Human hotspot TERT promoter (TERTp) mutations have been reported in a wide range of tumours. Several studies have shown that TERTp mutations are associated with clinicopathological features; in some ...instances, TERTp mutations were considered as biomarkers of poor prognosis. The rs2853669 SNP, located in the TERT promoter region, was reported to modulate the increased TERT expression levels induced by the recurrent somatic mutations. In this study we aimed to determine the frequency and prognostic value of TERTp mutations and TERT rs2853669 SNP in 504 gliomas from Portuguese and Brazilian patients. TERTp mutations were detected in 47.8% of gliomas (216/452). Glioblastomas (GBM) exhibited the highest frequency of TERTp mutations (66.9%); in this glioma subtype, we found a significant association between TERTp mutations and poor prognosis, regardless of the population. Moreover, in a multivariate analysis, TERTp mutations were the only independent prognostic factor. Our data also showed that the poor prognosis conferred by TERTp mutations was restricted to GBM patients carrying the rs2853669 A allele and not in those carrying the G allele. In conclusion, the presence of TERTp mutations was associated with worse prognosis in GBM patients, although such association depended on the status of the rs2853669 SNP. The status of the rs2853669 SNP should be taken in consideration when assessing the prognostic value of TERTp mutations in GBM patients. TERTp mutations and the rs2853669 SNP can be used in the future as biomarkers of glioma prognosis.
What's new?
Cancer cells avoid senescence in part by reactivating telomerase (TERT), a ribonucleoprotein that replenishes shortening telomeres. Here, the authors discover a positive association between TERT promoter mutations and unfavorable prognosis in glioblastoma patients from Portuguese and Brazilian origin. This association was only observed in patients with a specific allelic background (AA) in a TERT polymorphism (rs2853669) recently linked to enhanced TERT mRNA levels. The authors recommend considering the allelic status of rs2853669 when assessing the prognostic value of TERT promoter mutations in glioblastoma patients.
The 5'-methylthioadenosine phosphorylase (MTAP) gene is located in the chromosomal region 9p21.
deletion is a frequent event in a wide variety of human cancers; however, its biological role in ...tumorigenesis remains unclear. The purpose of this study was to characterize the MTAP expression profile in a series of gliomas and to associate it with patients' clinicopathological features. Moreover, we sought to evaluate, through glioma gene-edited cell lines, the biological impact of MTAP in gliomas. MTAP expression was evaluated in 507 glioma patients by immunohistochemistry (IHC), and the expression levels were associated with patients' clinicopathological features. Furthermore, an in silico study was undertaken using genomic databases totalizing 350 samples. In glioma cell lines, MTAP was edited, and following MTAP overexpression and knockout (KO), a transcriptome analysis was performed by NanoString Pan-Cancer Pathways panel. Moreover, MTAP's role in glioma cell proliferation, migration, and invasion was evaluated. Homozygous deletion of 9p21 locus was associated with a reduction of
mRNA expression in the TCGA (The Cancer Genome Atlas) - glioblastoma dataset (p < 0.01). In addition, the loss of
expression was markedly high in high-grade gliomas (46.6% of cases) determined by IHC and Western blotting (40% of evaluated cell lines). Reduced
expression was associated with a better prognostic in the adult glioblastoma dataset (
< 0.001). Nine genes associated with five pathways were differentially expressed in MTAP-knockout (KO) cells, with six upregulated and three downregulated in MTAP. Analysis of cell proliferation, migration, and invasion did not show any significant differences between MTAP gene-edited and control cells. Our results integrating data from patients as well as in silico and in vitro models provide evidence towards the lack of strong biological importance of MTAP in gliomas. Despite the frequent loss of MTAP, it seems not to have a clinical impact in survival and does not act as a canonic tumor suppressor gene in gliomas.
Copy number alterations (CNA) are one of the driving mechanisms of glioma tumorigenesis, and are currently used as important biomarkers in the routine setting. Therefore, we performed CNA profiling ...of 65 astrocytomas of distinct malignant grades (WHO grade I-IV) of Brazilian origin, using array-CGH and microsatellite instability analysis (MSI), and investigated their correlation with TERT and IDH1 mutational status and clinico-pathological features. Furthermore, in silico analysis using the Oncomine database was performed to validate our findings and extend the findings to gene expression level. We found that the number of genomic alterations increases in accordance with glioma grade. In glioblastomas (GBM), the most common alterations were gene amplifications (PDGFRA, KIT, KDR, EGFR, and MET) and deletions (CDKN2A and PTEN) Log-rank analysis correlated EGFR amplification and/or chr7 gain with better survival of the patients. MSI was observed in 11% of GBMs. A total of 69% of GBMs presented TERT mutation, whereas IDH1 mutation was most frequent in diffuse (85.7%) and anaplastic (100%) astrocytomas. The combination of 1p19q deletion and TERT and IDH1 mutational status separated tumor groups that showed distinct age of diagnosis and outcome. In silico validation pointed to less explored genes that may be worthy of future investigation, such as CDK2, DMRTA1, and MTAP Herein, using an extensive integrated analysis, we indicated potentially important genes, not extensively studied in gliomas, that could be further explored to assess their biological and clinical impact in astrocytomas.
Pyknons are specific human/primate-specific DNA motifs at least 16 nucleotides long that are repeated in blocks in intergenic and intronic regions of the genome and can be located in a new class of ...non-coding RNAs of variable length. Recent studies reported that pyknon deregulation could be involved in the carcinogenesis process, including colorectal cancer. We evaluated the expression profile of a set of 12 pyknons in a set of molecularly characterized colorectal cancer (CRC) patients. The pyknons (
PYK10
,
PYK14
,
PYK17
,
PYK26
,
PYK27
,
PYK40
,
PYK41
,
PYK42
,
PYK43
,
PYK44
,
PYK83
, and
PYK90
) expression was determined by qRT-PCR. A pilot analysis of 20 cases was performed, and consistent results were obtained for
PYK10
,
PYK17
,
PYK42
,
PYK44
, and
PYK83
. Further, the expression of the selected pyknons was evaluated in 73 CRC cases. Moreover, in 52 patients, we compared the expression profile in both tumor and normal tissues. All five pyknons analyzed showed significantly lower expression levels in the tumor compared to normal tissue. It was observed an association between expression of
PYK10
with
TP53
mutations (
p
= 0.029),
PYK17
to histologic grade (
p
= 0.035), and
PYK44
to clinical staging (
p
= 0.016). Moreover, levels of
PYK44
were significantly associated with the patient's poor overall survival (
p
= 0.04). We reported the significant downregulation of pyknons motifs in tumor tissue compared with the normal counterpart, and the association of lower
PYK44
expression with worse patient outcome. Further studies are needed to extend and validate these findings and determine the clinical-pathological impact.
PDF
