KDM4B promotes DNA damage response via STAT3 signaling and is a target of CREB in colorectal cancer cells

KDM4B Histone Demethylase Inhibition Attenuates Tumorigenicity of Malignant Melanoma Cells by Overriding the p53-Mediated Tumor Suppressor Pathway

Despite significant advances in the treatment of cutaneous melanoma (hereafter melanoma), the prognosis remains less favorable due to therapeutic resistance, which is presumably linked to epigenetic dysregulation. We hypothesized that the histone lysine demethylase KDM4B could play a pivotal role in controlling therapy-resistant melanoma. To validate our hypothesis, we retrieved RNA sequencing data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) program and observed upregulation of KDM4B in both primary and metastatic melanoma, which was associated with poor survival. To explore its role, we used murine B16, human SK-MEL-5, and G-361 melanoma cells as in vitro models of melanoma. We found that KDM4B inhibition using NCGC00244536 increased global levels of H3K9me3 and downregulated the expressions of cell cycle progression-related genes Cdk1, Cdk4, Ccnb1, and Ccnd1. Moreover, genetic ablation of KDM4B or its chemical inhibition using NCGC00244536 reduced p53 production by upregulating MDM2, which enhances the proteolytic degradation of p53. Interestingly, despite the reduction of p53, these interventions augmented apoptosis and senescence-induced cell death by activating pathways downstream of p53, as evidenced by reduced levels of pro-survival Bcl-2 and Bcl-xL proteins and increased production of pro-apoptotic cleaved caspase-3, caspase-7, Bax, and the senescence inducer Cdkn1a. Compared to the FDA-approved anti-melanoma agent dacarbazine, NCGC00244536 exhibited more pronounced cytotoxic and antiproliferative effects in melanoma cells. Importantly, NCGC00244536 demonstrated minimal cytotoxicity to low Kdm4b-expressing mouse embryonic fibroblasts. In conclusion, our findings suggest that KDM4B inhibition can override the antitumor effect of p53, and potentially serve as a therapeutic strategy for melanoma.

Histone demethylase KDM4B contributes to advanced clear cell renal carcinoma and association with copy number variations and cell cycle progression

Advanced renal cell carcinoma (RCC) poses a threat to patient survival. Epigenetic remodelling is the pathogenesis of renal cancer. Histone demethylase 4B (KDM4B) is overexpressed in many cancers through various pathways. However, the role of KDM4B in clear cell renal carcinoma has not yet been elucidated. The differential expression of KDM4B was first verified by analysing public databases. The expression of KDM4B in fresh tissues and pathology slides was further analysed by western blotting and immunohistochemical staining. KDM4B overexpression and knockdown cell lines were also established. Cell Counting Kit-8 (CCK-8) assay was used to detect cell growth. Transwell assays were performed to assess cell migration. Xenografts were used to evaluate tumour growth and metastasis in vivo. Finally, KDM4B expression levels associated with copy number variation (CNV) and cell cycle stage were evaluated based on single-cell RNA sequencing data. KDM4B was expressed at higher levels in tumour tissues than in the adjacent normal tissues. High levels of KDM4B are associated with worse pathological features and poorer prognosis. KDM4B also promotes cell proliferation and migration in vitro, as well as tumour growth and metastasis in vivo. Tumour cells with high KDM4B expression exhibited higher CNV levels and a greater proportion of cells in the G1/S transition phase. Our results confirm that KDM4B promotes the progression of clear cell renal carcinoma, is correlated with poor prognosis, and may be related to high levels of CNV and cell cycle progression.

