Genetic changes of MLH1 and MSH2 genes could explain constant findings on microsatellite instability in intracranial meningioma

Postreplicative mismatch repair safeguards the stability of our genome. The defects in its functioning will give rise to microsatellite instability. In this study, 50 meningiomas were investigated for microsatellite instability. Two major mismatch repair genes, MLH1 and MSH2, were analyzed using microsatellite markers D1S1611 and BAT26 amplified by polymerase chain reaction and visualized by gel electrophoresis on high-resolution gels. Furthermore, genes DVL3 (D3S1262), AXIN1 (D16S3399), and CDH1 (D16S752) were also investigated for microsatellite instability. Our study revealed constant presence of microsatellite instability in meningioma patients when compared to their autologous blood DNA. Altogether 38% of meningiomas showed microsatellite instability at one microsatellite locus, 16% on two, and 13.3% on three loci. The percent of detected microsatellite instability for MSH2 gene was 14%, and for MLH1, it was 26%, for DVL3 22.9%, for AXIN1 17.8%, and for CDH1 8.3%. Since markers also allowed for the detection of loss of heterozygosity, gross deletions of MLH1 gene were found in 24% of meningiomas. Genetic changes between MLH1 and MSH2 were significantly positively correlated (p = 0.032). We also noted a positive correlation between genetic changes of MSH2 and DVL3 genes (p = 0.034). No significant associations were observed when MLH1 or MSH2 was tested against specific histopathological meningioma subtype or World Health Organization grade. However, genetic changes in DVL3 were strongly associated with anaplastic histology of meningioma (χ2 = 9.14; p = 0.01). Our study contributes to better understanding of the genetic profile of human intracranial meningiomas and suggests that meningiomas harbor defective cellular DNA mismatch repair mechanisms

Frequency of loss of heterozygosity of the NF2 gene in schwannomas from Croatian patients

Aim To identify gross deletions in the NF2 gene in a panel of schwannomas from Croatian patients in order to establish their frequencies in Croatian population. Methods Changes of the NF2 gene were tested by polymerase chain reaction/loss of heterozygosity (LOH) using two microsatellite markers, D22S444 and D22S929. Results The analysis with both markers demonstrated that 43.75% of schwannomas exhibited LOH of the NF2 gene. The D22S444 region exhibited 45.5% of LOHs and the D22S929 region exhibited 14.3% of LOHs. Four LOHs were found in Antoni B, 2 in Antoni A, and 1 in Antoni A and B type tumors. Conclusion The frequency of changes observed in Croatian patients is broadly similar to that reported in other populations and thus confirms the existing hypothesis regarding the tumorigenesis of schwannomas and contributes to schwannoma genetic profile helping us to better understand its etiology and treatment

AXIN-1 protein expression and localization in glioblastoma [Izraženost i smještaj proteina aksina u glioblastomima]

The etiology and pathogenesis of tumors of the central nervous system are still inadequately explained. In the present study the expression patterns of a critical molecular component of wnt signaling pathway – axin 1 was investigated in 42 patients with glioblastoma, the most aggressive form of glial tumors. Immunostaining and image analysis revealed the quantity and localization of the protein. Downregulation of this tumor suppressor expression was observed in 31% of tumors when compared to the levels of axin in healthy brain tissues. Axin was observed in the cytoplasm in 69% of glioblastoma samples, in 21.4% in both the cytoplasm and nucleus and 9.5% had expression solely in the nucleus. Mean values of relative axin’s expression obtained by image analysis showed that the highest relative quantity of axin was measured when the protein was in the nucleus and the lowest relative quantity of axin when the protein was localized in the cytoplasm. Investigation on axin’s existence at the subcellular level in glioblastomas suggests that axin’s expression and spatial regulation is a dynamic process. Despite increasing knowledge on glioma biology and genetics, the prognostic tools for glioblastoma still need improvement. Our findings on expression of axin 1 may contribute to better understanding of glioblastoma molecular profile

Frequency of loss of heterozygosity of the NF2 gene in schwannomas from Croatian patients

