Germline copy number variation in the YTHDC2 gene: does it have a role in finding a novel potential molecular target involved in pancreatic adenocarcinoma susceptibility?

N6-methyladenosine-regulated ADIRF impairs lung adenocarcinoma metastasis and serves as a potential prognostic biomarker

Aberrant expression of adipogenic regulatory factors (ADIRF) in tumor cells is critical for tumor growth and metastasis. N6-methyladenosine (m6A) modifications have an important role in a variety of biological activities. Our study aimed to investigate the role of ADIRF in adenocarcinoma and to elucidate the regulatory role of m6A signaling on ADIRF. Differential expression of genes in tumor and normal tissues was analyzed using the LUAD dataset (GSE1987). The Kaplan-Meier method and receiver operating characteristic (ROC) curve analysis were performed to evaluate the prognostic and diagnostic value of ADIRF in LUAD. Loss-of-function or gain-of-function experiments were performed to study the effect of ADIRF on LUAD growth in vitro. The molecular mechanism of action of ADIRF in LUAD was confirmed using a dual-luciferase reporter system and MeRIP-qPCR. We identified a loss of ADIRF expression in LUAD tissues and cells. Furthermore, the restoration of ADIRF levels attenuated LUAD cell growth and metastasis in vitro. Mechanistically, an m6A "eraser," α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5), eliminated the ADIRF m6A modification motif and further blocked the binding of the YTH domain-containing 2 (YTHDC2)-binding protein to ADIRF. At the molecular level, ALKBH5 enrichment increased ADIRF mRNA levels and prevented the attenuation of ADIRF mRNA by YTHDC2. The effects of ALKBH5 overexpression could also extend to the inhibition of LUAD cell proliferation and metastasis. This study linked ADIRF with the m6A modifying regulators ALKBH5 and YTHDC2, providing a promising molecular intervention for LUAD and deepening the understanding of LUAD mechanisms.

Copy Number Variations in Pancreatic Cancer: From Biological Significance to Clinical Utility

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer, characterized by high tumor heterogeneity and a poor prognosis. Inter- and intra-tumoral heterogeneity in PDAC is a major obstacle to effective PDAC treatment; therefore, it is highly desirable to explore the tumor heterogeneity and underlying mechanisms for the improvement of PDAC prognosis. Gene copy number variations (CNVs) are increasingly recognized as a common and heritable source of inter-individual variation in genomic sequence. In this review, we outline the origin, main characteristics, and pathological aspects of CNVs. We then describe the occurrence of CNVs in PDAC, including those that have been clearly shown to have a pathogenic role, and further highlight some key examples of their involvement in tumor development and progression. The ability to efficiently identify and analyze CNVs in tumor samples is important to support translational research and foster precision oncology, as copy number variants can be utilized to guide clinical decisions. We provide insights into understanding the CNV landscapes and the role of both somatic and germline CNVs in PDAC, which could lead to significant advances in diagnosis, prognosis, and treatment. Although there has been significant progress in this field, understanding the full contribution of CNVs to the genetic basis of PDAC will require further research, with more accurate CNV assays such as single-cell techniques and larger cohorts than have been performed to date.

Identification of methyltransferase modification genes associated with prognosis and immune features of pancreatic adenocarcinoma

BACKGROUND

Pancreatic adenocarcinoma (PAAD) is a malignant tumor with a high mortality rate. Methylation modifications acted a crucial role to affect cancer progression. The current study aimed to explore the potential role of methylase regulators in PAAD prognosis and immune microenvironment.

METHODS

PubMed and TCGA databases were used to systematically analyze methylase regulators in PAAD. We identified three methylase clusters based on RNA methylase transcriptome data and obtained three gene clusters based on methylase modification-related differently expressed genes using principal component analysis (PCA) analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and Gene Ontology (GO) biological processes were performed to explore the processes enriched in the different subgroups and single sample gene-set enrichment analysis (ssGSEA) was used to analyze the relationship between subgroups and immune infiltration in PAAD.

RESULTS

We systematically screened 43 methylase regulators in PAAD samples and identified three methylase clusters with different clinical outcomes, as well as detected a significant relationship between methylase clusters and tumor immune infiltration. The top ten mutated genes include TP53, Kirsten rat sarcoma viral oncogene homolog (KRAS), titin gene (TTN), mucin 16 (MUC16), SMAD4, cyclin-dependent kinase inhibitor 2a (CDKN2A), Ryanodine receptor isoform-1 (RYR1), ring finger 43 (RNF43), protocadherin-15 (PCDH15), and AT-rich interacting domain-containing protein 1 A gene (ARID1A).

CONCLUSION

The current study constructed an m6A/m5C/m1A/m7G modulator genes and explored methylase modification-related genes, which were related to the prognosis of PAAD patients and the immune checkpoint point cytotoxic T-lymphocyte associated protein 4 (CTLA4). These findings may provide prognostic predictors and direction for immunotherapy strategies for the treatment of PAAD.

Overexpression of YTHDC2 contributes to the progression of prostate cancer and predicts poor outcomes in patients with prostate cancer

YTH domain-containing protein 2 (YTHDC2), a member of N6-methyladenosine (m6A) readers, has been reported to be closely associated with multiple cancer types. However, very little is known about the YTHDC2 gene and its involvement in prostate cancer. YTHDC2 protein expression level was analyzed and correlated to clinical outcomes in prostate cancer patients who underwent prostatectomy in Guizhou Provincial People's Hospital. The YTHDC2 expression level was also detected in prostate cancer cell lines and an immortalized prostate epithelial cell line BPH-1 and RWPE1 by quantitative real-time reverse transcription polymerase chain reaction. Furthermore, we established stable cell lines (DU145 and PC-3) transfected with either empty vector or the full-length YTHDC2 gene and conducted cell function assays in vitro. Fisher's exact test and Pearson χ² test were employed, Kaplan-Meier method was used for the survival analysis. Of 32 patient samples who enrolled in this study, YTHDC2 was significantly upregulated in prostate cancer (PCa) patients with higher Gleason scores and serum prostate-specific antigen levels. YTHDC2 expression was significantly elevated in all PCa cell lines compared to BPH-1 and RWPE1 (all p < 0.05). Functionally, the enforced expression of YTHDC2 markedly promoted cell growth, migration, and invasion efficacies in prostate cancer cells. Our data indicate that YTHDC2 upregulation may be potentially associated with the prognosis of prostate cancer patients.

