Different mutational characteristics of TSG in cell lines and surgical specimens.

One of the most crucial concerns of cancer research pertains to the differences between the neoplastic cells in tumor specimens in vivo and their counterparts in cell lines. The huge amount of results deposited in cancer genetic databases allows to address this issue from a wider perspective. Our analysis of the Sanger Institute Catalog Of Somatic Mutations In Cancer (COSMIC) database v61 showed a lower percentage of homozygous mutations in a group of tumor suppressor genes in surgical samples (in vivo) in comparison to their frequency in cell lines (in vitro). Similarly, the mutations resulting in the lack of protein (e.g., nonsense mutations or whole gene deletions) of several tumor suppressor genes (TSGs) were more frequently observed in vitro than in vivo. In this article, we suggest two potential explanations of these data. Firstly, TSG heterozygous mutations resulting in the modified protein (e.g., missense mutations) may be gradually (when the specific molecular context is achieved) changed to homozygous mutations resulting in the lack of protein during carcinogenesis. Secondly, among different independent pathways of tumorigenesis, those leading to homozygous nonsense mutations are characteristic for cells which are more efficiently stabilized in vitro. To conclude, these observations may be interesting for researchers working with cell line in vitro models illustrating the extent to which they reflect the tumors in vivo.

PIN3 duplication may be partially responsible for TP53 haploinsufficiency.

BACKGROUND: Previously we have suggested that cancer cells develop a mechanism(s) which allows for either: silencing of the wild-type TP53 transcription, degradation of the wild-type TP53 mRNA, or selective overproduction of the mutated TP53 mRNA, which is the subject of this article. Sequencing of TP53 on the respective cDNA and DNA templates from tumor samples were found to give discordant results. DNA analysis showed a pattern of heterozygous mutations, whereas the analysis of cDNA demonstrated the mutated template only. We hypothesized that different TP53 gene expression levels of each allele may be caused by the polymorphism within intron 3 (PIN3). The aim of this study was to test if one of the polymorphic variants of PIN3 (A1 or A2) in the heterozygotes is associated with a higher TP53 expression, and therefore, responsible for the haploinsufficiency phenomenon. METHODS: 250 tumor samples were tested. To analyze the involvement of PIN3 polymorphic variant (A1 or A2) on TP53 mRNA expression regulation, bacterial subcloning combined with sequencing analyses, dual luciferase reporter assays and bioinformatic analysis were performed. RESULTS: Haplotype analysis showed the predominance of the mutated template during the cDNA sequencing in all samples showing a heterozygous TP53 mutation and PIN3 heterozygosity. Out of 30 samples (from the total of 250 tested samples) which carried TP53 mutations and had a bias in allelic expression 6 were heterozygous for the A1/A2 polymorphism, and all 6 (p = 0.04) samples carried the mutation within the PIN3 longer allele (A2). Reporter assays revealed higher luciferase activity in cells transfected with the plasmid containing A2 construct than A1 and control. A2/A1 ratio ranged from 1.16 for AD293 cell line (p = 0.019) to 1.59 for SW962 cell line (p = 0.0019). Moreover, bioinformatic analyses showed that PIN3 duplication stabilized secondary DNA structures - G-quadruplexes. CONCLUSION: TP53 alleles are not equivalent for their impact on the regulation of expression of TP53 mRNA. Therefore, in PIN3-heterozygous cases a single TP53 mutation of the longer allele might sufficiently destabilize its function. Secondary DNA structures such as quadruplexes can also play a role in PIN3-dependent TP53 haploinsufficiency.

Molecular alterations in meningiomas: association with clinical data.

