Inhibition of DNMT suppresses the stemness of colorectal cancer cells through down-regulating Wnt signaling pathway

Wnt/β-catenin signaling pathway in carcinogenesis and cancer therapy

The Wnt/β-catenin signaling pathway plays a crucial role in various physiological processes, encompassing development, tissue homeostasis, and cell proliferation. Under normal physiological conditions, the Wnt/β-catenin signaling pathway is meticulously regulated. However, aberrant activation of this pathway and downstream target genes can occur due to mutations in key components of the Wnt/β-catenin pathway, epigenetic modifications, and crosstalk with other signaling pathways. Consequently, these dysregulations contribute significantly to tumor initiation and progression. Therapies targeting the Wnt/β-catenin signaling transduction have exhibited promising prospects and potential for tumor treatment. An increasing number of medications targeting this pathway are continuously being developed and validated. This comprehensive review aims to summarize the latest advances in our understanding of the role played by the Wnt/β-catenin signaling pathway in carcinogenesis and targeted therapy, providing valuable insights into acknowledging current opportunities and challenges associated with targeting this signaling pathway in cancer research and treatment.

Transcriptional regulation of cancer stem cell: regulatory factors elucidation and cancer treatment strategies

Cancer stem cells (CSCs) were first discovered in the 1990s, revealing the mysteries of cancer origin, migration, recurrence and drug-resistance from a new perspective. The expression of pluripotent genes and complex signal regulatory networks are significant features of CSC, also act as core factors to affect the characteristics of CSC. Transcription is a necessary link to regulate the phenotype and potential of CSC, involving chromatin environment, nucleosome occupancy, histone modification, transcription factor (TF) availability and cis-regulatory elements, which suffer from ambient pressure. Especially, the expression and activity of pluripotent TFs are deeply affected by both internal and external factors, which is the foundation of CSC transcriptional regulation in the current research framework. Growing evidence indicates that regulating epigenetic modifications to alter cancer stemness is effective, and some special promoters and enhancers can serve as targets to influence the properties of CSC. Clarifying the factors that regulate CSC transcription will assist us directly target key stem genes and TFs, or hinder CSC transcription through environmental and other related factors, in order to achieve the goal of inhibiting CSC and tumors. This paper comprehensively reviews the traditional aspects of transcriptional regulation, and explores the progress and insights of the impact on CSC transcription and status through tumor microenvironment (TME), hypoxia, metabolism and new meaningful regulatory factors in conjunction with the latest research. Finally, we present opinions on omnidirectional targeting CSCs transcription to eliminate CSCs and address tumor resistance.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

MicroRNA-143 as a potential tumor suppressor in cancer: An insight into molecular targets and signaling pathways

MicroRNAs (MiRNAs), which are highly conserved and small noncoding RNAs, negatively regulate gene expression and influence signaling pathways involved in essential biological activities, including cell proliferation, differentiation, apoptosis, and cell invasion. MiRNAs have received much attention in the past decade due to their significant roles in cancer development. In particular, microRNA-143 (miR-143) is recognized as a tumor suppressor and is downregulated in most cancers. However, it seems that miR-143 is upregulated in rare cases, such as prostate cancer stem cells, and acts as an oncogene. The present review will outline the current studies illustrating the impact of miR-143 expression levels on cancer progression and discuss its target genes and their relevant signaling pathways to discover a potential therapeutic way for cancer.

Virus hijacking of host epigenetic machinery to impair immune response

Epigenetic modifications, such as DNA hypermethylation, histone acetylation/methylation, or nucleosome positioning, result in differential gene expression. These modifications can have an impact on various pathways, including host antiviral immune responses. In this review, we summarize the current understanding of epigenetic modifications induced by viruses to counteract host antiviral immune responses, which are crucial for establishing and maintaining infection of viruses. Finally, we provide insights into the potential use of epigenetic modulators in combating viral infections and virus-induced diseases.

