Prolonged idasanutlin (RG7388) treatment leads to the generation of p53-mutated cells

The protein p53 protects the organism against carcinogenic events by the induction of cell cycle arrest and DNA repair program upon DNA damage. Virtually all cancers inactivate p53 either by mutations/deletions of the TP53 gene or by boosting negative regulation of p53 activity. The overexpression of MDM2 protein is one of the most common mechanisms utilized by p53wt cancers to keep p53 inactive. Inhibition of MDM2 action by its antagonists has proved its anticancer potential in vitro and is now tested in clinical trials. However, the prolonged treatment of p53wt cells with MDM2 antagonists leads to the development of secondary resistance, as shown first for Nutlin-3a, and later for three other small molecules. In the present study, we show that secondary resistance occurs also after treatment of p53wt cells with idasanutlin (RG7388, RO5503781), which is the only MDM2 antagonist that has passed phase II and entered phase III clinical trials, so far. Idasanutlin strongly activates p53, as evidenced by the induction of p21 expression and potent cell cycle arrest in all the three cell lines tested, i.e., MCF-7, U-2 OS, and SJSA-1. Notably, apoptosis was induced only in SJSA-1 cells, while MCF-7 and U-2 OS cells were able to restore the proliferation upon the removal of idasanutlin. Moreover, idasanutlin-treated U-2 OS cells could be cultured for long time periods in the presence of the drug. This prolonged treatment led to the generation of p53-mutated resistant cell populations. This resistance was generated de novo, as evidenced by the utilization of monoclonal U-2 OS subpopulations. Thus, although idasanutlin presents much improved activities compared to its precursor, it displays the similar weaknesses, which are limited elimination of cancer cells and the generation of p53-mutated drug-resistant subpopulations

Relationship between Pyruvate Kinase Activity and Cariogenic Biofilm Formation in Streptococcus mutans Biotypes in Caries Patients

Streptococcus mutans (MS) and its biotype I are the strains most frequently found in dental plaque of young children. Our results indicate that in children pyruvate kinase (PK) activity increases significantly in dental plaque, and this corresponds with caries progression. The MS strains isolated in this study or their main glycolytic metabolism connected with PK enzymes might be useful risk factors for studying the pathogenesis and target points of novel therapies for dental caries. The relationship between PK activity, cariogenic biofilm formation and selected biotypes occurrence was studied. S. mutans dental plaque samples were collected from supragingival plaque of individual deciduous molars in 143 subjects. PK activity was measured at different time points during biofilm formation. Patients were divided into two groups: initial stage decay, and extensive decay. Non-parametric analysis of variance and analysis of covariance were used to determine the connections between S. mutans levels, PK activity and dental caries biotypes. A total of 143 strains were derived from subjects with caries. Biotyping data showed that 62, 23, 50, and 8 strains were classified as biotypes I, II, III, IV, respectively. PK activity in biotypes I, II, and IV was significantly higher in comparison to that in biotype III. The correlation between the level of S. mutans in dental plaque and PK activity was both statistically significant (p < 0.05) and positive. The greater the level of S. mutans in the biofilm (colony count and total biomass), the higher the PK activity; similarly, a low bacterial count correlated with low PK activity

Acromegaly and late-onset primary hyperparathyroidism in a female with a rare MEN1 gene variant of yet undetermined clinical significance (p.Val167Ala)

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Nieinsulinowa hipoglikemia trzustkowa u dorosłych — przegląd genetyki