The aim of our study was to evaluate the frequency of deletions on chromosomes 1, 9, 10, 14, 18 and 22 in 75 benign and 15 atypical meningiomas and correlate them with clinical findings. Paired normal and tumor DNA samples were analyzed for loss of heterozygosity (LOH), using 24 microsatellite markers and PCR techniques. Statistical analysis showed that deletions on chromosomes 14 and 18 were significantly associated with tumor grade of meningiomas (p = 0.048 and p = 0.03, respectively). In addition, we found a marginally increased frequency of LOH on chromosome 9 in atypical meningiomas (p = 0.06). Interestingly, LOH on chromosome 14 was significantly associated with tumor size (p = 0.049), as the risk of developing a tumor of more than 4 cm in diameter was 6-times the risk of developing tumor with diameter below 4 cm. The most frequent genetic abnormality in meningiomas is 22 LOH, which seems to be confirmed by the present study in which high frequency of such abnormality was observed (67%). We found associations between chromosome 22 status and histological subtype. LOH on chromosome 22 was more frequent in fibrous meningiomas than in the meningothelial variant (p = 0.001). Besides that, we found a relationship between 22 LOH status and tumor localization: the frequency of LOH in skull base-localized tumors was significantly lower compared to parasagittal meningiomas (p = 0.0004). Our results indicated that allelic loss on chromosomes 9, 10, 14, 18 and 22 may be associated with meningioma pathogenesis and progression.

Limited importance of the dominant-negative effect of TP53 missense mutations.

BACKGROUND: Heterozygosity of TP53 missense mutations is related to the phenomenon of the dominant-negative effect (DNE). To estimate the importance of the DNE of TP53 mutations, we analysed the percentage of cancer cases showing a single heterozygous mutation of TP53 and searched for a cell line with a single heterozygous mutation of this gene. This approach was based on the knowledge that genes with evident DNE, such as EGFR and IDH1, represent nearly 100% of single heterozygous mutations in tumour specimens and cell lines. METHODS: Genetic analyses (LOH and sequencing) performed for early and late passages of several cell lines originally described as showing single heterozygous TP53 mutations (H-318, G-16, PF-382, MOLT-13, ST-486 and LS-123). Statistical analysis of IARC TP53 and SANGER databases. Genetic analyses of N-RAS, FBXW7, PTEN and STR markers to test cross-contamination and cell line identity. Cell cloning, fluorescence-activated cell sorting and SSCP performed for the PF-382 cell line. RESULTS: A database study revealed TP53 single heterozygous mutations in 35% of in vivo (surgical and biopsy) samples and only 10% of cultured cells (in vitro), although those numbers appeared to be overestimated. We deem that published in vivo TP53 mutation analyses are not as rigorous as studies in vitro, and we did not find any cell line showing a stable, single heterozygous mutation. G16, PF-382 and MOLT-13 cells harboured single heterozygous mutations temporarily. ST-486, H-318 and LS-123 cell lines were misclassified. Specific mutations, such as R175H, R273H, R273L or R273P, which are reported in the literature to exert a DNE, showed the lowest percentage of single heterozygous mutations in vitro (about 5%). CONCLUSION: We suggest that the currently reported percentage of TP53 single heterozygous mutations in tumour samples and cancer cell lines is overestimated. Thus, the magnitude of the DNE of TP53 mutations is questionable. This scepticism is supported by database investigations showing that retention of the wild-type allele occurs with the same frequency as either nonsense or missense TP53 mutations.

Glioblastoma-derived spheroid cultures as an experimental model for analysis of EGFR anomalies.

Glioblastoma cell cultures in vitro are frequently used for investigations on the biology of tumors or new therapeutic approaches. Recent reports have emphasized the importance of cell culture type for maintenance of tumor original features. Nevertheless, the ability of GBM cells to preserve EGFR overdosage in vitro remains controversial. Our experimental approach was based on quantitative analysis of EGFR gene dosage in vitro both at DNA and mRNA level. Real-time PCR data were verified with a FISH method allowing for a distinction between EGFR amplification and polysomy 7. We demonstrated that EGFR amplification accompanied by EGFRwt overexpression was maintained in spheroids, but these phenomena were gradually lost in adherent culture. We noticed a rapid decrease of EGFR overdosage already at the initial stage of cell culture establishment. In contrast to EGFR amplification, the maintenance of polysomy 7 resulted in EGFR locus gain and stabilization even in long-term adherent culture in serum presence. Surprisingly, the EGFRwt expression pattern did not reflect the latter phenomenon and we observed no overexpression of the tested gene. Moreover, quantitative analysis demonstrated that expression of the truncated variant of receptor-EGFRvIII was preserved in GBM-derived spheroids at a level comparable to the initial tumor tissue. Our findings are especially important in the light of research using glioblastoma culture as the experimental model for testing novel EGFR-targeted therapeutics in vitro, with special emphasis on the most common mutated form of receptor-EGFRvIII.