METTL3-Modulated circUHRF2 Promotes Colorectal Cancer Stemness and Metastasis through Increasing DDX27 mRNA Stability by Recruiting IGF2BP1

Increasing evidence has implicated that circular RNAs (circRNAs) exert important roles in colorectal cancer (CRC) occurrence and progression. However, the role of a novel circRNA, circUHRF2, remains unknown in CRC. Our work aimed at identifying the functional roles of circUHRF2 in CRC and illustrating the potential mechanisms. As assessed by quantitative real-time PCR (qRT-PCR), circUHRF2 and methyltransferase-like 3 (METTL3) were highly expressed in CRC specimens and cells. Sanger sequencing and RNase R assays were performed to verify the ring structure of circUHRF2. Notably, aberrantly increased expression of circUHRF2 was positively correlated with poor prognosis of CRC patients. Functional experiments indicated that CRC stemness, migration, and epithelial-mesenchymal transition (EMT) were suppressed by the knockdown of circUHRF2 or METTL3. Mechanistically, METTL3 enhanced circUHRF2 expression through N6-methyladenine (m⁶A) modification. Rescue experiments showed that overexpression of circUHRF2 reversed the repressive effect of METTL3 silencing on CRC progression. Moreover, circUHRF2 inhibited the loss of DEAD-box helicase 27 (DDX27) protein via promoting the interaction between insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) and DDX27 mRNA. DDX27 knockdown repressed CRC malignant properties, which was counteracted by circUHRF2 overexpression. The in vivo assays in nude mice demonstrated that circUHRF2 or METTL3 silencing exerted a suppressive effect on CRC growth and liver metastasis via repressing DDX27 protein expression. Taken together, METTL3-mediated m⁶A modification upregulated circUHRF2 and subsequently inhibited loss of DDX27 protein via recruitment of IGF2BP1, which conferred CRC stemness and metastasis. These findings shed light on CRC pathogenesis and suggest circUHRF2 as a novel target for CRC treatment.

Chromatin Dynamics in Digestive System Cancer: Commander and Regulator

Digestive system tumors have a poor prognosis due to complex anatomy, insidious onset, challenges in early diagnosis, and chemoresistance. Epidemiological statistics has verified that digestive system tumors rank first in tumor-related death. Although a great number of studies are devoted to the molecular biological mechanism, early diagnostic markers, and application of new targeted drugs in digestive system tumors, the therapeutic effect is still not satisfactory. Epigenomic alterations including histone modification and chromatin remodeling are present in human cancers and are now known to cooperate with genetic changes to drive the cancer phenotype. Chromatin is the carrier of genetic information and consists of DNA, histones, non-histone proteins, and a small amount of RNA. Chromatin and nucleosomes control the stability of the eukaryotic genome and regulate DNA processes such as transcription, replication, and repair. The dynamic structure of chromatin plays a key role in this regulatory function. Structural fluctuations expose internal DNA and thus provide access to the nuclear machinery. The dynamic changes are affected by various complexes and epigenetic modifications. Variation of chromatin dynamics produces early and superior regulation of the expression of related genes and downstream pathways, thereby controlling tumor development. Intervention at the chromatin level can change the process of cancer earlier and is a feasible option for future tumor diagnosis and treatment. In this review, we introduced chromatin dynamics including chromatin remodeling, histone modifications, and chromatin accessibility, and current research on chromatin regulation in digestive system tumors was also summarized.

Epigenomic interplay in tumor heterogeneity: Potential of epidrugs as adjunct therapy

"Heterogeneity" in tumor mass has immense importance in cancer progression and therapy. The impact of tumor heterogeneity is an emerging field and not yet fully explored. Tumor heterogeneity is mainly considered as intra-tumor heterogeneity and inter-tumor heterogeneity based on their origin. Intra-tumor heterogeneity refers to the discrepancy within the same cancer mass while inter-tumor heterogeneity refers to the discrepancy between different patients having the same tumor type. Both of these heterogeneity types lead to variation in the histopathological as well as clinical properties of the cancer mass which drives disease resistance towards therapeutic approaches. Cancer stem cells (CSCs) act as pinnacle progenitors for heterogeneity development along with various other genetic and epigenetic parameters that are regulating this process. In recent times epigenetic factors are one of the most studied parameters that drive oxidative stress pathways essential during cancer progression. These epigenetic changes are modulated by various epidrugs and have an impact on tumor heterogeneity. The present review summarizes various aspects of epigenetic regulation in the tumor microenvironment, oxidative stress, and progression towards tumor heterogeneity that creates complications during cancer treatment. This review also explores the possible role of epidrugs in regulating tumor heterogeneity and personalized therapy against drug resistance.

Comprehensive Analysis of VCAN Expression Profiles and Prognostic Values in HCC

Background: Hepatocellular carcinoma (HCC) is the world’s most common cause of cancer death. Therefore, more molecular mechanisms need to be clarified to meet the urgent need to develop new detection and treatment strategies.

