Preclinical and clinical activity of the topoisomerase I inhibitor, karenitecin, in melanoma

CHI-KAT8i5 suppresses ESCC tumor growth by inhibiting KAT8-mediated c-Myc stability

The integrated analysis of histone modifier enzymes in solid tumors, especially in esophageal squamous cell carcinoma (ESCC), is still inadequate. Here, we investigate the expression levels of histone modifier enzymes in ESCC tissues. Notably, KAT8 (lysine acetyltransferase 8) is identified as a prognostic and therapeutic biomarker in ESCC. Esophageal-tissue-specific deletion of KAT8 in mice led to less tumor burden after induction of tumorigenesis via 4-nitroquinoline N-oxide (4NQO) treatment compared with wild-type mice. Meanwhile, silencing KAT8 significantly suppresses tumor growth in cell-line-derived xenograft (CDX) and patient-derived xenograft (PDX) models. Mechanically, we confirm that KAT8 regulates c-Myc protein stability by directly binding it. Furthermore, we design and screen a specific KAT8 inhibitor (CHI-KAT8i5) that significantly attenuates tumor growth in vitro and in vivo, providing promising potential for clinical application. Thus, our work identifies that KAT8 could serve as a potential clinically relevant biomarker and therapeutic target in patients with ESCC and that KAT8 inhibitor is a promising lead candidate for ESCC therapy.

Drug combinations of camptothecin derivatives promote the antitumor properties

Camptothecin (CPT) derivatives are widely used as small molecule chemotherapeutic agents and have demonstrated efficacy in the treatment of diverse solid tumors. A variety of derivatives have been developed to resolve the drawbacks of poor water solubility, high toxicity and rapid hydrolysis in vivo. However, the obstacles, such as acquired resistance and toxicity, still exist. The utilization of rational drug combinations has the potential to enhance the efficacy and mitigate the toxicity of CPT derivatives. This paper provides an overview of CPT derivatives in combination with other drugs, with a particular focus on cell cycle inhibitors, DNA synthesis inhibitors, anti-metastatic drugs and immunotherapy agents. Concurrently, the mechanisms of antitumor activity of combinations of different classes of drugs and CPT derivatives are elucidated. While the various combination strategies have yielded more favorable therapeutic outcomes, the efficacy and toxicity of the drug combinations are influenced by the inherent properties of the drugs involved. Moreover, a summary of the drug conjugates of CPT derivatives was provided, accompanied by an analysis of the structural activity relationship (SAR). This paves the way for the subsequent developments in drug combinations and delivery modes.

The role of silicon in drug discovery: a review

This review aims to highlight the role of silicon in drug discovery. Silicon and carbon are often regarded as being similar with silicon located directly beneath carbon in the same group in the periodic table. That being noted, in many instances a clear dichotomy also exists between silicon and carbon, and these differences often lead to vastly different physiochemical and biological properties. As a result, the utility of silicon in drug discovery has attracted significant attention and has grown rapidly over the past decade. This review showcases some recent advances in synthetic organosilicon chemistry and examples of the ways in which silicon has been employed in the drug-discovery field.

Unleashing the Potential of Camptothecin: Exploring Innovative Strategies for Structural Modification and Therapeutic Advancements

Camptothecin (CPT) is a potent anti-cancer agent targeting topoisomerase I (TOP1). However, CPT has poor pharmacokinetic properties, causes toxicities, and leads to drug resistance, which limit its clinical use. In this paper, to review the current state of CPT research. We first briefly explain CPT's TOP1 inhibition mechanism and the key hurdles in CPT drug development. Then we examine strategies to overcome CPT's limitations through structural modifications and advanced delivery systems. Though modifications alone seem insufficient to fully enhance CPT's therapeutic potential, structure-activity relationship analysis provides insights to guide optimization of CPT analogs. In comparison, advanced delivery systems integrating controlled release, imaging capabilities, and combination therapies via stimulus-responsive linkers and targeting moieties show great promise for improving CPT's pharmacological profile. Looking forward, multifaceted approaches combining selective CPT derivatives with advanced delivery systems, informed by emerging biological insights, hold promise for fully unleashing CPT's anti-cancer potential.