AIM: To identify gross deletions in the NF2 gene in a panel of schwannomas from Croatian patients in order to establish their frequencies in Croatian population. ----- METHODS: Changes of the NF2 gene were tested by polymerase chain reaction/loss of heterozygosity (LOH) using two microsatellite markers, D22S444 and D22S929. ----- RESULTS: The analysis with both markers demonstrated that 43.75% of schwannomas exhibited LOH of the NF2 gene. The D22S444 region exhibited 45.5% of LOHs and the D22S929 region exhibited 14.3% of LOHs. Four LOHs were found in Antoni B, 2 in Antoni A, and 1 in Antoni A and B type tumors. ----- CONCLUSION: The frequency of changes observed in Croatian patients is broadly similar to that reported in other populations and thus confirms the existing hypothesis regarding the tumorigenesis of schwannomas and contributes to schwannoma genetic profile helping us to better understand its etiology and treatment

Loss of heterozygosity of selected tumor suppressor genes in human testicular germ cell tumors

Human testicular germ cell tumors (TGCTs) are histologically heterogenous neoplasms with a variable malignant potential. Two main groups of germ cell tumors occur in men: seminomas and nonseminomas. In the present study, a set of four tumor suppressor genes was investigated in testicular cancers. CDH1, APC, p53, and nm23-H1 genes were tested for loss of heterozygosity (LOH). Thirty-eight testicular germ cell tumors (17 seminomas and 21 nonseminomas) were analyzed by PCR using restriction fragment length polymorphism or the dinucleotide/tetranucleotide repeat polymorphism method. An allelic loss of p53 at exon 4 was detected in five nonseminomas, whereas LOH of p53 at intron 6 occurred in one of the seminoma and two of the nonseminoma samples. Allelic losses of the APC gene were present in three seminomas and one nonseminoma, whereas one seminoma and three nonseminomas showed LOH of CDH1. The analysis of allelic losses showed no common structural genetic alterations in tumor tissues, although a different pattern of LOH was observed between the two main histological groups of TGCTs

Nucleotide variations of TP53 exon 4 found in intracranial meningioma and in silico prediction of their significance

The aim of the present study was to identify TP53 exon 4 mutations in patients with meningioma and to investigate their potential association with specific tumor pathology. Nucleotide alterations were investigated in 48 meningiomas via the direct sequencing of TP53 exon 4 in patient tumor and blood samples using the DNA Sanger method with the BigDyeTerminator v3.1 Cycle Sequencing kit and Applied Biosystems 3730XL apparatus. The results revealed that TP53 exon 4 was frequently altered in meningioma, occurring in 60.4% of the patients investigated. A total of 18 different alterations were detected in the meningioma samples assessed in the current study. The majority of these appeared more than once and some were repeatedly identified in several patients. Changes at codons 72 (c.215G>C) and 62 (c.186delA) were highly prevalent, occurring in 44.8% of patients. Other changes detected via frequency analysis included: Five substitutions on codon 105 (c.315C>T); four insertions on codon 70 (c.209_210insG); three insertions on codon 64 (c.190C>G), 82 (245C>T; 245delC; 243_244insA) and 104 (c.312G>A); and two insertions on codons 108 (c.322G>C), 71 (c.213C>A), 73 (c.217G>A), 91 (c.271T>C) and 100 (c.300G>T). Codons 68 (c.202_203insT), 77 (c.229C>T), 88 (c.263C>G) and 92 (c.276C>A) were altered once. Alterations on codons 82, 91, 108, 104, 105, 70 and 92 were characterized as possibly damaging by PolyPhen-2 and Mutation Taster2 tools. The current study also demonstrated that nucleotide alterations were significantly associated with the loss of p53 expression (P=0.04) and female patients (P=0.049), particularly codon 72. The results present novel data on the mutational spectrum of TP53 in meningeal brain tumors

