Epigenomic analysis in a cell-based model reveals the roles of H3K9me3 in breast cancer transformation

H4K20me3, H3K4me2 and H3K9me2 mediate the effect of ER on prognosis in breast cancer

Previous studies have indicated that histone methylations act as mediators in the relationship between oestrogen receptor (ER) and breast cancer prognosis, yet the mediating role has never been assessed. Therefore, we investigated seven histone methylations (H3K4me2, H3K4me3, H3K9me1, H3K9me2, H3K9me3, H3K27me3 and H4K20me3) to determine whether they mediate the prognostic impact of ER on breast cancer. Tissue microarrays were constructed from 1045 primary invasive breast tumours, and the expressions of histone methylations were examined by immunohistochemistry. Multifactorial logistic regression was used to analyse the associations between ER and histone methylations. Cox proportional hazard model was performed to assess the relationship between histone methylations and breast cancer prognosis. The mediation effects of histone methylations were evaluated by model-based causal mediation analysis. High expressions of H3K9me1, H3K9me2, H3K4me2, H3K27me3, H4K20me3 were associated with ER positivity, while high expression of H3K9me3 was associated ER negativity. Higher H3K9me2, H3K4me2 and H4K20me3 levels were associated with better prognosis. The association between ER and breast cancer prognosis was most strongly mediated by H4K20me3 (29.07% for OS; 22.42% for PFS), followed by H3K4me2 (11.5% for OS; 10.82% for PFS) and least by H3K9me2 (9.35% for OS; 7.34% for PFS). H4K20me3, H3K4me2 and H3K9me2 mediated the relationship between ER and breast cancer prognosis, which would help to further elucidate the impact of ER on breast cancer prognosis from an epigenetic perspective and provide new ideas for breast cancer treatment.

Discovery and characterization of anti-cancer peptides from a random peptide library

We performed a forward genetic screen to discover peptides that specifically target breast cancer cells using a Penetratin tagged, random 15mer peptide library. We identified a group of novel peptides that specifically inhibited the proliferation and survival of breast cancer cells without affecting normal primary mammary epithelial cells or fibroblasts. The intrinsic apoptotic pathway is activated by these peptides in the face of abnormal expression of numerous cell cycle regulatory genes. Associated alterations in histone marks, nuclear structure, and levels of critical RNA binding proteins vary in a peptide specific manner. This study demonstrates a novel method for the discovery of new potential therapeutic peptides.

Normalization of the ATP1A1 Signalosome Rescinds Epigenetic Modifications and Induces Cell Autophagy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. In metabolic dysfunction-associated steatohepatitis (MASH)-related HCC, cellular redox imbalance from metabolic disturbances leads to dysregulation of the α1-subunit of the Na/K-ATPase (ATP1A1) signalosome. We have recently reported that the normalization of this pathway exhibited tumor suppressor activity in MASH-HCC. We hypothesized that dysregulated signaling from the ATP1A1, mediated by cellular metabolic stress, promotes aberrant epigenetic modifications including abnormal post-translational histone modifications and dysfunctional autophagic activity, leading to HCC development and progression. Increased H3K9 acetylation (H3K9ac) and H3K9 tri-methylation (H3K9me3) were observed in human HCC cell lines, HCC-xenograft and MASH-HCC mouse models, and epigenetic changes were associated with decreased cell autophagy in HCC cell lines. Inhibition of the pro-autophagic transcription factor FoxO1 was associated with elevated protein carbonylation and decreased levels of reduced glutathione (GSH). In contrast, normalization of the ATP1A1 signaling significantly decreased H3K9ac and H3K9me3, in vitro and in vivo, with concomitant nuclear localization of FoxO1, heightening cell autophagy and cancer-cell apoptotic activities in treated HCC cell lines. Our results showed the critical role of the ATP1A1 signalosome in HCC development and progression through epigenetic modifications and impaired cell autophagy activity, highlighting the importance of the ATP1A1 pathway as a potential therapeutic target for HCC.