Polycomb genes expression as a predictor of poor clinical outcome in children with medulloblastoma.

INTRODUCTION: Medulloblastoma is the most frequent type of embryonal tumor in the pediatric population, accounting for 20-25% of all brain tumors in children. Recently, the suspected contribution of the Polycomb group (PcG) genes in medulloblastoma development was described. PcG genes play an important role in developmental processes; they are also involved in the self-renewal of hematopoietic and neural stem cells as well as in malignant transformation. PURPOSE: In this study, we evaluated the expression of BMI1and PCGF2, members of family of PcG genes, and their potential target, MYC oncogene, and analyzed their association with demographic and clinical data. MATERIALS AND METHODS: Thirty-one children (18 males and 13 females, aged from 0.4 to 17 years) with medulloblastoma were included in this study. The gene's expression level was measured by quantitative real-time PCR, obtained using the two-color multiplexing technique. RESULTS: We found that the higher expression levels of BMI1 and PCGF2 genes were associated with significantly decreased patient survival (p = 0.02 and p = 0.012, respectively). Significant differences between gender were found, with a higher expression level of the PCGF2 gene observed among females (p = 0.02). CONCLUSION: Our analysis showed correlation between BMI1 and PCGF2 gene's expression and survival in children with medulloblastoma.

Innovative biodegradable dibutyrylchitin dressing for the treatment of ulcers occurring during chronic venous insufficiency in patients with type 2 diabetes.

The aim of this study was to assess the course of the healing process following the use of dibutyrylchitin (DBC) dressing, a fully degradable material used in the treatment of ulcers which occur during chronic venous insufficiency common in patients suffering from type 2 diabetes. These diseases have a significant impact on the patients' standard of living, including the potential employment, and on the declining attendance at the current workplace. The implementation of this innovative therapeutic solution may positively affect the above-mentioned difficulties. An analysis of the healing process, following the application of the DBC dressing, was performed. Once the dressing was positioned on the wound, the analysis indicated that it underwent a process of degradation facilitated by the enzymes occurring naturally in the wound. When fully degraded, a further layer was applied. This process was repeated until the wound was fully healed. The study group consisted of 4 patients previously diagnosed with type 2 diabetes. During the observation period, the ulcers in all 4 cases had healed. The examined wound dressings adhered well to the wound surface and degraded within it. No side effects or adverse effects of the applied innovative therapy were observed. An addition of the biodegradable DBC dressing to the standard therapy procedure of ulcers occurring during chronic venous insufficiency among patients with type 2 diabetes indicate safe and effective treatment, which may have a direct reflection in the patient's professional capacity enhancement. It resulted in the complete healing of all ulcers in each of the observed cases. Int J Occup Med Environ Health. 2021;34(4):565-73.

ABCB1/MDR1 gene polymorphisms as a prognostic factor in colorectal cancer.

