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Chembiochem : a European Journal of... Apr 2020N-Nitroso-containing natural products are bioactive metabolites with antibacterial and anticancer properties. In particular, compounds containing the diazeniumdiolate...
N-Nitroso-containing natural products are bioactive metabolites with antibacterial and anticancer properties. In particular, compounds containing the diazeniumdiolate (N-nitrosohydroxylamine) group display a wide range of bioactivities ranging from cytotoxicity to metal chelation. Despite the importance of this structural motif, knowledge of its biosynthesis is limited. Herein we describe the discovery of a biosynthetic gene cluster in Streptomyces alanosinicus ATCC 15710 responsible for producing the diazeniumdiolate natural product l-alanosine. Gene disruption and stable isotope feeding experiments identified essential biosynthetic genes and revealed the source of the N-nitroso group. Additional biochemical characterization of the biosynthetic enzymes revealed that the non-proteinogenic amino acid l-2,3-diaminopropionic acid (l-Dap) is synthesized and loaded onto a free-standing peptidyl carrier protein (PCP) domain in l-alanosine biosynthesis, which we propose may be a mechanism of handling unstable intermediates generated en route to the diazeniumdiolate. These discoveries will facilitate efforts to determine the biochemistry of diazeniumdiolate formation.
Topics: Alanine; Azo Compounds; Bacterial Proteins; Biosynthetic Pathways; Molecular Structure; Multigene Family; Streptomyces
PubMed: 31643127
DOI: 10.1002/cbic.201900565 -
Oncotarget Mar 2023Homozygous deletion of upregulates synthesis of purine (DNSP) and increases the proliferation of neoplastic cells. This increases the sensitivity of breast cancer...
INTRODUCTION
Homozygous deletion of upregulates synthesis of purine (DNSP) and increases the proliferation of neoplastic cells. This increases the sensitivity of breast cancer cells to DNSP inhibitors such as methotrexate, L-alanosine and pemetrexed.
MATERIALS AND METHODS
7,301 cases of MBC underwent hybrid-capture based comprehensive genomic profiling (CGP). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. Tumor cell PD-L1 expression was determined by IHC (Dako 22C3).
RESULTS
208 (2.84%) of MBC featured loss. loss patients were younger ( = 0.002) and were more frequently ER- (30% vs. 50%; < 0.0001), triple negative (TNBC) (47% vs. 27%; < 0.0001) and less frequently HER2+ (2% vs. 8%; = 0.0001) than intact MBC. Lobular histology and mutations were more frequent in intact (14%) than loss MBC ( < 0.0001). (100%) and (97%) loss (9p21 co-deletion) were significantly associated with loss ( < 0.0001). Likely associated with the increased TNBC cases, BRCA1 mutation was also more frequent in loss MBC (10% vs. 4%; < 0.0001). As for immune checkpoint inhibitors biomarkers, higher TMB >20 mut/Mb levels in the intact MBC ( < 0.0001) and higher PD-L1 low expression (1-49% TPS) in the loss ( = 0.002) were observed.
CONCLUSIONS
loss in MBC has distinct clinical features with genomic alterations (GA) affecting both targeted and immunotherapies. Further efforts are necessary to identify alternative means of targeting PRMT5 and MTA2 in -ve cancers to benefit from the high-MTA environment of -deficient cancers.
Topics: Humans; B7-H1 Antigen; Homozygote; Triple Negative Breast Neoplasms; Sequence Deletion; Purine-Nucleoside Phosphorylase; Genomics; Histone Deacetylases; Repressor Proteins; Protein-Arginine N-Methyltransferases
PubMed: 36913304
DOI: 10.18632/oncotarget.28376 -
Biomedicines Mar 2022Glioblastoma (GBM) is a lethal brain cancer exhibiting high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work shows that...
Glioblastoma (GBM) is a lethal brain cancer exhibiting high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work shows that homozygous deletion, a genetic alteration occurring in about half of all GBMs, promotes stemness in GBM cells. Exploiting MTAP loss-conferred deficiency in purine salvage, we demonstrate that purine blockade via treatment with L-Alanosine (ALA), an inhibitor of de novo purine synthesis, attenuates stemness of -deficient GBM cells. This ALA-induced reduction in stemness is mediated in part by compromised mitochondrial function, highlighted by ALA-induced elimination of mitochondrial spare respiratory capacity. Notably, these effects of ALA are apparent even when the treatment was transient and with a low dose. Finally, in agreement with diminished stemness and compromised mitochondrial function, we show that ALA sensitizes GBM cells to temozolomide (TMZ) in vitro and in an orthotopic GBM model. Collectively, these results identify purine supply as an essential component in maintaining mitochondrial function in GBM cells and highlight a critical role of mitochondrial function in sustaining GBM stemness. We propose that purine synthesis inhibition can be beneficial in combination with the standard of care for -deficient GBMs, and that it may be feasible to achieve this benefit without inflicting major toxicity.
PubMed: 35453502
DOI: 10.3390/biomedicines10040751