Mice lacking RAP1 show early onset and higher rates of DEN-induced hepatocellular carcinomas in female mice

Circle-seq reveals that eccDNA may be a key blood biomarker for HBV-associated liver cancer

INTRODUCTION

Extrachromosomal circular DNA (eccDNA) regulates tumor occurrence and development. Relevant eccDNA profiles have been established for various types of cancer; however, the eccDNA expression profiles in the blood of patients with hepatocellular carcinoma (HCC) and liver cirrhosis (LC) remain unknown. The present study aimed to investigate the eccDNA expression profiles in the blood of patients with HCC and LC.

METHODS

Circle-seq was used to detect eccDNAs in the blood samples. Full transcript sequencing was used to analyze the RNA in the samples. Geno Ontology enrichment and Kyoto Encyclopedia of Genes and Genome pathway analyses were performed on differentially expressed eccDNA-related genes. The identified eccDNA is combined with mRNA to screen target genes using bioinformatics analysis. EccDNAs were confirmed through polymerase chain reaction and Sanger sequencing.

RESULTS

Overall, 103,235 eccDNAs were identified in HCC, whereas 67,110 eccDNAs were detected in LC. In total, 7,095 upregulated eccDNAs and 1,284 downregulated eccDNAs were identified. Following analysis of differential genes using bioinformatics, six candidate genes were screened out based on gene expression and cancer relevance. Experiments have verified that LAMA4 [circle112550019-112550510] and KANK1 [circle674459-674907] are real and expressed target genes, and their source genes are closely related to the survival time of patients with liver cancer.

CONCLUSION

Our research results revealed the main characteristics of eccDNAs in the blood of patients with HBV-related HCC and LC. It was found that eccDNAs were mainly less than 1,000 bp in length. Difference analysis showed that some eccDNAs had consistent and overlapping expressions with mRNAs. We found that LAMA4 [circle112550019-112550510] and KANK1 [circle674459-674907] are target genes related to HCC, and both of them may become potential biomarkers for the diagnosis and prognosis of HCC.

Maternal-Periconceptional Vitamin B12 Deficiency in Wistar Rats Leads to Sex-Specific Programming for Cardiometabolic Disease Risk in the Next Generation

BACKGROUND

Maternal vitamin B12 deficiency plays a vital role in fetal programming, as corroborated by previous studies on murine models and longitudinal human cohorts.

OBJECTIVES

This study assessed the effects of diet-induced maternal vitamin B12 deficiency on F1 offspring in terms of cardiometabolic health and normalization of these effects by maternal-periconceptional vitamin B12 supplementation.

METHODS

A diet-induced maternal vitamin B12 deficient Wistar rat model was generated in which female rats were either fed a control AIN-76A diet (with 0.01 g/kg vitamin B12) or the same diet with vitamin B12 removed. Females from the vitamin B12-deficient group were mated with males on the control diet. A subset of vitamin B12-deficient females was repleted with vitamin B12 on day 1 of conception. The offspring in the F1 generation were assessed for changes in body composition, plasma biochemistry, and molecular changes in the liver. A multiomics approach was used to obtain a mechanistic insight into the changes in the offspring liver.

RESULTS

We showed that a 36% reduction in plasma vitamin B12 levels during pregnancy in F0 females can lead to continued vitamin B12 deficiency (60%-70% compared with control) in the F1 offspring and program them for cardiometabolic adversities. These adversities, such as high triglycerides and low high-density lipoprotein cholesterol, were seen only among F1 males but not females. DNA methylome analysis of the liver of F1 3-mo-old offspring highlights sexual dimorphism in the alteration of methylation status of genes critical to signaling processes. Proteomics and targeted metabolomics analysis confirm that sex-specific alterations occur through modulations in PPAR signaling and steroid hormone biosynthesis pathway. Repletion of deficient mothers with vitamin B12 at conception normalizes most of the molecular and biochemical changes.