OBJECTIVE: To analyse the single-nucleotide polymorphisms (SNPs): ABCB1(1236C>T), ABCB1(2677G>T/A), ABCB1(3435C>T) and haplotypes in the ABCB1/MDR1 gene, which could contribute to genetic risk of colorectal cancer (CRC). Disease association between the ABCB1/MDR1 genotype, allele, haplotype frequencies and histological features, such as TNM classification, localization of primary carcinoma, grade of malignancy, histological type of tumour, lymphoid infiltration and vessel invasion were estimated. In this study, the potential role of SNPs of the ABCB1/MDR1 gene as a prognostic marker for CRC was analysed. MATERIALS AND METHODS: Tumour specimens of 95 patients with CRC were studied. Using automated sequencing or PCR-RFLP method, DNA for three common SNPs of ABCB1/MDR1 was extracted and analysed. The results of genotyping and haplotype analysis with histopathological features, grading and clinical staging of neoplasms were correlated. RESULTS: A statistically significant higher frequency of T(1236) allele in T1/T2 (89.7%), M0 groups (81.6%) and I/II clinical staging (82.7%) in comparison with T3/T4 (68.2%), M1 groups (47.4%) and III/IV clinical staging (65.1%) was detected. Furthermore, multivariate analysis according to Cox's proportional hazard model indicated that the T(1236) allele is a good, independent prognostic factor and the presence of this allele decreases the risk of death in comparison with a group without this allele (HR = 0.26; p = 0.0424). In addition, a statistically significant higher frequency of C(3435) allele and significant differences in the C(3435) allele distribution in N1/N2 group (91.7% and 62.5%, respectively) than N0 group (71.2% and 44.9%, respectively) was found. Each of the eight possible haplotypes was noted in M0 or I/II group and only seven in M1 or III/IV group. Haplotype T(1236)-G(2677)-C(3435) only in less advanced CRC subjects (9.6% in I/II and 9.2% in M0 group) was detected. In addition, significant differences in haplotype distributions between M0 or I/II and M1 or III/IV group were found (p = 0.01 and p = 0.05, respectively). CONCLUSIONS: These results suggest association between T(1236) allele and T(1236)-G(2677)-C(3435) haplotype and less advanced CRC, so these genetic markers may play a role as potentially good prognostic factors. Differences in haplotype distributions and degree of clinical staging may suggest that some other potential SNPs, especially in regulatory region of ABCB1/MDR1 gene, may influence P-glycoprotein function and CRC progression.

Arrested neural and advanced mesenchymal differentiation of glioblastoma cells-comparative study with neural progenitors.

BACKGROUND: Although features of variable differentiation in glioblastoma cell cultures have been reported, a comparative analysis of differentiation properties of normal neural GFAP positive progenitors, and those shown by glioblastoma cells, has not been performed. METHODS: Following methods were used to compare glioblastoma cells and GFAP+NNP (NHA): exposure to neural differentiation medium, exposure to adipogenic and osteogenic medium, western blot analysis, immunocytochemistry, single cell assay, BrdU incorporation assay. To characterize glioblastoma cells EGFR amplification analysis, LOH/MSI analysis, and P53 nucleotide sequence analysis were performed. RESULTS: In vitro differentiation of cancer cells derived from eight glioblastomas was compared with GFAP-positive normal neural progenitors (GFAP+NNP). Prior to exposure to differentiation medium, both types of cells showed similar multilineage phenotype (CD44+/MAP2+/GFAP+/Vimentin+/Beta III-tubulin+/Fibronectin+) and were positive for SOX-2 and Nestin. In contrast to GFAP+NNP, an efficient differentiation arrest was observed in all cell lines isolated from glioblastomas. Nevertheless, a subpopulation of cells isolated from four glioblastomas differentiated after serum-starvation with varying efficiency into derivatives indistinguishable from the neural derivatives of GFAP+NNP. Moreover, the cells derived from a majority of glioblastomas (7 out of 8), as well as GFAP+NNP, showed features of mesenchymal differentiation when exposed to medium with serum. CONCLUSION: Our results showed that stable co-expression of multilineage markers by glioblastoma cells resulted from differentiation arrest. According to our data up to 95% of glioblastoma cells can present in vitro multilineage phenotype. The mesenchymal differentiation of glioblastoma cells is advanced and similar to mesenchymal differentiation of normal neural progenitors GFAP+NNP.

ABCB1 gene polymorphisms and haplotype analysis in colorectal cancer.