Mettl3-mediated m6 A modification of Lrp2 facilitates neurogenesis through Ythdc2 and elicits antidepressant-like effects

N⁶ -methyladenosine (m⁶ A) is the most abundant mRNA modification affecting diverse biological processes. However, the functions and precise mechanisms of m⁶ A signaling in adult hippocampal neurogenesis and neurogenesis-related depression remain largely enigmatic. We found that depletion of Mettl3 or Mettl14 in neural stem cells (NSCs) dramatically reduced m⁶ A abundance, proliferation, and neuronal genesis, coupled with enhanced glial differentiation. Conversely, overexpressing Mettl3 promoted proliferation and neuronal differentiation. Mechanistically, the m⁶ A modification of Lrp2 mRNA by Mettl3 enhanced its stability and translation efficiency relying on the reader protein Ythdc2, which in turn promoted neurogenesis. Importantly, mice lacking Mettl3 manifested reduced hippocampal neurogenesis, which could contribute to spatial memory decline, and depression-like behaviors. We found that these defective behaviors were notably reversed by Lrp2 overexpression. Moreover, Mettl3 overexpression in the hippocampus of depressive mice rescues behavioral defects. Our findings uncover the biological role of m⁶ A modification in Lrp2-mediated neurogenesis via m⁶ A-binding protein Ythdc2, and propose a rationale that targeting Mettl3-Ythdc2-Lrp2 axis regulation of neurogenesis might serve as a promising antidepressant strategy.

Insight into the structure, physiological function, and role in cancer of m6A readers—YTH domain-containing proteins

YT521-B homology (YTH) domain-containing proteins (YTHDF1-3, YTHDC1-2) are the most crucial part of N6-methyladenosine (m6A) readers and play a regulatory role in almost all stages of methylated RNA metabolism and the progression of various cancers. Since m6A is identified as an essential post-transcriptional type, YTH domain-containing proteins have played a key role in the m6A sites of RNA. Hence, it is of great significance to study the interaction between YTH family proteins and m6A-modified RNA metabolism and tumor. In this review, their basic structure and physical functions in RNA transcription, splicing, exporting, stability, and degradation as well as protein translation are introduced. Then we discussed the expression regulation of YTH domain-containing proteins in cancers. Furthermore, we introduced the role of the YTH family in cancer biology and systematically demonstrated their functions in various aspects of tumorigenesis and development. To provide a more institute understanding of the role of YTH family proteins in cancers, we summarized their functions and specific mechanisms in various cancer types and presented their involvement in cancer-related signaling pathways.

Impact of Different Selection Approaches for Identifying Lynch Syndrome-Related Colorectal Cancer Patients: Unity Is Strength

Lynch syndrome (LS) is an inherited genetic condition associated with increased predisposition to colorectal cancer (CRC) and other tumors and is caused by germline mutations in Mismatch Repair (MMR) or EPCAM genes. The identification of LS carriers is currently based on germline testing of subjects with MMR-deficient (dMMR) tumors or fulfilling clinical criteria, but the most efficient strategies to select patients who should be offered genetic testing are yet not well defined. In order to assess the most suitable selection mode to identify LS-related CRC patients, we retrospectively collected and analyzed all clinical and molecular information of 854 CRC patients, recruited from 2013 to 2021 at the University Hospital Policlinico "P. Giaccone" of Palermo (Italy), 100 of which were selected based on revised Bethesda guidelines, Amsterdam criteria II, or tissue MMR deficiency, and genetically tested for germline variants in LS-susceptibility genes. Our study showed that 32 out of 100 CRC patients harbored germline likely pathogenic/pathogenic variants in MMR genes. The analysis of tissue microsatellite instability (MSI) status according to the revised Bethesda guidelines has been to be the best selection approach. However, using different selection approaches as complementary strategies is useful to identify LS carriers, reducing underdiagnosis of this syndrome.

BRCA1/2 variants of unknown significance in hereditary breast and ovarian cancer (HBOC) syndrome: looking for the hidden meaning

Hereditary breast and ovarian cancer syndrome is caused by germline mutations in BRCA1/2 genes. These genes are very large and their mutations are heterogeneous and scattered throughout the coding sequence. In addition to the above-mentioned mutations, variants of uncertain/unknown significance (VUSs) have been identified in BRCA genes, which make more difficult the clinical management of the patient and risk assessment. In the last decades, several laboratories have developed different databases that contain more than 2000 variants for the two genes and integrated strategies which include multifactorial prediction models based on direct and indirect genetic evidence, to classify the VUS and attribute them a clinical significance associated with a deleterious, high-low or neutral risk. This review provides a comprehensive overview of literature studies concerning the VUSs, in order to assess their impact on the population and provide new insight for the appropriate patient management in clinical practice.

Can the tumor-agnostic evaluation of MSI/MMR status be the common denominator for the immunotherapy treatment of patients with several solid tumors?

