Whole Exome Sequencing Identifies a Novel Hedgehog-Interacting Protein G516R Mutation in Locally Advanced Papillary Thyroid Cancer

Whole-exome sequencing and bioinformatic analyses revealed differences in gene mutation profiles in papillary thyroid cancer patients with and without benign thyroid goitre background

Background

Papillary thyroid cancer (PTC) is the most common thyroid malignancy. Concurrent presence of cytomorphological benign thyroid goitre (BTG) and PTC lesion is often detected. Aberrant protein profiles were previously reported in patients with and without BTG cytomorphological background. This study aimed to evaluate gene mutation profiles to further understand the molecular mechanism underlying BTG, PTC without BTG background and PTC with BTG background.

Methods

Patients were grouped according to the histopathological examination results: (i) BTG patients (n = 9), (ii) PTC patients without BTG background (PTCa, n = 8), and (iii) PTC patients with BTG background (PTCb, n = 5). Whole-exome sequencing (WES) was performed on genomic DNA extracted from thyroid tissue specimens. Nonsynonymous and splice-site variants with MAF of ≤ 1% in the 1000 Genomes Project were subjected to principal component analysis (PCA). PTC-specific SNVs were filtered against OncoKB and COSMIC while novel SNVs were screened through dbSNP and COSMIC databases. Functional impacts of the SNVs were predicted using PolyPhen-2 and SIFT. Protein-protein interaction (PPI) enrichment of the tumour-related genes was analysed using Metascape and MCODE algorithm.

Results

PCA plots showed distinctive SNV profiles among the three groups. OncoKB and COSMIC database screening identified 36 tumour-related genes including BRCA2 and FANCD2 in all groups. BRAF and 19 additional genes were found only in PTCa and PTCb. "Pathways in cancer", "DNA repair" and "Fanconi anaemia pathway" were among the top networks shared by all groups. However, signalling pathways related to tyrosine kinases were the most significantly enriched in PTCa while "Jak-STAT signalling pathway" and "Notch signalling pathway" were the only significantly enriched in PTCb. Ten SNVs were PTC-specific of which two were novel; DCTN1 c.2786C>G (p.Ala929Gly) and TRRAP c.8735G>C (p.Ser2912Thr). Four out of the ten SNVs were unique to PTCa.

Conclusion

Distinctive gene mutation patterns detected in this study corroborated the previous protein profile findings. We hypothesised that the PTCa and PTCb subtypes differed in the underlying molecular mechanisms involving tyrosine kinase, Jak-STAT and Notch signalling pathways. The potential applications of the SNVs in differentiating the benign from the PTC subtypes requires further validation in a larger sample size.

Blocking CDK7-Mediated NOTCH1-cMYC Signaling Attenuates Cancer Stem Cell Activity in Anaplastic Thyroid Cancer

Background: Anaplastic thyroid cancer (ATC) is an aggressive solid cancer in humans with few treatment options. Recent studies suggest that aberrant gene transcription could contribute to aggressive ATC progression. To test this hypothesis, we assessed if blocking cyclin-dependent protein 7 (CDK7) activity could impede ATC progression through attenuation of cancer stem cell (CSC) activity. Methods: We treated cell lines isolated from human ATC (THJ-11T and -16T) and xenograft mice induced by these cells with the CDK7 inhibitor THZ1. Through integrative transcriptome analyses we found that the NOTCH1-cMYC signaling axis was a potential target of CDK7 inhibition in ATC. To determine the regulatory action of NOTCH1-cMYC signaling in CSC maintenance, we evaluated the effect of a selective NOTCH1 inhibitor, crenigacestat, on CSC capacities in ATC. Results: THZ1 markedly inhibited proliferation of ATC cells and xenograft tumor growth by blocking cell cycle progression and inducing apoptosis. NOTCH1 was sensitive to suppressive transcription mediated by CDK7 inhibition and was highly enriched in tumorspheres from ATC cells. Treatment of ATC cells with either crenigacestat or THZ1 blocked formation of tumorspheres, decreased aldehyde dehydrogenase activity, and suppressed in vivo initiation and growth of tumors induced by ATC cells, indicating that NOTCH1 was a critical regulator of CSC activity in ATC. Furthermore, we demonstrated that cMYC was a downstream target of NOTCH1 signaling that collaboratively maintained CSC activity in ATC. Of note, genomic analysis showed that low CDK7 expression contributed to longer disease-free survival of thyroid cancer patients. Conclusions: NOTCH1 is a newly identified CSC regulator. Targeting NOTCH1-cMYC signaling is a promising therapeutic strategy for ATC.

