TERF1

Abstract: Telomere encompasses a (TTAGGG)n tandem repeats, and its dysfunction has emerged as the epicenter of driving carcinogenesis by promoting genetic instability. Indeed, they play an essential role in stabilizing chromosomes and therefore protecting them from end-to-end fusion and DNA degradation. Telomere length homeostasis is regulated by several key players including shelterin complex genes, telomerase, and various other regulators. Targeting these regulatory players can be a good approach to combat cancer as telomere length is increasingly correlated with cancer initiation and progression. In this review, we have aimed to describe the telomere length regulator's role in prognostic significance and important drug targets in breast cancer. Moreover, we also assessed alteration in telomeric function by various telomere length regulators and compares this to the regulatory mechanisms that can be associated with clinical biomarkers in cancer. Using publicly available software we summarized mutational and CpG island prediction analysis of the TERT gene breast cancer patient database. Studies have reported that the TERT gene has prognostic significance in breast cancer progression however mechanistic approaches are not defined yet. Interestingly, we reported using the UCSC Xena web-based tool, we confirmed a positive correlation of shelterin complex genes TERF1 and TERF2 in recurrent free survival, indicating the critical role of these genes in breast cancer prognosis. Moreover, the epigenetic landscape of DNA damage repair genes in different breast cancer subtypes also being analyzed using the UCSC Xena database. Together, these datasets provide a comprehensive resource for shelterin complex gene profiles and define epigenetic landscapes of DNA damage repair genes which reveals the key role of shelterin complex genes in breast cancer with the potential to identify novel and actionable targets for treatment.

Abstract: Background Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterised by dystrophic nails, abnormal skin pigmentation and oral leukoplakia. Patients are at very high risk of cancer and other medical problems. They have exceedingly short telomeres for their age and approximately 60% have a germline mutation in a gene important in telomere biology ( DKC1 , TERC , TERT , TINF2 , NOP10 , or NHP2 ). The shelterin complex consists of six proteins encoded by TINF2 , ACD , POT1 , TERF1 , TERF2 and TERF2IP , which are essential for telomeric stability. TINF2 mutations are present in 11–25% of patients with DC. Methods Bi-directional sequence analysis was conducted of all exons, intron–exon boundaries and the proximal promoter of the other five shelterin genes to determine whether mutations in these genes were associated with DC. Sixteen mutation-negative patients, nine with DC and seven patients with short telomeres and bone marrow failure, were evaluated. Results Two variants were identified, ACD Ex1+189 G→A and TERF1 Ex9+59 G→A, which were each present in one patient and a healthy parent but absent in 364 controls. Three other variants were rare (<1%) but present in both patients and controls. Discussion These data suggest that except for TINF2 , mutations in shelterin genes are not a common cause of DC.

Abstract: Background: Telomeres, which are bound with shelterin protein complex, play an important role in maintaining genomic stability and its dysfunction may lead to carcinogenesis. Here, we aimed to analyze whether shelterin complex gene expression and telomere length variation, play any role in gallbladder carcinogenesis. Methods: Telomere length analysis was carried out by monochrome multiplex qPCR, whereas expression analysis of shelterin genes was carried out using RT-qPCR. Statistical analysis was carried out using SigmaPlot 11 software. Results: We found significantly reduced telomere length in tumor tissues, and this reduction was seen in both, tumors with or without gallstones in comparison to adjacent non tumor and gallstone (chronic calculous cholecystitis: Inflamed) tissues. Inflamed tissues showed increased telomere length as compared to both adjacent non tumor and tumor tissues. Expression analysis of five shelterin genes showed significant downregulation of TERF1, POT1, and TINF2 genes in inflamed tissues as compared to non tumor and tumor tissues. POT1 was also found to be significantly upregulated in tumor tissues and specifically in tumor tissues with gallstones compared to inflamed tissues. Conclusion: This study, thus, suggests that, gallstone does not affect telomere length and even after having increased telomere length, decreased expression of some shelterin genes in inflamed tissue might cause telomeres to cap improperly, possibly leading to telomere dysfunction and further, gallbladder carcinogenesis. Also, increased expression of POT1 in tumor tissues with gallstones could act as a diagnostic marker in patients with gallstones.

Abstract: Objective To detect mutations of human telomeric repeat binding factor 1 (TERF1) gene in 11 malignant hematopoietic cell lines, which have positive telomerase activity, and evaluate the significance of the mutations. Methods Genome structure of TERF1 was predicted by using biology information program, and verified by PCR and sequencing. Telomerase activity was detected by telomeric repeat amplification (TRAP)-ELISA. PCR and sequencing were used to detect mutation of each exon of TERF1 in 11 cell lines, including myelogenous leukemia cell lines K562, HL-60, U-937, NB4, THP-1, HEL and Dami; lymphoblastic leukemia cell lines 6T-CEM, Jurkat and Raji and MDS-RAEB cell line MUTZ-1. Five DNA samples from healthy volunteers were detected as normal controls. Results TERF1 gene has 10 exons and spans 38.6 kb. All the 11 cell lines showed positive telomerase activity. No mutation was found in all exons of TERF1 in the 11 cell lines. However, 4 variants were found in intron1, 2 and 8 near exon1, exon2 and exon9, respectively. The variants in MUTZ-1 was different from those in leukemia cell lines; but no difference was found between the variants in myelogenous and lymphoblastic leukemia cell lines. Conclusion TERF1 mutation is probably not among the main factors of the gene dysfunction in malignant hematopoietic diseases.