Alterations in short-repetitive DNA sequences, known as microsatellite instability (MSI), can reflect deficiencies in Mismatch Repair (MMR) system which represents a major player in DNA integrity maintenance. The incidence of MSI-H/dMMR has been shown to be variable depending on the tumor type. Several studies confirmed that dMMR/MSI status, although less frequent than PD-L1 expression, may better predict response to immune-checkpoint inhibitors (ICIs) in patients with solid tumors. In October 2016, the FDA granted pembrolizumab as breakthrough therapy for the treatment of non-CRC, MSI-H/dMMR tumors, providing, for the first time, a tumor-agnostic indication. In the next future, the tissue-agnostic evaluation of MSI-H/dMMR could become the common denominator for the immunotherapy treatment of patients with different advanced solid tumors, in order to select patient subgroups which may benefit from this therapy. In this Review we provided an overview of the main clinical studies describing the association between MSI-H/dMMR tumors and immunotherapy response.

Genome-Wide Identification of N6-Methyladenosine Associated SNPs as Potential Functional Variants for Type 1 Diabetes

OBJECTIVES

N6-methyladenosine (m6A) is essential in the regulation of the immune system, but the role that its single nucleotide polymorphisms (SNPs) play in the pathogenesis of type 1 diabetes (T1D) remains unknown. This study demonstrated the association between genetic variants in m6A regulators and T1D risk based on a case-control study in a Chinese population.

METHODS

The tagging SNPs in m6A regulators were genotyped in 1005 autoantibody-positive patients with T1D and 1257 controls using the Illumina Human OmniZhongHua-8 platform. Islet-specific autoantibodies were examined by radioimmunoprecipitation in all the patients. The mixed-meal glucose tolerance test was performed on 355 newly diagnosed patients to evaluate their residual islet function. The functional annotations for the identified SNPs were performed in silico. Using 102 samples from a whole-genome expression microarray, key signaling pathways associated with m6A regulators in T1D were comprehendingly evaluated.

RESULTS

Under the additive model, we observed three tag SNPs in the noncoding region of the PRRC2A (rs2260051, rs3130623) and YTHDC2 (rs1862315) gene are associated with T1D risk. Although no association was found between these SNPs and islet function, patients carrying risk variants had a higher positive rate for ZnT8A, GADA, and IA-2A. Further analyses showed that rs2260051[T] was associated with increased expression of PRRC2A mRNA (P = 7.0E-13), and PRRC2A mRNA was significantly higher in peripheral blood mononuclear cell samples from patients with T1D compared to normal samples (P = 0.022). Enrichment analyses indicated that increased PRRC2A expression engages in the most significant hallmarks of cytokine-cytokine receptor interaction, cell adhesion and chemotaxis, and neurotransmitter regulation pathways. The potential role of increased PRRC2A in disrupting immune homeostasis is through the PI3K/AKT pathway and neuro-immune interactions.

CONCLUSION

This study found intronic variants in PRRC2A and YTHDC2 associated with T1D risk in a Chinese Han population. PRRC2A rs2260051[T] may be implicated in unbalanced immune homeostasis by affecting the expression of PRRC2A mRNA. These findings enriched our understanding of m6A regulators and their intronic SNPs that underlie the pathogenesis of T1D.

Identification of m6A methyltransferase-related genes predicts prognosis and immune infiltrates in head and neck squamous cell carcinoma

Background

Head and neck squamous cell carcinoma (HNSCC) accounts for 90% of head and neck malignant tumors. As the early symptoms of HNSCC are not obvious, and it is prone to recurrence and metastasis, making the overall survival (OS) rate of patients very low. Existing studies have shown m6A methylation plays a crucial role in various cancers, but it is rarely studied in HNSCC. This study aimed to explore the expression of m6A methylation-related genes in HNSCC and its correlation with prognosis, and to explore its relationship with immune infiltration.

Methods

The gene expression data of HNSCC patient tumor samples (tumor =510) and adjacent normal tissue samples (normal =50) were extracted from The Cancer Genome Atlas (TCGA) database, and the expression characteristics of m6A regulatory factors were described. Kaplan-Meier survival analysis was used to analyze the relationship between m6A regulatory factors and OS and disease-specific survival (DSS). Least absolute shrinkage and selection operator (LASSO) regression was used to construct the m6A regulatory factor-HNSCC risk prediction model. In addition, the relationship between m6A methylation-related genes and tumor immune infiltration were discussed.

Results

The differential expression of 20 genes were identified by TCGA, and 18 genes (IGF2BP2, IGF2BP1, IGF2BP3, VIRMA, YTHDF1, YTHDF2, YTHDF3, ZC3H13, METTL14, ALKBH5, METTL3, RBMX, WTAP, YTHDC1, FTO, HNRNPC, HNRNPA2B1, and RBM15) were overexpressed in HNSCC. The survival rate of different gene expression levels was different. The high expression of YTHDC1 and YTHDC2 indicated better OS. Furthermore, for DSS, increased expression of YTHDC2 was also correlated with better clinical outcomes (P<0.05). At the same time, we drew a 3-gene risk score model in the TCGA-HNSCC cohort, and the survival curve showed compared with low-risk patients, high-risk patients had significantly worse OS (P<0.05). Gene enrichment analysis showed EPITHELIAL_MESENCHYMAL_TRANSITIO, MTORC1_SIGNALING, MYC_TARGETS_V1, MYC_TARGETS_V2, MYOGENESIS pathways, high TP53 mutations, and suppressive immunity were related to the high-risk group. The low-risk group was related to ALLOGRAFT_REJECTION, COMPLEMENT, IL6_JAK_STAT3_SIGNALING, INTERFERON_ALPHA_RESPONSE, INTERFERON_GAMMA_RESPONSE pathways, low TP53 mutations, and active immunity.