Targeting transcriptional regulators for treatment of anaplastic thyroid cancer

Dysregulation of genes perpetuates cancer progression. During carcinogenesis, cancer cells acquire dependency of aberrant transcriptional programs (known as “transcription addiction”) to meet the high demands for uncontrolled proliferation. The needs for particular transcription programs for cancer growth could be cancer-type-selective. The dependencies of certain transcription regulators could be exploited for therapeutic benefits. Anaplastic thyroid cancer (ATC) is an extremely aggressive human cancer for which new treatment modalities are urgently needed. Its resistance to conventional treatments and the lack of therapeutic options for improving survival might have been attributed to extensive genetic heterogeneity due to subsequent evolving genetic alterations and clonal selections during carcinogenesis. Despite this genetic complexity, mounting evidence has revealed a characteristic transcriptional addiction of ATC cells resulting in evolving diverse oncogenic signaling for cancer cell survival. The transcriptional addiction has presented a huge challenge for effective targeting as shown by the failure of previous targeted therapies. However, an emerging notion is that many different oncogenic signaling pathways activated by multiple upstream driver mutations might ultimately converge on the transcriptional responses, which would provide an opportunity to target transcriptional regulators for treatment of ATC. Here, we review the current understanding of how genetic alterations in cancer distorted the transcription program, leading to acquisition of transcriptional addiction. We also highlight recent findings from studies aiming to exploit the opportunity for targeting transcription regulators as potential therapeutics for ATC.

Whole-Exome Sequencing in Papillary Microcarcinoma: Potential Early Biomarkers of Lateral Lymph Node Metastasis

BACKGROUND

Early identification of patients with high-risk papillary thyroid microcarcinoma (PTMC) that is likely to progress has become a critical challenge. We aimed to identify somatic mutations associated with lateral neck lymph node (LN) metastasis (N1b) in patients with PTMC.

METHODS

Whole-exome sequencing (WES) of 14 PTMCs with no LN metastasis (N0) and 13 N1b PTMCs was performed using primary tumors and matched normal thyroid tissues.

RESULTS

The mutational burden was comparable in N0 and N1b tumors, as the median number of mutations was 23 (range, 12 to 46) in N0 and 24 (range, 12 to 50) in N1b PTMC (P=0.918). The most frequent mutations were detected in PGS1, SLC4A8, DAAM2, and HELZ in N1b PTMCs alone, and the K158Q mutation in PGS1 (four patients, Fisher's exact test P=0.041) was significantly enriched in N1b PTMCs. Based on pathway analysis, somatic mutations belonging to the receptor tyrosine kinase-RAS and NOTCH pathways were most frequently affected in N1b PTMCs. We identified four mutations that are predicted to be pathogenic in four genes based on Clinvar and Combined Annotation-Dependent Depletion score: BRAF, USH2A, CFTR, and PHIP. A missense mutation in CFTR and a nonsense mutation in PHIP were detected in N1b PTMCs only, although in one case each. BRAF mutation was detected in both N0 and N1b PTMCs.

CONCLUSION

This first comprehensive WES analysis of the mutational landscape of N0 and N1b PTMCs identified pathogenic genes that affect biological functions associated with the aggressive phenotype of PTMC.

Novel somatic variants involved in biochemical activity of pure growth hormone-secreting pituitary adenoma without GNAS variant

We aimed to identify somatic genetic alterations in pure growth hormone (GH)-secreting pituitary adenomas without GNAS variants. Patients with GH-secreting pituitary adenoma who underwent transsphenoidal adenomectomy at Severance Hospital, Yonsei University College of Medicine were recruited. Somatic genetic alterations were profiled by whole-exome sequencing (WES) and targeted resequencing. WES was performed using DNA from nine GH-secreting pituitary tumors and corresponding blood samples. Absence of GNAS variant was confirmed by Sanger sequencing. For targeted resequencing of 140 fixed tissues, 48 WES-derived candidate genes and 7 GH-secreting pituitary adenoma-associated genes were included. Forty-eight genes with 59 somatic variants were identified by WES. In targeted resequencing, variants in 26 recurrent genes, including MAST4, PRIM2, TNN, STARD9, DNAH11, DOCK4, GPR98, BCHE, DARS, CUBN, NGDN, PLXND1, UNC5B, and COL22A1, were identified, but variants in previously reported genes were not detected. BCHE, DARS, NGDN, and UNC5B variants were associated with increased GH-secreting pituitary tumor biochemical activity, which was confirmed in vitro. Although recurrent point variants were rare, several somatic variants were identified in sporadic pure GH-secreting pituitary adenomas. Several somatic variants may affect pathways involved in the tumorigenesis and biochemical activities of GH-secreting pituitary adenomas.