Survival is associated with repressive histone trimethylation markers in both HR-positive HER2-negative and triple-negative breast cancer patients

About 30% of patients with hormone receptor (HR)-positive breast cancers and up to 50% of human epidermal growth factor receptor 2 (HER2)-positive patients develop progression due to treatment resistance, highlighting the need for more differentiated tumor classifications within the breast cancer molecular subtype to optimize the therapies. We aim to examine the roles of histone modification markers. The levels of common repressive histone markers, histone H3 lysine 9 trimethylation (H3K9me3), histone H3 lysine 27 trimethylation (H3K27me3), and histone H4 lysine 20 trimethylation (H4K20me3), in tumors were evaluated by immunohistochemistry for 914 breast cancer patients. The subjects were followed up until December 2021. Hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) were estimated using Cox regression models. For H3K27me3, patients with the high level had a longer PFS rate (81.3%) than that with the low level (73.9%) within HR-positive/HER2-negative subtype during a follow-up of 85 months only in univariate analysis (P < 0.05). For H3K9me3, the significant association between the high level of it and the longer OS [HR = 0.57, P < 0.05] was found within HR-positive/HER2-negative subtype in multivariate analysis. For H4K20me3, patients with the high level had a longer both OS [HR = 0.38] and PFS [HR = 0.46] within HR-positive/HER2-negative subtype, while had a shorter OS [HR = 3.28] in triple-negative breast cancer (TNBC) in multivariate analysis (all P < 0.05). H3K9me3 and H3K27me3 were the potential prognostic markers for breast cancer patients with HR-positive/HER2-negative subtype. Importantly, H4K20me3 was a robust prognostic marker for both HR-positive/HER2-negative and TNBC patients.

Association of H3K9me3 with breast cancer prognosis by estrogen receptor status

Background

Cellular experiments revealed that a decreased histone H3 lysine 9 trimethylation (H3K9me3) level was associated with the upregulation of oncogenes in breast cancer cells. Moreover, the role of H3K9me3 in breast cancer was closely associated with estrogen receptor (ER) status. Therefore, we aimed to examine the prognostic value of H3K9me3 on breast cancer by ER status. The level of H3K9me3 in tumors were evaluated with tissue microarrays by immunohistochemistry for 917 women diagnosed with primary invasive breast cancer. Hazard ratios (HRs) and their 95% confidence intervals (CIs) for overall survival (OS) and progression-free survival (PFS) were estimated using Cox regression models. Interaction between H3K9me3 and ER on the prognosis was assessed on multiplicative scale.

Results

The level of H3K9me3 in tumor tissues was lower than that in adjacent tissues. The high level of H3K9me3 was associated with a better OS (HR = 0.43, 95% CI: 0.21–0.86) and PFS (HR = 0.49, 95% CI: 0.29–0.81) among only ER-positive but not ER-negative tumors. Moreover, the interaction between the level of H3K9me3 and ER status (negative and positive) on the prognosis was significant (P_interaction = 0.011 for OS; P_interaction = 0.022 for PFS). Furthermore, the ER-positive tumors were stratified by ER-low and ER-high positive tumors, and the prognostic role of H3K9me3 was significant among only ER-high positive patients (HR = 0.34, 95% CI: 0.13–0.85 for OS; HR = 0.47, 95% CI: 0.26–0.86 for PFS).

Conclusions

Our study showed that the prognostic value of H3K9me3 on breast cancer was related to ER status and expression level, and the high level of H3K9me3 was associated with a better prognosis among ER-positive tumors, particularly ER-high positive tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01363-y.

Establishing a Novel Gene Signature Related to Histone Modifications for Predicting Prognosis in Lung Adenocarcinoma

Background

Epigenetic modifications have been revealed to play an important role in tumorigenesis and tumor development. This study aims to analyze the role of histone modifications and the prognostic values of histone modifications in lung adenocarcinoma (LUAD). The promoters and enhancers of protein encoding genes (PCGs) were the regions of enriched histone modifications.

Methods

Expression profiles and clinical information of LUAD samples were downloaded from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Histone modification data of LUAD cell lines were downloaded from Encyclopedia of DNA Elements (ENCODE) database. Limma R package was used to identify differentially expressed PCGs. To identify molecular subtypes, consensus clustering was conducted based on the expression of dysregulated PCGs with abnormal histone modifications. Univariate Cox regression analysis and stepwise Akaike information criterion (stepAIC) were utilized to establish a prognostic model.

