The p300 Inhibitor A-485 Exerts Antitumor Activity in Growth Hormone Pituitary Adenoma

Characteristics of anticancer activity of CBP/p300 inhibitors - Features of their classes, intracellular targets and future perspectives of their application in cancer treatment

Due to the contribution of highly homologous acetyltransferases CBP and p300 to transcription elevation of oncogenes and other cancer promoting factors, these enzymes emerge as possible epigenetic targets of anticancer therapy. Extensive efforts in search for small molecule inhibitors led to development of compounds targeting histone acetyltransferase catalytic domain or chromatin-interacting bromodomain of CBP/p300, as well as dual BET and CBP/p300 inhibitors. The promising anticancer efficacy in in vitro and mice models led CCS1477 and NEO2734 to clinical trials. However, none of the described inhibitors is perfectly specific to CBP/p300 since they share similarity of a key functional domains with other enzymes, which are critically associated with cancer progression and their antagonists demonstrate remarkable clinical efficacy in cancer therapy. Therefore, we revise the possible and clinically relevant off-targets of CBP/p300 inhibitors that can be blocked simultaneously with CBP/p300 thereby improving the anticancer potential of CBP/p300 inhibitors and pharmacokinetic predicting data such as absorption, distribution, metabolism, excretion (ADME) and toxicity.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the quantification of the acetyl-coenzyme A competitive p300/CBP catalytic inhibitor A-485 in biological samples

The small molecule A-485 competitively inhibits the histone acetyltransferase domain of CBP (cyclic-adenosine monophosphate response element-binding protein)/p300. Apart from its antineoplastic activity, researchers are exploring its potential benefits in treating osteoporosis and its impact on energy metabolism. However, so far, only limited pharmacokinetic data are available, and the crucial determination of A-485 concentration in various biological materials with small sample volumes remains unpublished. A rapid and sensitive LC-tandem mass spectrometry method has been developed and validated to quantify A-485 in mouse serum and tissue. In this method, serum samples underwent precipitation with acetonitrile, while cell lysates were appropriately diluted. The determination of A-485 utilized a reversed-phase column with a mobile phase gradient, and detection was carried out in multiple reaction monitoring mode. The lower standard sample, with a concentration of 7.8 ng/mL, served as the lower limit of quantification, while the upper standard was established at 1000 ng/mL. A-485 concentrations were assessed in both serum samples and the lysate of all examined tissues, revealing swift metabolic clearance. The analytical method outlined here is deemed appropriate for subsequent studies. The ability to measure the active ingredient in various compartments facilitates the determination of accurate pharmacokinetic parameters. In the event of human use of A-485, the analysis method can be seamlessly transferred to human samples.

Targeting the SPHK1/S1P/S1PR2 axis ameliorates GH-secreted pituitary adenoma progression

BACKGROUND

Growth hormone-secreted pituitary adenoma (GHPA) is a prominent subtype of pituitary adenoma (PA) associated with progressive somatic disfigurement, various complications, and elevated mortality rates. Existing treatment options have limited efficacy, highlighting the urgent need for novel pharmacological interventions. Previous studies have revealed that sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P)/S1P receptors (S1PRs) signalling have critical roles in the tumour microenvironment, but their role in GHPA remains unclear.

METHODS

We performed integrative analyses including bioinformatics analyses, functional studies, and clinical validation to investigate the pathological roles of SPHK1/S1P and evaluated the effectiveness of the S1P receptor 2 (S1PR2) inhibitor JTE-013 in GHPA treatment.

RESULTS

SPHK1/S1P signalling is abnormally expressed in patients with GHPA. Knockdown of SPHK1 suppresses S1P-mediated cell proliferation in GH3 Cells. Mechanistically, S1P inhibits apoptosis and autophagy while promoting the secretion of Growth Hormone (GH) by binding to the S1P receptor subtype 2 (S1PR2) in GH3 cells. Moreover, the function of S1PR2 in GH3 cells is mediated by the downstream Akt-Creb pathway. We then identify the S1PR2 as a novel target for therapeutic intervention in GHPA. Systemic administration of the potent and selective S1PR2 antagonist, JTE-013, significantly reduces both tumour size and GH secretion. Importantly, we identify preoperative serum S1P levels as a biomarker predicting poor prognosis in GHPA patients at follow-up.