Methods: We used TCGAportal, Kaplan–Meier Plotter, the Cistrome DB Toolkit Database, MExpress, GEPIA2, and other databases to discuss the expression profiles, possible biological function, and potential prognostic value of versican (VCAN) in HCC. We conducted cell experiments such as Transwell migration and invasion assays, wound healing assay, and CCK8 experiment to explore the function of VCAN in HCC.

Result: We selected three HCC transcriptome databases GSE124535, GSE136247, and GSE144269 and analyzed the overexpressed genes contained in them. The overlapping genes were found by the Venn map, and two interacting network modules were found by Mcode. Module 1 was mainly related to mitosis and cell cycle, and module 2 was mainly related to EMT, angiogenesis, glycolysis, and so on. We found that the seed gene in module 2 is VCAN. Data from TCGAportal showed that compared with normal tissues, the expression of VCAN was up-regulated in HCC tissues. The patients with high expression of VCAN had shorter distant recurrence-free survival and overall survival. Multiple possible VCAN interactions had also been identified. These results revealed that the level of VCAN was higher in the subtypes of HCC with higher malignant degree and was connected to the poor prognosis. In addition, the treatment of VCAN with DNA methyltransferase inhibitors and transcription factor inhibitors may improve the prognosis of patients with HCC.

Conclusion: Our findings systematically elucidated the expression profile and different prognostic values of VCAN in HCC, which may provide new therapeutic targets and potential prognostic biomarkers for HCC patients.

miR-498/DNMT3b Axis Mediates Resistance to Radiotherapy in Esophageal Cancer Cells

Objective: To explore the role of miR-498 in the radiotherapy resistance of esophageal cancer (EC) and its underlying mechanism. Methods: In vivo models of EC tissues with radioresistance or radiosensitivity were isolated from 72 EC patients who received radiotherapy. In vitro models were established after irradiation of KYSE30 cells. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot were employed to measure the expression levels of miR-498 and DNMT3b in EC cells sensitive or resistant to irradiation. Then, protein expression of DNMT3b was verified by immunohistochemistry. The cell viability, colony formation rate, and cell apoptotic rate of EC were correspondingly assessed by CCK-8, colony formation assay, and Annexin V/PI (propidium iodide) double staining. Western blot was utilized to perform the expression levels of PI3K, p-PI3K, AKT, and p-AKT in EC cell lines after irradiation. Results: Highly expressed DNMT3b and lowly expressed miR-498 were found in EC tissues. EC tissues with radiosensitivity had higher miR-498 level and lower DNMT3b expression than EC tissues with radioresistance. Overexpression of miR-498 or knockdown of DNMT3b enhanced the radiosensitivity of EC cells. DNMT3b was a target gene of miR-498. DNMT3b diminished the radiosensitization of miR-498 in EC cells. Conclusions: MiR-498 enhances the sensitivity of EC cells to radiation by DNMT3b inhibition, and exerts biological functions by inactivating the PI3K/AKT signaling pathway.

Targeting Epigenetic Modifiers of Tumor Plasticity and Cancer Stem Cell Behavior

Tumor heterogeneity poses one of the greatest challenges to a successful treatment of cancer. Tumor cell populations consist of different subpopulations that have distinct phenotypic and genotypic profiles. Such variability poses a challenge in successfully targeting all tumor subpopulations at the same time. Relapse after treatment has been previously explained using the cancer stem cell model and the clonal evolution model. Cancer stem cells are an important subpopulation of tumor cells that regulate tumor plasticity and determine therapeutic resistance. Tumor plasticity is controlled by genetic and epigenetic changes of crucial genes involved in cancer cell survival, growth and metastasis. Targeting epigenetic modulators associated with cancer stem cell survival can unlock a promising therapeutic approach in completely eradicating cancer. Here, we review various factors governing epigenetic dysregulation of cancer stem cells ranging from the role of epigenetic mediators such as histone and DNA methyltransferases, histone deacetylases, histone methyltransferases to various signaling pathways associated with cancer stem cell regulation. We also discuss current treatment regimens targeting these factors and other promising inhibitors in clinical trials.

