Histone H3K9 methyltransferase SETDB1 overexpression correlates with pediatric high-grade gliomas progression and prognosis

SETDB1 amplification in osteosarcomas: Insights from its role in healthy tissues and other cancer types

Epigenetic modifications, which reversibly regulate gene expression without altering the DNA sequence, are increasingly described in the literature as essential elements in the processes leading to cancer development. SETDB1 regulates histone 3 (H3) K9 di- and trimethylation, promoting heterochromatin formation, and plays a key role in gene silencing. Epigenetic deregulation of SETDB1 expression appears to be involved in different cancers types, particularly in aggressive, relapsing or treatment-resistant subtypes. Despite advances in research, the full range of mechanisms through which this protein acts remains unclear; however, it is evident that SETDB1 has a pivotal role, particularly in the mesenchymal stem cells differentiation, tumor evasion and treatment resistance. Its role in genetically complex sarcomas, such as osteosarcoma, has not been fully explored, although recent Omics analyses suggest its presence and amplification in osteosarcoma. Given its involvement in osteoblastogenesis and adipogenesis, we discuss the potential of SETDB1 as a key target for new therapeutic strategies in osteosarcoma.

The Role of Chronic Inflammation in Pediatric Cancer

Inflammation plays a crucial role in wound healing and the host immune response following pathogenic invasion. However, unresolved chronic inflammation can result in tissue fibrosis and genetic alterations that contribute to the pathogenesis of human diseases such as cancer. Recent scientific advancements exploring the underlying mechanisms of malignant cellular transformations and cancer progression have exposed significant disparities between pediatric and adult-onset cancers. For instance, pediatric cancers tend to have lower mutational burdens and arise in actively developing tissues, where cell-cycle dysregulation leads to gene, chromosomal, and fusion gene development not seen in adult-onset counterparts. As such, scientific findings in adult cancers cannot be directly applied to pediatric cancers, where unique mutations and inherent etiologies remain poorly understood. Here, we review the role of chronic inflammation in processes of genetic and chromosomal instability, the tumor microenvironment, and immune response that result in pediatric tumorigenesis transformation and explore current and developing therapeutic interventions to maintain and/or restore inflammatory homeostasis.

Progress Toward Epigenetic Targeted Therapies for Childhood Cancer

Among the most significant discoveries from cancer genomics efforts has been the critical role of epigenetic dysregulation in cancer development and progression. Studies across diverse cancer types have revealed frequent mutations in genes encoding epigenetic regulators, alterations in DNA methylation and histone modifications, and a dramatic reorganization of chromatin structure. Epigenetic changes are especially relevant to pediatric cancers, which are often characterized by a low rate of genetic mutations. The inherent reversibility of epigenetic lesions has led to an intense interest in the development of epigenetic targeted therapies. Additionally, the recent appreciation of the interplay between the epigenome and immune regulation has sparked interest in combination therapies and synergistic immunotherapy approaches. Further, the recent appreciation of epigenetic variability as a driving force in cancer evolution has suggested new roles for epigenetic therapies in limiting plasticity and resistance. Here, we review recent progress and emerging directions in the development of epigenetic targeted therapeutics and their promise across the landscape of childhood cancers.

Immunohistochemical study of histone protein 3 modification in pediatric osteosarcoma identifies reduced H3K27me3 as a marker of poor treatment response