PURPOSE: The aim of this study was to determine the significance of three most common single-nucleotide polymorphisms (SNPs) of ABCB1 gene in the development of colorectal cancer and to estimate the influence of these SNPs to surviving patients' treatment combination adjuvant therapy 5-fluorouracil/leucovorin. Haplotype structure of ABCB1 was analysed, and degree of linkage disequilibrium (LD) between SNPs of ABCB1 was estimated. MATERIALS AND METHODS: Tumour specimens of 95 patients with colorectal cancer and blood samples of 95 healthy cases were studied. Genotyping of ABCB1 gene was performed by automated sequencing or polymerase chain reaction-restriction fragment length polymorphism method. Comparison of frequencies of alleles/genotypes/haplotypes between the studied group (colorectal cancer samples) and the control group (blood samples) were analysed. These results were correlated with the surviving patients after treatment of adjuvant chemotherapy. RESULTS: Significant differences in ABCB1 (1236C>T) (p = 0.00043) and ABCB1 (2677G>T/A) (p = 0.04) genotype distribution and T(1236) allele distribution (CT(1236) or TT(1236) vs CC(1236); p = 0.0499, OR = 0.55, Fi-Yule coefficient = 0.14) were found. A strong LD between ABCB1 (1236C>T) and ABCB1 (2677G>T/A) SNPs (D' = 0.621, r (2) = 0.318) was detected. All SNPs were located in one haplotype block. There were significant differences in haplotype distributions between colorectal cancer patients and healthy population (p = 0.03). Significant differences in survival probability of colorectal cancer patients' treatment chemotherapy according to allele of ABCB1 (3435C>T) was observed. Survival probability of patients with wild-type C(3435) allele were higher than among patients without this allele (p = 0.04572). CONCLUSIONS: These results suggested that three studied SNPs of ABCB1 were located in one haplotype block. Differences in ABCB1 (1236C>T) and ABCB1 (2677G>T/A) genotypes and T(1236) allele distribution between investigated populations indicate significant impact of these SNPs on risk of development of colorectal cancer. Polymorphism ABCB1 (3435C>T) may be a prediction marker of cancer chemotherapy effectiveness. Differences in haplotype distributions between colorectal cancer patients and healthy population suggested that other potential SNPs, especially in regulatory region of ABCB1 gene, may influence P-glycoprotein expression and function.

Successful elimination of non-neural cells and unachievable elimination of glial cells by means of commonly used cell culture manipulations during differentiation of GFAP and SOX2 positive neural progenitors (NHA) to neuronal cells.

BACKGROUND: Although extensive research has been performed to control differentiation of neural stem cells - still, the response of those cells to diverse cell culture conditions often appears to be random and difficult to predict. To this end, we strived to obtain stabilized protocol of NHA cells differentiation - allowing for an increase in percentage yield of neuronal cells. RESULTS: Uncommitted GFAP and SOX2 positive neural progenitors - so-called, Normal Human Astrocytes (NHA) were differentiated in different environmental conditions to: only neural cells consisted of neuronal [MAP2+, GFAP-] and glial [GFAP+, MAP2-] population, non-neural cells [CD44+, VIMENTIN+, FIBRONECTIN+, MAP2-, GFAP-, S100beta-, SOX2-], or mixture of neural and non-neural cells.In spite of successfully increasing the percentage yield of glial and neuronal vs. non-neural cells by means of environmental changes, we were not able to increase significantly the percentage of neuronal (GABA-ergic and catecholaminergic) over glial cells under several different cell culture testing conditions. Supplementing serum-free medium with several growth factors (SHH, bFGF, GDNF) did not radically change the ratio between neuronal and glial cells--i.e., 1,1:1 in medium without growth factors and 1,4:1 in medium with GDNF, respectively. CONCLUSION: We suggest that biotechnologists attempting to enrich in vitro neural cell cultures in one type of cells - such as that required for transplantology purposes, should consider the strong limiting influence of intrinsic factors upon extracellular factors commonly tested in cell culture conditions.

Diverse molecular pattern in a bihemispheric glioblastoma (butterfly glioma) in a 16-year-old boy.