Molecular subgroup establishment and signature creation of lncRNAs associated with acetylation in lung adenocarcinoma

BACKGROUND

The significance of long non-coding RNAs (lncRNAs) as pivotal mediators of histone acetylation and their influential role in predicting the prognosis of lung adenocarcinoma (LUAD) has been increasingly recognized. However, there remains uncertainty regarding the potential utility of acetylation-related lncRNAs (ARLs) in prognosticating the overall survival (OS) of LUAD specimens.

METHODS

The RNA-Seq and clinical information were downloaded from The Cancer Genome Atlas (TCGA). Through the differential analysis, weighted correlation network analysis (WGCNA), Pearson correlation test and univariate Cox regression, we found out the prognosis associated ARLs and divided LUAD specimens into two molecular subclasses. The ARLs were employed to construct a unique signature through the implementation of the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm. Subsequently, the predictive performance was evaluated using ROC analysis and Kaplan-Meier survival curve analysis. Finally, ARL expression in LUAD was confirmed by quantitative real-time PCR (qRT-PCR).

RESULTS

We triumphantly built a ARLs prognostic model with excellent predictive accuracy for LUAD. Univariate and multivariate Cox analysis illustrated that risk model served as an independent predictor for influencing the overall survival OS of LUAD. Furthermore, a nomogram exhibited strong prognostic validity. Additionally, variations were observed among subgroups in the field of immunity, biological functions, drug sensitivity and gene mutations within the field.

CONCLUSIONS

Nine ARLs were identified as promising indicators of personalized prognosis and drug selection for people suffering with LUAD.

Antitumor effect of Melaleuca alternifolia essential oil and its main component terpinen-4-ol in combination with target therapy in melanoma models

Essential oils (EOs) have been recently emerging for their promising biological activities in preventing tumorigenesis or progression of different tumor histotypes, including melanoma. In this study, we investigated the antitumor activity of a panel of EOs in different tumor models. The ability of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol, to sensitize the target therapy currently used for melanoma treatment was also assessed. Our results demonstrated that EOs differently affect the viability of human cancer cells and led us to select six EOs effective in melanoma and lung cancer cells, without toxic effects in human fibroblasts. When combined with dabrafenib and/or trametinib, Melaleuca alternifolia synergistically reduced the viability of melanoma cells by activating apoptosis. Through machine learning classification modeling, α-terpineol, tepinolene, and terpinen-4-ol, three components of Melaleuca alternifolia, were identified as the most likely relevant components responsible for the EO's antitumor effect. Among them, terpinen-4-ol was recognized as the Melaleuca alternifolia component responsible for its antitumor and proapoptotic activity. Overall, our study holds promise for further analysis of EOs as new anticancer agents and supports the rationale for their use to improve target therapy response in melanoma.

Recent Progress in the Development of Quinoline Derivatives for the Exploitation of Anti-Cancer Agents

BACKGROUND

Along with the progress in medicine and therapies, the exploitation of anti-cancer agents focused more on the vital signaling pathways and key biological macromolecules. With rational design and advanced synthesis, quinoline derivatives have been utilized frequently in medicinal chemistry, especially in developing anti-cancer drugs or candidates.

METHODS

Using DOI searching, articles published before 2020 all over the world have been reviewed as comprehensively as possible.

RESULTS

In this review, we selected the representative quinoline derivate drugs in market or clinical trials, classified them into five major categories with detailed targets according to their main mechanisms, discussed the relationship within the same mechanism, and generated a summative discussion with prospective expectations. For each mechanism, the introduction of the target was presented, with the typical examples of quinoline derivate drugs.

CONCLUSION

This review has highlighted the quinoline drugs or candidates, suited them into corresponding targets in their pathways, summarized and discussed. We hope that this review may help the researchers who are interested in discovering quinoline derivate anti-cancer agents obtain considerable understanding of this specific topic. Through the flourishing period and the vigorous strategies in clinical trials, quinoline drugs would be potential but facing new challenges in the future.

Hybrid topoisomerase I and HDAC inhibitors as dual action anticancer agents

Recent studies have shown that HDAC inhibitors act synergistically with camptothecin derivatives in combination therapies. To exploit this synergy, new hybrid molecules targeting simultaneously topoisomerase I and HDAC were designed. In particular, a selected multivalent agent containing a camptothecin and a SAHA-like template showed a broad spectrum of antiproliferative activity, with IC₅₀ values in the nanomolar range. Preliminary in vivo results indicated a strong antitumor activity on human mesothelioma primary cell line MM473 orthotopically xenografted in CD-1 nude mice and very high tolerability.

