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result(s) for
"Rachakonda, Sivaramakrishna"
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TERT Promoter Mutations in Familial and Sporadic Melanoma
by
Horn, Susanne
,
Rachakonda, P. Sivaramakrishna
,
Hemminki, Kari
in
Binding Sites
,
Cell Line, Tumor
,
Cell lines
2013
Cutaneous melanoma occurs in both familial and sporadic forms. We investigated a melanoma-prone family through linkage analysis and high-throughput sequencing and identified a disease-segregating germline mutation in the promoter of the telomerase reverse transcriptase (TERT) gene, which encodes the catalytic subunit of telomerase. The mutation creates a new binding motif for Ets transcription factors and ternary complex factors (TCFs) near the transcription start and, in reporter gene assays, caused up to twofold increase in transcription. We then screened the TERT promoter in sporadic melanoma and observed recurrent ultraviolet signature somatic mutations in 125 of 168 (74%) of human cell lines derived from metastatic melanomas, 45 of 53 corresponding metastatic tumor tissues (85%), and 25 of 77 (33%) primary melanomas. The majority of those mutations occurred at two positions in the TERT promoter and also generated binding motifs for Ets/TCF transcription factors.
Journal Article
TERT promoter mutations in bladder cancer affect patient survival and disease recurrence through modification by a common polymorphism
by
de Verdier, Petra J.
,
Ryk, Charlotta
,
Wiklund, N. Peter
in
Aged, 80 and over
,
Alleles
,
Base Sequence
2013
The telomerase reverse transcriptase (TERT) promoter, an important element of telomerase expression, has emerged as a target of cancer-specific mutations. Originally described in melanoma, the mutations in TERT promoter have been shown to be common in certain other tumor types that include glioblastoma, hepatocellular carcinoma, and bladder cancer. To fully define the occurrence and effect of the TERT promoter mutations, we investigated tumors from a well-characterized series of 327 patients with urothelial cell carcinoma of bladder. The somatic mutations, mainly at positions −124 and −146 bp from ATG start site that create binding motifs for E-twenty six/ternary complex factors (Ets/TCF), affected 65.4% of the tumors, with even distribution across different stages and grades. Our data showed that a common polymorphism rs2853669, within a preexisting Ets2 binding site in the TERT promoter, acts as a modifier of the effect of the mutations on survival and tumor recurrence. The patients with the mutations showed poor survival in the absence [hazard ratio (HR) 2.19, 95% confidence interval (CI) 1.02–4.70] but not in the presence (HR 0.42, 95% CI 0.18–1.01) of the variant allele of the polymorphism. The mutations in the absence of the variant allele were highly associated with the disease recurrence in patients with Tis, Ta, and T1 tumors (HR 1.85, 95% CI 1.11–3.08). The TERT promoter mutations are the most common somatic lesions in bladder cancer with clinical implications. The association of the mutations with patient survival and disease recurrence, subject to modification by a common polymorphism, can be a unique putative marker with individualized prognostic potential.
Journal Article
Coding and noncoding somatic mutations in candidate genes in basal cell carcinoma
2020
Basal cell carcinoma (BCC) represents the most commonly diagnosed human cancer among persons of European ancestry with etiology mainly attributed to sun-exposure. In this study we investigated mutations in coding and flanking regions of
PTCH1
and
TP53
and noncoding alterations in the
TERT
and
DPH3
promoters in 191 BCC tumors. In addition, we measured CpG methylation within the
TERT
hypermethylated oncological region (THOR) and transcription levels of the reverse transcriptase subunit. We observed mutations in
PTCH1
in 58.6% and
TP53
in 31.4% of the tumors. Noncoding mutations in
TERT
and
DPH3
promoters were detected in 59.2% and 38.2% of the tumors, respectively. We observed a statistically significant co-occurrence of mutations at the four investigated loci. While
PTCH1
mutations tended to associate with decreased patient age at diagnosis;
TP53
mutations were associated with light skin color and increased number of nevi;
TERT
and
DPH3
promoter with history of cutaneous neoplasms in BCC patients. Increased reverse transcriptase subunit expression was observed in tumors with
TERT
promoter mutations and not with THOR methylation. Our study signifies, in addition to the protein altering mutations in the
PTCH1
and
TP53
genes, the importance of noncoding mutations in BCC, particularly functional alterations in the
TERT
promoter.