The Contrasting Delayed Effects of Transient Exposure of Colorectal Cancer Cells to Decitabine or Azacitidine

Simple Summary

Decitabine and azacitidine are cytosine analogs representing the class of drugs interfering with DNA methylation. Due to their molecular homology and similar clinical application these drugs are viewed as interchangeable. Despite their unique epigenetic mechanism of action, the studies of the prolonged activity of decitabine and azacitidine are rare. Our head-to-head comparison revealed profound differences in the activities of decitabine and azacitidine important in their anti-cancer potential and clinical application. We show that azacitidine, despite significant immediate toxicity, has negligible long-term effects. Contrary, decitabine, which does not exert initial toxicity, profoundly worsened the condition of the cancer cells over time. The effects of decitabine need a relatively long time to develop. This property is crucial for the proper design of studies or therapy involving decitabine. It undermines opinion about the similar therapeutic mechanism and interchangeability of decitabine and azacitidine.

Abstract

(1) Background: Decitabine and azacitidine are cytosine analogues representing the class of drugs interfering with DNA methylation. Due to their molecular homology and similar clinical application, both drugs are often regarded as interchangeable. Despite their unique mechanism of action the studies designed for observation and comparison of the prolonged activity of these drugs are rare. (2) Methods: The short-time (20–72 h) and long-term (up to 20 days) anti-cancer activity of decitabine and azacitidine has been studied in colorectal cancer cells. We observe the impact on cell culture’s viability, clonogenicity, proliferation, and expression of CDKN1A, CCND1, MDM2, MYC, CDKN2A, GLB1 genes, and activity of SA-β-galactosidase. (3) Results: Decitabine has much stronger anti-clonogenic activity than azacitidine. We show that azacitidine, despite significant immediate toxicity, has negligible long-term effects. Contrary, decitabine, which does not exert initial toxicity, profoundly worsened the condition of the cells over time. On the 13th day after treatment, the viability of cells was decreased and proliferation inhibited. These functional changes were accompanied by up-regulation of expression CDKN1A, CCND1, and CDKN2A genes and increased activation of SA-β-galactosidase, indicating cellular senescence. (4) Conclusions: Our head-to-head comparison revealed profound differences in the activities of decitabine and azacitidine important in their anti-cancer potential and clinical application. The effects of decitabine need relatively long time to develop. This property is crucial for proper design of studies and therapy concerning decitabine and undermines opinion about the similar therapeutic mechanism and interchangeability of these drugs.

Colorectal liver metastasis: molecular mechanism and interventional therapy

Colorectal cancer (CRC) is one of the most frequently occurring malignancy tumors with a high morbidity additionally, CRC patients may develop liver metastasis, which is the major cause of death. Despite significant advances in diagnostic and therapeutic techniques, the survival rate of colorectal liver metastasis (CRLM) patients remains very low. CRLM, as a complex cascade reaction process involving multiple factors and procedures, has complex and diverse molecular mechanisms. In this review, we summarize the mechanisms/pathophysiology, diagnosis, treatment of CRLM. We also focus on an overview of the recent advances in understanding the molecular basis of CRLM with a special emphasis on tumor microenvironment and promise of newer targeted therapies for CRLM, further improving the prognosis of CRLM patients.

Wnt Signaling Pathway Is among the Drivers of Liver Metastasis

Liver metastasis, originating either from a primary liver or other cancer types, represent a large cancer-related burden. Therefore, studies that add to better understanding of its molecular basis are needed. Herein, the role of the Wnt signaling pathway in liver metastasis is outlined. Its role in hepatocellular carcinoma (HCC) epithelial-mesenchymal transition (EMT), motility, migration, metastasis formation, and other steps of the metastatic cascade are presented. Additionally, the roles of the Wnt signaling pathway in the liver metastasis formation of colorectal, breast, gastric, lung, melanoma, pancreatic, and prostate cancer are explored. The special emphasis is given to the role of the Wnt signaling pathway in the communication between the many of the components of the primary and secondary cancer microenvironment that contribute to the metastatic outgrowth in the liver. The data presented herein are a review of the most recent publications and advances in the field that add to the idea that the Wnt pathway is among the drivers of liver metastasis and that its targeting could potentially relieve liver metastasis–related complications.