Glioblastoma multiforme (GBM), the most common malignant brain tumor of adults, is relatively rare in children. In a GBM affecting a 16-year-old boy, the tumor spread across the corpus callosum (butterfly glioma). This type of bilateral hemispheric growth has previously been thought to result from spread along the white matter tracts. Two samples obtained from opposite sides of the same tumor were analyzed comprehensively for loss of heterozygosity (LOH) and microsatellite instability (MSI). Amplification of EGFR and MDM2 was studied by means of multiplex polymerase chain reaction. Exons 5, 6, 7, and 8 of TP53 were screened for mutations by sequencing. In neither specimen were molecular alterations found in the EGFR, MDM2, or TP53 genes. The specimen obtained from the right hemisphere exhibited a high level of MSI and LOH in chromosome arms 5q, 9p, and 13q. The specimen from the left hemisphere exhibited LOH in chromosome arms 3p, 5q, 9p, 9q, 10p, 10q, and 13q. Here we propose four plausible hypothetical scenarios underlying the tumorigenesis of this GBM.

Gliomas: association of histology and molecular genetic analysis of chromosomes 1p, 10q, and 19q.

The aim of our study was to evaluate the frequencies of loss of heterozygosity (LOH) on chromosomes 1p, 10q, and 19q in gliomas and to correlate them with the histological diagnosis and with patient age and gender. We found deletions within chromosome 1p to be significantly associated with the histological subtype of glial tumor (P < 0.05); frequency of 1p deletions increased from astrocytoma (0%) through glioblastoma (31%) and oligoastrocytoma (57%) to oligodendroglioma (63%). In patients with 1p LOH, the odds for having astrocytoma or glioblastoma were approximately 10-fold and 4-fold lower, respectively, than oligodendroglioma. The odds for having oligoastrocytoma were similar to oligodendroglioma (OR = 1.3). The frequency of 10q LOH in patients with glioblastoma was significantly higher than in patients with oligodendroglioma (89% vs. 36%; P < 0.005). In patients with oligodendroglioma, most cases with LOH on chromosome 1p also had LOH 19q (90%), one case of 1p LOH also had a deletion on 10q. Statistical analyses revealed a significant association between deletions on 1p and 19q (P < 0.05). Our data provide evidence that use of molecular genetic analyses of chromosomes 1p, 19q, and 10q might improve the diagnosis of gliomas.

Phenotype of the DYT1 mutation in the TOR1A gene in a Polish population of patients with dystonia. A preliminary report.

BACKGROUND AND PURPOSE: DYT1 dystonia is the most common form of inherited primary dystonia. The aim of the study was: 1) to evaluate the prevalence of the DYT1 mutation in a population of Polish patients with early-onset generalized dystonia and with other forms of familial dystonia, 2) to evaluate the frequency of the DYT1 mutation in patients with writer's cramp, 3) to characterize the phenotype of the DYT1 mutation in the Polish population, and 4) to define the group of patients in whom genetic testing is recommended. MATERIAL AND METHODS: The following groups of patients were included in the study: 1) patients with early-onset (<30 years) generalized dystonia and those patients with onset after age 30 years who have relatives with early-onset dystonia, 2) patients with writer's cramp (focal or as part of segmental dystonia) independently of age of onset, 3) asymptomatic (adult only) relatives of the diagnosed DYT1 carriers. Genetic tests were performed in 63 subjects---28 sporadic cases of dystonia, 20 patients with familial dystonia, and 15 asymptomatic relatives of patients with confirmed DYT1 mutation. RESULTS: The DYT1 mutation was found in 17 subjects--10 patients with dystonia and 7 asymptomatic relatives (from 6 families). In all mutation carriers dystonia occurred in one limb before age 26 years. In 8 patients, generalization of dystonia was observed and in 2 cases it remained in a focal form. CONCLUSIONS: 1. The prevalence of DYT1 mutation among patients with early-onset (

Ammonia affects the activity and expression of soluble and particulate GC in cultured rat astrocytes.