CONCLUSIONS

Maternal vitamin B12 deficiency has a programming effect on the next generation and increases the risk for cardiometabolic syndrome in a sex-specific manner. Normalization of the molecular risk markers on vitamin B12 supplementation indicates a causal role.

Prediction of liver cancer prognosis based on immune cell marker genes

Introduction

Monitoring the response after treatment of liver cancer and timely adjusting the treatment strategy are crucial to improve the survival rate of liver cancer. At present, the clinical monitoring of liver cancer after treatment is mainly based on serum markers and imaging. Morphological evaluation has limitations, such as the inability to measure small tumors and the poor repeatability of measurement, which is not applicable to cancer evaluation after immunotherapy or targeted treatment. The determination of serum markers is greatly affected by the environment and cannot accurately evaluate the prognosis. With the development of single cell sequencing technology, a large number of immune cell-specific genes have been identified. Immune cells and microenvironment play an important role in the process of prognosis. We speculate that the expression changes of immune cell-specific genes can indicate the process of prognosis.

Method

Therefore, this paper first screened out the immune cell-specific genes related to liver cancer, and then built a deep learning model based on the expression of these genes to predict metastasis and the survival time of liver cancer patients. We verified and compared the model on the data set of 372 patients with liver cancer.

Result

The experiments found that our model is significantly superior to other methods, and can accurately identify whether liver cancer patients have metastasis and predict the survival time of liver cancer patients according to the expression of immune cell-specific genes.

Discussion

We found these immune cell-specific genes participant multiple cancer-related pathways. We fully explored the function of these genes, which would support the development of immunotherapy for liver cancer.

Lifelong docosahexaenoic acid intervention ameliorates aging in the telomere-DNA-mitochondria axis in telomerase-deficient mice

The health benefits of n-3 polyunsaturated fatty acids (PUFAs) in multiple age-related diseases are associated with telomere length. Telomerase is intimately related to inflammation and oxidative stress, but whether the underlying function of n-3 PUFAs on telomere maintenance is based on telomerase activation or related mechanisms remains unclear. Herein, we utilized late-generation (G4) telomerase-deficient (Terc^-/-) mice to perform a lifelong docosahexaenoic acid (DHA) intervention to determine the potential of DHA in telomere maintenance and health promotion. Unfortunately, DHA failed to prolong mouse longevity in either intrinsic or premature aging. However, intriguingly, lifelong dietary DHA intervention slowed the aging phenotypes and profoundly attenuated telomere attrition in blood leukocytes and multiple tissues, consistent with decreased β-galactosidase activity and other senescence hallmarks with no observed sex differences. Notably, DHA intervention alleviated telomere attrition-induced γ-H2AX accumulation dependent on poly (ADP-ribose) polymerase 1 (PARP1) recruitment, and further regulated mitochondrial dysfunction critically involved in the DNA damage response. Together with the improvement of mitochondria function, the blocked reactive oxygen species (ROS) accumulation and suppression of the nuclear factor-κB (NF-κB)/nucleotide-binding domain-like receptor protein 3 (NLRP3)/caspase-1 pathways partially indicated anti-oxidative and anti-inflammatory effects of DHA. These data revealed a regulatory paradigm involving DHA in the telomere-DNA-mitochondria feedback loop mediated by DNA damage response and inflammation in alleviating senescence, which may hold potential as a translatable intervention in telomere-related diseases during aging.

Thymoquinone Suppresses Angiogenesis in DEN-Induced Hepatocellular Carcinoma by Targeting miR-1-3p