CONCLUSION

Our study shows that blocking SPHK1/S1P/S1PR2 axis can ameliorate the progression of GHPA, providing evidence of a promising therapeutic target for GHPA.

From Genes to Therapy: Pituitary Adenomas in the Era of Precision Medicine

This review presents a comprehensive analysis of pituitary adenomas, a type of brain tumor with diverse behaviors and complexities. We cover various treatment approaches, including surgery, radiotherapy, chemotherapy, and their integration with newer treatments. Key to the discussion is the role of biomarkers in oncology for risk assessment, diagnosis, prognosis, and the monitoring of pituitary adenomas. We highlight advances in genomic, epigenomic, and transcriptomic analyses and their contributions to understanding the pathogenesis and molecular pathology of these tumors. Special attention is given to the molecular mechanisms, including the impact of epigenetic factors like histone modifications, DNA methylation, and transcriptomic changes on different subtypes of pituitary adenomas. The importance of the tumor immune microenvironment in tumor behavior and treatment response is thoroughly analyzed. We highlight potential breakthroughs and innovations for a more effective management and treatment of pituitary adenomas, while shedding light on the ongoing need for research and development in this field to translate scientific knowledge into clinical advancements, aiming to improve patient outcomes.

Comparative Analysis of Drug-like EP300/CREBBP Acetyltransferase Inhibitors

The human acetyltransferase paralogues EP300 and CREBBP are master regulators of lysine acetylation whose activity has been implicated in various cancers. In the half-decade since the first drug-like inhibitors of these proteins were reported, three unique molecular scaffolds have taken precedent: an indane spiro-oxazolidinedione (A-485), a spiro-hydantoin (iP300w), and an aminopyridine (CPI-1612). Despite increasing use of these molecules to study lysine acetylation, the dearth of data regarding their relative biochemical and biological potencies makes their application as chemical probes a challenge. To address this gap, here we present a comparative study of drug-like EP300/CREBBP acetyltransferase inhibitors. First, we determine the biochemical and biological potencies of A-485, iP300w, and CPI-1612, highlighting the increased potencies of the latter two compounds at physiological acetyl-CoA concentrations. Cellular evaluation shows that inhibition of histone acetylation and cell growth closely aligns with the biochemical potencies of these molecules, consistent with an on-target mechanism. Finally, we demonstrate the utility of comparative pharmacology by using it to investigate the hypothesis that increased CoA synthesis caused by knockout of PANK4 can competitively antagonize the binding of EP300/CREBBP inhibitors and demonstrate proof-of-concept photorelease of a potent inhibitor molecule. Overall, our study demonstrates how knowledge of the relative inhibitor potency can guide the study of EP300/CREBBP-dependent mechanisms and suggests new approaches to target delivery, thus broadening the therapeutic window of these preclinical epigenetic drug candidates.

Prolactin and Growth Hormone Signaling and Interlink Focused on the Mammosomatotroph Paradigm: A Comprehensive Review of the Literature

Prolactin (PRL) and growth hormone (GH) are peptide hormones that bind to the class 1 cytokine receptor superfamily, a highly conserved cell surface class of receptors. Both hormones control their own secretion via a negative autocrine loop in their own mammosomatotroph, lactotroph or somatotroph. In this regard, GH and PRL are regulated by similar signaling pathways involving cell growth and hormone secretion. Thus, GH and PRL dysregulation and pituitary neuroendocrine tumor (PitNET) development may have common pathogenic pathways. Based on cell linage, lactotroph and somatotroph PitNETs come from pituitary-specific POU-class homeodomain transcription factor (Pit-1). Mammosomatotroph and plurihormonal PitNETs are a unique subtype of PitNETs that arise from a single-cell population of Pit-1 lineage. In contrast, mixed somatotroph-lactotroph PitNETs are composed of two distinct cell populations: somatotrophs and lactotrophs. Morphologic features that distinguish indolent PitNETs from locally aggressive ones are still unidentified, and no single prognostic parameter can predict tumor aggressiveness or treatment response. In this review, we aim to explore the latest research on lactotroph and somatotroph PitNETs, the molecular mechanisms involved in PRL and GH axis regulation and the signaling pathways involved in their aggressiveness, particularly focused on mammosomatotroph and mixed subtypes. Finally, we summarize epidemiological, clinical, and radiological features of these exceptional tumors. We aim to shed light, from basic to clinical settings, on new perspectives and scientific gaps in this field.