TACH101, a first-in-class pan-inhibitor of KDM4 histone demethylase

Histone lysine demethylase 4 (KDM4) is an epigenetic regulator that facilitates the transition between transcriptionally silent and active chromatin states by catalyzing the removal of methyl groups on histones H3K9, H3K36, and H1.4K26. KDM4 overamplification or dysregulation has been reported in various cancers and has been shown to drive key processes linked to tumorigenesis, such as replicative immortality, evasion of apoptosis, metastasis, DNA repair deficiency, and genomic instability. KDM4 also plays a role in epigenetic regulation of cancer stem cell renewal and has been linked to more aggressive disease and poorer clinical outcomes. The KDM4 family is composed of four main isoforms (KDM4A-D) that demonstrate functional redundancy and cross-activity; thus, selective inhibition of one isoform appears to be ineffective and pan-inhibition targeting multiple KDM4 isoforms is required. Here, we describe TACH101, a novel, small-molecule pan-inhibitor of KDM4 that selectively targets KDM4A-D with no effect on other KDM families. TACH101 demonstrated potent antiproliferative activity in cancer cell lines and organoid models derived from various histologies, including colorectal, esophageal, gastric, breast, pancreatic, and hematological malignancies. In vivo , potent inhibition of KDM4 led to efficient tumor growth inhibition and regression in several xenograft models. A reduction in the population of tumor-initiating cells was observed following TACH101 treatment. Overall, these observations demonstrate the broad applicability of TACH101 as a potential anticancer agent and support its advancement into clinical trials.

CpG Site-Based Signature Predicts Survival of Colorectal Cancer

BACKGROUND

A critical unmet medical need in clinical management of colorectal cancer (CRC) pivots around lack of noninvasive and or minimally invasive techniques for early diagnosis and prognostic prediction of clinical outcomes. Because DNA methylation can capture the regulatory landscape of tumors and can be measured in body fluids, it provides unparalleled opportunities for the discovery of early diagnostic and prognostics markers predictive of clinical outcomes. Here we investigated use of DNA methylation for the discovery of potential clinically actionable diagnostic and prognostic markers for predicting survival in CRC.

METHODS

We analyzed DNA methylation patterns between tumor and control samples to discover signatures of CpG sites and genes associated with CRC and predictive of survival. We conducted functional analysis to identify molecular networks and signaling pathways driving clinical outcomes.

RESULTS

We discovered a signature of aberrantly methylated genes associated with CRC and a signature of thirteen (13) CpG sites predictive of survival. We discovered molecular networks and signaling pathways enriched for CpG sites likely to drive clinical outcomes.

CONCLUSIONS

The investigation revealed that CpG sites can predict survival in CRC and that DNA methylation can capture the regulatory state of tumors through aberrantly methylated molecular networks and signaling pathways.

The Diverse Roles of Histone Demethylase KDM4B in Normal and Cancer Development and Progression

Histone methylation status is an important process associated with cell growth, survival, differentiation and gene expression in human diseases. As a member of the KDM4 family, KDM4B specifically targets H1.4K26, H3K9, H3K36, and H4K20, which affects both histone methylation and gene expression. Therefore, KDM4B is often regarded as a key intermediate protein in cellular pathways that plays an important role in growth and development as well as organ differentiation. However, KDM4B is broadly defined as an oncoprotein that plays key roles in processes related to tumorigenesis, including cell proliferation, cell survival, metastasis and so on. In this review, we discuss the diverse roles of KDM4B in contributing to cancer progression and normal developmental processes. Furthermore, we focus on recent studies highlighting the oncogenic functions of KDM4B in various kinds of cancers, which may be a novel therapeutic target for cancer treatment. We also provide a relatively complete report of the progress of research related to KDM4B inhibitors and discuss their potential as therapeutic agents for overcoming cancer.

Drug resistance in colorectal cancer: An epigenetic overview

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Despite significant progress that has been made in therapies against CRC over the past decades, drug resistance is still a major limitation in CRC treatment. Numerous investigations have unequivocally shown that epigenetic regulation plays an important role in CRC drug resistance because of the high rate of epigenetic alterations in multiple genes during cancer development or drug treatment. Furthermore, the reversibility of epigenetic alterations provides novel therapeutic strategies to overcome drug resistance using small molecules, which can target non-coding RNAs or reverse histone modification and DNA methylation. In this review, we discuss epigenetic regulation in CRC drug resistance and the possible role of preventing or reversing CRC drug resistance using epigenetic therapy in CRC treatment.