Hepatocellular carcinoma (HCC) is characterized by its high vascularity and metastasis. Thymoquinone (TQ), the main bio-active constituent of Nigella sativa, has shown anticancer and hepatoprotective effects. TQ's anticancer effect is mediated through miRNA regulation. miR-1-3p plays a significant role in various cancers but its role in HCC invasiveness remains poorly understood. Bio-informatics analysis predicted that the 3'-UTR of TIMP3 is a target for miR-1-3p; Rats were equally divided into four groups: Group 1, the negative control; Group 2 received TQ; Group 3 received DEN; and Group 4 received DEN after pretreatment with TQ. The expression of TIMP3, MMP2, MMP9, and VEGF in rats' liver was determined immunohistochemically. RT-qPCR was used to measure the miR-1-3p level in rats' liver, and TIMP3, MMP2, MMP9, and VEGF in the HepG2 cells after being transfected with miR-1-3p mimic or inhibitor; In rats pretreated with TQ, a decreased expression of MMP2, MMP9 and VEGF, and increased expression levels of TIMP3 and miR-1-3p were detected. Treating the HepG2 cells with miR-1-3p mimic led to the upregulation of TIMP3 and downregulation of MMP2, MMP9, and VEGF, and showed a significant delay in wound healing; These results suggested that the anti-angiogenic effect of TQ in HCC may be mediated through the regulation of miR-1-3p.

Aberrant expression and localization of the RAP1 shelterin protein contribute to age-related phenotypes

Short telomeres induce a DNA damage response (DDR) that evokes apoptosis and senescence in human cells. An extant question is the contribution of telomere dysfunction-induced DDR to the phenotypes observed in aging and telomere biology disorders. One candidate is RAP1, a telomere-associated protein that also controls transcription at extratelomeric regions. To distinguish these roles, we generated a knockin mouse carrying a mutated Rap1, which was incapable of binding telomeres and did not result in eroded telomeres or a DDR. Primary Rap1 knockin embryonic fibroblasts showed decreased RAP1 expression and re-localization away from telomeres, with an increased cytosolic distribution akin to that observed in human fibroblasts undergoing telomere erosion. Rap1 knockin mice were viable, but exhibited transcriptomic alterations, proinflammatory cytokine/chemokine signaling, reduced lifespan, and decreased healthspan with increased body weight/fasting blood glucose levels, spontaneous tumor incidence, and behavioral deficits. Taken together, our data present mechanisms distinct from telomere-induced DDR that underlie age-related phenotypes.

Tieing together loose ends: telomere instability in cancer and aging

Telomere maintenance is essential for maintaining genome integrity in both normal and cancer cells. Without functional telomeres, chromosomes lose their protective structure and undergo fusion and breakage events that drive further genome instability, including cell arrest or death. One means by which this loss can be overcome in stem cells and cancer cells is via re-addition of G-rich telomeric repeats by the telomerase reverse transcriptase (TERT). During aging of somatic tissues, however, insufficient telomerase expression leads to a proliferative arrest called replicative senescence, which is triggered when telomeres reach a critically short threshold that induces a DNA damage response. Cancer cells express telomerase but do not entirely escape telomere instability as they often possess short telomeres; hence there is often selection for genetic alterations in the TERT promoter that result in increased telomerase expression. In this review, we discuss our current understanding of the consequences of telomere instability in cancer and aging, and outline the opportunities and challenges that lie ahead in exploiting the reliance of cells on telomere maintenance for preserving genome stability.

RAP1/TERF2IP-A Multifunctional Player in Cancer Development

Simple Summary

RAP1 (TERF2IP) is a member of the shelterin complex that protects telomeric DNA and plays a critical role in maintaining chromosome stability. However, mammalian RAP1 was recently found to have additional functions apart from telomeres, acting as a regulator of the NF-κB pathway and transcription factor, and has been suggested that they have putative roles in cancer development. Here, we focus on the main roles of RAP1 in different mechanisms of oncogenesis, progression, and chemoresistance, and consider the clinical significance of findings about its regulation and biological functions.

Abstract

Mammalian RAP1 (TERF2IP), the most conserved shelterin component, plays a pleiotropic role in the regulation of a variety of cellular processes, including cell metabolism, DNA damage response, and NF-κB signaling, beyond its canonical telomeric role. Moreover, it has been demonstrated to be involved in oncogenesis, progression, and chemoresistance in human cancers. Several mutations and different expression patterns of RAP1 in cancers have been reported. However, the functions and mechanisms of RAP1 in various cancers have not been extensively studied, suggesting the necessity of further investigations. In this review, we summarize the main roles of RAP1 in different mechanisms of cancer development and chemoresistance, with special emphasis on the contribution of RAP1 mutations, expression patterns, and regulation by non-coding RNA, and briefly discuss telomeric and non-telomeric functions.