MiR-320a Acts as a Tumor Suppressor in Somatotroph Pituitary Neuroendocrine Tumors by Targeting BCAT1

INTRODUCTION

Aberrant miR-320a has been reported to be involved in the tumorigenesis of several cancers. In our previous study, we identified the low expression of circulating miR-320a in patients with somatotroph pituitary neuroendocrine tumor (PitNET); however, the role of miR-320a in somatotroph PitNET proliferation is still unclear.

METHODS

Cell viability and colony formation assays were used to detect the effect of miR-320a and BCAT1 on GH3 cells. TargetScan was used to identify the target genes of miR-320a. Dual-luciferase reporter gene assay was used to explore the relation between miR-320a and BCAT1. Transcriptome and proteome analyses were performed between somatotroph PitNETs and healthy controls. The expression level of miR-320a in somatotroph PitNETs were detected by RT-qPCR and Western blot.

RESULTS

miR-320a mimics inhibit cell proliferation, while miR-320a inhibitors promote cell proliferation in GH3 cells. An overlap analysis using a Venn diagram revealed that BCAT1 is the only target gene of miR-320a overexpressed in somatotroph PitNETs compared to healthy controls, as revealed by both microarray and proteomics results. A dual-luciferase reporter gene assay showed that miR-320a may bind to the BCAT1-3'UTR. The transfection of miR-320a mimics downregulated the expression and miR-320a inhibitors and upregulated the expression of BCAT1 in GH3 cells. The interference of BCAT1 expression in GH3 cells downregulated cell proliferation and growth. Pan-cancer analyses demonstrated that high BCAT1 expression often indicates a poor prognosis.

CONCLUSION

Our findings illustrate that miR-320a may function as a tumor suppressor and BCAT1 may promote tumor progression. miR-320a may inhibit the growth of somatotroph PitNETs by targeting BCAT1.

Comparative analysis of drug-like EP300/CREBBP acetyltransferase inhibitors

The human acetyltransferase paralogs EP300 and CREBBP are master regulators of lysine acetylation whose activity has been implicated in various cancers. In the half-decade since the first drug-like inhibitors of these proteins were reported, three unique molecular scaffolds have taken precedent: an indane spiro-oxazolidinedione (A-485), a spiro-hydantoin (iP300w), and an aminopyridine (CPI-1612). Despite increasing use of these molecules to study lysine acetylation, the dearth of data regarding their relative biochemical and biological potencies makes their application as chemical probes a challenge. To address this gap, here we present a comparative study of drug-like EP300/CREBBP acetyltransferase inhibitors. First, we determine the biochemical and biological potencies of A-485, iP300w, and CPI-1612, highlighting the increased potency of the latter two compounds at physiological acetyl-CoA concentrations. Cellular evaluation shows that inhibition of histone acetylation and cell growth closely aligns with the biochemical potencies of these molecules, consistent with an on-target mechanism. Finally, we demonstrate the utility of comparative pharmacology by using it to investigate the hypothesis that increased CoA synthesis caused by knockout of PANK4 can competitively antagonize binding of EP300/CREBBP inhibitors and demonstrate proof-of-concept photorelease of a potent inhibitor molecule. Overall, our study demonstrates how knowledge of relative inhibitor potency can guide the study of EP300/CREBBP-dependent mechanisms and suggests new approaches to target delivery, thus broadening the therapeutic window of these preclinical epigenetic drug candidates.