Neurotoxic effects of ammonia are mediated by increased accumulation of nitric oxide (NO), which combines with free radicals to form a highly toxic compound, peroxynitrite. Previous experiments in vivo and in vitro have suggested that this phenomenon engages neuron-derived NO and is coupled to changes in the accumulation of cGMP. The present study accounted for the facts that: (i) astrocytes, not neurons are the morphological target of ammonia, and (ii) both NO-dependent, soluble (sGC) and NO-independent, particulate guanylate cyclase (pGC) mediate cGMP production in the cells. Neocortical rat astrocytes were treated for 1 or 24 h with 5 mM ammonium chloride ("ammonia") and then subjected to: (i) cGMP measurement, and (ii) mRNA and/or protein expression analysis of alpha1 and beta1 subunits of sGC and two pGC forms: pGC-A and pGC-B. Treatment with ammonia for 1h increased accumulation of cGMP and sGCbeta1 mRNA expression, without producing significant changes in the protein expression. This was followed by a decrease of cGMP level at 24 h treatment, associated with a decreased expression of sGCbeta1 and sGCalpha1 mRNA and sGCbeta1 protein. Expression of pGC-A and pGC-B mRNA was elevated in ammonia-treated astrocytes after 24 h. Accordingly, increased cGMP accumulation was noted in the presence of a specific sGC inhibitor (ODQ). The results show that ammonia affects cGMP production in astrocytes, and that this may involve not only sGC but also pGC.

KCTD11 expression in medulloblastoma is lower than in adult cerebellum and higher than in neural stem cells.

Medulloblastoma (MB) is the most common malignant brain tumor of childhood, and the most frequent associated genetic alteration is loss of heterozygosity on chromosome region 7p13. Two genes mapping to this region, KCTD11 (alias REN) and HIC1, have been proposed as involved in MB pathogenesis. We used real-time polymerase chain reaction in 20 tissue samples of primary MB to examine the transcriptional level of the two genes, with reference to two types of controls: adult cerebellum and fetal neural stem cells. A significant reduction of KCTD11 expression relative to adult normal cerebellum was detected in 14 of 20 (70%) of MB samples. Neural stem cells had even lower levels of KCTD11 expression than did MB. HIC1 gene expression was low ( approximately 100 times lower than KCTD11 expression) in MB, and low also in both adult cerebellum and neural stem cells. Hypermethylation of the 5'UTR or the central region of HIC1 (or both) was detected in a significant number of MB samples, as well as in cerebellum and neural stem cells. Our data suggest that KCTD11 may play an important role in MB tumorigenesis, but do not support the role of HIC1 in this tumor development. We argue that recognition of the gene or genes important in MB tumorigenesis depends in part on defining an appropriate control.

Regulation of PrPC expression: nerve growth factor (NGF) activates the prion gene promoter through the MEK1 pathway in PC12 cells.

A high expression of PrP(C) in cells is one factor that increases the risk of conversion to the misfolded, disease-associated form (PrP(Sc)) characteristic of transmissible spongiform encephalopathies. Thus, developing a method to control the level of PrP(C) expression in cells could be one way to delay or prevent the onset of clinical signs of these diseases. In this study the mechanisms controlling the expression of the Prnp gene in PC12 cells and in rat brain were examined. We observed a slight activation of a cloned fragment of the human PRNP gene promoter using the luciferase reporter system in PC12 cells stimulated with nerve growth factor (NGF). The activating effect of NGF was enhanced by mitogen-activated protein kinase (MEK1) and suppressed by myristylated serine/threonine kinase (myrAKT). These results suggest that MEK1 is a positive activator of the PRNP promoter that inhibits the AKT pathway. Independent experiments suggested that high expression of PrP(C) in the brain depends on the rate of translation and/or the efficiency of PrP(C) stabilization. We also investigated the epigenic status of the Prnp promoter. We observed no increase of PrP(C) or Prnp mRNA levels in PC12 cells after treatment with the DNA-demethylating agent. The Prnp promoter did not display methylation either in NGF-treated and untreated PC12 cells, or in the rat brain. These results improve the understanding of the regulation of the Prnp gene promoter, a DNA regulatory element controlling the expression of PrP(C), a protein involved in several neurological diseases.

Synthesis and physicochemical characterization of chitin dihexanoate--A new biocompatible chitin derivative--In comparison to chitin dibutyrate.