The most common pediatric primary malignant bone tumor, osteosarcoma, is often described as genetically non-recurrent and heterogeneous. Neoadjuvant chemotherapy is typically followed by resection and assessment of treatment response, which helps inform prognosis. Identifying biomarkers that may impact chemotherapy response and survival could aid in upfront risk stratification and identify patients in highest need of innovative therapies for future clinical trials. Relative to conventional genetics, little is known about osteosarcoma epigenetics. We aimed to characterize the methylation and phosphorylation status in osteosarcoma using histone markers found in primary diagnostic biopsies and their paired metastases. We constructed two tissue microarray sets from 58 primary diagnostic samples and 54 temporally-separated but related metastatic or recurrent samples, with tissue blocks available from 2002-2022. Clinical charts were reviewed for post-therapy necrosis response, presence of metastatic disease or recurrence, and overall survival. We evaluated 6 histone H3 residues using immunohistochemistry, including H3K4me3, H3K9me3, H3K27me2, H3K27me3, H3S10T11phos, and H3S28phos. Tumors were scored with low (<25%) or high (≥25%) nuclear staining of tumor cells. Diagnostic biopsies with low H3K27me3 nuclear staining were associated with poor treatment response (≤90% necrosis) at the time of definitive excision (P<0.05). We observed loss of H3S10T11phos expression in metastatic and recurrent resections specimens compared to the primary tumor (P<0.05). Expression patterns for the remaining histone markers did not show significant associations with disease parameters or survival. Although larger cohort studies are needed, these results support the expanded evaluation of histone markers, particularly H3K27me3 and H3S10T11phos, in osteosarcoma biology and risk stratification.

SETDB1: Progress and prospects in cancer treatment potential and inhibitor research

SET domain bifurcated methyltransferase 1 (SETDB1) serves as a histone lysine methyltransferase, catalyzing the di- and tri-methylation of histone H3K9. Mounting evidence indicates that the abnormal expression or activity of SETDB1, either through amplification or mutation, plays a crucial role in tumorigenesis and progression. This is particularly evident in the context of tumor immune evasion and resistance to immune checkpoint blockade therapy. Furthermore, there is a robust association between SETDB1 dysregulation and an unfavorable prognosis across various types of tumors. The oncogenic role of SETDB1 primarily arises from its methyltransferase function, which contributes to the establishment of a condensed and transcriptionally inactive heterochromatin state. This results in the inactivation of genes that typically hinder cancer development and silencing of retrotransposons that could potentially trigger an immune response. These findings underscore the substantial potential for SETDB1 as an anti-tumor therapeutic target. Nevertheless, despite significant strides in recent years in tumor biology research, challenges persist in SETDB1-targeted therapy. To better facilitate the development of anti-tumor therapy targeting SETDB1, we have conducted a comprehensive review of SETDB1 in this account. We present the structure and function of SETDB1, its role in various tumors and immune regulation, as well as the advancements made in SETDB1 antagonists. Furthermore, we discuss the challenges encountered and provide perspectives for the development of SETDB1-targeted anti-tumor therapy.

The functions of SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) in biological process and disease

Histone methyltransferase SETDB1 (SET domain bifurcated histone lysine methyltransferase 1, also known as ESET or KMT1E) is known to be involved in the deposition of the di- and tri-methyl marks on H3K9 (H3K9me2 and H3K9me3), which are associated with transcription repression. SETDB1 exerts an essential role in the silencing of endogenous retroviruses (ERVs) in embryonic stem cells (mESCs) by tri-methylating H3K9 (H3K9me3) and interacting with DNA methyltransferases (DNMTs). Additionally, SETDB1 is engaged in regulating multiple biological processes and diseases, such as ageing, tumors, and inflammatory bowel disease (IBD), by methylating both histones and non-histone proteins. In this review, we provide an overview of the complex biology of SETDB1, review the upstream regulatory mechanisms of SETDB1 and its partners, discuss the functions and molecular mechanisms of SETDB1 in cell fate determination and stem cell, as well as in tumors and other diseases. Finally, we discuss the current challenges and prospects of targeting SETDB1 for the treatment of different diseases, and we also suggest some future research directions in the field of SETDB1 research.

Impact of Solute Carrier Transporters in Glioma Pathology: A Comprehensive Review

Solute carriers (SLCs) are essential for brain physiology and homeostasis due to their role in transporting necessary substances across cell membranes. There is an increasing need to further unravel their pathophysiological implications since they have been proposed to play a pivotal role in brain tumor development, progression, and the formation of the tumor microenvironment (TME) through the upregulation and downregulation of various amino acid transporters. Due to their implication in malignancy and tumor progression, SLCs are currently positioned at the center of novel pharmacological targeting strategies and drug development. In this review, we discuss the key structural and functional characteristics of the main SLC family members involved in glioma pathogenesis, along with their potential targeting options to provide new opportunities for CNS drug design and more effective glioma management.