A Phase I Clinical Trial of the Poly(ADP-ribose) Polymerase Inhibitor Veliparib and Weekly Topotecan in Patients with Solid Tumors

Purpose: To determine the dose limiting toxicities (DLT), maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of veliparib in combination with weekly topotecan in patients with solid tumors. Correlative studies were included to assess the impact of topotecan and veliparib on poly(ADP-ribose) levels in peripheral blood mononuclear cells, serum pharmacokinetics of both agents, and potential association of germline repair gene mutations with outcome.Experimental Design: Eligible patients had metastatic nonhematologic malignancies with measurable disease. Using a 3 + 3 design, patients were treated with veliparib orally twice daily on days 1-3, 8-10, and 15-17 and topotecan intravenously on days 2, 9, and 16 every 28 days. Tumor responses were assessed by RECIST.Results: Of 58 patients enrolled, 51 were evaluable for the primary endpoint. The MTD and RP2D was veliparib 300 mg twice daily on days 1-3, 8-10, and 15-17 along with topotecan 3 mg/m2 on days 2, 9, and 16 of a 28-day cycle. DLTs were grade 4 neutropenia lasting >5 days. The median number of cycles was 2 (1-26). The objective response rate was 10%, with 1 complete and 4 partial responses. Twenty-two patients (42%) had stable disease ranging from 4 to 26 cycles. Patients with germline BRCA1, BRCA2, or RAD51D mutations remained on study longer than those without homologous recombination repair (HRR) gene mutations (median 4 vs. 2 cycles).Conclusions: Weekly topotecan in combination with veliparib has a manageable safety profile and appears to warrant further investigation. Clin Cancer Res; 24(4); 744-52. ©2017 AACR.

Silicon-containing analogs of camptothecin as anticancer agents

The plant pentacyclic alkaloid camptothecin and its structural analogs were extensively studied. These compounds are interesting due to the antitumor activity associated with their ability to inhibit topoisomerase I in tumor cells. During the last decades of the 20th century, a large number of the silicon-containing camptothecins (silatecans) were synthesized. 7-tert-Butyldimethylsilyl-10-hydroxy-camptothecin (DB-67 or AR-67) has enhanced lipophilicity and demonstrates a antitumor activity superior to its carbon analog. To date, certain silatecans are under clinical trials and their ultimate role in cancer therapy appears promising. In this review, we present chemical methodologies for the synthesis of silicon-containing camptothecins, their chemical properties, biological activity, and results of clinical trials.

Immunodetection of human topoisomerase I-DNA covalent complexes

A number of established and investigational anticancer drugs slow the religation step of DNA topoisomerase I (topo I). These agents induce cytotoxicity by stabilizing topo I-DNA covalent complexes, which in turn interact with advancing replication forks or transcription complexes to generate lethal lesions. Despite the importance of topo I-DNA covalent complexes, it has been difficult to detect these lesions within intact cells and tumors. Here, we report development of a monoclonal antibody that specifically recognizes covalent topo I-DNA complexes, but not free topo I or DNA, by immunoblotting, immunofluorescence or flow cytometry. Utilizing this antibody, we demonstrate readily detectable topo I-DNA covalent complexes after treatment with camptothecins, indenoisoquinolines and cisplatin but not nucleoside analogues. Topotecan-induced topo I-DNA complexes peak at 15-30 min after drug addition and then decrease, whereas indotecan-induced complexes persist for at least 4 h. Interestingly, simultaneous staining for covalent topo I-DNA complexes, phospho-H2AX and Rad51 suggests that topotecan-induced DNA double-strand breaks occur at sites distinct from stabilized topo I-DNA covalent complexes. These studies not only provide new insight into the action of topo I-directed agents, but also illustrate a strategy that can be applied to study additional topoisomerases and their inhibitors in vitro and in vivo.

