Regulation of mutant TERT by BRAF V600E/MAP kinase pathway through FOS/GABP in human cancer

TERT upstream promoter methylation regulates TERT expression and acts as a therapeutic target in TERT promoter mutation-negative thyroid cancer

BACKGROUND

DNA hypermethylation and hotspot mutations were frequently observed in the upstream and core promoter of telomerase reverse transcriptase (TERT), respectively, and they were associated with increased TERT expression and adverse clinical outcomes in thyroid cancer. In TERT promoter mutant cancer cells, the hypomethylated TERT mutant allele was active and the hypermethylated TERT wild-type allele was silenced. However, whether and how the upstream promoter methylation regulates TERT expression in TERT mutation-negative cells were largely unknown.

METHODS

DNA demethylating agents 5-azacytidine and decitabine and a genomic locus-specific demethylation system based on dCas9-TET1 were used to assess the effects of TERT upstream promoter methylation on TERT expression, cell growth and apoptosis of thyroid cancer cells. Regulatory proteins binding to TERT promoter were identified by CRISPR affinity purification in situ of regulatory elements (CAPTURE) combined with mass spectrometry. The enrichments of selected regulatory proteins and histone modifications were evaluated by chromatin immunoprecipitation.

RESULTS

The level of DNA methylation at TERT upstream promoter and expression of TERT were significantly decreased after treatment with 5-azacytidine or decitabine in TERT promoter wild-type thyroid cancer cells. Genomic locus-specific demethylation of TERT upstream promoter induced TERT downregulation, along with cell apoptosis and growth inhibition. Consistently, demethylating agents sharply inhibited the growth of thyroid cancer cells harboring hypermethylated TERT but had little effect on cells with TERT hypomethylation. Moreover, we identified that the chromatin remodeling protein CHD4 binds to methylated TERT upstream promoter and promotes its transcription by suppressing the enrichment of H3K9me3 and H3K27me3 at TERT promoter.

CONCLUSIONS

This study uncovered the mechanism of promoter methylation mediated TERT activation in TERT promoter mutation-negative thyroid cancer cells and indicated TERT upstream promoter methylation as a therapeutic target for thyroid cancer.

Risk stratification by combining common genetic mutations and TERT promoter methylation in papillary thyroid cancer

PURPOSE

Risk stratification based on somatic mutations in TERT promoter and BRAF/RAS has been well established for papillary thyroid cancer (PTC), and there is emerging evidence showed that TERT promoter methylation was frequently observed in thyroid cancer patients with adverse features. This study was aimed to comprehensive explore the prognostic value of BRAF/RAS mutations, TERT promoter mutations, and TERT promoter methylation in PTC.

METHODS

The relationships of BRAF/RAS mutations, TERT promoter mutations, and TERT promoter methylation with clinical characteristics and outcomes of PTC were analyzed in 382 patients with PTC.

RESULTS

TERT promoter mutation and hypermethylation were collectively observed in 52 (13.6%) samples and associated with BRAF/RAS mutation, aggressive clinical characteristics, and poor clinical outcomes of PTC. Coexistence of BRAF/RAS and TERT alterations was found in 45 of 382 (11.8%) PTC patients and strongly associated with old patient age, extrathyroidal extension, advanced pathologic T stage and metastasis. Importantly, patients with both BRAF/RAS and TERT alterations had higher rates of tumor recurrence (13.6% vs 1.5%, P = 0.042) and disease progression (24.4% vs 3.3%, P < 0.001) than patients without any alterations, and cox regression analysis revealed that the coexistence of BRAF/RAS and TERT alterations, but not BRAF/RAS or TERT alterations alone, increased the risk of progression-free interval with an adjusted HR of 10.35 (95% CI: 1.79-59.81, P = 0.009).

CONCLUSIONS

This study suggested that comprehensively analysis of BRAF/RAS mutations, TERT promoter mutation and methylation is an effective strategy to identify high-risk patients with PTC.

Homogentisic acid metabolism inhibits papillary thyroid carcinoma proliferation through ROS and p21-induced cell cycle arrest

Thyroid cancer is one of the most common primary endocrine malignancies worldwide, and papillary thyroid carcinoma (PTC) is the predominant histological type observed therein. Although PTC has been studied extensively, our understanding of the altered metabolism and metabolic profile of PTC tumors is limited. We identified that the content of metabolite homogentisic acid (HGA) in PTC tissues was lower than that in adjacent non-cancerous tissues. We evaluated the potential of HGA as a novel molecular marker in the diagnosis of PTC tumors, as well as its ability to indicate the degree of malignancy. Studies have further shown that HGA contributes to reactive oxygen species (ROS) associated oxidative stress, leading to toxicity and inhibition of proliferation. In addition, HGA caused an increase in p21 expression levels in PTC cells and induced G1 arrest. Moreover, we found that the low HGA content in PTC tumors was due to the low expression levels of tyrosine aminotransferase (TAT) and p-hydroxyphenylpyruvate hydroxylase (HPD), which catalyze the conversion of tyrosine to HGA. The low expression levels of TAT and HPD are strongly associated with a higher probability of PTC tumor invasion and metastasis. Our study demonstrates that HGA could be used to diagnose PTC and provides mechanisms linking altered HGA levels to the biological behavior of PTC tumors.

Genetic trio of BRAF and TERT alterations and rs2853669TT in papillary thyroid cancer aggressiveness

BACKGROUND

BRAF V600E and TERT promoter alterations are core components in current genetics-based risk assessment for precision management of papillary thyroid cancer. It remains unknown whether this approach could achieve even better precision through a widely recognized prognostic single-nucleotide variation (SNV, formerly SNP), rs2853669T>C, in the TERT promoter.

METHODS

The genetic status of alterations and SNV were examined by sequencing genomic DNA from papillary thyroid cancer in 608 patients (427 women and 181 men) aged 47 years (interquartile range = 37-57), with a median follow-up time of 75 months (interquartile range = 36-123), and their relationship with clinical outcomes was analyzed. A luciferase reporter assay was performed to examine TERT promoter activities.

RESULTS

TERT promoter alterations showed a strong association with papillary thyroid cancer recurrence in the presence of genotype TT of rs2853669 (adjusted hazard ratio [HR] = 2.12, 95% confidence interval [CI] = 1.10 to 4.12) but not TC/CC (adjusted HR = 1.17, 95% CI = 0.56 to 2.41). TERT and BRAF alterations commonly coexisted and synergistically promoted papillary thyroid cancer recurrence. With this genetic duet, TT of rs2853669 showed a robustly higher disease recurrence than TC/CC (adjusted HR = 14.26, 95% CI = 2.86 to 71.25). Patients with the genetic trio of BRAF V600E, TERT alteration, and TT of rs2853669 had a recurrence of 76.5% vs recurrence of 8.4% with neither variation and with TC/CC (HR = 13.48, 95% CI = 6.44 to 28.21). T allele of rs2853669 strongly increased TERT promoter activities, particularly the variant promoters.

CONCLUSIONS

The SNV rs2853669T>C dramatically refines the prognostic power of BRAF V600E and TERT promoter alterations to a higher precision, suggesting the need for including this SNV in the current genetics-based risk prognostication of papillary thyroid cancer.

A Phase 2 Study of Encorafenib in Combination with Binimetinib in Patients with Metastatic BRAF-Mutated Thyroid Cancer in Japan

Background: Driver mutations at BRAF V600 are frequently identified in papillary thyroid cancer and anaplastic thyroid cancer (ATC), in which BRAF inhibitors have shown clinical effectiveness. This Japanese phase 2 study evaluated the efficacy and safety of a BRAF inhibitor, encorafenib, combined with an MEK inhibitor, binimetinib, in patients with BRAF V600-mutated thyroid cancer. Methods: This phase 2, open-label, uncontrolled study was conducted at 10 institutions targeted patients with BRAF V600-mutated locally advanced or distant metastatic thyroid cancer not amenable to curative treatment who became refractory/intolerant to ≥1 previous vascular endothelial growth factor receptor-targeted regimen(s) or were considered ineligible for those. The primary endpoint was centrally assessed objective response rate (ORR). The secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Results: We enrolled 22 patients with BRAFV600E-mutated thyroid cancer: 17 had differentiated thyroid cancer (DTC), and 5 had ATC. At data cutoff (October 26, 2022), the median follow-up was 11.5 (range = 3.4-19.0) months. The primary endpoint of centrally assessed ORR was 54.5% (95% confidence interval [CI] 32.2-75.6; partial response in 12 patients and stable disease in 10). The ORRs in patients with DTC and ATC were 47.1% (8 of 17) and 80.0% (4 of 5), respectively. The medians for DOR and PFS by central assessment and for OS were not reached in the overall population, the DTC subgroup, or the ATC subgroup. At 12 months, the rate of ongoing response was 90.9%, and the PFS and OS rates were 78.8% and 81.8%, respectively. All patients developed ≥1 adverse events (AEs): grade 3 AEs in 6 patients (27.3%). No patients developed grade 4-5 AEs. The most common grade 3 AE was lipase increased (4 patients [18.2%]). Those toxicities were mostly manageable with appropriate monitoring and dose adjustment. Conclusions: Treatment with encorafenib plus binimetinib met the primary endpoint criteria and demonstrated clinical benefit in patients with BRAFV600E-mutated thyroid cancer regardless of its histological type, such as DTC or ATC, with no new safety concerns identified. Encorafenib plus binimetinib could thus be a new treatment option for BRAF V600-mutated thyroid cancer. Clinical Trial Registration number: Japan Registry of Clinical Trials: jRCT2011200018.