Conclusions

The m6A methyltransferase-related genes can predict the prognosis of HNSCC and are related to immune infiltration.

The pathological tissue expression pattern and clinical significance of m6A-regulatory genes in non-small cell lung cancer

BACKGROUND

Aberrant expression of m6A-related proteins contributes to the occurrence and progression of non-small cell lung cancer (NSCLC). Current studies mainly focus on single m6A regulatory genes and their underlying mechanisms, and the expression of multiple m6A regulatory proteins in NSCLC remains unclear. Therefore, it is necessary to systematically examine these proteins, particularly in clinical specimens.

METHODS

Bioinformatic analysis was used to determine the expression of m6A regulatory genes and their correlation with common gene mutations, such as TP53, EGFR, and KRAS, using The Cancer Genome Atlas (TCGA) and the AE-meta databases. Immunohistochemistry was employed to analyze the protein expression of m6A regulatory proteins in 61 benign lung tissues and 316 NSCLC tissues. Statistical analysis was performed to calculate the correlation between the expression of m6A regulatory proteins and clinicopathological features, survival, and common gene mutations in lung carcinoma patients.

RESULTS

Analysis of the mRNA levels of 13 core m6A regulators, using information from TCGA and the AE-meta databases, revealed that YTHDF1 levels were upregulated in NSCLC compared with those in adjacent normal tissues. Immunohistochemical staining showed that the expression of METTL3, ALKBH5, YTHDC2, and YTHDF1 was significantly upregulated in NSCLC tissues. Further analyses demonstrated a positive correlation between differentially expressed m6A regulatory proteins, including METTL3, ALKBH5, YTHDC2, and YTHDF1, and the poor clinicopathological features and survival of NSCLC patients. According to the statistics of NSCLC patients enrolled in this study, the protein levels of METTL3 in patients with EGFR exon-19 mutation were higher than those in patients with wild-type EGFR.

CONCLUSION

Our results indicate that m6A regulators, including METTL3, ALKBH5, YTHDC2, and YTHDF1, could serve as predictive markers of NSCLC, which will facilitate early detection and diagnosis of NSCLC.

YTHDC2-Mediated circYTHDC2 N6-Methyladenosine Modification Promotes Vascular Smooth Muscle Cells Dysfunction Through Inhibiting Ten-Eleven Translocation 2

Type 2 diabetes condition mediated vascular smooth muscle cell (VSMCs) dysfunction. However, the mechanism of VSMCs dysfunction in diabetic patients needs further elucidation. VSMCs are an important component of the vascular wall, participate in the process of vascular remodeling, and play a vital role in the vascular complications of diabetes. Studies have found that circular RNAs (circRNAs) play a key regulatory role in the occurrence and development of VSMCs dysfunction. In this study, we stimulated VSMCs with high glucose and identified a new circular RNA, circYTHDC2, using circRNA chip analysis. circYTHDC2 was highly expressed in VSMCs treated with high glucose. Knockout of circYTHDC2 significantly inhibited the proliferation and migration of VSMCs. Metformin treatment significantly inhibited the expression of YTHDC2 and circYTHDC2. The upstream mechanism analysis revealed that the stability of circYTHDC2 was regulated by YTHDC2-mediated m6A modification. Furthermore, circYTHDC2 negatively regulates the expression of Ten-Eleven Translocation 2 (TET2) by targeting the unstable motif of TET2 3′UTR, thereby promoting dedifferentiated “synthetic type” transformation of VSMC. Taken together, these results suggest that the YTHDC2/circYTHDC2/TET2 pathway is an important target of metformin in preventing the progression of VSMCs dysfunction under high glucose.

Hearing Function: Identification of New Candidate Genes Further Explaining the Complexity of This Sensory Ability

To date, the knowledge of the genetic determinants behind the modulation of hearing ability is relatively limited. To investigate this trait, we performed Genome-Wide Association Study (GWAS) meta-analysis using genotype and audiometric data (hearing thresholds at 0.25, 0.5, 1, 2, 4, and 8 kHz, and pure-tone averages of thresholds at low, medium, and high frequencies) collected in nine cohorts from Europe, South-Eastern USA, Caucasus, and Central Asia, for an overall number of ~9000 subjects. Three hundred seventy-five genes across all nine analyses were tagged by single nucleotide polymorphisms (SNPs) reaching a suggestive p-value (p < 10⁻⁵). Amongst these, 15 were successfully replicated using a gene-based approach in the independent Italian Salus in the Apulia cohort (n = 1774) at the nominal significance threshold (p < 0.05). In addition, the expression level of the replicated genes was assessed in published human and mouse inner ear datasets. Considering expression patterns in humans and mice, eleven genes were considered particularly promising candidates for the hearing function: BNIP3L, ELP5, MAP3K20, MATN2, MTMR7, MYO1E, PCNT, R3HDM1, SLC9A9, TGFB2, and YTHDC2. These findings represent a further contribution to our understanding of the genetic basis of hearing function and its related diseases.

The role of YTH domain containing 2 in epigenetic modification and immune infiltration of pan-cancer

YTH domain containing 2 (YTHDC2) is the largest N6‐Methyladenosine (m⁶A) binding protein of the YTH protein family and the only member containing ATP‐dependent RNA helicase activity. For further analysing its biological role in epigenetic modification, we comprehensively explored YTHDC2 from gene expression, genetic alteration, protein‐protein interaction (PPI) network, immune infiltration, diagnostic value and prognostic value in pan‐cancer, using a series of databases and bioinformatic tools. We found that YTHDC2 with Missense mutation could cause a different prognosis in uterine corpus endometrial carcinoma (UCEC), and its different methylation level could lead to a totally various prognosis in adrenocortical carcinoma (ACC), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), lung squamous cell carcinoma (LUSC) and UCEC. The main molecular mechanisms of YTHDC2 focused on catalytic activity, helicase activity, snRNA binding, spliceosome and mRNA surveillance. Additionally, YTHDC2 was notably correlated with tumour immune infiltration. Moreover, YTHDC2 had a high diagnostic value for seven cancer types and a prognostic value for brain lower grade glioma (LGG), rectum adenocarcinoma (READ) and skin cutaneous melanoma (SKCM). Collectively, YTHDC2 plays a significant role in epigenetic modification and immune infiltration and maybe a potential biomarker for diagnosis and prognosis in certain cancers.

