Biology subjects

Tiriac, H.

Publications and source records attributed to Tiriac, H..

3 recordsLinked to original sources

bioRxiv2022

Glutamine mimicry suppresses tumor progression through asparagine metabolism in pancreatic ductal adenocarcinoma

In pancreatic ductal adenocarcinoma (PDAC), glutamine is a critical nutrient that drives a wide array of metabolic and biosynthetic processes that support tumor growth. Despite this established dependency, the targeting of specific enzymes involved in glutamine metabolism is yet to yield any clinical benefit. Here, we have examined the therapeutic potential of 6-diazo-5-oxo-L-norleucine (DON), a glutamine antagonist that broadly inhibits glutamine metabolism. We found that DON treatment significantly blocks PDAC tumor growth and attenuates metastasis. Interestingly, we link the effectiveness of DON in PDAC to asparagine (Asn) metabolism. By inhibiting asparagine synthetase (ASNS), DON significantly reduces intracellular Asn production and Asn supplementation rescues the anti-proliferative effects of DON. We discern that PDAC cells upregulate expression of ASNS as a metabolic adaptation and that modulating ASNS levels can impact DON efficacy. Strikingly, in patient-derived organoids, DON responsiveness is inversely correlated with ASNS expression, a feature that is not observed for other metabolic enzymes targeted by DON. We find that treatment with L-asparaginase (ASNase), an enzyme that catabolizes free Asn, synergizes with DON to impact the viability of PDAC cells. Finally, we identify that a combination therapy of DON and ASNase has a significant impact on metastasis. These results shed light on the mechanisms that drive the effects of glutamine mimicry and point to the utility of co-targeting adaptive responses to control PDAC progression.

cancer biology↗

bioRxiv2022

Treatment of pancreatic cancer with irreversible electroporation and intratumoral CD40 antibody stimulates systemic immune responses that inhibit liver metastasis in an orthotopic model.

BackgroundPancreatic cancer (PC) has a poor prognosis, and most patients present with either locally advanced or distant metastatic disease. Irreversible Electroporation (IRE) is a non-thermal method of ablation used clinically in locally advanced PC, but most patients eventually develop distant recurrence. We have previously shown that IRE alone is capable of generating protective, neoantigen-specific immunity. Here we aim to generate meaningful therapeutic immune effects by combining IRE with local (intratumoral) delivery of a CD40 agonistic antibody (CD40Ab). MethodsKPC46 organoids were generated from a tumor-bearing male KrasLSL-G12D-p53LSL-R172H-Pdx-1-Cre (KPC) mouse. Orthotopic tumors were established in the pancreatic tail of B6/129 F1J mice via laparotomy. Mice were randomized to treatment with either sham laparotomy, IRE alone, CD40Ab alone, or IRE followed immediately by CD40Ab injection. Metastatic disease and immune infiltration in the liver were analyzed 14 days post-procedure using flow cytometry and multiplex immunofluorescence imaging with spatial analysis. Candidate neoantigens were identified by mutanome profiling of tumor tissue for ex vivo functional analyses. ResultsThe combination of IRE+CD40Ab improved median survival to greater than 35 days, significantly longer than IRE (21 days) or CD40Ab (24 days) alone (p<0.01). CD40Ab decreased metastatic disease burden, with less disease in the combination group than in the sham group or IRE alone. Immunohistochemistry of liver metastases revealed a more than two-fold higher infiltration of CD8+ T-cells in the IRE+CD40Ab group than in any other group (p<0.01). Multiplex immunofluorescence imaging revealed a 4-6-fold increase in the density of CD80+CD11c+ activated dendritic cells (p<0.05), which were spatially distributed throughout the tumor unlike the sham group, where they were restricted to the periphery. In contrast, CD4+FoxP3+ T-regulatory cells (p<0.05) and Ly6G+ MDSCs (P<0.01) were reduced and restricted to the tumor periphery in the IRE+CD40Ab group. T-cells from the IRE+CD40Ab group recognized significantly more peptides representing candidate neoantigens than did T-cells from the IRE or untreated control groups. ConclusionsIRE can induce local tumor regression and neoantigen-specific immune responses. Addition of CD40Ab to IRE improved dendritic cell activation and neoantigen recognition, while generating a strong systemic anti-tumor T-cell response that inhibited metastatic disease progression. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/510847v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1a42713org.highwire.dtl.DTLVardef@16be8org.highwire.dtl.DTLVardef@15362eaorg.highwire.dtl.DTLVardef@182f988_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

The autophagy initiating kinase ULK1 is required for pancreatic cancer cell growth and survival

Amongst cancer subtypes, pancreatic ductal adenocarcinoma (PDA) has been demonstrated to be most sensitive to autophagy inhibition, which may be due to unique metabolic rewiring in these cells. The serine/threonine kinase ULK1 forms the catalytic center of a complex mediating the first biochemical step of autophagy. ULK1 directly recieves signals from mTORC1 and AMPK to trigger autophagy under stress and nutrient poor conditions. Studies in genetic engineered mouse models of cancer have revealed that deletion of core downstream autophagy genes (ATG5, ATG7) at the time of tumor iniation leads to a profound block in tumor progression leading to the development of autophagy inhibitors as cancer therapeutics. However, most preclinical studies and all clinical studies have relied on non-specific lysomotropic agents such as chloroquine and its derivatives, whose toxicity and off-target issues preclude further clinical development and which do not represent the impact of solely biochemically disrupting the autophagy pathway. Furthermore, druggable targets in the core autophagy pathway are quite limited, with ULK1 and ULK2 representing the only protein kinases in the pathway. Here we explore the genetic requirement for ULK1 and ULK2 in human PDA cancer cell lines and xenografts, and take advantage of new small molecule ULK1 inhibitors to demonstrate that ULK inhibition can overcome autophagy induction triggered by PDA therapeutics including chemotherapy and MEK inhibition. Finally we show that ULK inhibitors increase MHC Class I in PDA cells, suggestion a potential therapeutic avenue for such agents in combination with checkpoint immunotherapy.

cancer biology↗