Recurrent co-alteration of HDGF and SETDB1 on chromosome 1q drives cutaneous melanoma progression and poor prognosis

SETDB1, an H3K9-specific methyltransferase: An attractive epigenetic target to combat cancer

SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) is an important epigenetic regulator catalyzing histone H3 lysine 9 (H3K9) methylation, specifically di-/tri-methylation. This regulation promotes gene silencing through heterochromatin formation. Aberrant SETDB1 expression, and its oncogenic role is evident in many cancers. Thus, SETDB1 is a valid target with novel therapeutic benefits. In this review, we explore the structural and biochemical features of SETDB1, its regulatory mechanisms, and its role in various cancers. We also discuss recent discoveries in small molecules targeting SETDB1 and provide suggestions for future research.

Cytoplasmic localization of SETDB1‑induced Warburg effect via c‑MYC‑LDHA axis enhances migration and invasion in breast carcinoma

SET domain bifurcated 1 (SETDB1), a pivotal histone lysine methyltransferase, is transported to the cytoplasm via a chromosome region maintenance 1 (CMR1)‑dependent pathway, contributing to non‑histone methylation. However, the function and underlying mechanism of cytoplasmic SETDB1 in breast cancer remain elusive. In the present study, immunohistochemistry revealed that elevated cytoplasmic SETDB1 was correlated with lymph node metastasis and more aggressive breast cancer subtypes. Functionally, wound healing and Transwell assays showed that cytoplasmic SETDB1 is key for cell migration and invasion, as well as induction of epithelial‑mesenchymal transition (EMT), which was reversed by leptomycin B (LMB, a CMR1 inhibitor) treatment. Furthermore, RNA‑seq and metabolite detection revealed that cytoplasmic SETDB1 was associated with metabolism pathway and elevated levels of metabolites involved in the Warburg effect, including glucose, pyruvate, lactate and ATP. Immunoblotting and reverse transcription‑quantitative PCR verified that elevation of cytoplasmic SETDB1 contributed to elevation of c‑MYC expression and subsequent upregulation of lactate dehydrogenase A (LDHA) expression. Notably, gain‑ and loss‑of‑function approaches revealed that LDHA overexpression in T47D cells enhanced migration and invasion by inducing EMT, while its depletion in SETDB1‑overexpressing MCF7 cells reversed SETDB1‑induced migration and invasion, as well as the Warburg effect and EMT. In conclusion, subcellular localization of cytoplasmic SETDB1 may be a pivotal factor in breast cancer progression. The present study offers valuable insight into the novel functions and mechanisms of cytoplasmic SETDB1.

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.

Low-Pass Genomic Sequencing Reveals Novel Subtypes of Pancreatic Cystic Neoplasms

BACKGROUND

Over the years, the detection rate of pancreatic cystic neoplasms (PCNs) has significantly increased; however, the differential diagnosis and identification of high-risk PCNs remain challenging. We sought to investigate whether chromosomal instability (CIN) features in cell-free DNA in the cystic fluid of PCNs could help to identify high-risk PCNs.

METHODS

Pancreatic cystic fluid samples from 102 patients with PCNs were intraoperatively collected for detection of CIN using an ultrasensitive chromosomal aneuploidy detector. Clinical and imaging data were retrospectively collected, and statistical analysis was performed to assess the potential role of CIN in clinical practice.

RESULTS

CIN was investigated in a total of 100 patients. Sixteen of 26 serous cystic cystadenomas (SCAs) harbored deletions of chr3p and/or chr6p, whereas low rates of CIN were detected in mucinous cystic neoplasms. Most malignant PCNs presented with more than one type of CIN; amplification of chr1q and chr8q found in nine and seven of 11 malignant PCNs (81.8% and 63.6%), respectively, could aid in distinguishing high-risk IPMNs from low-risk ones, with a higher sensitivity than imaging. A combination of the mural nodule imaging feature and amplification of chr1q and chr8q achieved a sensitivity of 70.0% and a specificity of 82.4% in identifying high-risk IPMNs.

CONCLUSIONS

Our work revealed the distinct CIN signature of different types of PCNs. Deletions of chr3p and chr6p defined a subtype of SCAs. Gains of chr1q and chr8q were associated with insidious malignant PCNs and helped identify high-risk IPMNs.

HDGF promotes gefitinib resistance by activating the PI3K/AKT and MEK/ERK signaling pathways in non-small cell lung cancer