Priručnik za vježbe iz biologije 1

Sveučilišni priručnik za vježbe iz Biologije 1 autora: Lidija Šver, Ana Bielen, Ivana Babić, Tomislav Vladušić, Reno Hrašćan, Ksenija Durgo, Jasna Franekić detaljno je i pristupačno napisano djelo namjenjeno prvenstveno studentima prve godine Prehrambeno-biotehnološkog fakuteta, no zbog multidisciplinarnosti ovaj priručnik može biti koršten i na drugim srodnim fakultetima ili višim razredima gimnazije bilo kao izvor fundamentalnih znanja iz biologije, bilo kao vodič za izvođenje određenih vježbi koje su opisane u samom priručniku. Priručnik je napisan na 244 stranice, a uključuje poglavlja: Napuci za rad na praktikumu iz modula Biologija 1 gdje su date detaljne upute o pravilima rada i ponašanja u praktikumu, pisanju znanstvenih naziva rodova i vrsta te informacije o vođenju laboratorijskog dnevnika. Slijedeće poglavlje bavi se mikroskopom, te je objašnjena građa i funkcija svakog pojedinog dijela mikroskopa te su predložene vježbe koje se izvode kako bi se izvježbale tehnike pravilnog mikroskopiranja. Drugo poglavlje bavi se građom stanične membrane, objašnjeni su fenomeni prijenosa tvari kroz membranu te su navedene vježbe kojima se zakonitosti prijenosa tvari krozn membranu mogu dokazati. U trećem poglavlju detaljno je obrađena stanična stijenka te se predloženim vježbama dokazuje građa i funkcija stanične stijenke biljnih stanica, komunikacija među biljnim stanicama te sekundarne promjene stanične stijenke. Četvrto poglavlje se bavi citoskeletom eukariotske stanice, mikrotubulima i mikrofilamentima te aktinskim filamentima. U petom su poglavlju detaljno obrađeni plastidi, a predloženim praktičnim dijelom studenti se upoznaju s kromoplastima, leukoplastima te kloroplastima, njihovim smještajem i ulogom u stanici. U šestom poglavlju objašnjena je uloga i smještaj ulja i masti te ugljikohidrata u stanici, detaljno su opisani kvalitativni testovi za dokazivanje ugljikohidrata te su predloženi i detaljno objašnjeni testovi kojima studenti mogu dokazivati određene skupine. Sedmo je poglavlje posvećeno DNA molekuli, njenom otkriću, građi i replikaciji, osmo se poglavlje bavi RNA molekulama, mehanizmima njihovog nastanka, procesiranja mRNA u eukariotima te procesom translacije. Deveto se poglavlje bavi produktima translacije-proteinima te metodama kojima se protein mogu dokazati. U desetom i jedanaestom poglavlju detaljno su objašnjeni procesi mitoze i mejoze te su predložene vježbe kojima je moguće pratiti promjene stupnja kondenzacije, položaja i broja molekula DNA te broja kromosoma tijekom procesa mitoze i mejoze. U dvanaestom poglavlju objašnjeni su Mendelovi postulati nasljeđivanja te su opisane metode monohibridnog križanja, test križanja te dihibridnog križanja. U trinaestom poglavlju studenti se upoznaju s genomom, životnim ciklusom te tehnikama uzgoja vinske mušice koja se koristi kao eksperimentalni model višestaničnog eukariotskog organizma. Detaljno je opisan postupak dokazivanja mutacija i nasljeđivanja svojstava vezanih uz spol vinske mušice. Četrnaesto i petnaesto poglavlje obrađuje teme vezane za međudjelovanje gena i populacijsku genetiku

AXIN-1 Protein Expression and Localization in Glioblastoma

The etiology and pathogenesis of tumors of the central nervous system are still inadequately explained. In the present study the expression patterns of a critical molecular component of wnt signaling pathway – axin 1 was investigated in 42 patients with glioblastoma, the most aggressive form of glial tumors. Immunostaining and image analysis revealed the quantity and localization of the protein. Downregulation of this tumor suppressor expression was observed in 31% of tumors when compared to the levels of axin in healthy brain tissues. Axin was observed in the cytoplasm in 69% of glioblastoma samples, in 21.4% in both the cytoplasm and nucleus and 9.5% had expression solely in the nucleus. Mean values of relative axin’s expression obtained by image analysis showed that the highest relative quantity of axin was measured when the protein was in the nucleus and the lowest relative quantity of axin when the protein was localized in the cytoplasm. Investigation on axin’s existence at the subcellular level in glioblastomas suggests that axin’s expression and spatial regulation is a dynamic process. Despite increasing knowledge on glioma biology and genetics, the prognostic tools for glioblastoma still need improvement. Our findings on expression of axin 1 may contribute to better understanding of glioblastoma molecular profile