Results

We identified a total of 699 epigenetic dysregulated genes with 122 of them significantly correlating with LUAD prognosis. We constructed three molecular subtypes (C1, C2, and C3) based on the 122 prognostic genes. C2 had the longest overall survival while C1 had the worst prognosis. In addition, three subtypes had differential immune infiltration and the response to immune checkpoint inhibitors. Moreover, we identified a risk model containing 5 epi-PCGs that had favorable performance to predict prognosis in different datasets.

Conclusions

This study further supported the critical histone modifications in LUAD development. Three subtypes may provide guidance for the immunotherapy of LUAD patients. Importantly, the prognostic model had great potential to predict LUAD prognosis.

KRAB-ZFPs and cancer stem cells identity

Studies on carcinogenesis continue to provide new information about different disease-related processes. Among others, much research has focused on the involvement of cancer stem cells (CSCs) in tumor initiation and progression. Studying the similarities and differences between CSCs and physiological stem cells (SCs) allows for a better understanding of cancer biology. Recently, it was shown that stem cell identity is partially governed by the Krϋppel-associated box domain zinc finger proteins (KRAB-ZFPs), the biggest family of transcription regulators. Several KRAB-ZFP factors exert a known effect in tumor cells, acting as tumor suppressor genes (TSGs) or oncogenes, yet their role in CSCs is still poorly characterized. Here, we review recent studies regarding the influence of KRAB-ZFPs and their cofactor protein TRIM28 on CSCs phenotype, stemness features, migration and invasion potential, metastasis, and expression of parental markers.

Epigenetic Dysregulation Induces Translocation of Histone H3 into Cytoplasm

In eukaryote cells, core components of chromatin, such as histones and DNA, are packaged in nucleus. Leakage of nuclear materials into cytosol will induce pathological effects. However, the underlying mechanisms remain elusive. Here, cytoplasmic localization of nuclear materials induced by chromatin dysregulation (CLIC) in mammalian cells is reported. H3K9me3 inhibition by small chemicals, HP1α knockdown, or knockout of H3K9 methylase SETDB1, induces formation of cytoplasmic puncta containing histones H3.1, H4 and cytosolic DNA, which in turn activates inflammatory genes and autophagic degradation. Autophagy deficiency rescues H3 degradation, and enhances the activation of inflammatory genes. MRE11, a subunit of MRN complex, enters cytoplasm after heterochromatin dysregulation. Deficiency of MRE11 or NBS1, but not RAD50, inhibits CLIC puncta in cytosol. MRE11 depletion represses tumor growth enhanced by HP1α deficiency, suggesting a connection between CLIC and tumorigenesis. This study reveals a novel pathway that heterochromatin dysregulation induces translocation of nuclear materials into cytoplasm, which is important for inflammatory diseases and cancer.

Proline-rich 11 (PRR11) drives F-actin assembly by recruiting the actin-related protein 2/3 complex in human non-small cell lung carcinoma

The actin cytoskeleton is extremely dynamic and supports diverse cellular functions in many physiological and pathological processes, including tumorigenesis. However, the mechanisms that regulate the actin-related protein 2/3 (ARP2/3) complex and thereby promote actin polymerization and organization in cancer cells are not well-understood. We previously implicated the proline-rich 11 (PRR11) protein in lung cancer development. In this study, using immunofluorescence staining, actin polymerization assays, and siRNA-mediated gene silencing, we uncovered that cytoplasmic PRR11 is involved in F-actin polymerization and organization. We found that dysregulation of PRR11 expression results in F-actin rearrangement and nuclear instability in non-small cell lung cancer cells. Results from molecular mechanistic experiments indicated that PRR11 associates with and recruits the ARP2/3 complex, facilitates F-actin polymerization, and thereby disrupts the F-actin cytoskeleton, leading to abnormal nuclear lamina assembly and chromatin reorganization. Inhibition of the ARP2/3 complex activity abolished irregular F-actin polymerization, lamina assembly, and chromatin reorganization due to PRR11 overexpression. Notably, experiments with truncated PRR11 variants revealed that PRR11 regulates F-actin through different regions. We found that deletion of either the N or C terminus of PRR11 abrogates its effects on F-actin polymerization and nuclear instability and that deletion of amino acid residues 100-184 or 100-200 strongly induces an F-actin structure called the actin comet tail, not observed with WT PRR11. Our findings indicate that cytoplasmic PRR11 plays an essential role in regulating F-actin assembly and nuclear stability by recruiting the ARP2/3 complex in human non-small cell lung carcinoma cells.