Hepatoma-derived growth factor (HDGF) expression is associated with poor prognosis in non-small cell lung cancer (NSCLC); however, whether HDGF affects gefitinib resistance in NSCLC remains unknown. This study aimed to explore the role of HDGF in gefitinib resistance in NSCLC and to discover the underlying mechanisms. Stable HDGF knockout or overexpression cell lines were generated to perform experiments in vitro and in vivo. HDGF concentrations were determined using an ELISA kit. HDGF overexpression exacerbated the malignant phenotype of NSCLC cells, while HDGF knockdown exerted the opposite effects. Furthermore, PC-9 cells, which were initially gefitinib-sensitive, became resistant to gefitinib treatment after HDGF overexpression, whereas HDGF knockdown enhanced gefitinib sensitivity in H1975 cells, which were initially gefitinib-resistant. Higher levels of HDGF in plasma or tumor tissue also indicated gefitinib resistance. The effects of HDGF on promoting the gefitinib resistance were largely attenuated by MK2206 (Akt inhibitor) or U0126 (ERK inhibitor). Mechanistically, gefitinib treatment provoked HDGF expression and activated the Akt and ERK pathways, which were independent of EGFR phosphorylation. In summary, HDGF contributes to gefitinib resistance by activating the Akt and ERK signaling pathways. The higher HDGF levels may predict poor efficacy for TKI treatment, thus it has the potential to serve as a new target for overcoming tyrosine kinase inhibitor resistance in combating NSCLC.

The Challenging Melanoma Landscape: From Early Drug Discovery to Clinical Approval

Melanoma is recognized as the most dangerous type of skin cancer, with high mortality and resistance to currently used treatments. To overcome the limitations of the available therapeutic options, the discovery and development of new, more effective, and safer therapies is required. In this review, the different research steps involved in the process of antimelanoma drug evaluation and selection are explored, including information regarding in silico, in vitro, and in vivo experiments, as well as clinical trial phases. Details are given about the most used cell lines and assays to perform both two- and three-dimensional in vitro screening of drug candidates towards melanoma. For in vivo studies, murine models are, undoubtedly, the most widely used for assessing the therapeutic potential of new compounds and to study the underlying mechanisms of action. Here, the main melanoma murine models are described as well as other animal species. A section is dedicated to ongoing clinical studies, demonstrating the wide interest and successful efforts devoted to melanoma therapy, in particular at advanced stages of the disease, and a final section includes some considerations regarding approval for marketing by regulatory agencies. Overall, considerable commitment is being directed to the continuous development of optimized experimental models, important for the understanding of melanoma biology and for the evaluation and validation of novel therapeutic strategies.

SETDB1 in cancer: overexpression and its therapeutic implications

SET Domain Bifurcated Histone Lysine Methyltransferase 1 (SETDB1, ESET, KMT1E) is a H3K9 methyltransferase involved in gene silencing. In recent years, SETDB1 has been implicated as an oncogene in various cancers, highlighting a critical need to better understand the mechanisms underlying SETDB1 amplification, overexpression, and activation. In the following review, we first examine the history of SETDB1, starting from its discovery in 1999 and ending with recent findings. We follow with an outline of the structure and subcellular location of SETDB1, as well as potential mechanisms for regulation of its nuclear transport. Subsequently, we introduce SETDB1's various functions, including its roles in promyelocytic leukemia nuclear body (PML-NB) formation, the methylation and activation of Akt, the silencing of the androgen receptor (AR) gene, retroelement silencing, the inhibition of tumor suppressor p53, and its role in promoting intestinal differentiation and survival. The Cancer Cell Line Encyclopedia (CCLE) screened SETDB1 dependency in 796 cancer cell lines, identifying SETDB1 as a common essential gene in 531 of them, demonstrating that SETDB1 expression is critical for the survival of the majority of cancers. Therefore, we provide a detailed review of the oncogenic effects of SETDB1 overexpression in breast cancer, non-small cell lung cancer, prostate cancer, colorectal cancer, acute myeloid leukemia, glioma, melanoma, pancreatic ductal adenocarcinoma, liver cancer, nasopharyngeal carcinoma, gastric carcinoma, and endometrial cancer. Accordingly, we review several methods that have been used to target SETDB1, such as using Mithramycin A, Mithralog EC-8042, 3'-deazaneplanocin A (DZNep), and paclitaxel. Finally, we conclude by highlighting remaining gaps in knowledge and challenges surrounding SETDB1. Ultimately, our review captures the wide scope of findings on SETDB1's history, function, its implications in cancer, and provides suggestions for future research in the field.

SATB2 induction of a neural crest mesenchyme-like program drives melanoma invasion and drug resistance

Recent genomic and scRNA-seq analyses of melanoma demonstrated a lack of recurrent genetic drivers of metastasis, while identifying common transcriptional states correlating with invasion or drug resistance. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:BRAFV600E;tp53-/- model, in which malignant progression is characterized by minimal genetic evolution. We undertook an overexpression-screen of 80 epigenetic/transcriptional regulators and found neural crest-mesenchyme developmental regulator SATB2 to accelerate aggressive melanoma development. Its overexpression induces invadopodia formation and invasion in zebrafish tumors and human melanoma cell lines. SATB2 binds and activates neural crest-regulators, including pdgfab and snai2. The transcriptional program induced by SATB2 overlaps with known MITF^lowAXL^high and AQP1⁺NGFR1^high drug-resistant states and functionally drives enhanced tumor propagation and resistance to Vemurafenib in vivo. In summary, we show that melanoma transcriptional rewiring by SATB2 to a neural crest mesenchyme-like program can drive invasion and drug resistance in autochthonous tumors.