Combining Algorithms to Find Signatures That Predict Risk in Early-Stage Stomach Cancer

This study applied two mathematical algorithms, lattice up-stream targeting (LUST) and D-basis, to the identification of prognostic signatures from cancer gene expression data. The LUST algorithm looks for metagenes, which are sets of genes that are either overexpressed or underexpressed in the same patients. Whereas LUST runs unsupervised by clinical data, the D-basis algorithm uses implications and association rules to relate gene expression to clinical outcomes. The D-basis selects a small subset of the metagene (a signature) to predict survival. The two algorithms, LUST and D-basis, were combined and applied to mRNA expression and clinical data from The Cancer Genome Atlas (TCGA) for 203 stage 1 and 2 stomach cancer patients. Two small (four-gene) signatures effectively predict survival in early-stage stomach cancer patients. These signatures could be used as a guide for treatment. The first signature (DU4) consists of genes that are underexpressed on the long-survival/low-risk group: FLRT2, KCNB1, MYOC, and TNXB. The second signature consists of genes that are overexpressed on the short-survival/high-risk group: ASB5, SFRP1, SMYD1, and TACR2. Another nine-gene signature (REC9) predicts recurrence: BNC2, CCDC8, DPYSL3, MOXD1, MXRA8, PRELP, SCARF2, TAGLN, and ZNF423. Each patient is assigned a score that is a linear combination of the expression levels for the genes in the signature. Scores below a selected threshold predict low-risk/long survival, whereas high scores indicate a high risk of short survival. The metagenes associate with TCGA cluster C1. Both our signatures and cluster C1 identify tumors that are genomically silent, and have a low mutation load or mutation count. Furthermore, our signatures identify tumors that are predominantly in the WHO classification of poorly cohesive and the Lauren class of diffuse samples, which have a poor prognosis.

Interplay between Epigenetics and Cellular Metabolism in Colorectal Cancer

Cellular metabolism alterations have been recognized as one of the most predominant hallmarks of colorectal cancers (CRCs). It is precisely regulated by many oncogenic signaling pathways in all kinds of regulatory levels, including transcriptional, post-transcriptional, translational and post-translational levels. Among these regulatory factors, epigenetics play an essential role in the modulation of cellular metabolism. On the one hand, epigenetics can regulate cellular metabolism via directly controlling the transcription of genes encoding metabolic enzymes of transporters. On the other hand, epigenetics can regulate major transcriptional factors and signaling pathways that control the transcription of genes encoding metabolic enzymes or transporters, or affecting the translation, activation, stabilization, or translocation of metabolic enzymes or transporters. Interestingly, epigenetics can also be controlled by cellular metabolism. Metabolites not only directly influence epigenetic processes, but also affect the activity of epigenetic enzymes. Actually, both cellular metabolism pathways and epigenetic processes are controlled by enzymes. They are highly intertwined and are essential for oncogenesis and tumor development of CRCs. Therefore, they are potential therapeutic targets for the treatment of CRCs. In recent years, both epigenetic and metabolism inhibitors are studied for clinical use to treat CRCs. In this review, we depict the interplay between epigenetics and cellular metabolism in CRCs and summarize the underlying molecular mechanisms and their potential applications for clinical therapy.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

Hsa_circ_0040809 regulates colorectal cancer development by upregulating methyltransferase DNMT1 via targeting miR-515-5p

BACKGROUND

Circular RNAs (circRNAs) are key regulators in the progression of various cancers. Abnormal DNA methylation patterns feature prominently in the regulation of the expression of tumor-related genes. This study is aimed at investigating the molecular mechanism of circ_0040809 affecting colorectal cancer (CRC) progression by regulating DNA methyltransferase 1 (DNMT1).

METHODS

circ_0040809 was selected from the circRNA microarray datasets (GSE142837 and GSE138589). Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to examine the expression of circ_0040809, miR-515-5p, and DNMT1 mRNA in paired cancerous and paracancerous tissues of 40 CRC patients, as well as in cell lines. Western blotting was conducted for detecting DNMT1 protein expression in CRC cells. Cell proliferation, migration, and apoptosis were assessed through CCK-8, Transwell, and flow cytometry assays. Bioinformatics and dual-luciferase gene assay were conducted to predict and verify, respectively, the targeted relationships between circ_0040809 and miR-515-5p, as well as between miR-515-5p and DNMT1 mRNA.

RESULTS

In CRC tissues and cells, circ_0040809 and DNMT1 expression are markedly increased, whereas miR-515-5p expression is decreased. Also, high circ_0040809 expression is significantly linked to shorter overall survival. Cell function compensation experiments reveal that circ_0040809 silencing inhibits CRC cell proliferation and migration and promotes apoptosis, while circ_0040809 overexpression has the opposite effects. Mechanistically, circ_0040809 competitively binds to miR-515-5p to elevate DNMT1 expression. Rescue assay reveals that overexpressed miR-515-5p partly counteracts the tumor-facilitating impact of circ_0040809.