Activation of TC10-Like Transcription by Lysine Demethylase KDM4B in Colorectal Cancer Cells

Malignant colorectal cancers (CRCs) are characterized by enhanced migration and invasion thus acquiring the ability to metastasize. We have previously shown that the small GTPase TC10-like (TCL) contributes to aggressive migration and invasion in malignant CRC cells. TCL expression is differentially expressed in CRC cells and can be upregulated by hypoxia although the underlying epigenetic mechanism is not fully appreciated. Here, we report that differential TCL expression in CRC cells appeared to be associated with histone H3K9 methylation. RNAi screening revealed that the lysine demethylase KDM4B was essential for TCL transcription in CRC cells. KDM4B interacted with and was recruited by the sequence-specific transcription factor ETS-related gene 1 (ERG1) to the TCL promoter to activate transcription. Mechanistically, KDM4B mediated H3K9 demethylase facilitated the assembly of pre-initiation complex (PIC) on the TCL promoter. KDM4B knockdown attenuated migration and invasion of CRC cells. Importantly, KDM4B expression was upregulated in human CRC specimens of advanced stages compared to those of lower grades and associated with poor prognosis. Together, these data uncover a novel epigenetic mechanism underlying malignant transformation of CRC cells and suggest that KDM4B may be considered as a therapeutic target in CRC intervention.

KDM4B Overexpression Promotes the Growth, Migration, and Invasion of Rheumatoid Arthritis Fibroblast-Like Synoviocytes by Activating STAT3 Pathway

In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) present a unique aggressive phenotype and have a passive response to the inflammatory microenvironment, which are critical for the disease’s progression. KDM4B, as a histone demethylase, functions as an oncogenic factor in many cancers and is implicated in osteoclastogenesis as well as pro-inflammatory cytokine release in inflammatory diseases. However, the effects of KDM4B on RA FLS have not been reported. To investigate this issue, our study determined the expression of KDM4B in RA FLS using RT-qPCR and western blot. The effects of KDM4B on RA FLS viability, apoptosis, migration, and invasion were detected by MTT, flow cytometry, transwell migration, and invasion assays. Furthermore, the interaction of KDM4B with STAT3 signaling was studied by western blot, MTT, flow cytometry, transwell migration, and invasion assays. The experimental results showed that KDM4B expression was upregulated in RA synovial tissues and FLS as compared to healthy control tissues and normal FLS. Knockdown of KDM4B obviously suppressed RA FLS viability, migration and invasion, and induced apoptosis. In addition, knockdown of KDM4B in RA FLS decreased the expression of p-STAT3 and MMP-9 but increased cleaved caspase-3 expression compared with the control group. Moreover, KDM4B overexpression could promote cell growth, migration and invasion, and suppress apoptosis in RA FLS by activating STAT3 signaling. Therefore, these findings provide new insight for understanding the pathogenesis of RA and indicate that KDM4B may have a potential to be an effective therapeutic target for RA.

Histone methylation can either promote or reduce cellular radiosensitivity by regulating DNA repair pathways

Radiotherapy is one of the primary modalities for cancer treatment, and its efficiency usually relies on cellular radiosensitivity. DNA damage repair is a core content of cellular radiosensitivity, and the primary mechanism of which includes non-homologous end-joining (NHEJ) and homologous recombination (HR). By affecting DNA damage repair, histone methylation regulated by histone methyltransferases (HMTs) and histone demethylases (HDMs) participates in the regulation of cellular radiosensitivity via three mechanisms: (a) recruiting DNA repair-related proteins, (b) regulating the expressions of DNA repair genes, and (c) mediating the dynamic change of chromatin. Interestingly, both aberrantly high and low levels of histone methylation could impede DNA repair processes. Here we reviewed the mechanisms of the dual effects of histone methylation on cell response to radiation. Since some inhibitors of HMTs and HDMs are reported to increase cellular radiosensitivity, understanding their molecular mechanisms may be helpful in developing new drugs for the therapy of radioresistant tumors.