Risk stratification for radioactive iodine refractoriness using molecular alterations in distant metastatic differentiated thyroid cancer

Objective

Patients with radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) are often diagnosed with delay and constrained to limited treatment options. The correlation between RAI refractoriness and the underlying genetic characteristics has not been extensively studied.

Methods

Adult patients with distant metastatic DTC were enrolled and assigned to undergo next-generation sequencing of a customized 26-gene panel (ThyroLead). Patients were classified into RAIR-DTC or non-RAIR groups to determine the differences in clinicopathological and molecular characteristics. Molecular risk stratification (MRS) was constructed based on the association between molecular alterations identified and RAI refractoriness, and the results were classified as high, intermediate or low MRS.

Results

A total of 220 patients with distant metastases were included, 63.2% of whom were identified as RAIR-DTC. Genetic alterations were identified in 90% of all the patients, with BRAF (59.7% vs. 17.3%), TERT promoter (43.9% vs. 7.4%), and TP53 mutations (11.5% vs. 3.7%) being more prevalent in the RAIR-DTC group than in the non-RAIR group, except for RET fusions (15.8% vs. 39.5%), which had the opposite pattern. BRAF and TERT promoter are independent predictors of RAIR-DTC, accounting for 67.6% of patients with RAIR-DTC. MRS was strongly associated with RAI refractoriness (P<0.001), with an odds ratio (OR) of high to low MRS of 7.52 [95% confidence interval (95% CI), 3.96-14.28; P<0.001] and an OR of intermediate to low MRS of 3.20 (95% CI, 1.01-10.14; P=0.041).

Conclusions

Molecular alterations were associated with RAI refractoriness, with BRAF and TERT promoter mutations being the predominant contributors, followed by TP53 and DICER1 mutations. MRS might serve as a valuable tool for both prognosticating clinical outcomes and directing precision-based therapeutic interventions.

Genomic alterations in thyroid cancer: biological and clinical insights

Tumours can arise from thyroid follicular cells if they acquire driver mutations that constitutively activate the MAPK signalling pathway. In addition, a limited set of additional mutations in key genes drive tumour progression towards more aggressive and less differentiated disease. Unprecedented insights into thyroid tumour biology have come from the breadth of thyroid tumour sequencing data from patients and the wide range of mutation-specific mechanisms identified in experimental models, in combination with the genomic simplicity of thyroid cancers. This knowledge is gradually being translated into refined strategies to stratify, manage and treat patients with thyroid cancer. This Review summarizes the biological underpinnings of the genetic alterations involved in thyroid cancer initiation and progression. We also provide a rationale for and discuss specific examples of how to implement genomic information to inform both recommended and investigational approaches to improve thyroid cancer prognosis, redifferentiation strategies and targeted therapies.

The regulations of telomerase reverse transcriptase (TERT) in cancer

Abnormal activation of telomerase occurs in most cancer types, which facilitates escaping from cell senescence. As the key component of telomerase, telomerase reverse transcriptase (TERT) is regulated by various regulation pathways. TERT gene changing in its promoter and phosphorylation respectively leads to TERT ectopic expression at the transcription and protein levels. The co-interacting factors play an important role in the regulation of TERT in different cancer types. In this review, we focus on the regulators of TERT and these downstream functions in cancer regulation. Determining the specific regulatory mechanism will help to facilitate the development of a cancer treatment strategy that targets telomerase and cancer cell senescence. As the most important catalytic subunit component of telomerase, TERT is rapidly regulated by transcriptional factors and PTM-related activation. These changes directly influence TERT-related telomere maintenance by regulating telomerase activity in telomerase-positive cancer cells, telomerase assembly with telomere-binding proteins, and recruiting telomerase to the telomere. Besides, there are also non-canonical functions that are influenced by TERT, including the basic biological functions of cancer cells, such as proliferation, apoptosis, cell cycle regulation, initiating cell formation, EMT, and cell invasion. Other downstream effects are the results of the influence of transcriptional factors by TERT. Currently, some small molecular inhibitors of TERT and TERT vaccine are under research as a clinical therapeutic target. Purposeful work is in progress.

TERT promoter methylation is associated with high expression of TERT and poor prognosis in papillary thyroid cancer

The telomerase reverse transcriptase (TERT) is overexpressed and associated with poor prognosis in papillary thyroid cancer (PTC), the most common subtype of thyroid cancer. The overexpression of TERT in PTC was partially attributed to transcriptional activation by two hotspot mutations in the core promoter region of this gene. As one of the major epigenetic mechanisms of gene expression regulation, DNA methylation has been proved to regulate several tumor-related genes in PTC. However, the association of TERT promoter DNA methylation with TERT expression and PTC progression is still unclear. By treating PTC cell lines with demethylating agent decitabine, we found that the TERT promoter methylation and the genes' expression were remarkably decreased. Consistently, PTC patients with TERT hypermethylation had significantly higher TERT expression than patients with TERT hypomethylation. Moreover, TERT hypermethylated patients showed significant higher rates of poor clinical outcomes than patients with TERT hypomethylation. Results from the cox regression analysis showed that the hazard ratios (HRs) of TERT hypermethylation for overall survival, disease-specific survival, disease-free interval (DFI) and progression-free interval (PFI) were 4.81 (95% CI, 1.61-14.41), 8.28 (95% CI, 2.14-32.13), 3.56 (95% CI, 1.24-10.17) and 3.32 (95% CI, 1.64-6.71), respectively. The HRs for DFI and PFI remained significant after adjustment for clinical risk factors. These data suggest that promoter DNA methylation upregulates TERT expression and associates with poor clinical outcomes of PTC, thus holds the potential to be a valuable prognostic marker for PTC risk stratification.

CircGLIS3 inhibits thyroid cancer invasion and metastasis through miR-146b-3p/AIF1L axis

PURPOSE

Studies have shown that circRNA is involved in the occurrence and development of human cancers. However, it remains unclear that the contribution of circRNA in thyroid carcinoma and its role in the process of tumorigenesis.

METHODS

The expression profile of circRNA-miRNA-mRNA in thyroid carcinoma was detected by RNA sequencing and verified by qRT-PCR. The characteristics of circGLIS3 were verified by RNase R and actinomycin assays, subcellular fractionation, and fluorescence in situ hybridization. The functions of circGLIS3 and AIF1L were detected by wound healing, transwell, 3D culture and Western blot. RNA Immunoprecipitation (RIP), RNA pulldown and dual-luciferase reporter assays were used to verify the target genes of circGLIS3 and downstream miRNAs. Functional rescue experiments were performed by transfecting miRNA mimics or siRNA of target genes. Finally, metastatic mouse models were used to investigate circGLIS3 function in vivo.

RESULTS

In this study, we discovered a novel circRNA (has_circ_0007368, named as circGLIS3) by RNA sequencing. CircGLIS3 was down-regulated in thyroid carcinoma tissues and cells line, and was negatively associated with malignant clinical features of thyroid carcinoma. Functional studies found that circGLIS3 could inhibit the migration and invasion of thyroid carcinoma cells, and was related to the EMT process. Mechanistically, circGLIS3 can upregulate the expression of the AIF1L gene by acting as a miR-146b-3p sponge to inhibit the progression of thyroid carcinoma.

CONCLUSION

Our study identified circGLIS3 as a novel tumor suppressor in thyroid cancer, indicating the potential of circGLIS3 as a promising diagnostic and prognostic marker for thyroid cancer.

Therapeutic inhibition of ATR in differentiated thyroid cancer

Ataxia telangiectasia and Rad3-related protein (ATR) is a critical component of the DNA damage response and a potential target in the treatment of cancers. An ATR inhibitor, BAY 1895344, was evaluated for its use in differentiated thyroid cancer (DTC) therapy. BAY 1895344 inhibited cell viability in four DTC cell lines (TPC1, K1, FTC-133, and FTC-238) in a dose-dependent manner. BAY 1895344 treatment arrested DTC cells in the G2/M phase, increased caspase-3 activity, and caused apoptosis. BAY 1895344 in combination with either sorafenib or lenvatinib showed mainly synergistic effects in four DTC cell lines. The combination of BAY 1895344 with dabrafenib plus trametinib revealed synergistic effects in K1 cells that harbor BRAFV600E. BAY 1895344 monotherapy retarded the growth of K1 and FTC-133 tumors in xenograft models. The combinations of BAY 1895344 plus lenvatinib and BAY 1895344 with dabrafenib plus trametinib were more effective than any single therapy in a K1 xenograft model. No appreciable toxicity appeared in animals treated with either a single therapy or a combination treatment. Our findings provide the rationale for the development of clinical trials of BAY 1895344 in the treatment of DTC.