CONCLUSIONS

circ_0040809 facilitates CRC cell proliferation and migration, and inhibits apoptosis, through modulating miR-515-5p/DNMT1 axis. Our study implies that targeting circ_0040809 may be a therapy strategy for CRC treatment.

5-aza-2'-deoxycitidine inhibits cell proliferation, extracellular matrix formation and Wnt/β-catenin pathway in human uterine leiomyomas

BACKGROUND

Uterine leiomyoma is a benign tumor with unclear pathogenesis and inaccurate treatment. This tumor exhibits altered DNA methylation related to disease progression. DNMT inhibitors as 5-aza-2'-deoxycytidine (5-aza-CdR), have been suggested to treat tumors in which DNA methylation is altered. We aimed to evaluate whether DNA methylation reversion with 5-aza-CdR reduces cell proliferation and extracellular matrix (ECM) formation in uterine leiomyoma cells to provide a potential treatment option.

METHODS

Prospective study using uterine leiomyoma and adjacent myometrium tissues and human uterine leiomyoma primary (HULP) cells (n = 16). In tissues, gene expression was analyzed by qRT-PCR and DNMT activity by ELISA. Effects of 5-aza-CdR treatment on HULP cells were assessed by CellTiter, western blot, and qRT-PCR.

RESULTS

DNMT1 gene expression was higher in uterine leiomyoma vs myometrium. Similarly, DNMT activity was greater in uterine leiomyoma and HULP cells (6.5 vs 3.8 OD/h/mg; 211.3 vs 63.7 OD/h/mg, respectively). After 5-aza-CdR treatment on HULP cells, cell viability was reduced, significantly so at 10 μM (85.3%). Treatment with 10 μM 5-aza-CdR on HULP cells significantly decreased expression of proliferation marker PCNA (FC = 0.695) and of ECM proteins (COLLAGEN I FC = 0.654; PAI-1, FC = 0.654; FIBRONECTIN FC = 0.733). 5-aza-CdR treatment also decreased expression of Wnt/β-catenin pathway final targets, including WISP1 protein expression (10 μM, FC = 0.699), c-MYC gene expression (2 μM, FC = 0.745 and 10 μM, FC = 0.728), and MMP7 gene expression (5 μM, FC = 0.520 and 10 μM, FC = 0.577).

CONCLUSIONS

5-aza-CdR treatment inhibits cell proliferation, ECM formation, and Wnt/β-catenin signaling pathway targets in HULP cells, suggesting that DNA methylation inhibition is a viable therapeutic target in uterine leiomyoma.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

Regulation of Formation, Stemness and Therapeutic Resistance of Cancer Stem Cells

Over the past 20 years cancer stem cells (CSCs) have been proposed as key players in the tumorigenesis and progression, which are closely related to the initiation, metastasis and therapeutic resistance of cancer. Evidences have been provided that both genetic and epigenetic factors contribute to the regulation of the formation and stemness maintenance as well as the therapeutic resistance of CSCs via affecting various signal pathways. In addition, the interaction between CSCs and tumor microenvironment has also been revealed to be involved in the above-described processes. With the aim of targeting CSCs to improve treatment outcome, we herein discuss the mechanisms that orchestrate the characteristic of CSCs by the three elements and potential therapeutic strategies. We also summarize how several key regulatory factors function in the regulation of not only the formation and stemness maintenance, but also the therapeutic resistance of CSCs. Thus, future studies focusing on these key factors would be helpful for the development of novel drugs targeting CSCs.

Targeting stemness of cancer stem cells to fight colorectal cancers

Cancer initiating/ stem cells (CSCs) undergo self-renewal and differentiation that contributes to tumor initiation, recurrence and metastasis in colorectal cancer (CRC). Targeting of colorectal cancer stem cells (CCSCs) holds significant promise in eradicating cancer cells and ultimately curing patients with cancer. In this review, we will introduce the current progress of CCSC studies, including the specific surface markers of CCSCs, the intrinsic signaling pathways that regulate the stemness and differentiation characteristics of CCSCs, and the tumor organoid model for CCSC research. We will focus on how these studies will lead to the progress in targeting specific surface markers or signaling pathways on CCSCs by monoclonal antibodies, or by natural or synthetic compounds, or by immunotherapy. As CSCs are highly heterogeneous and plastic, we suggest that combinatory approaches that target the stemness network may represent an important strategy for eradicating cancers.