  Hyperinsulinaemic hypoglycaemia (HH) is also classically referred to as “nesidioblastosis”. Heterogeneous clinical manifestation of the disease causes risk of late diagnosis or even misdiagnosis. In infants and children, it can lead to serious and permanent damage to the central nervous system, which leads to the manifesting mental retardation. HH is characterised by unregulated insulin secretion from pancreatic β-cells. This effect has been correlated with nine genes: ABCC8, KCNJ11, GCK, GLUD-1, HADH1, SLC16A1, HNF4A, HNF1A, and UCP2. Mutations in these genes were found in approximately 48% of cases. The genetic background of the remaining cases is unknown. Understanding the genetic basis of familial hyperinsulinism has changed the early look at the disease. It has allowed for the differentiation of specific types of the disease. Depending on which of the nine disease-associated loci bears a pathogenic mutation, they differ in phenotype and pattern of inheritance. This review provides a brief overview of the genetic mechanisms of HH and its possible clinical presentations. (Endokrynol Pol 2015; 66 (4): 344–354)    Hipogligemia hiperinsulinemiczna (HH) określana jest również terminem „nesidioblastoza”. Różnorodna kliniczna manifestacja choroby powoduje ryzyko późnej diagnozy, a nawet braku rozpoznania. U niemowląt i dzieci nesidioblastoza prowadzić może do ciężkich i trwałych uszkodzeń centralnego systemu nerwowego, manifestujących się w postaci niedorozwoju umysłowego. Hipogligemia hiperinsulinemiczna charakteryzuje się nieuregulowanym wydzielaniem insuliny przez komórki β trzustki. Efekt ten powiązany został z dziewięcioma genami: ABCC8, KCNJ11, GCK, GLUD-1, HADH1, SLC16A1, HNF4A, HNF1A i UCP2. Mutacje występujące w wymienionych genach znajdowane są u 48% chorych. Genetyczne podłoże pozostałych przypadków pozostaje nieznane. Zrozumienie genetycznej przyczyny rodzinnej postaci hiperisnulinizmu zmieniło sposób, w jaki postrzegano chorobę. Pozwoliło na wyróżnienie poszczególnych jej typów. W zależność od tego, w którym z dziewięciu zasocjowanych z chorobą loci występuje patogenna mutacja, typy różnią się fenotypem i sposobem dziedziczenia. Praca stanowi krótki przegląd genetycznych patomechanizmów choroby obserwowanych w HH oraz ich możliwych prezentacji klinicznych. (Endokrynol Pol 2015; 66 (4): 344–354)

Whole-exome sequencing as a tool for searching for genetic background modifiers in MEN1 patients with neuroendocrine pancreatic tumours, including insulinomas

Introduction: Multiple endocrine neoplasia type 1 (MEN1) is a monogenic disease caused by inactivating variants in the MEN1 gene. Although the reason for its development is well-known, disease phenotypes are unpredictable and differ even among carriers of the same pathogenic driver mutation. Genetic, epigenetic, and environmental factors may play a role in driving the individual phenotype. Those factors, however, still mostly remain unidentified. In our work, we focused on the inherited genetic background in pancreatic neuroendocrine neoplasms (pNENs) in MEN1 patients, and the pancreatic tumour subgroup with insulinoma. Material and methods: Whole exome sequencing was performed in MEN1 patients. The symptoms of interest were pancreatic neuroendocrine tumours in one analysis and insulinoma in the second. The study included families as well as unrelated cases. Genes with variants that are not neutral to the encoded gene product were defined in symptom-positive patients as compared to symptom-negative controls. The interpretation of the results was based on functional annotations and pathways shared between all patients with the given symptom in the course of MEN1. Results: Whole-exome screening of family members and unrelated patients with and without pNENs revealed a number of pathways that are common for all the analysed cases with pNENs. Those included pathways crucial for morphogenesis and development, proper insulin signalling, and structural cellular organization. An additional analysis of insulinoma pNEN patients revealed additional pathways engaged in glucose and lipid homeostasis, and several non-canonical insulin-regulating mechanisms. Conclusions: Our results show the existence of pathways that are identified in a non-literature-predefined manner, which might have a modifying function in MEN1, differentiating the specific clinical outcomes. Those results, although preliminary, provide evidence of the reasonableness of performing large-scale studies addressing the genetic background of MEN1 patients in determining their individual outcomes