RAD52 aptamer regulates DNA damage repair and STAT3 in BRCA1/BRCA2‑deficient human acute myeloid leukemia

RAD52 (Radiation sensitive 52) is a key factor in DNA damage repair (DDR) bypass, which participates in single-strand annealing (SSA) after DNA damage end excision, while breast cancer type 1 susceptibility protein (BRCA1)/breast cancer type 2 susceptibility protein (BRCA2) play critical roles in homologous recombination (HR) repair. The present study aimed to determine whether RAD52-induced regulation of repair bypass occurs in acute myeloid leukemia (AML) cells and to explore the underlying mechanism. Herein, we applied an RAD52 aptamer to AML cells with downregulated BRCA1/2. RAD52 aptamer inhibited AML cell proliferation detected by cell counting, promoted cell apoptosis obtained by flow cytometry, and suppressed DNA damage repair behavior measured by comet assay and flow cytometry, after drug intervention during low expression of BRCA1/2. During this process, DDR-related cell cycle checkpoint proteins were activated, and the cells were continuously arrested in the S/G2 phase, which affected the cell damage repair process. Concurrently, the expression levels of apoptosis-related proteins were also altered. Furthermore, the expression of STAT3 and p-STAT3 was downregulated by the RAD52 aptamer, suggesting that RAD52 affects the STAT3 signaling pathway. In summary, we present a possible role for RAD52 in DDR of BRCA1/2-deficient AML cells that involves the STAT3 signaling pathway.

Tudor domain of histone demethylase KDM4B is a reader of H4K20me3

The lysine histone demethylase KDM4B is overexpressed in several types of cancers and plays dual roles in genome stability maintenance. Although KDM4B is able to recognize several histone methylations, the underlying molecular mechanism is still unknown. In this study, we purified the KDM4B chromatin-associated hybrid tudor domains (HTDs) and plant home domains (PHDs) and performed the pull-down assay to screen the tri-methyl modified histone peptides that could be efficiently recognized by KDM4B. Our results showed that both HTD alone and the combination of HTD and PHD were able to specifically bind to H3K4me3 and H4K20me3. Because H4K20me3 is essential for KDM4B's rapid recruitment to DNA damage site, we further aligned the multiple tudor peptide sequence and identified two conserved residues Y993 and W987 that are critical for KDM4B-H4K20me3 interaction. The surface plasmon resonance analysis revealed that HTD displayed a rapid H4K20me3 bind-dissociate pattern. These findings therefore provided mechanistic insights into the binding of tudor domain of KDM4B protein with H4K20me3.

HJC0152 suppresses human non-small-cell lung cancer by inhibiting STAT3 and modulating metabolism

Objectives

Signal transducer and activator of transcription 3 (STAT3) is constitutively activated and overexpressed in many cancers, including non–small‐cell lung cancer (NSCLC). We recently developed HJC0152 as an orally active STAT3 inhibitor. This study focused on investigating HJC0152's effect and mechanism of action in NSCLC.

Materials and methods

We analysed cell proliferation by MTT assays, cell migration by wound healing and transwell assays, protein levels by Western blot, and apoptosis and reactive oxygen species (ROS) level by flow cytometry. A nude mouse tumorigenesis model was established for in vivo experiment. UHPLC‐QTOF/MS was used for untargeted metabolomic relative quantitation analysis.

Results

We found that HJC0152 exhibited activity against human NSCLC cells in vitro and NSCLC xenograft tumours in vivo via regulating STAT3 signalling and metabolism. HJC0152 efficiently reduced NSCLC cell proliferation, promoted ROS generation, induced apoptosis, triggered DNA damage and reduced motility in A549 and H460 NSCLC cells. Moreover, HJC0152 significantly inhibited the growth of A549 xenograft tumours in vivo. HJC0152 also affected metabolism, significantly decreasing and perturbating levels of several metabolites in the purine, glutathione and pyrimidine metabolism pathways.

Conclusions

HJC0152 reduces cellular capacity to scavenge free radicals, leading to ROS generation and accumulation and apoptosis. This study provides a rationale for further developing HJC0152 as a potential therapy for NSCLC and provides insights into the mechanisms by which HJC0152 exerts its anti‐cancer effects.

Advances in histone demethylase KDM4 as cancer therapeutic targets

The KDM4 subfamily H3K9 histone demethylases are epigenetic regulators that control chromatin structure and gene expression by demethylating histone H3K9, H3K36, and H1.4K26. The KDM4 subfamily mainly consists of four proteins (KDM4A-D), all harboring the Jumonji C domain (JmjC) but with differential substrate specificities. KDM4A-C proteins also possess the double PHD and Tudor domains, whereas KDM4D lacks these domains. KDM4 proteins are overexpressed or deregulated in multiple cancers, cardiovascular diseases, and mental retardation and are thus potential therapeutic targets. Despite extensive efforts, however, there are very few KDM4-selective inhibitors. Defining the exact physiological and oncogenic functions of KDM4 demethylase will provide the foundation for the discovery of novel potent inhibitors. In this review, we focus on recent studies highlighting the oncogenic functions of KDM4s and the interplay between KDM4-mediated epigenetic and metabolic pathways in cancer. We also review currently available KDM4 inhibitors and discuss their potential as therapeutic agents for cancer treatment.