Chitin dihexanoate (DHCH) is the novel biocompatible and technologically friendly highly substituted chitin diester. Here we described optimization of DHCH and chitin dibutyrate (dibutyryl chitin, DBC) synthesis conditions (temperature and reaction time) to obtain desired polymers with high reaction yield, high substitution degree (close to 2) and appropriately high molecular weights. A two-step procedure, employing acidic anhydrides (hexanoic or butyric anhydride) as the acylation agent and methanesulfonic acid both as the catalyst and the reaction medium, was applied. Chemical structures of DBC and DHCH were confirmed by NMR ((1)H and (13)C) and IR investigations. Mechanical properties, thermogravimetric analysis, differential scanning calorimetry and biocompatibility (Neutral red uptake assay, Skin Sensitization and Irritation Tests) were assessed. Both polymers proved highly biocompatible (non-cytotoxic in vitro, non-irritating and non-allergic to skin) and soluble in several organic solvents (dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetone, ethanol and others). It is worth emphasizing that DHCH and DBC can be easily processed by solvent casting method and the salt-leaching method, what gives the opportunity to prepare highly porous structures, which can be further successfully applied as the material for wound dressings and scaffolds for tissue engineering.

IDH1R132H in Neural Stem Cells: Differentiation Impaired by Increased Apoptosis.

BACKGROUND: The high frequency of mutations in the isocitrate dehydrogenase 1 (IDH1) gene in diffuse gliomas indicates its importance in the process of gliomagenesis. These mutations result in loss of the normal function and acquisition of the neomorphic activity converting α-ketoglutarate to 2-hydroxyglutarate. This potential oncometabolite may induce the epigenetic changes, resulting in the deregulated expression of numerous genes, including those related to the differentiation process or cell survivability. METHODS: Neural stem cells were derived from human induced pluripotent stem cells following embryoid body formation. Neural stem cells transduced with mutant IDH1R132H, empty vector, non-transduced and overexpressing IDH1WT controls were differentiated into astrocytes and neurons in culture. The neuronal and astrocytic differentiation was determined by morphology and expression of lineage specific markers (MAP2, Synapsin I and GFAP) as determined by real-time PCR and immunocytochemical staining. Apoptosis was evaluated by real-time observation of Caspase-3 activation and measurement of PARP cleavage by Western Blot. RESULTS: Compared with control groups, cells expressing IDH1R132H retained an undifferentiated state and lacked morphological changes following stimulated differentiation. The significant inhibitory effect of IDH1R132H on neuronal and astrocytic differentiation was confirmed by immunocytochemical staining for markers of neural stem cells. Additionally, real-time PCR indicated suppressed expression of lineage markers. High percentage of apoptotic cells was detected within IDH1R132H-positive neural stem cells population and their derivatives, if compared to normal neural stem cells and their derivatives. The analysis of PARP and Caspase-3 activity confirmed apoptosis sensitivity in mutant protein-expressing neural cells. CONCLUSIONS: Our study demonstrates that expression of IDH1R132H increases apoptosis susceptibility of neural stem cells and their derivatives. Robust apoptosis causes differentiation deficiency of IDH1R132H-expressing cells.

Genetic heterogeneity of RPMI-8402, a T-acute lymphoblastic leukemia cell line.

Thorough examination of genetic heterogeneity of cell lines is uncommon. In order to address this issue, the present study analyzed the genetic heterogeneity of RPMI-8402, a T-acute lymphoblastic leukemia (T-ALL) cell line. For this purpose, traditional techniques such as fluorescence in situ hybridization and immunocytochemistry were used, in addition to more advanced techniques, including cell sorting, Sanger sequencing and massive parallel sequencing. The results indicated that the RPMI-8402 cell line consists of several genetically different cell subpopulations. Furthermore, massive parallel sequencing of RPMI-8402 provided insight into the evolution of T-ALL carcinogenesis, since this cell line exhibited the genetic heterogeneity typical of T-ALL. Therefore, the use of cell lines for drug testing in future studies may aid the progress of anticancer drug research.