DNA methylation integratedly modulates the expression of Pit-Oct-Unt transcription factors in esophageal squamous cell carcinoma

Background: Dysregulation of Pit-Oct-Unc family transcription factors has been implicated in esophageal squamous cell carcinoma (ESCC). In this study, we evaluated the expression and promoter methylation status of Octamer (OCT) transcription factor genes in human ESCC clinical specimens to investigate the mechanism underlying this observation along with the clinical significance.

Methods: Total DNA or RNA was extracted from ESCC tissue specimens and the mRNA level of genes encoding the transcription factors OCT1, OCT2, OCT3/OCT4, OCT5, OCT7, OCT9, and OCT11 were evaluated by quantitative PCR. The DNA methylation status of gene promoters was assessed by bisulfite pyrosequencing and next-generation sequencing. The relationship between the expression of these transcription factors and ESCC proliferation was investigated in vitro and in vivo with the colony formation assay and a mouse xenograft tumor model, respectively. We also examined the correlation between OCT gene expression and promoter methylation and clinicopathologic characteristics of ESCC.

Results:OCT1 was upregulated whereas OCT4, OCT6, and OCT11 were downregulated in ESCC compared to non-tumor tissue. OCT2, OCT7, and OCT9 were undetected in all samples. OCT1, OCT6, and OCT11 levels were negatively correlated with the methylation of their respective promoters, but there was no relationship between OCT4 expression and promoter methylation status.

Conclusion: Changes in promoter methylation rate underlie the observed alterations in OCT1, OCT6, and OCT11 expression in ESCC, whereas another mechanism is likely responsible for the dysregulation of OCT4.

Exposure to cadmium and copper triggers cytotoxic effects and epigenetic changes in human colorectal carcinoma HT-29 cells

Recent scientific evidence suggests a link between epigenetic changes (DNA methylation) and tumorigenesis. Moreover, a potential carcinogenic mechanism of cadmium was associated with changes in DNA methylation. In this study we investigated the impact of CdCl₂ and CuSO₄ aqueous solutions on DNA methylation in HT-29 cells by quantifying DNA methyltransferase (DNMT1, DNMT3A and DNMT3B) mRNA expression. Furthermore, we also studied the cytotoxic and anti-migratory potential of these substances. The results showed a dose-dependent decrease of viable cell percentage following 24 h of exposure (at concentrations of 0.05; 0.2; 1; 10 and 100 µg/ml), and an inhibitory effect on HT-29 cell migration capacity. In addition, RT-qPCR results showed that cadmium acts as a hypomethylating agent by suppressing DNMT expression, whereas copper acts as a hypermethylating compound by increasing DNMT expression. These findings suggest a cytotoxic potential of both cadmium and copper on HT-29 cells and their capacity to induce epigenetic changes.

DNA methyltransferase expression is associated with cell proliferation in salivary mucoepidermoid carcinoma

OBJECTIVES

The present study investigated the correlation between the expression of DNA methyltransferase (DNMT)1, DNMT3A, and DNMT3B and the proliferation of mucoepidermoid carcinomas (MECs) using the molecular markers Ki-67 and cyclin D1. This study also demonstrates the effects of 5-aza-2-deoxycytidine (5AC) on the MEC tumor cell lines in relation to DNMT1 and DNMT3A expression, and cell-cycle arrest.

MATERIALS AND METHODS

The immunohistochemistry of DNMT1, DNMT3A, DNMT3B, Ki-67, and cyclin D1 was analyzed in 40 samples of MEC and 15 samples of healthy minor salivary glands. The effects of 5AC on DNMT1 and DNMT3B expression in MEC cell lines were analyzed by Western blot, and the effects of 5AC on the cell cycle were analyzed using flow cytometry.

RESULTS

The expression of DNMT1 and DNMT3B was more intense in MECs than in healthy salivary glands. A strong correlation was found between the expression of the DNMTs and the proliferation markers. This correlation was validated In Vitro, where treatment with 5AC reduced the expression of the DNMTs and the percentage of cells at the G2/M phase of the cell cycle.