The Long Noncoding RNA UCA1 Negatively Regulates Melanogenesis in Melanocytes

The long noncoding RNA UCA1 was first discovered in bladder cancer and is known to regulate the proliferation and migration of melanoma. However, its role in melanogenesis is unclear. In this study, we aimed to explore the role and mechanism of UCA1 in melanogenesis. Our findings showed that the expression of UCA1 was negatively correlated with melanin content in melanocytes and pigmented nevus. Overexpression of UCA1 in melanocytes decreased melanin content and the expression of melanogenesis-related genes, whereas knockdown of UCA1 in melanocytes had the opposite effect. High-throughput sequencing revealed that microphthalmia-associated transcription factor (MITF), an important transcription factor affecting melanogenesis, was also negatively correlated with the expression of UCA1. Furthermore, the transcription factor CRE-binding protein (CREB), which promotes MITF expression, was negatively regulated by UCA1. The cAMP/protein kinase A (PKA), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) signaling pathways, which are upstream of the CREB/MITF/melanogenesis axis, were activated or inhibited in response to silencing or enhancing UCA1 expression, respectively. In addition, enhanced UCA1 expression downregulates the expression of melanogenesis-related genes induced by UVB in melanocytes. In conclusion, UCA1 may negatively regulate the CREB/MITF/melanogenesis axis through inhibiting the cAMP/PKA, ERK, and JNK signaling pathways in melanocytes. UCA1 may be a potential therapeutic target for the treatment of pigmented skin diseases.

CLDN8 promotes colorectal cancer cell proliferation, migration, and invasion by activating MAPK/ERK signaling

Background

Claudin 8 (CLDN8), an integral membrane protein that constitutes tight junctions in cell membranes, was recently implicated in tumor progression. However, its roles in colorectal cancer (CRC) progression and metastasis remain unknown.

Methods

In this study, we examined the effect of CLDN8 on the progression of CRC, including cell proliferation, migration, and invasion, and determines its underlying molecular mechanism using in vitro CRC cell lines and in vivo mouse xenograft models.

Results

We found that CLDN8 expression in human CRC tissues was significantly higher than that in adjacent normal tissues. The knockdown of CLDN8 markedly suppressed the proliferation, migration, and invasion of SW480 and HT-29 CRC cells, whereas the overexpression of CLDN8 notably promoted tumor progression in SW480 and HT-29 CRC cells. Mechanistic studies revealed that CLDN8 upregulated p-ERK (p-PKB/AKT) and MMP9 in CRC cells. Notably, the MAPK/ERK inhibitor PD98095 dramatically attenuated the effects of CLDN8 on p-ERK and MMP9. Moreover, PD98095 remarkably blocked the tumor-promoting activity of CLDN8. The knockdown of CLDN8 also inhibited the in vivo tumor growth in a nude mouse xenograft model. Collectively, CLDN8 promoted CRC cell proliferation, migration, and invasion, at least in part, by activating the MAPK/ERK signaling pathway.

Conclusion

These findings suggest that CLDN8 exhibits an oncogenic effect in human CRC progression.

Identification and functional analysis of microRNAs in rats following focal cerebral ischemia injury

MicroRNA sequencing (miRNA‑seq) was performed in the present study to investigate miRNA expression profiles in infarcted brain areas following focal cerebral ischemia induced by middle cerebral artery occlusion in rats. In total, 20 miRNAs were identified to be upregulated and 17 to be downregulated in the infarct area. The expression levels of six differentially expressed miRNAs (DEmiRs), miR‑211‑5p, miR‑183‑5p, miR‑10b‑3p, miR‑182, miR‑217‑5p and miR‑96‑5p, were examined by reverse transcription‑​quantitative polymerase chain reaction. Subsequently, a miRNA‑mRNA network was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to investigate the functions of the mRNAs targeted by these DEmiRs. The present study aimed to investigate the association between miRNAs and cerebral ischemia to provide potential insight into the molecular mechanisms underlying ischemic stroke.