Reactivation of telomerase reverse transcriptase expression in cancer: the role of TERT promoter mutations

Telomerase activity and telomere elongation are essential conditions for the unlimited proliferation of neoplastic cells. Point mutations in the core promoter region of the telomerase reverse transcriptase (TERT) gene have been found to occur at high frequencies in several tumour types and considered a primary cause of telomerase reactivation in cancer cells. These mutations promote TERT gene expression by multiple mechanisms, including the generation of novel binding sites for nuclear transcription factors, displacement of negative regulators from DNA G-quadruplexes, recruitment of epigenetic activators and disruption of long-range interactions between TERT locus and telomeres. Furthermore, TERT promoter mutations cooperate with TPP1 promoter nucleotide changes to lengthen telomeres and with mutated BRAF and FGFR3 oncoproteins to enhance oncogenic signalling in cancer cells. TERT promoter mutations have been recognized as an early marker of tumour development or a major indicator of poor outcome and reduced patients survival in several cancer types. In this review, we summarize recent findings on the role of TERT promoter mutations, telomerase expression and telomeres elongation in cancer development, their clinical significance and therapeutic opportunities.

Telomerase Upregulation Induces Progression of Mouse BrafV600E-Driven Thyroid Cancers and Triggers Nontelomeric Effects

Mutations in the promoter of the telomerase reverse transcriptase (TERT) gene are the paradigm of a cross-cancer alteration in a noncoding region. TERT promoter mutations (TPM) are biomarkers of poor prognosis in cancer, including thyroid tumors. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert-123C>T) and crossed it with thyroid-specific BrafV600E-mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all BrafV600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of BrafV600E+Tert-123C>T and BrafV600E+K5-Tert mice progressed to poorly differentiated cancers at week 20, respectively. Tert-upregulated tumors showed increased mitosis and necrosis in areas of solid growth, and older animals displayed anaplastic-like features, that is, spindle cells and macrophage infiltration. Murine TPM increased Tert transcription in vitro and in vivo, but temporal and intratumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine, and chemokine signaling, were overactivated. These models constitute useful preclinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs.

IMPLICATIONS

Telomerase-driven cancer progression activates pathways that can be dissected and perhaps therapeutically exploited.

Clinical use of Molecular Data in Thyroid Nodules and Cancer

Over the past 3 decades, advances in the molecular genetics of thyroid cancer (TC) have been translated into diagnostic tests, prognostic markers, and therapeutic agents. The main drivers in differentiated TC pathogenesis are single-point mutations and gene fusions in components of the Mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase-protein kinase B/Akt (PI3K/Akt) pathways. Other important genetic alterations in the more advanced types of TC include TERT promoter, TP53, EIF1AX, and epigenetic alterations. Using this knowledge, several molecular tests have been developed for cytologically indeterminate thyroid nodules. Currently, 3 commercially available tests are in use including a DNA/RNA-based test (ThyroSeq v.3), an RNA-based test (Afirma Gene Sequencing Classifier), and a hybrid DNA/miRNA test, ThyGeNEXT/ThyraMIR. These tests are mostly used to rule out malignancy in Bethesda III and IV thyroid nodules because they all have high sensitivities and negative predictive values. Their common use, predominantly in the United States, has resulted in a significant reduction in unnecessary thyroid surgeries for benign nodules. Some of these tests also provide information on the underlying molecular drivers of TC; this may support decision making in initial TC management planning, although this practice has not yet been widely adopted. More importantly, molecular testing is essential in patients with advanced disease before using specific mono-kinase inhibitors (eg, selpercatinib for RET-altered TC) because these drugs are ineffective in the absence of a specific molecular target. This mini-review discusses the utilization of molecular data in the clinical management of patients with thyroid nodules and TC in these different clinical situations.

Pathogenesis of cancers derived from thyroid follicular cells

The genomic simplicity of differentiated cancers derived from thyroid follicular cells offers unique insights into how oncogenic drivers impact tumour phenotype. Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action. The magnitude of the flux through the MAPK signalling pathway determines key elements of thyroid cancer biology, including differentiation state, invasive properties and the cellular composition of the tumour microenvironment. Progression of disease results from genomic lesions that drive immortalization, disrupt chromatin accessibility and cause cell cycle checkpoint dysfunction, in conjunction with a tumour microenvironment characterized by progressive immunosuppression. This Review charts the genomic trajectories of these common endocrine tumours, while connecting them to the biological states that they confer.

Mechanistic Insights of Thyroid Cancer Progression

Differentiated thyroid cancers (DTCs) are primarily initiated by mutations that activate the MAPK signaling cascade, typically at BRAF or RAS oncoproteins. DTCs can evolve to more aggressive forms, specifically, poorly differentiated (PDTC) and anaplastic thyroid cancers (ATC), by acquiring additional genetic alterations which deregulate key pathways. In this review, we focused on bona fide mutations involved in thyroid cancer progression for which consistent mechanistic data exist. Here we summarized the relevant literature, spanning approximately 2 decades, highlighting genetic alterations that are unquestionably enriched in PDTC/ATC. We describe the relevant functional data obtained in multiple in vitro and in vivo thyroid cancer models employed to study genetic alterations in the following genes and functional groups: TP53, effectors of the PI3K/AKT pathway, TERT promoter, members of the SWI/SNF chromatin remodeling complex, NF2, and EIF1AX. In addition, we briefly discuss other genetic alterations that are selected in aggressive thyroid tumors but for which mechanistic data is still either limited or nonexistent. Overall, we argue for the importance conveyed by preclinical studies for the clinical translation of genomic knowledge of thyroid cancers.

Genetic characteristics of advanced oral tongue squamous cell carcinoma in young patients

OBJECTIVES

We aimed to investigate genetic alterations in oral tongue squamous cell carcinoma (OTSCC) based on age and the clinical significance of these alterations in young OTSCC patients.

MATERIALS AND METHODS

We detected genetic alterations in 44 cases of advanced OTSCC through next-generation sequencing and analyzed and compared patients either younger or older than 45 years. Further analysis was conducted on a validation group of 96 OTSCC patients aged ≤ 45 years to examine the clinical and prognostic associations of TERT promoter (TERTp) mutations.

RESULTS

TP53 mutation was the most common genetic alteration in advanced OTSCC (88.6%), followed by TERTp mutation (59.1%), CDKN2A mutation (31.8%), FAT1 mutation (9.1%), NOTCH1 mutation (9.1%), EGFR amplification (18.2%), and CDKN2A homozygous deletion (4.5%). TERTp mutation was the only genetic alteration significantly enriched in young patients (81.3% in young versus 46.4% in older; P < 0.024). Within the validation group of young patients, TERTp mutation was identified in 30 cases (30/96, 31.3%) and tended to be related to both smoking and alcohol consumption (P = 0.072), higher stage (P = 0.002), more frequent perineural invasion (P = 0.094), and worse overall survival (P = 0.012) than wild type.

CONCLUSION

Our findings suggest that TERTp mutation is more frequent in young patients with advanced OTSCC and is associated with worse clinical outcomes. Therefore, TERTp mutation may serve as a prognostic biomarker for OTSCC in young patients. The findings of this study may help in developing personalized treatment strategies for OTSCC based on age and genetic alterations.

InTERTwined: how TERT promoter mutations impact BRAFV600E-driven thyroid cancers

Thyroid cancers are often initiated by the acquisition of a BRAFV600E mutation. BRAFV600E-driven thyroid tumors display a wide range of behaviors, from the slow-growing papillary carcinomas to the highly aggressive anaplastic. Mutations in the promoter of TERT (telomerase reverse transcriptase) gene were discovered a decade ago and identified as prevalent events in thyroid cancers. Multiple studies showed that TERT promoter mutations, particularly when co-occurring with BRAFV600E, are markers of poor prognosis across thyroid cancer subtypes, and can be implemented for routine clinical stratification. Mechanistically, TERT promoter mutations reactivate telomerase expression via the differential recruitment of transcriptional complexes. Re-expression of TERT impacts tumor biology, plausibly via both the well-known function of telomerase maintaining telomeres and by affecting other cancer-relevant processes.

Prediction of Tumor Development and Urine-Based Liquid Biopsy for Molecule-Targeted Therapy of Gliomas

The timing of the acquisition of tumor-specific gene mutations and the systems by which these gene mutations are acquired during tumorigenesis were clarified. Advances in our understanding of tumorigenesis are being made every day, and therapies targeting fundamental genetic alterations have great potential for cancer treatment. Moreover, our research team successfully estimated tumor progression using mathematical modeling and attempted early diagnosis of brain tumors. We developed a nanodevice that enables urinary genetic diagnosis in a simple and noninvasive manner. Mainly on the basis of our research and experience, this review article presents novel therapies being developed for central nervous system cancers and six molecules, which upon mutation cause tumorigenesis and tumor progression. Further understanding of the genetic characteristics of brain tumors will lead to the development of precise drugs and improve individual treatment outcomes.