CONCLUSION

The expression of DNMT1, DNMT3A, DNMT3B is correlated significantly with the expression of Ki-67 and cyclin D1. The treatment with 5AC reduces DNMT expression and decreases the percentage of cells at the G2/M phase of the cell cycle, while increasing the cells at the G0/G1 phase.

Photothermogenetic inhibition of cancer stemness by near-infrared-light-activatable nanocomplexes

Strategies for eradicating cancer stem cells (CSCs) are urgently required because CSCs are resistant to anticancer drugs and cause treatment failure, relapse and metastasis. Here, we show that photoactive functional nanocarbon complexes exhibit unique characteristics, such as homogeneous particle morphology, high water dispersibility, powerful photothermal conversion, rapid photoresponsivity and excellent photothermal stability. In addition, the present biologically permeable second near-infrared (NIR-II) light-induced nanocomplexes photo-thermally trigger calcium influx into target cells overexpressing the transient receptor potential vanilloid family type 2 (TRPV2). This combination of nanomaterial design and genetic engineering effectively eliminates cancer cells and suppresses stemness of cancer cells in vitro and in vivo. Finally, in molecular analyses of mechanisms, we show that inhibition of cancer stemness involves calcium-mediated dysregulation of the Wnt/β-catenin signalling pathway. The present technological concept may lead to innovative therapies to address the global issue of refractory cancers.

Cancer stem cells (CSCs) are known to induce chemotherapy resistance, and cause tumour relapse and metastasis. Here, the authors develop photoactive nanocarbon complexes with second near-infrared photothermal ability to target cancer cells overexpressing the receptor TRPV2 and show it to suppress CSCs through dysregulation of the Wnt/β-catenin signalling pathway.

DNA hypermethylation in disease: mechanisms and clinical relevance

Increasing numbers of studies implicate abnormal DNA methylation in cancer and many non-malignant diseases. This is consistent with numerous findings about differentiation-associated changes in DNA methylation at promoters, enhancers, gene bodies, and sites that control higher-order chromatin structure. Abnormal increases or decreases in DNA methylation contribute to or are markers for cancer formation and tumour progression. Aberrant DNA methylation is also associated with neurological diseases, immunological diseases, atherosclerosis, and osteoporosis. In this review, I discuss DNA hypermethylation in disease and its interrelationships with normal development as well as proposed mechanisms for the origin of and pathogenic consequences of disease-associated hypermethylation. Disease-linked DNA hypermethylation can help drive oncogenesis partly by its effects on cancer stem cells and by the CpG island methylator phenotype (CIMP); atherosclerosis by disease-related cell transdifferentiation; autoimmune and neurological diseases through abnormal perturbations of cell memory; and diverse age-associated diseases by age-related accumulation of epigenetic alterations.

Silencing BRIT1 Facilitates the Abilities of Invasiveness and Migration in Trophoblast Cells

Background

The improper invasion of trophoblast cells (TC) can cause various diseases. BRCT-repeat inhibitor of hTERT expression (BRIT1) is involved in the invasion of tumors. Here, we analyzed the effects of BRIT1 on the invasion of TC.

Material/Methods

The expression of BRIT1 in JEG-3, B6Tert, and HTR8/SVneo cells was evaluated by transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. The viability, invasion, and migration of HTR8/SVneo cells were measured using cell counting kit-8 (CCK-8) and Transwell assays. The activities of pro-matrix metalloproteinase-2 (pro-MMP-2) and pro-MMP-9 were tested by gelatin zymography assay. The levels of invasion- and Wnt/β-catenin pathway-related factors were assessed by RT-qPCR and Western blotting.

Results

Levels of BRIT1 in HTR8/SVneo cells were higher than that of JEG-3 and B6Tert cells. The transfection efficiency of BRIT1 siRNA-2 was better than BRIT1 siRNA-1 in HTR8/SVneo cells. BRIT1 siRNA-2 did not change cell viability, whereas it promoted cell invasion and migration. BRIT1 siRNA-2 enhanced the activities of pro-MMP-2 and pro-MMP-9, as well MMP-2 and MMP-9 levels, and reduced tissue inhibitor of metalloproteinases-1 (TIMP-1) and TIMP-2 expression. Moreover, BRIT1 siRNA-2 significantly increased the levels of Wnt2, Wnt3, and β-catenin.

Conclusions

BRIT1 silencing accelerated the invasion and migration of TC and activated the Wnt/β-catenin pathway. Our results may provide new insights for finding new molecular targets to cure disease caused by insufficient invasion of TC.