Prognostic Implication of the m6A RNA Methylation Regulators in Rectal Cancer

N6-methyladenosine (m⁶A) is a very common and abundant RNA modifications occurring in nearly all types of RNAs. Although the dysregulated expression of m⁶A regulators is implicated in cancer progression, our understanding of the prognostic value of the m⁶A regulators in rectal cancer is still quite limited. In this study, we analyzed the RNA expression levels of the 17 m⁶A regulator genes of 95 rectal cancer and 10 normal rectal samples from the The Cancer Genome Atlas Rectum Adenocarcinoma (TCGA-READ) dataset. Lasso regression analysis was conducted to build a prognostic model and calculate the risk score. The rectal cancer patients were then devided into the high-risk and low-risk groups according to the mean risk score. The prognostic value of the identified model was separately evaluated in the TCGA-READ and GSE87211 datasets. GSEA was conducted to analyze the functional difference of high-risk and low-risk rectal cancer patients. Our analysis revealed that rectal cancer patients with lower expression of YTHDC2 and METTL14 had a remarkable worse overall survival (P < 0.05). The prognostic value of the model was validated in GSE87211 datasets, with AUC = 0.612 for OS and AUC = 0.651 for RFS. Furthermore, the m⁶A modification-based risk score system is associated with activation of distinct signaling pathways, such as DNA repair, epithelial-mesenchymal transition, G₂M checkpoint and the MYC pathway, that may contribute to the progression of rectal cancer. In conclusion, our findings demonstrated that the m⁶A RNA methylation regulators, specifically YTHDC2 and METTL14, were significantly down-regulated and might be potential prognostic biomarkers in rectal cancer.

LINC00857 promotes cell proliferation and migration in colorectal cancer by interacting with YTHDC1 and stabilizing SLC7A5

Colorectal cancer (CRC) is one of the most lethal malignances in humans. Hence, it is of great significance to identify regulatory molecules in CRC progression. Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are involved in cancer malignancy. It has been reported that long intergenic non-protein coding RNA 857 (LINC00857) acts as a vital oncogene in many types of cancer by promoting cell proliferation and migration. However, the role of LINC00857 in CRC remains unclear. In the present study, LINC00857 was upregulated in CRC tissue samples and cells. Next, in vitro loss-of-function experiments demonstrated that LINC00857 knockdown suppressed CRC cell viability, proliferation and migration, as well as epithelial-mesenchymal transition and increased cell apoptosis. Mechanistically, LINC00857 abundantly interacted with the RNA-binding protein YTH domain containing 1 (YTHDC1). YTHDC1 ultimately combined with solute carrier family 7 member 5 (SLC7A5) and increased SLC7A5 mRNA stability. Finally, a series of rescue experiments indicated that LINC00857 promoted the proliferation and migration of CRC cells by regulating mRNA stability. Thus, the present findings illustrated that LINC00857 functions as an oncogene in CRC cells via the YTHDC1/SLC7A5 axis.

Role of RNA N6-Methyladenosine Modification in Male Infertility and Genital System Tumors

Epigenetic alterations, particularly RNA methylation, play a crucial role in many types of disease development and progression. Among them, N6-methyladenosine (m6A) is the most common epigenetic RNA modification, and its important roles are not only related to the occurrence, progression, and aggressiveness of tumors but also affect the progression of many non-tumor diseases. The biological effects of RNA m6A modification are dynamically and reversibly regulated by methyltransferases (writers), demethylases (erasers), and m6A binding proteins (readers). This review summarized the current finding of the RNA m6A modification regulators in male infertility and genital system tumors and discussed the role and potential clinical application of the RNA m6A modification in spermatogenesis and male genital system tumors.

YTH Domain Proteins: A Family of m6A Readers in Cancer Progression

N⁶-methyladenosine (m⁶A) is the most abundant internal modification in eukaryotic messenger RNAs (mRNAs). m⁶A RNA methylation is involved in all stages of RNA life cycle, from RNA processing, nuclear output, translation regulation to RNA degradation, indicating that m⁶A has various functions affecting RNA metabolism positively or negatively. Reading proteins are vital in regulating the translation and stability of m⁶A mRNAs positively or negatively. Recent studies have enhanced the understanding of the molecular mechanism of the YT521-B homology (YTH) domain family and the modification of m⁶A. This study aimed to review the specific mechanisms, functions, and interactions of the YTH domain protein family. It also discussed future research directions, thus providing new ideas for the clinical diagnosis and targeted therapy of cancer.

BRCA1/2 pathogenic variants in triple-negative versus luminal-like breast cancers: genotype-phenotype correlation in a cohort of 531 patients

Background

Several available data suggest the association between specific molecular subtypes and BRCA1/2 mutational status. Previous investigations showed the association between BRCA1/2 pathogenic variants (PVs) in specific genomic regions and phenotypic variations of cancer relative risk, while the role of PV type and location in determining the breast cancer (BC) phenotypic features remains still unclear. The aim of this research was to describe the germline BRCA1/2 PVs in triple-negative breast cancer (TNBC) versus luminal-like BC and their potential leverage on BC phenotype.