Component Identification of Phenolic Acids in Cell Suspension Cultures of Saussureainvolucrata and Its Mechanism of Anti-Hepatoma Revealed by TMT Quantitative Proteomics

Saussurea involucrata (S. involucrata) had been reported to have anti-hepatoma function. However, the mechanism is complex and unclear. To evaluate the anti-hepatoma mechanism of S. involucrata comprehensively and make a theoretical basis for the mechanical verification of later research, we carried out this work. In this study, the total phenolic acids from S. involucrata determined by a cell suspension culture (ESPI) was mainly composed of 4,5-dicaffeoylquinic acid, according to the LC-MS analysis. BALB/c nude female mice were injected with HepG2 cells to establish an animal model of liver tumor before being divided into a control group, a low-dose group, a middle-dose group, a high-dose group, and a DDP group. Subsequently, EPSI was used as the intervention drug for mice. Biochemical indicators and differences in protein expression determined by TMT quantitative proteomics were used to resolve the mechanism after the low- (100 mg/kg), middle- (200 mg/kg), and high-dose (400 mg/kg) interventions for 24 days. The results showed that EPSI can not only limit the growth of HepG2 cells in vitro, but also can inhibit liver tumors significantly with no toxicity at high doses in vivo. Proteomics analysis revealed that the upregulated differentially expressed proteins (DE proteins) in the high-dose group were over three times that in the control group. ESPI affected the pathways significantly associated with the protein metabolic process, metabolic process, catalytic activity, hydrolase activity, proteolysis, endopeptidase activity, serine-type endopeptidase activity, etc. The treatment group showed significant differences in the pathways associated with the renin-angiotensin system, hematopoietic cell lineage, etc. In conclusion, ESPI has a significant anti-hepatoma effect and the potential mechanism was revealed.

Non-canonical roles of canonical telomere binding proteins in cancers

Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.

Telomeres and Telomerase in the Development of Liver Cancer

Liver cancer is one of the most common cancer types worldwide and the fourth leading cause of cancer-related death. Liver carcinoma is distinguished by a high heterogeneity in pathogenesis, histopathology and biological behavior. Dysregulated signaling pathways and various gene mutations are frequent in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), which represent the two most common types of liver tumors. Both tumor types are characterized by telomere shortening and reactivation of telomerase during carcinogenesis. Continuous cell proliferation, e.g., by oncogenic mutations, can cause extensive telomere shortening in the absence of sufficient telomerase activity, leading to dysfunctional telomeres and genome instability by breakage-fusion-bridge cycles, which induce senescence or apoptosis as a tumor suppressor mechanism. Telomerase reactivation is required to stabilize telomere functionality and for tumor cell survival, representing a genetic risk factor for the development of liver cirrhosis and liver carcinoma. Therefore, telomeres and telomerase could be useful targets in hepatocarcinogenesis. Here, we review similarities and differences between HCC and iCCA in telomere biology.

Telomere-dependent and telomere-independent roles of RAP1 in regulating human stem cell homeostasis

RAP1 is a well-known telomere-binding protein, but its functions in human stem cells have remained unclear. Here we generated RAP1-deficient human embryonic stem cells (hESCs) by using CRISPR/Cas9 technique and obtained RAP1-deficient human mesenchymal stem cells (hMSCs) and neural stem cells (hNSCs) via directed differentiation. In both hMSCs and hNSCs, RAP1 not only negatively regulated telomere length but also acted as a transcriptional regulator of RELN by tuning the methylation status of its gene promoter. RAP1 deficiency enhanced self-renewal and delayed senescence in hMSCs, but not in hNSCs, suggesting complicated lineage-specific effects of RAP1 in adult stem cells. Altogether, these results demonstrate for the first time that RAP1 plays both telomeric and nontelomeric roles in regulating human stem cell homeostasis.