Journal Article
Polymorphisms in CXCR3 ligands predict early CXCL9 recovery and severe chronic GVHD
by
Rachakonda, Sivaramakrishna P
,
Penack Olaf
,
Dreger, Peter
in
Cancer
,
Health risk assessment
,
Ligands
2021
Chronic graft-versus-host disease (cGVHD) is a major cause of mortality and morbidity after allogeneic stem cell transplantation (alloSCT). The individual risk of severe cGVHD remains difficult to predict and may involve CXCR3 ligands. This study investigated the role of single-nucleotide polymorphisms (SNPs) of CXCL4, CXCL9, CXCL10, and CXCL11, and their day +28 serum levels, in cGVHD pathogenesis. Eighteen CXCR3 and CXCL4, CXCL9–11 SNPs as well as peri-transplant CXCL9–11 serum levels were analyzed in 688 patients without (training cohort; n = 287) or with statin-based endothelial protection cohort (n = 401). Clinical outcomes were correlated to serum levels and SNP status. Significant polymorphisms were further analyzed by luciferase reporter assays. Findings were validated in an independent cohort (n = 202). A combined genetic risk comprising four CXCR3 ligand SNPs was significantly associated with increased risk of severe cGVHD in both training cohort (hazard ratio (HR) 2.48, 95% confidence interval (CI) 1.33–4.64, P = 0.004) and validation cohort (HR 2.95, 95% CI 1.56–5.58, P = 0.001). In reporter assays, significantly reduced suppressive effects of calcineurin inhibitors in constructs with variant alleles of rs884304 (P < 0.001) and rs884004 (P < 0.001) were observed. CXCL9 serum levels at day +28 after alloSCT correlated with both genetic risk and risk of severe cGVHD (HR 1.38, 95% CI 1.10–1.73, P = 0.006). This study identifies patients with high genetic risk to develop severe cGVHD.
Journal Article
Telomeres and Telomere Length: A General Overview
2020
Telomeres are highly conserved tandem nucleotide repeats that include proximal double-stranded and distal single-stranded regions that in complex with shelterin proteins afford protection at chromosomal ends to maintain genomic integrity. Due to the inherent limitations of DNA replication and telomerase suppression in most somatic cells, telomeres undergo age-dependent incremental attrition. Short or dysfunctional telomeres are recognized as DNA double-stranded breaks, triggering cells to undergo replicative senescence. Telomere shortening, therefore, acts as a counting mechanism that drives replicative senescence by limiting the mitotic potential of cells. Telomere length, a complex hereditary trait, is associated with aging and age-related diseases. Epidemiological data, in general, support an association with varying magnitudes between constitutive telomere length and several disorders, including cancers. Telomere attrition is also influenced by oxidative damage and replicative stress caused by genetic, epigenetic, and environmental factors. Several single nucleotide polymorphisms at different loci, identified through genome-wide association studies, influence inter-individual variation in telomere length. In addition to genetic factors, environmental factors also influence telomere length during growth and development. Telomeres hold potential as biomarkers that reflect the genetic predisposition together with the impact of environmental conditions and as targets for anti-cancer therapies.
Journal Article
Somatic Mutations in Exocrine Pancreatic Tumors: Association with Patient Survival
by
Rizzato, Cosmeri
,
Beghelli, Stefania
,
Rachakonda, P. Sivaramakrishna
in
Aberration
,
Aged
,
Analysis
2013
KRAS mutations are major factors involved in initiation and maintenance of pancreatic tumors. The impact of different mutations on patient survival has not been clearly defined. We screened tumors from 171 pancreatic cancer patients for mutations in KRAS and CDKN2A genes. Mutations in KRAS were detected in 134 tumors, with 131 in codon 12 and only 3 in codon 61. The GGT>GAT (G12D) was the most frequent mutation and was present in 60% (80/134). Deletions and mutations in CDKN2A were detected in 43 tumors. Analysis showed that KRAS mutations were associated with reduced patient survival in both malignant exocrine and ductal adenocarcinomas (PDAC). Patients with PDACs that had KRAS mutations showed a median survival of 17 months compared to 30 months for those without mutations (log-rank P = 0.07) with a multivariate hazard ratio (HR) of 2.19 (95%CI 1.09-4.42). The patients with G12D mutation showed a median survival of 16 months (log-rank-test P = 0.03) and an associated multivariate HR 2.42 (95%CI 1.14-2.67). Although, the association of survival in PDAC patients with CDKN2A aberrations in tumors was not statistically significant, the sub-group of patients with concomitant KRAS mutations and CDKN2A alterations in tumors were associated with a median survival of 13.5 months compared to 22 months without mutation (log-rank-test P = 0.02) and a corresponding HR of 3.07 (95%CI 1.33-7.10). Our results are indicative of an association between mutational status and survival in PDAC patients, which if confirmed in subsequent studies can have potential clinical application.
Journal Article
Custom gene expression panel for evaluation of potential molecular markers in hepatocellular carcinoma
by
Velavan, Thirumalaisamy P.