Function of AP2/ERF Transcription Factors Involved in the Regulation of Specialized Metabolism in Ophiorrhiza pumila Revealed by Transcriptomics and Metabolomics

The hairy roots (HR) of Ophiorrhiza pumila produce camptothecin (CPT), a monoterpenoid indole alkaloid used as a precursor in the synthesis of chemotherapeutic drugs. O. pumila HR culture is considered as a promising alternative source of CPT, however, the knowledge about the biosynthetic pathway and regulatory mechanism is still limited. In this study, five genes that encode AP2/ERF transcription factors, namely OpERF1-OpERF5, were isolated from HR of O. pumila. Phylogenetic analysis of AP2/ERF protein sequences suggested the close evolutionary relationship of OpERF1 with stress-responsive ERF factors in Arabidopsis and of OpERF2 with ERF factors reported to regulate alkaloid production, such as ORCA3 in Catharanthus roseus, NIC2 locus ERF in tobacco, and JRE4 in tomato. We generated the transgenic HR lines of O. pumila, ERF1i and ERF2i, in which the expression of OpERF1 and OpERF2, respectively, was suppressed using RNA interference technique. The transcriptome and metabolome of these suppressed HR were analyzed for functional characterization of OpERF1 and OpERF2. Although significant changes were not observed in the metabolome, including CPT and related compounds, the suppression of OpERF2 resulted in reduced expression of genes in the 2-C-methyl-d-erythritol 4-phosphate and secologanin-strictosidine pathways, which supply a precursor, strictosidine, for CPT biosynthesis. Furthermore, while it was not conclusive for OpERF1, enrichment analysis of differentially expressed genes in the suppressed HR showed that the gene ontology terms for oxidation-reduction, presumably involved in secondary metabolite pathways, were enriched in the ERF2i downregulated gene set. These results suggest a positive role of OpERF2 in regulating specialized metabolism in O. pumila.

Natural product and natural product derived drugs in clinical trials

The 25 Natural Product (NP)-derived drugs launched since 2008 and the 100 NP-derived compounds and 33 Antibody Drug Conjugates (ADCs) in clinical trials or in registration at the end of 2013 are reviewed.

Myeloprotection by cytidine deaminase gene transfer in antileukemic therapy

Gene transfer of drug resistance (CTX-R) genes can be used to protect the hematopoietic system from the toxicity of anticancer chemotherapy and this concept recently has been proven by overexpression of a mutant O(6)-methylguaninemethyltransferase in the hematopoietic system of glioblastoma patients treated with temozolomide. Given its protection capacity against such relevant drugs as cytosine arabinoside (ara-C), gemcitabine, decitabine, or azacytidine and the highly hematopoiesis-specific toxicity profile of several of these agents, cytidine deaminase (CDD) represents another interesting candidate CTX-R gene and our group recently has established the myeloprotective capacity of CDD gene transfer in a number of murine transplant studies. Clinically, CDD overexpression appears particularly suited to optimize treatment strategies for acute leukemias and myelodysplasias given the efficacy of ara-C (and to a lesser degree decitabine and azacytidine) in these disease entities. This article will review the current state of the art with regard to CDD gene transfer and point out potential scenarios for a clinical application of this strategy. In addition, risks and potential side effects associated with this approach as well as strategies to overcome these problems will be highlighted.

HDAC inhibitor-based therapies: can we interpret the code?

Abnormal epigenetic control is a common early event in tumour progression, and aberrant acetylation in particular has been implicated in tumourigenesis. One of the most promising approaches towards drugs that modulate epigenetic processes has been seen in the development of inhibitors of histone deacetylases (HDACs). HDACs regulate the acetylation of histones in nucleosomes, which mediates changes in chromatin conformation, leading to regulation of gene expression. HDACs also regulate the acetylation status of a variety of other non-histone substrates, including key tumour suppressor proteins and oncogenes. Histone deacetylase inhibitors (HDIs) are potent anti-proliferative agents which modulate acetylation by targeting histone deacetylases. Interest is increasing in HDI-based therapies and so far, two HDIs, vorinostat (SAHA) and romidepsin (FK228), have been approved for treating cutaneous T-cell lymphoma (CTCL). Others are undergoing clinical trials. Treatment with HDIs prompts tumour cells to undergo apoptosis, and cell-based studies have shown a number of other outcomes to result from HDI treatment, including cell-cycle arrest, cell differentiation, anti-angiogenesis and autophagy. However, our understanding of the key pathways through which HDAC inhibitors affect tumour cell growth remains incomplete, which has hampered progress in identifying malignancies other than CTCL which are likely to respond to HDI treatment.