Patients & methods

We retrospectively collected and analyzed all clinical information of 531 patients with BC genetically tested for germline BRCA1/2 PVs by Next-Generation Sequencing analysis at University Hospital Policlinico "P. Giaccone" of Palermo (Sicily) from January 2016 to February 2020.

Results

Our results corroborate the evidence that BRCA1-related tumors often have a profile which resembles the TNBC subtype, whereas BRCA2-associated tumors have a profile that resembles luminal-like BC, especially the Luminal B subtype. Interestingly, our findings suggest that the PVs identified in TNBC were not largely overlapping with those in luminal-like tumors. Differences in the frequency of two PVs potentially associated with different molecular tumor subtypes were observed. BRCA1-633delC was detected with relatively higher prevalence in patients with TNBC, whereas BRCA2-1466delT was found mainly in Luminal B tumors, but in no TNBC patient.

Conclusion

Future studies examining the type and location of BRCA1/2 PVs within different molecular subtypes are required to verify our hypothesis and could provide an interesting insight into the complex topic of genotype-phenotype correlations. Additionally, a more in-depth understanding of the potential correlations between BRCA PVs and clinical and phenotypic features of hereditary BC syndrome patients could be the key to develop better strategies of prevention and surveillance in BRCA-positive carriers without disease.

The m6A reader protein YTHDC2 is a potential biomarker and associated with immune infiltration in head and neck squamous cell carcinoma

Background

Increasing evidence has shown that N6-methyladenosine (m6A) RNA methylation regulators have important biological functions in human cancers. However, there are few studies on the value of m6A reader protein YTHDC2 in the diagnosis and tumor-infiltrating of head and neck squamous cell carcinoma (HNSCC). Therefore, it is important to understand the potential clinical value of YTHDC2 in the prognosis and immune infiltration of HNSCC.

Methods

In this study, gene expression profiles and the corresponding clinical information of 270 HNSCC patients were downloaded from the Gene Expression Omnibus (GEO) database. The gene co-expression network was established to verify whether YTHDC2 was related to the prognosis of HNSCC and verified again in the public database. The correlations between YTHDC2 and immune infiltration was investigated via Tumor Immune Estimation Resource (TIMER) and Gene Expression Profiling Interactive Analysis (GEPIA).

Results

The results showed that YTHDC2 appeared in the blue module related to survival time and survival state and had a close correlation with the prognosis and immune infiltration level of HNSCC in public database. Patients with low expression of YTHDC2 had poor overall survival (OS) and recurrence-free survival (RFS) than those with high expression. In addition, the expression of YTHDC2 was positively correlated with the level of CD4+ T cell subpopulations infiltration in HNSCC.

Conclusions

Through this study, we found that YTHDC2 is a tumor suppressor gene with high expression in normal tissues and low expression in tumor tissues. In addition, YTHDC2 is correlated with the immune infiltrating levels of B cells, CD8+ T cells, CD4+ T cells, neutrophils, and dendritic cells in HNSCC, which may become a potential marker for prognosis and immune infiltration of HNSCC.

Downregulation of m6 A reader YTHDC2 promotes tumor progression and predicts poor prognosis in non-small cell lung cancer

Background

m⁶A modification affects the pathological progress of many diseases by affecting RNA stability and translocation. YTHDC2, a m⁶A reader, is associated with multiple cancers; however, little is known of its role in non‐small cell lung cancer (NSCLC).

Methods

The GEPIA, Oncomine and GEO databases were analyzed to assess expression of YTHDC2 in NSCLC patients. Quantitative polymerase chain reaction, western blot and immunohistochemistry were used to detect YTHDC2 expression in different NSCLC cell lines (H1299, H460, H292 and A549) and patients. The effects of YTHDC2 on NSCLC cell lines (A549 and H1299) proliferation and migration were employed using CCK8 and transwell assays. The potential target RNAs of YTHDC2 were obtained from the POSTAR database. Functional enrichment analysis of YTHDC2 targeted RNAs was performed using the Metascape database.

Results

GEPIA, Oncomine and GEO databases showed low expression of YTHDC2 in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) patients. YTHDC2 expression was significantly decreased in different NSCLC cell lines and our clinical samples. Moreover, low expression of YTHDC2 was significantly associated with poor differentiation, lymph node metastasis, tumor size and stage. In addition, YTHDC2 could suppress the proliferation and migration ability of A549 and H1299 cell lines. Kaplan‐Meier Plotter database analysis revealed that patients with low level of YTHDC2 had a significantly poor prognosis. Finally, functional enrichment analysis of YTHDC2 targeted RNAs indicated several enriched pathways related to cancer.

Conclusions

These findings elucidate that YTHDC2 suppresses tumorigenesis in NSCLC, indicating that YTHDC2 may be a promising therapeutic target for NSCLC.

Key points

Significant findings of the study

This study demonstrated that the downregulation of YTHDC2 promotes tumor progression and predicts poor prognosis in non‐small cell lung cancer (NSCLC).

What this study adds

YTHDC2 might be a promising therapeutic target for non‐small cell lung cancer (NSCLC).

Gene signature and prognostic merit of M6a regulators in colorectal cancer

IMPACT STATEMENT

Although new diagnostic techniques and treatments are increasingly updated for CRC, the clinical outcomes of CRC patients are still not encouraging with a low survival rate. N6-methyladenosine (m6A) as a popular modification on mRNA is associated with multiple types of cancers. Our purpose is to identify gene signature and prognostic ability of m6A modulators in CRC. For the first time, we identified genetic changes of m6A modulators and built prognostic gene signature in CRC, which may provide effective targets for the diagnosis and management of CRC.