TERT Expression Induces Resistance to BRAF and MEK Inhibitors in BRAF-Mutated Melanoma In Vitro

Because BRAF-mutated melanomas are addicted to the Mitogen Activated Protein Kinase (MAPK) pathway they show a high response rate to BRAF and MEK inhibitors. However, the clinical responses to these inhibitors are often short-lived with the rapid onset of resistance to treatment. Deciphering the molecular mechanisms driving resistance has been the subject of intense research. Recent in vitro and clinical data have suggested a link between expression of telomerase and resistance to targeted therapy in melanoma. TERT promoter mutations are the main mechanism for the continuous upregulation of telomerase in melanoma and co-occur frequently with BRAF alterations. To understand how TERT promoter mutations could be associated with resistance to targeted therapy in melanoma, we conducted translational and in vitro studies. In a cohort of V600E-BRAF-mutated melanoma patients, we showed that the TERT promoter mutation status and TERT expression tended to be associated with response to BRAF and MEK inhibitors. We demonstrated that TERT overexpression in BRAF-mutated melanoma cells reduced sensitivity to BRAF and MEK independently of TERT's telomer maintenance activity. Interestingly, inhibition of TERT reduced growth of BRAF-mutated melanoma including resistant cells. TERT expression in melanoma can therefore be a new biomarker for resistance to MAPK inhibitors as well as a novel therapeutic target.

Approach to risk stratification for papillary thyroid carcinoma based on molecular profiling: institutional analysis

BACKGROUND

Currently, treatment recommendations for papillary thyroid carcinoma are not based on the genetic background causing tumourigenesis. The aim of the present study was to correlate the mutational profile of papillary thyroid carcinoma with clinical parameters of tumour aggressiveness, to establish recommendations for risk-stratified surgical treatment.

METHOD

Papillary thyroid carcinoma tumour tissue of patients undergoing thyroid surgery at the University Medical Centre Mainz underwent analysis of BRAF, TERT promoter and RAS mutational status as well as potential RET and NTRK rearrangements. Mutation status was correlated with clinical course of disease.

RESULTS

One hundred and seventy-one patients operated for papillary thyroid carcinoma were included. The median age was 48 years (range 8-85) and 69 per cent (118/171) of patients were females. One hundred and nine papillary thyroid carcinomas were BRAF-V600E mutant, 16 TERT promotor mutant and 12 RAS mutant; 12 papillary thyroid carcinomas harboured RET rearrangements and two papillary thyroid carcinomas showed NTRK rearrangements. TERT promoter mutant papillary thyroid carcinomas had a higher risk of distant metastasis (OR 51.3, 7.0 to 1048.2, P < 0.001) and radioiodine-refractory disease (OR 37.8, 9.9 to 169.5, P < 0.001). Concomitant BRAF and TERT promoter mutations increased the risk of radioiodine-refractory disease in papillary thyroid carcinoma (OR 21.7, 5.6 to 88.9, P < 0.001). RET rearrangements were associated with a higher count of tumour-affected lymph nodes (OR 7950.9, 233.7 to 270495.7, P < 0.001) but did not influence distant metastasis or radioiodine-refractory disease.

CONCLUSIONS

Papillary thyroid carcinoma with concomitant BRAF-V600E and TERT promoter mutations demonstrated an aggressive course of disease, suggesting the need for a more extensive surgical strategy. RET rearrangement-positive papillary thyroid carcinoma did not affect the clinical outcome, potentially obviating the need for prophylactic lymphadenectomy.

Interrogation of TERT promoter hotspot mutations in ameloblastoma and ameloblastic carcinoma

BACKGROUND

TERT promoter mutations increase telomerase activity, conferring cell immortality. The coexistence of TERT promoter mutations with BRAFV600E is associated with aggressiveness. Ameloblastoma and ameloblastic carcinoma are infiltrative neoplasms that harbor BRAFV600E; however, it remains unknown if these odontogenic tumors also show TERT promoter mutations.

METHODS

Genomic DNA of paraffin-embedded ameloblastomas (n = 6) and ameloblastic carcinomas (n = 3) were Sanger-sequenced to assess the hotspot TERT promoter mutations C228T and C250T. BRAFV600E status was screened by TaqMan allele-specific quantitative polymerase chain reaction.

RESULTS

None of the samples harbored TERT promoter mutations. The BRAFV600E mutation was positive in 3 of 6 of ameloblastomas and in 1 of 3 of ameloblastic carcinomas.

CONCLUSION

The absence of TERT promoter mutation in the samples indicates that this molecular event is not relevant to the tumors' pathogenesis. Further studies are necessary to explore undefined genetic or epigenetic mechanisms related to TERT-upregulation in ameloblastoma, and the telomerase activity in ameloblastic carcinoma.

Clinical, Morphological, and Molecular Study on Grade 2 and 3 Pleomorphic Xanthoastrocytoma

PURPOSE

Pleomorphic xanthoastrocytoma (PXA) is an uncommon astrocytoma that tends to occur in children and young adults and has a relatively favorable prognosis. The 2021 WHO classification of tumors of the central nervous system (CNS WHO), 5th edition, rates PXAs as grade 2 and grade 3. The histological grading was based on mitotic activity (≥2.5 mitoses/mm²). This study specifically evaluates the clinical, morphological, and, especially, the molecular characteristics of grade 2 and 3 PXAs.

METHODS

Between 2003 and 2021, we characterized 53 tumors with histologically defined grade 2 PXA (n = 36, 68%) and grade 3 PXA (n = 17, 32%).

RESULTS

Compared with grade 2 PXA, grade 3 PXA has a deeper location and no superiority in the temporal lobe and is more likely to be accompanied by peritumoral edema. In histomorphology, epithelioid cells and necrosis were more likely to occur in grade 3 PXA. Molecular analysis found that the TERT promoter mutation was more prevalent in grade 3 PXA than in grade 2 PXA (35% vs. 3%; p = 0.0005) and all mutation sites were C228T. The cases without BRAF V600E mutation or with necrosis in grade 3 PXA had a poor prognosis (p = 0.01).

CONCLUSION

These data define PXA as a heterogeneous astrocytoma. Grade 2 and grade 3 PXAs have different clinical and histological characteristics as well as distinct molecular profiles. TERT promoter mutations may be a significant genetic event associated with anaplastic progression. Necrosis and BRAF V600E mutation play an important role in the prognosis of grade 3 PXA.

Molecular Heterogeneity in BRAF-Mutant Gliomas: Diagnostic, Prognostic, and Therapeutic Implications

Over the last few decades, deciphering the alteration of molecular pathways in brain tumors has led to impressive changes in diagnostic refinement. Among the molecular abnormalities triggering and/or driving gliomas, alterations in the MAPK pathway reign supreme in the pediatric population, as it is encountered in almost all low-grade pediatric gliomas. Activating abnormalities in the MAPK pathway are also present in both pediatric and adult high-grade gliomas. Across those alterations, BRAF p.V600E mutations seem to define homogeneous groups of tumors in terms of prognosis. The recent development of small molecules inhibiting this pathway retains the attention of neurooncologists on BRAF-altered tumors, as conventional therapies showed no significant effect, nor prolonged efficiency on the high-grade or low-grade unresectable forms. Nevertheless, tumoral heterogeneity and especially molecular alteration(s) associated with MAPK-pathway abnormalities are not fully understood with respect to how they might lead to the specific dismal prognosis of those gliomas and/or affect their response to targeted therapies. This review is an attempt to provide comprehensive information regarding molecular alterations related to the aggressiveness modulation in BRAF-mutated gliomas and the current knowledge on how to use those targeted therapies in such situations.

Telomerase reactivation induces progression of mouse Braf V600E -driven thyroid cancers without telomere lengthening

Mutations in the promoter of the telomerase reverse transcriptase ( TERT ) gene are the paradigm of a cross-cancer alteration in a non-coding region. TERT promoter mutations (TPMs) are biomarkers of poor prognosis in several tumors, including thyroid cancers. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert -123C>T ) and crossed it with thyroid-specific Braf V600E -mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all Braf V600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of Braf V600E +Tert -123C>T and Braf V600E +K5-Tert mice progressed to poorly differentiated thyroid cancers at week 20, respectively. Braf+Tert tumors showed increased mitosis and necrosis in areas of solid growth, and older animals from these cohorts displayed anaplastic-like features, i.e., spindle cells and macrophage infiltration. Murine Tert promoter mutation increased Tert transcription in vitro and in vivo , but temporal and intra-tumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine and chemokine signaling, were overactivated. Braf+Tert animals remained responsive to MAPK pathway inhibitors. These models constitute useful pre-clinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs.