Simultaneous Expression of Long Non-Coding RNA FAL1 and Extracellular Matrix Protein 1 Defines Tumour Behaviour in Young Patients with Papillary Thyroid Cancer

Simple Summary

FAL1 upregulation has been reported in many types of human cancers. The up-regulatory mechanism was identified in ovarian cancer but was not investigated in other type of cancers. Using The Cancer Genome Atlas (TCGA) database, we identified simultaneous upregulation of FAL1 adjacent to chromosome 1q21.3. Among 53 putative transcription factors for FAL1 and neighbouring genes, we selected c-JUN and JUND as the best candidates. This simultaneous upregulation defines molecular biological features representing RAS-driven PTC-enriched immune-related gene sets. These findings suggest that the simultaneous upregulation might be a potential diagnostic and therapeutic target for RAS-driven PTC.

Abstract

We investigated the regulatory mechanism of FAL1 and unravelled the molecular biological features of FAL1 upregulation in papillary thyroid cancer (PTC). Correlation analyses of FAL1 and neighbouring genes adjacent to chromosome 1q21.3 were performed. Focal amplification was performed using data from copy number alterations in The Cancer Genome Atlas (TCGA) database. To identify putative transcriptional factors, PROMO and the Encyclopaedia of DNA Elements (ENCODE) were used. To validate c-JUN and JUND as master transcription factors for FAL1 and ECM1, gene set enrichment analysis was performed according to FAL1 and ECM1 expression. Statistical analyses of the molecular biological features of FAL1- and ECM1-upregulated PTCs were conducted. FAL1 expression significantly correlated with that of neighbouring genes. Focal amplification of chromosome 1q21.3 was observed in ovarian cancer but not in thyroid carcinoma. However, PROMO suggested 53 transcription factors as putative common transcriptional factors for FAL1 and ECM1 simultaneously. Among them, we selected c-JUN and JUND as the best candidates based on ENCODE results. The expression of target genes of JUND simultaneously increased in FAL1- and ECM1-upregulated PTCs, especially in young patients. The molecular biological features represented RAS-driven PTC and simultaneously enriched immune-related gene sets. FAL1 and ECM1 expression frequently increased simultaneously and could be operated by JUND. The simultaneous upregulation might be a potential diagnostic and therapeutic target for RAS-driven PTC.

Intratumor heterogeneity: A new perspective on colorectal cancer research

Colorectal cancers generally consist of multiple subclones. These subclones have their own unique characteristics, resulting in intratumor heterogeneity (ITH). As the discussion of ITH has advanced, a model describing the relationship of ITH to the tumor has gradually emerged. ITH can be divided into two types of intraprimary tumor heterogeneity and intraindividual tumor heterogeneity, the former for further understanding of tumor composition, and the latter for providing more information about evolutionary patterns. With the rapid development of new methods, such as next‐generation, polyguanine region sequencing, and Image detection, researchers may unravel the secrets underlying ITH. The higher the ITH of the tumor, the richer the interaction between the subclones maybe, or the greater the chance of the tumor getting more powerful subclones may be, thus increasing the malignant potential of the tumor. Existing evidence suggests that ITH may increase the ability of tumors to resist treatment and can be used as an independent influence on the prognosis of colorectal cancer. We reviewed 80 recent studies to give researchers a new perspective on colorectal cancer. There is still a limited amount of research in this area. Further study of the relationship between ITH and clinical endpoints may lead to the development of new treatment strategies.

Cancer Publication Portal: an online tool for summarizing and searching human cancer-genomic publications

A search of PubMed lists >582,000 citations with the keywords “cancer” and “gene”. The large volume of cancer genomic publications necessitates the development of text-mining tools to help cancer researchers navigate and summarize articles efficiently. We developed a Cancer Publication Portal (CPP) to help researchers efficiently search and summarize cancer genomic publications, based on one or more genes of interest. CPP integrates data from several sources, including PubTator, the Medical Subject Headings (MeSH) database; the HUGO Gene Nomenclature Committee human gene name database; PubMed, a database of biomedical literature citations; and the National Cancer Institute (NCI) Thesaurus. Following each query, results are summarized and include the publication frequency for each cancer type, as well as publication frequencies for cancer terms, pharmacological agents, genomic mutations, and additional genes stratified by cancer type. Cancer terms were identified by comparing titles and abstracts from cancer-related (N=851,868) and non-cancer related articles (N=2,607,020). CPP allows a user to quickly obtain publication statistics, such as the frequency of articles mentioning EGFR across cancer types, and to explore associations, such as the association between pharmacological agent and cancer type. Result summaries are interactive, so additional filters can be easily added as the literature is explored.  After a search is completed, a PubTator collection can be quickly created, in order to view article titles and abstracts in PubTator. CPP currently includes information for ~1.1 million cancer-related publications associated with >23,000 human genes. Database URL: https://gdancik.github.io/bioinformatics/CPP/.