Fundamental concepts of protein therapeutics and spacing in oncology: an updated comprehensive review

Current treatment regimens in cancer cases cause significant side effects and cannot effectively eradicate the advanced disease. Hence, much effort has been expended over the past years to understand how cancer grows and responds to therapies. Meanwhile, proteins as a type of biopolymers have been under commercial development for over three decades and have been proven to improve the healthcare system as effective medicines for treating many types of progressive disease, such as cancer. Following approving the first recombinant protein therapeutics by FDA (Humulin), there have been a revolution for drawing attention toward protein-based therapeutics (PTs). Since then, the ability to tailor proteins with ideal pharmacokinetics has provided the pharmaceutical industry with an important noble path to discuss the clinical potential of proteins in oncology research. Unlike traditional chemotherapy molecules, PTs actively target cancerous cells by binding to their surface receptors and the other biomarkers particularly associated with tumorous or healthy tissue. This review analyzes the potential and limitations of protein therapeutics (PTs) in the treatment of cancer as well as highlighting the evolving strategies by addressing all possible factors, including pharmacology profile and targeted therapy approaches. This review provides a comprehensive overview of the current state of PTs in oncology, including their pharmacology profile, targeted therapy approaches, and prospects. The reviewed data show that several current and future challenges remain to make PTs a promising and effective anticancer drug, such as safety, immunogenicity, protein stability/degradation, and protein-adjuvant interactions.

Survivin: A Potential Marker of Resistance to Somatostatin Receptor Ligands

CONTEXT

Invasive and somatostatin receptor ligand (SRL)-resistant pituitary tumors represent a challenge in the clinical practice of endocrinologists. Efforts have been made to elucidate reliable makers for both. Survivin and eukaryotic translation initiation factor-binding protein 1 (4EBP1) are upregulated in several cancers and involved in apoptosis and cell proliferation.

OBJECTIVE

We explored the role of these markers in somatotropinomas.

METHODS

Immunostains for survivin and 4EBP1, and also for somatostatin receptor type 2 (SSTR2), Ki-67, and cytokeratin 18, were analyzed in tissue microarrays containing 52 somatotropinoma samples. Tumor invasiveness was evaluated in all samples while drug resistance was evaluated in 34 patients who received SRL treatment. All these parameters were correlated with first-generation SRL (fg-SRL) responsiveness and tumor invasiveness.

RESULTS

Low survivin expression (P = 0.04), hyperintense signal on T2 weighted image (T2WI) (P = 0.01), younger age (P = 0.01), sparsely granular adenomas (SGA) (P = 0.04), high postoperative growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels (P = 0.049 and P < 0.001, respectively), and large postoperative tumor size (P = 0.02) were associated with resistance to fg-SRL. Low survivin and SSTR2 expression and high 4EBP1 expression were associated with SGA (P = 0.04, P = 0.01, and P = 0.001, respectively). Younger age (P = 0.03), large tumor pre- and postoperative (P = 0.04 and P = 0.006, respectively), low SSTR2 expression (P = 0.03), and high baseline GH and IGF-1 (P = 0.01 and P = 0.02, respectively) were associated with tumor invasiveness. However, survivin, 4EBP1, Ki-67, and granulation patterns were not associated with tumor invasion.

CONCLUSION

This study suggests that low survivin expression is predictive of resistance to fg-SRL in somatotropinomas, but not of tumor invasiveness.

Effects of the Acetyltransferase p300 on Tumour Regulation from the Novel Perspective of Posttranslational Protein Modification

p300 acts as a transcription coactivator and an acetyltransferase that plays an important role in tumourigenesis and progression. In previous studies, it has been confirmed that p300 is an important regulator in regulating the evolution of malignant tumours and it also has extensive functions. From the perspective of non-posttranslational modification, it has been proven that p300 can participate in regulating many pathophysiological processes, such as activating oncogene transcription, promoting tumour cell growth, inducing apoptosis, regulating immune function and affecting embryo development. In recent years, p300 has been found to act as an acetyltransferase that catalyses a variety of protein modification types, such as acetylation, propanylation, butyylation, 2-hydroxyisobutyration, and lactylation. Under the catalysis of this acetyltransferase, it plays its crucial tumourigenic driving role in many malignant tumours. Therefore, the function of p300 acetyltransferase has gradually become a research hotspot. From a posttranslational modification perspective, p300 is involved in the activation of multiple transcription factors and additional processes that promote malignant biological behaviours, such as tumour cell proliferation, migration, and invasion, as well as tumour cell apoptosis, drug resistance, and metabolism. Inhibitors of p300 have been developed and are expected to become novel anticancer drugs for several malignancies. We review the characteristics of the p300 protein and its functional role in tumour from the posttranslational modification perspective, as well as the current status of p300-related inhibitor research, with a view to gaining a comprehensive understanding of p300.