Real-world EUROCRINE® registry data challenge the reliability of Bethesda cytopathology for thyroid surgery indication

Objectives

Fine-needle aspiration cytology (FNAC) is recommended by international guidelines for the preoperative evaluation of suspicious thyroid nodules >1 cm. Despite robust evidence from endocrine centers demonstrating the key role of FNAC results for the indication of surgery, the method is not routinely used in European clinics. The database EUROCRINE^®, which was introduced in 2015 with the scope of registering operations of the endocrine system, allows for a large-scale analysis of the current service reality in Europe concerning FNAC use and associated accuracy.

Methods

Operations performed to "exclude malignancy", registered from January 2015 to December 2018 in EUROCRINE^®, were analyzed. Parameters of accuracy were calculated for FNAC. FNAC results were considered "test positive" in the case of Bethesda category IV, V, and VI, since these categories usually prompt surgical interventions in European centers for thyroid surgery. Bethesda category II and III were considered "test negative".

Results

Of 8,791 operations, 5,780 had preoperative FNAC (65.7%). The overall malignancy rate was 28.3% (2,488/8,791). Malignancy rates were 68.8% for Bethesda VI, 69.9% for Bethesda V, 32.6% for Bethesda IV, 28.2% for III, 20.2% for Bethesda II, and 24.5% for Bethesda I. After exclusion of papillary microcarcinomas (PTMCs), the sensitivity of FNAC was 71.7% and specificity 43.5%, the positive predictive value was 29.1% and the negative predictive value 82.7%.

Conclusions

Although the indication to "exclude malignancy" was the predominant reason that prompted thyroid resection in the present cohort, FNAC was only used in about 65.7% of cases. When performed, FNAC was associated with unexpectedly low accuracy. Interestingly, in Bethesda II, 20.2% of malignant entities were present (13.3% after the exclusion of PTMCs).

GABP couples oncogene signaling to telomere regulation in TERT promoter mutant cancer

Telomerase activation counteracts senescence and telomere erosion caused by uncontrolled proliferation. Epidermal growth factor receptor (EGFR) amplification drives proliferation while telomerase reverse transcriptase promoter (TERTp) mutations underlie telomerase reactivation through recruitment of GA-binding protein (GABP). EGFR amplification and TERTp mutations typically co-occur in glioblastoma, the most common and aggressive primary brain tumor. To determine if these two frequent alterations driving proliferation and immortality are functionally connected, we combine analyses of copy number, mRNA, and protein data from tumor tissue with pharmacologic and genetic perturbations. We demonstrate that proliferation arrest decreases TERT expression in a GABP-dependent manner and elucidate a critical proliferation-to-immortality pathway from EGFR to TERT expression selectively from the mutant TERTp through activation of AMP-mediated kinase (AMPK) and GABP upregulation. EGFR-AMPK signaling promotes telomerase activity and maintains telomere length. These results define how the tumor cell immortality mechanism keeps pace with persistent oncogene signaling and cell cycling.

TERT promoter mutations are common in human cancer and confer cellular immortality. McKinney et al. describe the interaction between TERT promoter mutations, EGFR amplification, and the cell cycle in glioblastoma. The results demonstrate how proliferation drivers cooperate with telomere maintenance mechanisms to counteract telomere shortening caused by unlimited cell division.

Conserved features of TERT promoter duplications reveal an activation mechanism that mimics hotspot mutations in cancer

Mutations in the TERT promoter represent the genetic underpinnings of tumor cell immortality. Beyond the two most common point mutations, which selectively recruit the ETS factor GABP to activate TERT, the significance of other variants is unknown. In seven cancer types, we identify duplications of wildtype sequence within the core promoter region of TERT that have strikingly similar features including an ETS motif, the duplication length and insertion site. The duplications recruit a GABP tetramer by virtue of the native ETS motif and its precisely spaced duplicated counterpart, activate the promoter and are clonal in a TERT expressing multifocal glioblastoma. We conclude that recurrent TERT promoter duplications are functionally and mechanistically equivalent to the hotspot mutations that confer tumor cell immortality. The shared mechanism of these divergent somatic genetic alterations suggests a strong selective pressure for recruitment of the GABP tetramer to activate TERT.

Up-Regulation of RACGAP1 Promotes Progressions of Hepatocellular Carcinoma Regulated by GABPA via PI3K/AKT Pathway

Hepatocellular carcinoma (HCC) is one of the dominating tumors causing death due to lack of timely discovery and valid treatment. Abnormal increase of Rac GTPase activating protein 1 (RACGAP1) has been verified to be an oncogene in plenty tumors. The profound mechanism of RACGAP1 was rarely reported in HCC. In this study, we explored the function and mechanism of RACGAP1 in HCC through multiple analysis and experiments. RACGAP1 expression was up-regulated in HCC samples and the high expression of RACGAP1 was an independent prognostic risk factor for HCC patients. Meanwhile, RACGAP1 promoted developments of HCC both in vitro and in vivo. We verified that RACGAP1 promoted proliferation of HCC via PI3K/AKT/CDK2 and PI3K/AKT/GSK3β/Cyclin D1 signaling pathway. RACGAP1 accelerated the invasion and metastasis of HCC via phosphorylation of GSK3β and nuclear translocation of β-catenin. Furthermore, by luciferase reporter assay and Chromatin immunoprecipitation (ChIP) assay, we confirmed Recombinant GA Binding Protein Transcription Factor Alpha (GABPA) regulated the transcription of RACGAP1. All these findings revealed that RACGAP1 promotes the progression of HCC through a novel mechanism, which might be a new therapeutic target for HCC patients.

Case report: response to the ERK1/2 inhibitor ulixertinib in BRAF D594G cutaneous melanoma

Melanoma is characterized by oncogenic mutations in pathways regulating cell growth, proliferation, and metabolism. Greater than 80% of primary melanoma cases harbor aberrant activation of the mitogen-activated protein kinase kinase/extracellular-signal-regulated kinase (MEK/ERK) pathway, with oncogenic mutations in BRAF, most notably BRAF V600E, being the most common. Significant progress has been made in BRAF-mutant melanoma using BRAF and MEK inhibitors; however, non-V600 BRAF mutations remain a challenge with limited treatment options. We report the case of an individual diagnosed with stage III BRAF D594G-mutant melanoma who experienced an extraordinary response to the ERK1/2 inhibitor ulixertinib as fourth-line therapy. Ulixertinib was obtained via an intermediate expanded access protocol with unique flexibility to permit both single-agent and combination treatments, dose adjustments, breaks in treatment to undergo surgery, and long-term preventive treatment following surgical resection offering this patient the potential for curative treatment.

TERT Promoter Mutations and Telomerase in Melanoma

Malignant melanoma is an extremely malignant tumor with a high mortality rate and an increasing incidence with a high mutation load. The frequency of mutations in the TERT promoter exceeds the frequency of any known noncoding mutations in melanoma. A growing number of recent studies suggest that the most common mutations in the TERT promoter (ATG start site −124C>T and −146C>T) are associated with increased TERT mRNA expression, telomerase activity, telomere length, and poor prognosis. Recently, it has been shown that TERT promoter mutations are more correlated with the occurrence, development, invasion, and metastasis of melanoma, as well as emerging approaches such as the therapeutic potential of chemical inhibition of TERT promoter mutations, direct telomerase inhibitors, combined targeted therapy, and immunotherapies. In this review, we describe the latest advances in the role of TERT promoter mutations and telomerase in promoting the occurrence, development, and poor prognosis of melanoma and discuss the clinical significance of the TERT promoter and telomerase in the treatment of melanoma.

Clinicopathological indicators for TERT promoter mutation in papillary thyroid carcinoma

OBJECTIVE

Mutations in the telomerase reverse transcriptase (TERT) promoter have been reported as a convincing prognostic factor in papillary thyroid carcinomas (PTCs). We aimed to investigate the frequency of TERT promoter mutations in patients with thyroid cancer and identify the clinicopathological factors associated with them in PTCs.

DESIGN

A total of 1086 consecutive cases of thyroid cancer composed of mostly PTCs were included in this study. TERT promoter and BRAF mutations were detected by pyrosequencing and their associations with clinicopathological features of tumour were analyzed.

RESULTS

TERT promoter mutations were observed in 1.9% of PTCs, 6.7% of follicular thyroid carcinomas, 8.3% of Hurthle cell carcinomas and 25.0% of poorly differentiated thyroid carcinomas and in a single case of anaplastic thyroid carcinoma. In PTCs, aggressive clinicopathological features, higher stage and BRAF V600E mutation were all found to be associated with TERT promoter mutations. Distant metastasis and disease recurrence were more frequent in TERT promoter-mutated PTCs. In multivariate analysis, age ≥55 years, tall cell variant, mitoses ≥3/10 high-power fields, tumour necrosis, and gross extrathyroidal extension (ETE) were identified as independent factors associated with TERT promoter mutations in PTCs.