Analysis of Genetic Alteration Signatures and Prognostic Values of m6A Regulatory Genes in Head and Neck Squamous Cell Carcinoma

Genetic alteration involving N6-methyladenosine (m6A) regulatory genes is a frequent characteristic of multiple tumors. Nevertheless, little is known regarding their genetic alteration signatures and prognostic values in head and neck squamous cell carcinoma (HNSCC). In this study, RNA sequence profiles and copy number variation (CNV) data of 506 HNSCC patients were downloaded from The Cancer Genome Atlas (TCGA) database. Correlation analysis involving alteration of m6A regulatory genes, clinicopathological characteristics, and patient survival was performed using R language. The results suggest that alteration of m6A regulatory genes was correlated with clinical staging. Patients with high expression of ALKBH5, FTO, METTL14, WTAP, YTHDC1, YTHDF1, and YTHDF2 had poor overall survival (OS) than those with low expression. Univariate and multivariate Cox regression analyses showed that ALKBH5 and YTHDC2 were independent risk factors for OS. However, patients with high YTHDC2 expression had better OS. Moreover, according to machine learning results, YTHDC2 was found to be the most important gene among the 10 m6A regulators. Additionally, high expression of YTHDC2 was correlated with activation of apoptosis and ubiquitin-mediated proteolysis. Here, we identified alterations to m6A regulatory genes in HNSCC for the first time and found that seven m6A regulators were associated with poor prognosis, especially ALKBH5, whereas YTHDC2 was associated with better prognosis. These m6A-related regulators could act as novel prognostic biomarkers for HNSCC. Our findings provide clues for understanding RNA epigenetic modifications in HNSCC.

Hereditary Breast and Ovarian Cancer in Families from Southern Italy (Sicily)-Prevalence and Geographic Distribution of Pathogenic Variants in BRCA1/2 Genes

Recent advances in the detection of germline pathogenic variants (PVs) in BRCA1/2 genes have allowed a deeper understanding of the BRCA-related cancer risk. Several studies showed a significant heterogeneity in the prevalence of PVs across different populations. Because little is known about this in the Sicilian population, our study was aimed at investigating the prevalence and geographic distribution of inherited BRCA1/2 PVs in families from this specific geographical area of Southern Italy. We retrospectively collected and analyzed all clinical information of 1346 hereditary breast and/or ovarian cancer patients genetically tested for germline BRCA1/2 PVs at University Hospital Policlinico "P. Giaccone" of Palermo from January 1999 to October 2019. Thirty PVs were more frequently observed in the Sicilian population but only some of these showed a specific territorial prevalence, unlike other Italian and European regions. This difference could be attributed to the genetic heterogeneity of the Sicilian people and its historical background. Therefore hereditary breast and ovarian cancers could be predominantly due to BRCA1/2 PVs different from those usually detected in other geographical areas of Italy and Europe. Our investigation led us to hypothesize that a higher prevalence of some germline BRCA PVs in Sicily could be a population-specific genetic feature of BRCA-positive carriers.

m6 A RNA methylation regulators contribute to malignant progression in rectal cancer

N6,2'-O-dimethyladenosine (m⁶ A) RNA methylation, which is correlated with cancer initiation and progression, is dynamically regulated by m⁶ A RNA methylation regulators, including writers, erasers, and readers. Two subgroups of rectal cancer, including cluster1 and cluster2, were identified based on consensus clustering to m⁶ A RNA methylation regulators. A protein-protein interaction network was constructed and hub genes were identified. The results demonstrated that the expression of WTAP was significantly associated with YTHDC1 and YTHDF2. The principal component analysis was used to compare the transcriptional profile between cluster1 and cluster2 subgroups. By using two identified m⁶ A RNA methylation regulators, we constructed a risk signature to predict the survival outcomes of rectal cancer. The results revealed that YTHDC2 and YTHDF2 were protective genes with HR < 1. The coefficients obtained from the least absolute shrinkage and selection operator algorithm were used to calculate the risk score. Patients were then divided into low- and high-risk groups based on the median risk score. The survival analysis demonstrated that there were significant differences in overall survival between these two groups (p < .05). The results of the univariate analysis showed that the risk score, AJCC stage, M stage, and age were associated with overall survival. The results of the multivariate Cox regression analysis showed that the risk score and age were still significantly associated with the overall survival (p < .05). To conclude, m⁶ A RNA methylation regulators can be regarded as potentially useful biomarkers for predicting the prognosis and designing a treatment strategy in rectal cancer.

A dynamic reversible RNA N6 -methyladenosine modification: current status and perspectives

N⁶ -methyladenosine (m⁶ A), as the most abundant RNA epigenetic modifications, has been shown to play critical roles in various biological functions. Research about enzymes that can catalyze and remove m⁶ A have revealed its comprehensive roles in messenger RNA (mRNA) metabolism and other physiological processes. The "readers" including YTH domain-containing proteins, hnRNPC, hnRNPG, hnRNPA2B1, IGF2BP1, IGF2BP2, and IGF2BP3, which can affect the fates of mRNA in an m⁶ A-dependent manner. In this review, we focus on recent advances in the research of the m⁶ A modifications, especially about the latest functions of its writers, erasers, readers in RNA metabolism, cancer, and lipid metabolism. In the end, we provide insights into the underlying molecular mechanisms of m⁶ A modifications.