Adaptive EGF expression sensitizes pancreatic cancer cells to ionizing radiation through activation of the cyclin D1/P53/PARP pathway

It is well-known that the activation status of the P53, signal transducer and activator of transcription (Stat)3 and nuclear factor (NF)‑κB signaling pathways determines the radiosensitivity of cancer cells. However, the function of these pathways in radiosensitive vs radioresistant cancer cells remains elusive. The present study demonstrated that adaptive expression of epidermal growth factor (EGF) following exposure to ionizing radiation (IR) may induce radiosensitization of pancreatic cancer (PC) cells through induction of the cyclin D1/P53/poly(ADP‑ribose) polymerase pathway. By contrast, adaptively expressed interleukin (IL)‑6 and insulin‑like growth factor (IGF)‑1 may promote radioresistance of PC cells, likely through activation of the Stat3 and NF‑κB pathways. In addition, cyclin D1 and survivin, which are specifically expressed in the G1/S and G2/M phase of the cell cycle, respectively, are mutually exclusive in radiosensitive and radioresistant PC cells, while Bcl‑2 and Bcl‑xL expression does not differ between radiosensitive and radioresistant PC cells. Therefore, adaptively expressed EGF and IL‑6/IGF‑1 may alter these pathways to promote the radiosensitivity of PC cancers. The findings of the present study highlight potential makers for the evaluation of radiosensitivity and enable the development of effective regimens for cancer radiotherapy.

KDM4B: A Nail for Every Hammer?

Epigenetic changes are well-established contributors to cancer progression and normal developmental processes. The reversible modification of histones plays a central role in regulating the nuclear processes of gene transcription, DNA replication, and DNA repair. The KDM4 family of Jumonj domain histone demethylases specifically target di- and tri-methylated lysine 9 on histone H3 (H3K9me3), removing a modification central to defining heterochromatin and gene repression. KDM4 enzymes are generally over-expressed in cancers, making them compelling targets for study and therapeutic inhibition. One of these family members, KDM4B, is especially interesting due to its regulation by multiple cellular stimuli, including DNA damage, steroid hormones, and hypoxia. In this review, we discuss what is known about the regulation of KDM4B in response to the cellular environment, and how this context-dependent expression may be translated into specific biological consequences in cancer and reproductive biology.

The identification of the ATR inhibitor VE-822 as a therapeutic strategy for enhancing cisplatin chemosensitivity in esophageal squamous cell carcinoma

Inducing DNA damage is known to be one of the mechanisms of cytotoxic chemotherapy agents for cancer such as cisplatin. The endogenous DNA damage response confers chemoresistance to these agents by repairing DNA damage. The initiation and transduction of the DNA damage response (DDR) signaling pathway, which is dependent on the activation of ATM (ataxia-telangiectasia mutated) and ATR (ataxia telangiectasia and Rad3-related), is essential for DNA damage repair, the maintenance of genomic stability and cell survival. Therefore, ATM or ATR inhibition is considered as a promising strategy for sensitizing cancer cells to chemotherapy. This study is aimed to explore the effect of ATR inhibitor on sensitizing ESCC (esophageal squamous cell carcinoma) cells to cisplatin, and whether ATM deficiency could impact the sensitization. We found that 21.5% of ESCC cases had ATM deficiency and that patients with ATR activation after neoadjuvant chemotherapy had worse chemotherapy response and poorer overall survival than that without ATR activation (32 mons vs. >140mons). Then, it was shown that VE-822 inhibited ATR-CHK1 pathway activation, leading to the accumulation of cisplatin-modified DNA. And it inhibited cell proliferation, induced cell cycle arrest in G1 phase and enhanced cell apoptosis. Moreover, VE-822 significantly sensitized ESCC cells to cisplatin, and these two drugs had synergistic effects, especially in ATM-deficient cells, in vitro and in vivo. Our results suggest that ATR inhibition combining with cisplatin is a new strategy for managing patients with ESCC, especially those with ATM-deficiency. However, this is an idea that requires further validation.