CONCLUSIONS

This study revealed a relatively low frequency of TERT promoter mutations in Korean patients with PTC. Certain clinicopathological features including old age, tall cell variant, increased mitoses, tumour necrosis and gross ETE were found to be indicative of TERT promoter mutations in PTCs, suggesting that mutational analysis in a particular group of PTCs can be effective in regions with low mutation rates.

The genetic duet of BRAF V600E and TERT promoter mutations predicts the poor curative effect of radioiodine therapy in papillary thyroid cancer

OBJECTIVE

The BRAF V600E and TERT promoter mutations are well known to be associated with poor clinical outcomes of papillary thyroid cancer (PTC). Radioactive iodide (RAI)-refractory can be evaluated in advance of treatment, for which predictive biomarkers may be helpful. The present study is to analyze the correlation of both mutations with the curative effect of radioiodine therapy.

METHODS

A total of 126 patients who underwent RAI therapy from October 2016 to August 2019 were recruited. Treatment and follow-up were defined according to criteria used in the 2015 ATA guidelines. The RAI response of patients was assessed as excellent response (ER) and RAI-refractory at the end of follow-up.

RESULTS

When dividing the 126 patients into 4 groups, the no mutation, only BRAF V600E mutation, only TERT promoter mutation, and coexistence of two mutation groups were found in 15.8%, 68.3%, 2.4%, and 13.5% patients. RAI-refractory was found in 52.9% (9/17) patients with the coexisting BRAF and TERT mutations. In logistic regression analysis, M1, BRAF, and TERT mutation were confirmed to be independent factors predicting the RAI-refractory. Moreover, 35.3%, 41.2%, and 23.5% of patients in the BRAF and TERT mutation group were assessed as ER, SIR, and BIR respectively. Kaplan-Meier analyses revealed that the genetic duet of BRAF V600E and TERT promoter mutations was associated with a lower ER reached time.

CONCLUSIONS

We found that BRAF V600E and TERT promoter mutation is significantly correlated with the poor curative effect of RAI therapy in PTC.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: ChiCTR1800018760.

A Comprehensive Risk Assessment and Stratification Model of Papillary Thyroid Carcinoma Based on the Autophagy-Related LncRNAs

Background

Papillary thyroid carcinoma (PTC) is one of the most common malignant carcinomas in the endocrine system, and it has a growing incidence worldwide. Despite the development of diagnosis and treatment modalities for thyroid carcinoma, the outcome remains uncertain. Autophagy participates in the process of cancer invasion, malignancy, metastasis, and drug resistance. Emerging research has shown that long noncoding RNAs (lncRNAs) play an important role in the process of different types of cancers. However, the interaction between the process of autophagy and lncRNA and the value of autophagy-related lncRNA for risk assessment, prediction of drug sensitivity, and prognosis prediction in PTC patients remains unknown.

Materials and Methods

We screened 1,283 autophagy-related lncRNAs and identified 144 lncRNAs with prognostic value in The Cancer Genome Atlas (TCGA) cohorts. Univariate and multivariate Cox regression analyses were used to establish the prognosis-related autophagy-related lncRNA risk classification consisting of 10 lncRNAs to indicate the level of risk, according to which the patients were grouped into high-risk group and low risk-group.

Results

The high-risk group had dramatically worse overall survival compared with the low-risk group. Cox regression analysis was performed to confirm the independent prognostic value of the autophagy-related lncRNA risk stratification, and the time-dependent receiver operating characteristic curves of the risk stratification were 0.981 (1 year), 0.906 (3 years), and 0.963 (5 years). LncRNA CRNDE (LINC00180) is overexpressed in the tumor, and its high expression matched with poorer survival state. So, we chose it for further experiment. Finally, knockdown of the CRNDE in PTC increased the sensitivity to sorafenib.

Conclusion

Collectively, we successfully established a novel risk stratification for PTC based on the expression profiles of autophagy-related lncRNAs.

Downregulation and Hypermethylation of GABPB1 Is Associated with Aggressive Thyroid Cancer Features

Simple Summary

Promoter mutations of the telomerase reverse transcriptase (TERT) gene have been suggested as an oncogenic event in various cancers, including thyroid cancer (TC). GABPB1 is reported to activate TERT gene expression and has been proposed as a cancer therapeutic target. The aim of this study is to explore the fate of TC cells after disruption of GABPB1 and its role in TC. We found that besides the reported oncogenic role of GABPB1 in activating TERT, it also has tumor-suppressive functions in TC. Therefore, targeting GABPB1 for cancer therapy should be cautious since it may counteract its tumor-suppressive functions.

Abstract

Promoter mutations of the telomerase reverse transcriptase (TERT) gene occur frequently in thyroid carcinoma (TC), including papillary (PTC) and anaplastic subtypes (ATC). Given that the ETS family transcription factors GABPA and GABPB1 activate the mutant TERT promoter and induce TERT expression for telomerase activation, GABPB1 has been proposed as a cancer therapeutic target to inhibit telomerase. Here, we sought to determine the role of GABPB1 in TC pathogenesis. In TC-derived cells carrying the mutated TERT promoter, GABPB1 knockdown led to diminished TERT expression but significantly increased invasive potentials in vitro and metastatic potential in a xenograft zebrafish model and altered expression of markers for epithelial-to-mesenchymal transition. GABPB1 expression was downregulated in aggressive TCs. Low GABPB1 expression correlated with its promoter hypermethylation, which in turn was also associated with shorter disease-free survival. Consistently, DNA methylation inhibitors enhanced GABPB1 expression, as observed upon reduced promoter methylation. Our results suggest that GABPB1 is required for TERT expression and telomerase activation, but itself serves as a tumor suppressor to inhibit TC progression. Furthermore, aberrant DNA methylation leads to GABPB1 silencing, thereby promoting TC aggressiveness. Thus, caution is needed if targeting GABPB1 for cancer therapy is considered.

Mutations in the telomerase reverse transcriptase promoter and PIK3CA gene are common events in penile squamous cell carcinoma of Italian and Ugandan patients

Penile carcinoma develops either through human papillomavirus (HPV) related or unrelated carcinogenic pathways. Genetic alterations and nucleotide changes in coding regions (ie, TP53, CDKN2A, PIK3CA and NOTCH1) are main cancer driver events either in HPV positive or in HPV negative tumours. We investigated the presence of hotspot nucleotide mutations in TERT promoter (TERTp) and PIK3CA exon 9 and their relationship with HPV status in 69 penile cancer cases from Italian and Ugandan patients. Genetic variations and viral sequences have been characterised by end‐point polymerase chain reaction (PCR) and Sanger sequencing. The mutant allele frequencies (MAFs) of TERTp −124A/−146A and PIK3CA E545K have been determined by droplet digital PCR (ddPCR) assays. The results showed that TERTp mutations are highly prevalent in penile carcinoma (53.6%) and significantly more frequent in HPV negative (67.6%) than HPV positive (32.4%) cases (P = .0482). PIK3CA mutations were similarly distributed in virus‐related and unrelated cases (25.9% and 26.7%, respectively) and coexisted with TERTp changes in 15.8% of penile carcinoma samples. Notably, MAFs of co‐occurring mutations were frequently discordant indicating that PIK3CA E545K nucleotide changes are subsequent genetic events occurring in subclones of TERTp mutated cells. The frequencies of TERTp and PIK3CA mutations were higher among Italian compared to Ugandan cases and inversely correlated with the HPV status. In conclusion, TERTp mutations are very common in penile carcinoma and their coexistence with PIK3CA in a substantial number of cases may represent a novel oncogenic synergy relevant for patient stratification and use of therapeutic strategies against new actionable targets.

Telomerase in Cancer: Function, Regulation, and Clinical Translation

Simple Summary

Cells undergoing malignant transformation must circumvent replicative senescence and eventual cell death associated with progressive telomere shortening that occurs through successive cell division. To do so, malignant cells reactivate telomerase to extend their telomeres and achieve cellular immortality, which is a “Hallmark of Cancer”. Here we review the telomere-dependent and -independent functions of telomerase in cancer, as well as its potential as a biomarker and therapeutic target to diagnose and treat cancer patients.

Abstract

During the process of malignant transformation, cells undergo a series of genetic, epigenetic, and phenotypic alterations, including the acquisition and propagation of genomic aberrations that impart survival and proliferative advantages. These changes are mediated in part by the induction of replicative immortality that is accompanied by active telomere elongation. Indeed, telomeres undergo dynamic changes to their lengths and higher-order structures throughout tumor formation and progression, processes overseen in most cancers by telomerase. Telomerase is a multimeric enzyme whose function is exquisitely regulated through diverse transcriptional, post-transcriptional, and post-translational mechanisms to facilitate telomere extension. In turn, telomerase function depends not only on its core components, but also on a suite of binding partners, transcription factors, and intra- and extracellular signaling effectors. Additionally, telomerase exhibits telomere-independent regulation of cancer cell growth by participating directly in cellular metabolism, signal transduction, and the regulation of gene expression in ways that are critical for tumorigenesis. In this review, we summarize the complex mechanisms underlying telomere maintenance, with a particular focus on both the telomeric and extratelomeric functions of telomerase. We also explore the clinical utility of telomeres and telomerase in the diagnosis, prognosis, and development of targeted therapies for primary, metastatic, and recurrent cancers.