It's complicated… m6A-dependent regulation of gene expression in cancer

Cellular function relies on multiple pathways that are coordinated to ensure the proper execution of gene expression networks. Failure to coordinate the multiple programs active in the cell can have catastrophic consequences and lead to diseases such as cancer. At the post-transcriptional level, RNA modifications play important roles in the regulation of gene expression. N6-methyladenosine (m⁶A) is the most abundant internal messenger RNA (mRNA) modification and has gained increasing interest in the last few years as a dynamic regulator of RNA metabolism. Modifications regulate all stages of the RNA life cycle, from transcription to decay. Recent studies have pointed to the role of RNA methylation in cancer initiation and progression, and aberrant modification has served as a biomarker of early-stage diagnosis in several cancers. Here, we review the regulation of m⁶A, disruptions to methylation-dependent pathways that influence carcinogenesis, and potential avenues for m⁶A-related therapeutic strategies.

Clinical significance of germline copy number variation in susceptibility of human diseases

Germline copy number variation (CNV) is considered to be an important form of human genetic polymorphisms. Previous studies have identified amounts of CNVs in human genome by advanced technologies, such as comparative genomic hybridization, single nucleotide genotyping, and high-throughput sequencing. CNV is speculated to be derived from multiple mechanisms, such as nonallelic homologous recombination (NAHR) and nonhomologous end-joining (NHEJ). CNVs cover a much larger genome scale than single nucleotide polymorphisms (SNPs), and may alter gene expression levels by means of gene dosage, gene fusion, gene disruption, and long-range regulation effects, thus affecting individual phenotypes and playing crucial roles in human pathogenesis. The number of studies linking CNVs with common complex diseases has increased dramatically in recent years. Here, we provide a comprehensive review of the current understanding of germline CNVs, and summarize the association of germline CNVs with the susceptibility to a wide variety of human diseases that were identified in recent years. We also propose potential issues that should be addressed in future studies.

Germline copy number variations are associated with breast cancer risk and prognosis

Breast cancer is one of the most common cancers among women, and susceptibility is explained by genetic, lifestyle and environmental components. Copy Number Variants (CNVs) are structural DNA variations that contribute to diverse phenotypes via gene-dosage effects or cis-regulation. In this study, we aimed to identify germline CNVs associated with breast cancer susceptibility and their relevance to prognosis. We performed whole genome CNV genotyping in 422 cases and 348 controls using Human Affymetrix SNP 6 array. Principal component analysis for population stratification revealed 84 outliers leaving 366 cases and 320 controls of Caucasian ancestry for association analysis; CNVs with frequency > 10% and overlapping with protein coding genes were considered for breast cancer risk and prognostic relevance. Coding genes within the CNVs identified were interrogated for gene- dosage effects by correlating copy number status with gene expression profiles in breast tumor tissue. We identified 200 CNVs associated with breast cancer (q-value < 0.05). Of these, 21 CNV regions (overlapping with 22 genes) also showed association with prognosis. We validated representative CNVs overlapping with APOBEC3B and GSTM1 genes using the TaqMan assay. Germline CNVs conferred dosage effects on gene expression in breast tissue. The candidate CNVs identified in this study warrant independent replication.

Genome-wide association study identified copy number variants associated with sporadic colorectal cancer risk

Background

Multiple single nucleotide polymorphisms (SNPs) have been associated with colorectal cancer (CRC) risk. The role of structural or copy number variants (CNV) in CRC, however, remained unclear. We investigated the role of CNVs in patients with sporadic CRC.

Methods

A genome-wide association study (GWAS) was performed on 1000 Singapore Chinese patients aged 50 years or more with no family history of CRC and 1000 ethnicity-matched, age-matched and gender-matched healthy controls using the Affymetrix SNP 6 platform. After 16 principal component corrections, univariate and multivariate segmentations followed by association testing were performed on 1830 samples that passed quality assurance tests.

Results

A rare CNV region (CNVR) at chromosome 14q11 (OR=1.92 (95% CI 1.59 to 2.32), p=2.7e-12) encompassing CHD8, and common CNVR at chromosomes 3q13.12 (OR=1.54 (95% CI 1.33 to 1.77), p=2.9e-9) and 12p12.3 (OR=1.69 (95% CI 1.41 to 2.01), p=2.8e-9) encompassing CD47 and RERG/ARHGDIB, respectively, were significantly associated with CRC risk. CNV loci were validated in an independent replication panel using an optimised copy number assay. Whole-genome expression data in matched tumours of a subset of cases demonstrated that copy number loss at CHD8 was significantly associated with dysregulation of several genes that perturb the Wnt, TP53 and inflammatory pathways.

Conclusions

A rare CNVR at 14q11 encompassing the chromatin modifier CHD8 was significantly associated with sporadic CRC risk. Copy number loss at CHD8 altered expressions of genes implicated in colorectal tumourigenesis.

Ythdc2 is an N6-methyladenosine binding protein that regulates mammalian spermatogenesis

N6-methyladenosine (m6A) is the most common internal modification in eukaryotic mRNA. It is dynamically installed and removed, and acts as a new layer of mRNA metabolism, regulating biological processes including stem cell pluripotency, cell differentiation, and energy homeostasis. m6A is recognized by selective binding proteins; YTHDF1 and YTHDF3 work in concert to affect the translation of m6A-containing mRNAs, YTHDF2 expedites mRNA decay, and YTHDC1 affects the nuclear processing of its targets. The biological function of YTHDC2, the final member of the YTH protein family, remains unknown. We report that YTHDC2 selectively binds m6A at its consensus motif. YTHDC2 enhances the translation efficiency of its targets and also decreases their mRNA abundance. Ythdc2 knockout mice are infertile; males have significantly smaller testes and females have significantly smaller ovaries compared to those of littermates. The germ cells of Ythdc2 knockout mice do not develop past the zygotene stage and accordingly, Ythdc2 is upregulated in the testes as meiosis begins. Thus, YTHDC2 is an m6A-binding protein that plays critical roles during spermatogenesis.