Van Der Veken Pieter
• Fellow: Florindo Espadinha Margarida

Research team(s)

• Medicinal Chemistry (UAMC)

Project type(s)

• Research Project