Does Locally Advanced Thyroid Cancer Have Different Features? Results from a Single Academic Center

Background: Despite the fact that the majority of thyroid cancers are indolent, 15% of patients with well-differentiated carcinoma including papillary thyroid carcinoma (PTC) present with locally advanced thyroid cancer (LATC) at diagnosis. The current study analyzes a cohort of patients with LATC focusing on their risk for local recurrence, distant metastases, and overall survival. Materials and methods: From January 2010 to December 2020, 65 patients with LATC were retrieved, including 42 cases with preoperative cytological samples. BRAF^V600E and TERT mutations were performed on both cytology and histopathology specimens in this cohort. Results: Among the 65 cases, 42 (65%) were women. The median age was 60.1 years. Histological diagnoses included 25 (38.4%) with classic PTC and 30 (46.1%) aggressive variants of PTC, mostly tall cell variant (17 cases, 26.1%). Multifocality was seen in 33 cases (50.8%). All patients had nodal metastases. The most common site of extrathyroidal extension was the recurrent laryngeal nerve (69.2%). Staging revealed 21 cases were stage I, none were stage II, 33 were stage III, and 7 were stage IVa and 4 stage IVb. No differences were found between well and poorly/undifferentiated thyroid cancers. Conclusion: These data suggest that locally advanced thyroid cancers, including variants of PTC, exhibit a more aggressive biological course and should accordingly be more assertively managed.

TERT Promoter Revertant Mutation Inhibits Melanoma Growth through Intrinsic Apoptosis

Simple Summary

TERT -146 C>T frequently occurs in many cancer cells. Research targeting the telomerase reverse transcriptase (TERT) promoter contributes to a better understanding of cancer development and treatment. Many conventional cancer treatments aim to develop new drugs targeting TERT. Here, for TERT -146 we converted T to C. The proliferation, migration and invasion of melanoma cells in vitro, and the growth of the tumor in vivo were inhibited. Moreover, the downregulated protein expression of B-cell lymphoma 2 (Bcl-2) indicated that the TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis. These data elucidated the relationship between the TERT promoter revertant mutations and apoptosis for the first time, and also implied that TERT -146 may be a causal mutation of melanoma. This study provides a new insight into the TERT promoter revertant mutations and apoptosis. The TERT promoter provides preliminary validation of the potential tumor treatment.

Abstract

Human telomerase is a specialized DNA polymerase whose catalytic core includes both TERT and human telomerase RNA (hTR). Telomerase in humans, which is silent in most somatic cells, is activated to maintain the telomere length (TEL) in various types of cancer cells, including melanoma. In the vast majority of tumor cells, the TERT promoter is mutated to promote proliferation and inhibit apoptosis. Here, we exploited NG-ABEmax to revert TERT -146 T to -146 C in melanoma, and successfully obtained TERT promoter revertant mutant cells. These TERT revertant mutant cells exhibited significant growth inhibition both in vitro and in vivo. Moreover, A375^−146C/C cells exhibited telomere shortening and the downregulation of TERT at both the transcription and protein levels, and migration and invasion were inhibited. In addition, TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis via B-cell lymphoma 2 (Bcl-2), ultimately leading to cell death. Collectively, the results of our work demonstrate that reverting mutations in the TERT promoter is a potential therapeutic option for melanoma.

Multiple ETS Factors Participate in the Transcriptional Control of TERT Mutant Promoter in Thyroid Cancers

Simple Summary

Mutations in the promoter region of the telomerase reverse transcriptase (TERT) gene are enriched in patients with advanced thyroid tumors. Their consequence is the reactivation of TERT expression through mechanisms that involve specific transcription factors and other signaling inputs. Here, we show that, contrary to what it has been shown in other tumor types, multiple factors of the ETS family are able to control TERT transcription and they do so in both the presence and absence of promoter mutations. We also show that TERT expression is more dependent on the MAPK signaling pathway in thyroid cells without TERT promoter mutations. Our work points to an intricate, still not fully characterized, regulatory network of TERT transcription in thyroid tumors. We caution against the assumption of mechanisms identified in other cancer lineages being identical in TERT-mutant thyroid specimens.

Abstract

Hotspot mutations in the TERT (telomerase reverse transcriptase) gene are key determinants of thyroid cancer progression. TERT promoter mutations (TPM) create de novo consensus binding sites for the ETS (“E26 transformation specific”) family of transcription factors. In this study, we systematically knocked down each of the 20 ETS factors expressed in thyroid tumors and screened their effects on TERT expression in seven thyroid cancer cell lines with defined TPM status. We observed that, unlike in other TPM-carrying cancers such as glioblastomas, ETS factor GABPA does not unambiguously regulate transcription from the TERT mutant promoter in thyroid specimens. In fact, multiple members of the ETS family impact TERT expression, and they typically do so in a mutation-independent manner. In addition, we observe that partial inhibition of MAPK, a central pathway in thyroid cancer transformation, is more effective at suppressing TERT transcription in the absence of TPMs. Taken together, our results show a more complex scenario of TERT regulation in thyroid cancers compared with other lineages and suggest that compensatory mechanisms by ETS and other regulators likely exist and advocate for the need for a more comprehensive understanding of the mechanisms of TERT deregulation in thyroid tumors before eventually exploring TPM-specific therapeutic strategies.

TERT promoter mutations are associated with longer progression-free and overall survival in patients with BRAF-mutant melanoma receiving BRAF and MEK inhibitor therapy

BACKGROUND

Around 50% of cutaneous melanomas harbour therapeutically targetable BRAF V600 mutations. Reliable clinical biomarkers predicting duration of response to BRAF-targeted therapies are still lacking. Recent in vitro studies demonstrated that BRAF-MEK inhibitor therapy response is associated with tumour TERT promoter mutation status. We assessed this potential association in a clinical setting.

METHODS

The study cohort comprised 232 patients with metastatic or unresectable BRAF V600-mutated melanoma receiving combined BRAF/MEK inhibitor treatment, including a single-centre retrospective discovery cohort (N = 120) and a prospectively collected multicenter validation cohort (N = 112). Patients were excluded if they received BRAF or MEK inhibitors in an adjuvant setting, as monotherapy, or in combination with immunotherapy. Kaplan-Meier and univariate/multivariate Cox regression analyses were performed as appropriate.

RESULTS

median age at first diagnosis was 54 years (range 16-84 years). The majority of patients were men 147/232 (63.4%). Most tumours harboured TERT promoter mutations (72%, N = 167). A survival advantage was observed in both progression-free survival (PFS) and overall survival (OS) for patients with TERT promoter-mutant versus wild-type tumours in both the discovery cohort (mPFS of 9.6 months [N = 87] vs 5.0 months [N = 33]; hazard ratio [HR] = 0.56 [95% confidence interval {CI} 0.33-0.96] and mOS of 33.6 months vs 15.0 months; HR = 0.47 [95%CI 0.32-0.70]) as well as the validation cohort (mPFS of 7.3 months [N = 80] vs 5.8 months [N = 32]; HR = 0.67 [95%CI 0.41-1.10] and mOS of 51.1 months vs 15.0 months; HR = 0.33 [95%CI 0.18-0.63]). In the pooled cohort of TERT promoter-mutant (N = 167) versus wild-type (N = 65) tumours, respectively, PFS was 8.9 versus 5.5 months, (HR = 0.62; 95%CI 0.45-0.87; P = 0.004), and OS was 33.6 versus 17.0 months, (HR = 0.51; 95%CI 0.35-0.75, P = 0.0001).

CONCLUSIONS

In patients with melanoma receiving BRAF/MEK-targeted therapies, TERT promoter mutations are associated with longer survival. If validated in larger studies, TERT promoter mutation status should be included as a predictive biomarker in treatment algorithms for advanced melanoma.

Screening and verification of potential gene targets in esophageal carcinoma by bioinformatics analysis and immunohistochemistry

Background

To evaluate the potential of candidate proteins as diagnostic markers or drug targets in esophageal carcinoma (ESCA).

Methods

GSE20347, GSE17351, and GSE45670 were downloaded from Gene Expression Omnibus (GEO). Differently expressed genes (DEGs) between ESCA and normal esophageal tissues from patients were obtained. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed. The genes commonly featured in ESCA were screened by least absolute shrinkage and selection operator (LASSO) logistic regression and Boruta feature selection algorithm. The transcriptome data and corresponding clinical data of ESCA were downloaded from The Cancer Genome Atlas (TCGA) public database. Kaplan-Meier survival analysis was used to explore the core genes related to the prognosis of patients. A protein-protein interaction (PPI) network was generated by GeneMANIA to visualize the functional network between genes. Expressions of CRIP2, FOS, and HOXA10 genes in ESCA cells were verified by immunohistochemistry (IHC).