KATs off: Biomedical insights from lysine acetyltransferase inhibitors

Lysine acetyltransferase (KAT) enzymes including the p300, MYST, and GCN5 families play major roles in modulating the structure of chromatin and regulating transcription. Because of their dysregulation in various disease states including cancer, efforts to develop inhibitors of KATs have steadily gained momentum. Here we provide an overview of recent progress on the development of high quality chemical probes of the p300 and MYST family of KATs and how they are emerging as useful tools for basic and translational investigation.

Regulatory mechanisms of microRNAs in endocrine disorders and their therapeutic potential

MicroRNAs (miRNAs) are small endogenous non-coding RNA molecules capable of regulating gene expression at the post-transcriptional level either by translational inhibition or mRNA degradation and have recently been importantly related to the diagnosis and prognosis of the most relevant endocrine disorders. The endocrine system comprises various highly vascularized ductless organs regulating metabolism, growth and development, and sexual function. Endocrine disorders constitute the fifth principal cause of death worldwide, and they are considered a significant public health problem due to their long-term effects and negative impact on the patient's quality of life. Over the last few years, miRNAs have been discovered to regulate various biological processes associated with endocrine disorders, which could be advantageous in developing new diagnostic and therapeutic tools. The present review aims to provide an overview of the most recent and significant information regarding the regulatory mechanism of miRNAs during the development of the most relevant endocrine disorders, including diabetes mellitus, thyroid diseases, osteoporosis, pituitary tumors, Cushing's syndrome, adrenal insufficiency and multiple endocrine neoplasia, and their potential implications as disease biomarkers.

Inhibition of Acetylation, is it Enough to Fight Cancer?

Acetylation is a reversible post-translational modification (PTM) that regulates important cellular processes such as proliferation, DNA damage repair and cell cycle progress. When the balance is broken, these processes are affected and lead to carcinogenesis. Therefore, the study of acetylation has led to its proposal as a target pathway for anticancer therapies. Here, we discuss how acetylation regulates the cell cycle process, how it is modified in cancer cells and which are the key proteins in the regulation of apoptosis induction in cancer cells that can become targets to fight cancer. The inhibition of acetylation has been proposed as an emergent therapy against cancer, compounds such as 6-Penthadecyl salicylic acid (6SA), Curcumin, Garcinol and C646, among others, are currently studied because they show antitumor activity related to the inhibition of acetylation. Recently, the use of the acetylomics research tool has improved the study of acetylation as a target against tumor cells, but still the thresholds between promoting DNA instability and regulating gene expression by acetylation are not clear in many cell types.

The role of protein acetylation in carcinogenesis and targeted drug discovery

Protein acetylation is a reversible post-translational modification, and is involved in many biological processes in cells, such as transcriptional regulation, DNA damage repair, and energy metabolism, which is an important molecular event and is associated with a wide range of diseases such as cancers. Protein acetylation is dynamically regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs) in homeostasis. The abnormal acetylation level might lead to the occurrence and deterioration of a cancer, and is closely related to various pathophysiological characteristics of a cancer, such as malignant phenotypes, and promotes cancer cells to adapt to tumor microenvironment. Therapeutic modalities targeting protein acetylation are a potential therapeutic strategy. This article discussed the roles of protein acetylation in tumor pathology and therapeutic drugs targeting protein acetylation, which offers the contributions of protein acetylation in clarification of carcinogenesis, and discovery of therapeutic drugs for cancers, and lays the foundation for precision medicine in oncology.