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

Rapid decrease of CD16 (Fc\gammaRIII) expression on heat-shocked neutrophils and their recognition by macrophages

Accumulation of neutrophils in the site of inflammation is a typical mechanism of innate immunity. The accumulated neutrophils are exposed to stressogenic factors usually associated with inflammation. Here, we studied response of human peripheral blood neutrophils subjected to short, febrile-range heat stress. We show that 90 min heat stress slowed down the spontaneous apoptosis of neutrophils. In the absence of typical markers of apoptosis the heat-shocked neutrophils induced antiinflammatory effect in human monocyte-derived macrophages (hMDMs), yet without being engulfed. Importantly, the expression of Fc\gammaRIII (CD16) was sharply reduced. Surprisingly, concentration of the soluble CD16 did not change in heat-shocked neutrophil supernates indicating that the reduction of the cell surface CD16 was achieved mainly by inhibition of fresh CD16 delivery. Inhibitors of 90 kDa heat shock protein (HSP90), a molecular chaperone found in membrane platforms together with CD16 and CD11b, significantly increased the observed effects caused by heat shock. The presented data suggest a novel systemic aspect of increased temperature which relies on immediate modification by heat of a neutrophil molecular pattern. This effect precedes cell death and may be beneficial in the initial phase of inflammation providing a nonphlogistic signal to macrophages before it comes from apoptotic cells

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

Heterogeneity of the Clinical Presentation of the MEN1 LRG_509 c.781C>T (p.Leu261Phe) Variant Within a Three-Generation Family

Multiple neuroendocrine neoplasia type 1 (MEN1) is a rare genetic disorder with an autosomal dominant inheritance, predisposing carriers to benign and malignant tumors. The phenotype of MEN1 syndrome varies between patients in terms of tumor localization, age of onset, and clinical aggressiveness, even between affected members within the same family. We describe a heterogenic phenotype of the MEN1 variant c.781C>T (LRG_509t1), which was previously reported only once in a family with isolated hyperparathyroidism. A heterozygous missense variant in exon 4 of the gene was identified in the sequence of the MEN1 gene, i.e., c.781C>T, leading to the amino acid change p.Leu261Phe in a three-generation family. In the screened family, 5/6 affected members had already developed hyperparathyroidism. In the index patient and two other family members, an aggressive course of pancreatic neuroendocrine tumor (insulinoma and non-functioning neuroendocrine tumors) with dissemination was diagnosed. In the index patient, late diagnosis and slow progression of the disseminated neuroendocrine tumor have been observed (24 years of follow-up). The very rare variant of MEN1, LRG_509t1 c.781C>T /p.Leu261Phe (LRG_509p1), diagnosed within a three-generation family has a heterogenic clinical presentation. Further follow-up of the family members should be carried out to confirm the spectrum and exact time of clinical presentation

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

Not required for Clinical Vignette

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)