Results

Out of 11,207 genes, 430 DEGs were identified, including 210 up-regulated genes and 220 down-regulated genes. After taking the intersection of LASSO regression and Boruta algorithm, 15 core genes were identified. Survival analyses demonstrated that low expression of CRIP2 (P=2.643e-02), as well as high expression of FOS (P=4.837e-02) and HOXA10 (P=4.97e-02), was significantly associated with the worse prognosis of ESCA patients. The 3 genes were strongly correlated with the content of immune cells and the stage of tumors. The expression of CRIP2 was correlated with the sensitivity of patients to dasatinib; FOS expression was correlated with the sensitivity of patients to erlotinib, and HOXA10 expression affected the sensitivity of patients to cisplatin, dasatinib, erlotinib, and gefitinib. The cBioportal database showed that 56 patients (31%) had the above core gene mutations: CRIP2 (8%), FOS (10%), and HOXA10 (17%). The IHC showed that there were differences in the expressions of these core genes between ESCA patients and the normal population (P<0.05), with ESCA patients showing higher expression.

Conclusions

The low CRIP2 expression and high expressions of FOS and HOXA10 are associated with more advanced tumor stage, which may have the potential to be novel biomarkers for treatment selection in ESCA.

Epigenetic modification and BRAF gene mutation in thyroid carcinoma

Thyroid cancer remains the most prevailing endocrine malignancy, and a progressively increasing incidence rate has been observed in recent years, with 95% of thyroid cancer represented by differentiated thyroid carcinomas. The genetics and epigenetics of thyroid cancer are gradually increasing, and gene mutations and methylation changes play an important roles in its occurrence and development. Although the role of RAS and BRAF mutations in thyroid cancer have been partially clarified,but the pathogenesis and molecular mechanisms of thyroid cancer remain to be elucidated. Epigenetic modification refer to genetic modification that does not change the DNA sequence of a gene but causes heritable phenotypic changes in its expression. Epigenetic modification mainly includes four aspects: DNA methylation, chromatin remodelling, noncoding RNA regulation, and histone modification. This article reviews the importance of thyroid cancer epigenetic modification and BRAF gene mutation in the treatment of thyroid cancer.

Apoptosis Pathways Triggered by a Potent Antiproliferative Hybrid Chalcone on Human Melanoma Cells

The World Health Organization reported that approximately 324,000 new cases of melanoma skin cancer were diagnosed worldwide in 2020. The incidence of melanoma has been increasing over the past decades. Targeting apoptotic pathways is a potential therapeutic strategy in the transition to preclinical models and clinical trials. Some naturally occurring products and synthetic derivatives are apoptosis inducers and may represent a realistic option in the fight against the disease. Thus, chalcones have received considerable attention due to their potential cytotoxicity against cancer cells. We have previously reported a chalcone containing an indole and a pyridine heterocyclic rings and an α-bromoacryloylamido radical which displays potent antiproliferative activity against several tumor cell lines. In this study, we report that this chalcone is a potent apoptotic inducer for human melanoma cell lines SK-MEL-1 and MEL-HO. Cell death was associated with mitochondrial cytochrome c release and poly(ADP-ribose) polymerase cleavage and was prevented by a non-specific caspase inhibitor. Using SK-MEL-1 as a model, we found that the mechanism of cell death involves (i) the generation of reactive oxygen species, (ii) activation of the extrinsic and intrinsic apoptotic and mitogen-activated protein kinase pathways, (iii) upregulation of TRAIL, DR4 and DR5, (iv) downregulation of p21^Cip1/WAF1 and, inhibition of the NF-κB pathway.

EFFECT OF BRAFV600E AND TERT PROMOTER MUTATIONS ON THYROGLOBULIN RESPONSE IN DISTANT-METASTATIC DIFFERENTIATED THYROID CANCER

OBJECTIVE

To assess the impact of BRAF^V600E and telomerase reverse transcriptase (TERT) promoter mutations in distant-metastatic differentiated thyroid cancer (DM-DTC) patients based on thyroglobulin (Tg) response to radioactive iodine (RAI) therapy.

METHODS

BRAF^V600E and TERT mutations in primary tumors or metastatic lymph nodes of 114 DM-DTC patients were retrospectively examined. RAI avidity was evaluated based on posttreatment ¹³¹I-WBS. Tg response was dynamically assessed with a median follow-up of 56.50 months (interquartile range, 28.43-97.98 months).

RESULTS

BRAF^V600E was detected in 38.6% of cases and TERT mutation in 21.1% of cases, and both BRAF^V600E and TERT mutations were observed in 14.9% of cases. Patients with both mutations tended to be older at diagnosis (P<0.001), less multifocal (P=0.011) and have more aggressive histologic subtypes (P=0.011) and a higher Ki-67 index (P=0.003). Patients with neither mutation tended to be more RAI-avid than those with the BRAF^V600E mutant alone or both mutations (P=0.001, <0.001, respectively). Patients with both mutations presented more unfavorable Tg response than those without both mutations and with the BRAF^V600E mutant alone (P=0.001, 0.013, respectively). Tg progression-free survival (Tg-PFS) was shorter in patients with TERT mutation alone than in those with neither mutation (P=0.021), and it tended to be shorter when BRAF^V600E coexisted (P<0.001); however, no significant difference was observed between BRAF^V600E alone and neither mutation (P=0.890).

CONCLUSIONS

Coexistence of BRAF^V600E and TERT promoter mutations synergistically induce loss of RAI avidity and an undesirable Tg response in DM-DTC. TERT promoter mutation appears to affect Tg response more than the BRAF^V600E mutation.

Novel Inhibitor-Based Therapies for Thyroid Cancer-An Update

Thyroid cancers (TCs) are the most common tumors of the endocrine system and a constant rise in the number of TC cases has been observed for the past few decades. TCs are one of the most frequent tumors in younger adults, especially in women, therefore early diagnosis and effective therapy are especially important. Ultrasonography examination followed by fine needle biopsy have become the gold standard for diagnosis of TCs, as these strategies allow for early-stage detection and aid accurate qualification for further procedures, including surgical treatment. Despite all the advancements in detection and treatment of TCs, constant mortality levels are still observed. Therefore, a novel generation line of targeted treatment strategies is being developed, including personalized therapies with kinase inhibitors. Recent molecular studies on TCs demonstrate that kinase inhibitor-based therapies might be considered as the most promising. In the past decade, new kinase inhibitors with different mechanisms of action have been reported and approved for clinical trials. This review presents an up-to-date picture of new approaches and challenges of inhibitor-based therapies in treatment of TCs, focusing on the latest findings reported over the past two years.

Rapid and dramatic responses to dabrafenib and trametinib in BRAF V600E-mutated lung adenocarcinoma

V-raf murine sarcoma viral oncogene homologue B1 (BRAF) is a proto-oncogene that regulates cell proliferation and survival. BRAF V600E-mutated lung cancer has aggressive characteristics and is resistant to chemotherapies. Combination of BRAF-specific inhibitor dabrafenib and mitogen-activated protein kinase kinase (MEK) inhibitor trametinib is the standard treatment for BRAF V600E-mutated lung cancer. We report a case of BRAF V600E-mutated lung adenocarcinoma, which presented with respiratory distress due to deterioration of advanced cancer. The tumour responded rapidly and significantly to BRAF/MEK inhibitors, and the patient's symptoms improved within 2 weeks. BRAF/MEK inhibitors are effective treatment in BRAF-mutated lung cancer even under critical conditions.

TRIM28 is a transcriptional activator of the mutant TERT promoter in human bladder cancer

Bladder cancer (BC) has a 70% telomerase reverse transcriptase (TERT or hTERT in humans) promoter mutation prevalence, commonly at -124 base pairs, and this is associated with increased hTERT expression and poor patient prognosis. We inserted a green fluorescent protein (GFP) tag in the mutant hTERT promoter allele to create BC cells expressing an hTERT-GFP fusion protein. These cells were used in a fluorescence-activated cell sorting-based pooled CRISPR-Cas9 Kinome knockout genetic screen to identify tripartite motif containing 28 (TRIM28) and TRIM24 as regulators of hTERT expression. TRIM28 activates, while TRIM24 suppresses, hTERT transcription from the mutated promoter allele. TRIM28 is recruited to the mutant promoter where it interacts with TRIM24, which inhibits its activity. Phosphorylation of TRIM28 through the mTOR complex 1 (mTORC1) releases it from TRIM24 and induces hTERT transcription. TRIM28 expression promotes in vitro and in vivo BC cell growth and stratifies BC patient outcome. mTORC1 inhibition with rapamycin analog Ridaforolimus suppresses TRIM28 phosphorylation, hTERT expression, and cell viability. This study may lead to hTERT-directed cancer therapies with reduced effects on normal progenitor cells.