Epigenomics-Guided Drug Development: Recent Advances in Solving the Cancer Treatment "jigsaw puzzle"

The human epigenome plays a key role in determining cellular identity and eventually function. Drug discovery undertakings have focused mainly on the role of genomics in carcinogenesis, with the focus turning to the epigenome recently. Drugs targeting DNA and histone modifications are under development with some such as 5-azacytidine, decitabine, vorinostat, and panobinostat already approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This expert review offers a critical analysis of the epigenomics-guided drug discovery and development and the opportunities and challenges for the next decade. Importantly, the coupling of epigenetic editing techniques, such as clustered regularly interspersed short palindromic repeat (CRISPR)-CRISPR-associated protein-9 (Cas9) and APOBEC-coupled epigenetic sequencing (ACE-seq) with epigenetic drug screens, will allow the identification of small-molecule inhibitors or drugs able to reverse epigenetic changes responsible for many diseases. In addition, concrete and sustainable innovation in cancer treatment ought to integrate epigenome targeting drugs with classic therapies such as chemotherapy and immunotherapy.

The epigenetic landscapes of histone modifications on HSV-1 genome in human THP-1 cells

Histone positioning and modifications on viral genomes are important factors regulating virus replication. To investigate the dynamics of modified histones on the viral genome and their potential roles in antiviral response, we studied the dynamic changes of histone modifications across the HSV-1 genome in THP-1 cells. Histone modifications were detected on the HSV-1 genome soon after infection, including H3K9me3, H3K27me3, H3K4me3 and H3K27ac. These modifications emerged on the viral genome soon after infection and changed rapidly along with virus life cycle progression. The transcription repression marks, H3K9me3 and H3K27me3, decreased on the viral genome during the infection process; the transcription activation mark H3K27ac increased. Treatment with C646, an inhibitor of H3K27ac transferase p300, significantly repressed virus replication and viral gene expression. Our study reveals the relationship between histone modifications and viral gene expression and provides potential novel strategies for antiviral treatment.

DLX3 epigenetically regulates odontoblastic differentiation of hDPCs through H19/miR-675 axis

OBJECTIVES

A novel mutation (c.533 A > G; Q178R) in DLX3 gene is responsible for Tricho-Dento-Osseous (TDO) syndrome. As one of features of TDO syndrome is dentin hypoplasia, we explored the mechanism regarding dentin defects in TDO syndrome.

DESIGN

hDPCs were obtained from the healthy premolars, stably expressing hDPCs were generated using recombinant lentiviruses. Quantitative methylation analysis, DNMT3B activity, CHIP, and evaluation of odonto-differentiation ability of hDPCs assays were performed.

RESULTS

Novel mutant DLX3 (MU-DLX3) significantly inhibited the expression of long non-coding RNA H19 and resulted in hyper-methylation of H19 in MU group, rescue studies showed that up-regulation the expression of H19 and demethylation of H19 in MU group were able to rescue the effect of MU-DLX3. Subsequently, miR-675, encoded by H19, was also able to rescue the above effects of MU-DLX3. Thus, we proposed that MU-DLX3 regulated odontoblastic differentiation of hDPCs through H19/miR-675 axis. Through CHIP and DNMT3B activity assays disclosed the underlying mechanism by which MU-DLX3 altered H19 expression and methylation status in MU group by increasing H3K9me3 enrichment and DNMT3B activity.

CONCLUSIONS

Our new findings, for the first time, suggest that MU-DLX3 significantly inhibits hDPCs differentiation via H19/miR-675 axis and provides a new mechanism insight into how MU-DLX3 epigenetically alters H19 methylation status and expression contributes to dentin hypoplasia in TDO syndrome.