Cytotoxicity of de novo purine synthesis (DNPS) metabolites is critical to the pathogenesis of three known and one putative autosomal recessive disorder affecting DNPS. These rare disorders are caused by biallelic mutations in the DNPS genes phosphoribosylformylglycineamidine synthase (PFAS), phosphoribosylaminoimidazolecarboxylase/phosphoribosylaminoimidazolesuccinocarboxamide synthase (PAICS), adenylosuccinate lyase (ADSL), and aminoimidazole carboxamide ribonucleotide transformylase/inosine monophosphate cyclohydrolase (ATIC) and are clinically characterized by developmental abnormalities, psychomotor retardation, and nonspecific neurological impairment. At a biochemical level, loss of function of specific mutated enzymes results in elevated levels of DNPS ribosides in body fluids. The main pathogenic effect is attributed to the accumulation of DNPS ribosides, which are postulated to be toxic to the organism. Therefore, we decided to characterize the uptake and flux of several DNPS metabolites in HeLa cells and the impact of DNPS metabolites to viability of cancer cell lines and primary skin fibroblasts. We treated cells with DNPS metabolites and followed their flux in purine synthesis and degradation. In this study, we show for the first time the transport of formylglycinamide ribotide (FGAR), aminoimidazole ribotide (AIR), succinylaminoimidazolecarboxamide ribotide (SAICAR), and aminoimidazolecarboxamide ribotide (AICAR) into cells and their flux in DNPS and the degradation pathway. We found diminished cell viability mostly in the presence of FGAR and AIR. Our results suggest that direct cellular toxicity of DNPS metabolites may not be the primary pathogenetic mechanism in these disorders.

• Klíčová slova
• ADSL, AICAR, AIR, ATIC, FGAR, PAICS, PFAS, SAICAR, cytotoxicity, purine synthesis,
• Publikační typ
• časopisecké články MeSH

UNLABELLED: Molecular mechanisms of lapatinib resistance in breast cancer are not well understood. The aim of this study was to correlate expression of selected proteins involved in ErbB family signaling pathways with clinical efficacy of lapatinib. Study group included 270 HER2-positive advanced breast cancer patients treated with lapatinib and capecitabine. Immunohistochemical expression of phosphorylated adenosine monophosphate-activated protein (p-AMPK), mitogen-activated protein kinase (p-MAPK), phospho (p)-p70S6K, cyclin E, phosphatase and tensin homolog were analyzed in primary breast cancer samples. The best discriminative value for progression-free survival (PFS) was established for each biomarker and subjected to multivariate analysis. At least one biomarker was determined in 199 patients. Expression of p-p70S6K was independently associated with longer (HR 0.45; 95% CI: 0.25-0.81; p = 0.009), and cyclin E with shorter PFS (HR 1.83; 95% CI: 1.06-3.14; p = 0.029). Expression of p-MAPK (HR 1.61; 95% CI 1.13-2.29; p = 0.009) and cyclin E (HR 2.99; 95% CI: 1.29-6.94; p = 0.011) was correlated with shorter, and expression of estrogen receptor (HR 0.65; 95% CI 0.43-0.98; p = 0.041) with longer overall survival. Expression of p-AMPK negatively impacted response to treatment (HR 3.31; 95% CI 1.48-7.44; p = 0.004) and disease control (HR 3.07; 95% CI 1.25-7.58; p = 0.015). IN CONCLUSION: the efficacy of lapatinib seems to be associated with the activity of downstream signaling pathways - AMPK/mTOR and Ras/Raf/MAPK. Further research is warranted to assess the clinical utility of these data and to determine a potential role of combining lapatinib with MAPK pathway inhibitors.

• Klíčová slova
• breast cancer, epidermal growth factor receptor type 2, lapatinib, mTOR, p-MAPK,
• MeSH
• chinazoliny terapeutické užití   MeSH
• cyklin E metabolismus   MeSH
• dospělí MeSH
• fosforylace účinky léků   MeSH
• hodnocení výsledků zdravotní péče metody   statistika a číselné údaje   MeSH
• imunohistochemie metody   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• Kaplanův-Meierův odhad MeSH
• kinasy ribozomálního proteinu S6, 70-kDa metabolismus   MeSH
• lapatinib MeSH
• lidé středního věku MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy metabolismus   MeSH
• mladý dospělý MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• prediktivní hodnota testů MeSH
• prognóza MeSH
• proporcionální rizikové modely MeSH
• receptor erbB-2 antagonisté a inhibitory   metabolismus   MeSH
• receptory pro estrogeny metabolismus   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chinazoliny MeSH
• cyklin E MeSH
• inhibitory proteinkinas MeSH
• kinasy ribozomálního proteinu S6, 70-kDa MeSH
• lapatinib MeSH
• mitogenem aktivované proteinkinasy MeSH
• receptor erbB-2 MeSH
• receptory pro estrogeny MeSH