Targeting PSAT1 to mitigate metastasis in tumors with p53-72Pro variant

The single-nucleotide polymorphism(SNP)of p53,in particular the codon 72 variants,has recently been implicated as a critical regulator in tumor progression.However,the underlying mechanism remains elusive.Here we found that cancer cells carrying codon 72-Pro variant of p53 showed impaired metastatic potential upon serine supplementation.Proteome-wide mapping of p53-interacting proteins uncovered a specific interaction of the codon 72 proline variant(but not p5372R)with phosphoserine aminotransferase 1(PSAT1).Interestingly,p53^(72P)-PSAT1 interaction resulted in dissociation of peroxisome proliferator-activated receptor-γcoactivator 1α(PGC-1α)that otherwise bound to p53^(72P),leading to subsequent nuclear translocation of PGC-1αand activation of oxidative phosphorylation(OXPHOS)and tricarboxylic acid(TCA)cycle.Depletion of PSAT1 restored p53^(72P)-PGC-1αinteraction and impeded the OXPHOS and TCA function,resulting in mitochondrial dysfunction and metastasis suppression.Notably,pharmacological targeting the PSAT1-p53^(72P)interaction by aminooxyacetic acid(AOA)crippled the growth of liver cancer cells carrying the p53^(72P)variant in both in vitro and patient-derived xenograft models.Moreover,AOA plus regorafenib,an FDA-proved drug for hepatocellular carcinoma and colorectal cancer,achieved a better anti-tumor effect on tumors carrying the p53^(72P)variant.Therefore,our findings identified a gain of function of the p53^(72P)variant on mitochondrial function and provided a promising precision strategy to treat tumors vulnerable to p53^(72P)-PSAT1 perturbation.

Repurposing econazole as a pharmacological autophagy inhibitor to treat pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma(PDAC)is characterized by the highest mortality among carcinomas.The pathogenesis of PDAC requires elevated autophagy,inhibition of which using hydroxychloroquine has shown promise.However,current realization is impeded by its suboptimal use and unpredictable toxicity.Attempts to identify novel autophagy-modulating agents from already approved drugs offer a rapid and accessible approach.Here,using a patient-derived organoid model,we performed a comparative analysis of therapeutic responses among various antimalarial/fungal/parasitic/viral agents,through which econazole(ECON),an antifungal compound,emerged as the top candidate.Further testing in cell-line and xenograft models of PDAC validated this activity,which occurred as a direct consequence of dysfunctional autophagy.More specifically,ECON boosted autophagy initiation but blocked lysosome biogenesis.RNA sequencing analysis revealed that this autophagic induction was largely attributed to the altered expression of activation transcription factor 3(ATF3).Increased nuclear import of ATF3 and its transcriptional repression of inhibitor of differentiation-1(ID-1)led to inactivation of the AKT/mammalian target of rapamycin(m TOR)pathway,thus giving rise to autophagosome accumulation in PDAC cells.The magnitude of the increase in autophagosomes was sufficient to elicit ER stress-mediated apoptosis.Furthermore,ECON,as an autophagy inhibitor,exhibited synergistic effects with trametinib on PDAC.This study provides direct preclinical and experimental evidence for the therapeutic efficacy of ECON in PDAC treatment and reveals a mechanism whereby ECON inhibits PDAC growth.