,
Giang, Dao Phuong
,
Toan, Nguyen Linh
in
alpha-Fetoproteins
,
Architects
,
Biological markers
2022
Background
Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality worldwide. It is a highly heterogeneous disease with poor prognosis and limited treatment options, which highlights the need for reliable biomarkers. This study aims to explore molecular markers that allow stratification of HCC and may lead to better prognosis and treatment prediction.
Materials and methods
We studied 20 candidate genes (HCC hub genes, potential drug target genes, predominant somatic mutant genes) retrieved from literature and public databases with potential to be used as the molecular markers. We analysed expression of the genes by RT-qPCR in 30 HCC tumour and adjacent non-tumour paired samples from Vietnamese patients. Fold changes in expression were then determined using the 2
−∆∆CT
method, and unsupervised hierarchical clustering was generated using Cluster v3.0 software.
Results
Clustering of expression data revealed two subtypes of tumours (proliferative and normal-like) and four clusters for genes. The expression profiles of the genes
TOP2A, CDK1, BIRC5, GPC3, IGF2,
and
AFP
were strongly correlated. Proliferative tumours were characterized by high expression of the c
-MET, ARID1A, CTNNB1, RAF1, LGR5
, and
GLUL1
genes.
TOP2A, CDK1
, and
BIRC5
HCC hub genes were highly expressed (> twofold) in 90% (27/30), 83% (25/30), and 83% (24/30) in the tissue samples, respectively. Among the drug target genes, high expression was observed in the
GPC3, IGF2
and
c-MET
genes in 77% (23/30), 63% (19/30), and 37% (11/30), respectively. The somatic mutant Wnt/ß-catenin genes (
CTNNB1, GLUL and LGR5
) and
TERT
were highly expressed in 40% and 33% of HCCs, respectively. Among the HCC marker genes, a higher percentage of tumours showed
GPC3
expression compared to
AFP
expression [73% (23/30) vs. 43% (13/30)].
Conclusion
The custom panel and molecular markers from this study may be useful for diagnosis, prognosis, biomarker-guided clinical trial design, and prediction of treatment outcomes.
Journal Article
Telomerase reverse transcriptase promoter mutations in primary cutaneous melanoma
2014
We previously reported a disease segregating causal germline mutation in a melanoma family and recurrent somatic mutations in metastasized tumours from unrelated patients in the core promoter region of the telomerase reverse transcriptase (
TERT
) gene. Here we show that the
TERT
promoter mutations, besides causing an increased gene expression, associate with increased patient age, increased Breslow thickness and tumour ulceration in 287 primary melanomas. The mutations are more frequent at both intermittently and chronically sun-exposed sites than non-exposed sites and tend to co-occur with
BRAF
and
CDKN2A
alterations. The association with parameters generally connected with poor outcome, coupled with high recurrence and mechanistic relevance, raises the possibility of the eventual use of
TERT
promoter mutations in the disease management.
Cutaneous melanoma is an aggressive form of skin cancer. Here, the authors show that mutations in the TERT promoter of 287 primary melanomas are associated with age, Breslow thickness and tumour ulceration and frequently occur at sun-exposed sites.
Journal Article
Pancreatic Cancer Susceptibility Loci and Their Role in Survival
by
Key, Tim J.
,
Rizzato, Cosmeri
,
Werner, Jens
in
ABO Blood-Group System - genetics
,
ABO system
,
Adenocarcinoma
2011
Pancreatic cancer has one of the worst mortality rates of all cancers. Little is known about its etiology, particularly regarding inherited risk. The PanScan project, a genome-wide association study, identified several common polymorphisms affecting pancreatic cancer susceptibility. Single nucleotide polymorphisms (SNPs) in ABO, sonic hedgehog (SHH), telomerase reverse transcriptase (TERT), nuclear receptor subfamily 5, group A, member 2 (NR5A2) were found to be associated with pancreatic cancer risk. Moreover the scan identified loci on chromosomes 13q22.1 and 15q14, to which no known genes or other functional elements are mapped. We sought to replicate these observations in two additional, independent populations (from Germany and the UK), and also evaluate the possible impact of these SNPs on patient survival. We genotyped 15 SNPs in 690 cases of pancreatic ductal adenocarcinoma (PDAC) and in 1277 healthy controls. We replicated several associations between SNPs and PDAC risk. Furthermore we found that SNP rs8028529 was weakly associated with a better overall survival (OS) in both populations. We have also found that NR5A2 rs12029406_T allele was associated with a shorter survival in the German population. In conclusion, we found that rs8028529 could be, if these results are replicated, a promising marker for both risk and prognosis for this lethal disease.
Journal Article