Narciclasine, a novel topoisomerase I inhibitor, exhibited potent anti-cancer activity against cancer cells

Structurally diverse sesquiterpenoids with anti-MDR cancer activity from Penicillium roqueforti

Five novel nor-eremophilane-type sesquiterpenoids, peniroqueforins E-H and J (1-4 and 7), two new eremophilane-type sesquiterpenoids, peniroqueforins I and K (5 and 8), and a new eudesmane-type sesquiterpenoid, peniroqueforin L (9), along with four known compounds (6 and 10-12), were isolated and characterized from fungus Penicillium roqueforti (P. roqueforti). The structures and absolute configurations of these compounds were determined through comprehensive spectroscopic analyses, electronic circular dichroism (ECD) data analyses, and single-crystal X-ray diffraction methods. The anti-multi-drug resistance (MDR) cancer activity of these compounds was evaluated using SW620/Ad300 cells. Notably, the half maximal inhibitory concentration (IC50) value of paclitaxel (PTX) combined with 1 in SW620/Ad300 cells was 50.36 nmol·L-1, which was 65-fold more potent than PTX alone (IC50 3.26 μmol·L-1). Subsequent molecular docking studies revealed an affinity between compound 1 and P-glycoprotein (P-gp), suggesting that this nor-eremophilane-type sesquiterpenoid (1) could serve as a potential lead for MDR reversal in cancer cells through P-gp inhibition.

Identification of narciclasine as a novel NRF2 inhibitor

Cancer genome sequencing studies have identified somatic mutations in the KEAP1/NRF2 pathway. In an effort to identify novel NRF2 small molecule inhibitor(s), we have screened a natural compound library comprising 1330 chemicals in A549-ARE-GFP-luciferase cells and identified that narciclasine significantly inhibits NRF2-dependent luciferase activity. Narciclasine suppressed the expression of NRF2 and NRF2 target genes, caused significant oxidative stress, and sensitized cisplatin-mediated apoptosis in A549 cells. In addition, we have observed that WD Repeat Domain 43 (WDR43) serves as a direct target of narciclasine for the inhibition of NRF2 as narciclasine binds to recombinant WDR43 in vitro and silencing WDR43 attenuated the inhibition of NRF2 by narciclasine in A549 cells. Finally, we observed that administration of narciclasine significantly decreased the growth of A549 xenografts. Together, our results demonstrate that the inhibition of NRF2 by narciclasine is mediated by WDR43 and future studies are necessary to elucidate the exact mechanism of how WDR43 mediates the inhibition of NRF2 by narciclasine.

OSI-027 as a Potential Drug Candidate Targeting Upregulated Hub Protein TAF1 in Potential Mechanism of Sinonasal Squamous Cell Carcinoma: Insights from Proteomics and Molecular Docking

Sinonasal squamous cell carcinoma (SNSCC) is a rare tumor with high mortality and recurrence rates. However, SNSCC carcinogenesis mechanisms and potential therapeutic drugs have not been fully elucidated. This study investigated the key molecular mechanisms and hub proteins involved in SNSCC carcinogenesis using proteomics and bioinformatic analysis. Dysregulated proteins were validated by RT-qPCR in SNSCC and nasal polyp (NP) tissues. Proteomic analysis revealed that differentially expressed proteins were clustered using MCODE scores ≥ 4 into three modules. The specific hub proteins in each module were analyzed in carcinogenesis pathways using STRING, highlighting potential mechanisms of histone modification and spliceosome dysregulation. Spliceosome components SNRNP200 and SF3A3 were significantly downregulated in SNSCC by RT-qPCR. Web-based applications L1000CDS2 and iLINCS were applied to identify 10 potential repurposable drugs that could reverse the gene expression pattern associated with SNSCC. Docking studies of TAF1, a protein in histone modification, with these 10 small molecule inhibitors indicated OSI-027 to be the most promising due to its strong binding interactions with key residues. These findings suggest that hub proteins involved in the underlying mechanism of SNSCC carcinogenesis may serve as valuable targets for drug development, with OSI-027 emerging as a novel candidate against TAF1 in SNSCC.

Histochemical Localization and Cytotoxic Potential of Alkaloids in Phaedranassa lehmannii

Plants of the subfamily Amaryllidoideae are a source of unique and bioactive alkaloids called Amaryllidaceae alkaloids. The study of their anticancer potential has intensified in recent years. This work aims to locate and characterize the profile of cytotoxic alkaloids biosynthesized and stored in different tissues of Phaedranassa lehmannii Regel using different histochemical methods and chromatographic analysis. The histochemical analysis in the bulbs revealed the presence of alkaloids at the basal edge of the scale-like leaves and bud apical zone. The GC-MS analysis indicated that the bulbs biosynthesize crinane- (9.80 µg/g DW), galanthamine- (8.04 µg/g DW), lycorine- (7.38 µg/g DW), and narciclasine-type (3.75 µg/g DW) alkaloids. The root biosynthesizes alkaloids that are mainly distributed mostly in lycorine- (225.29 µg/g DW) and galanthamine-type (72.35 µg/g DW) alkaloids. The total alkaloids biosynthesized by the root (324.93 µg/g DW) exceeded eleven times the abundance of the alkaloids identified in the bulbs (28.97 µg/g DW). In addition, the total alkaloid fractions exhibited a dose-dependent cytotoxic effect in the evaluated concentrations, with IC50 values of 11.76 ± 0.99 µg/mL and 2.59 ± 0.56 µg/mL against human lung (A549) cancer cells and 8.00 ± 1.35 µg/mL and 18.74 ± 1.99 µg/mL against gastric (AGS) cancer cells. The present study provided evidence to locate and characterize the alkaloids of P. lehmannii grown under nursery conditions as a species producing potential antiproliferative alkaloids.

Purification and immobilization of β-glucosidase using surface modified mesoporous silica Santa Barbara Amorphous 15 for eco-friendly preparation of sagittatoside A

Functionalized mesoporous materials have become a promising carrier for enzyme immobilization. In this study, Santa Barbara Amorphous 15 (SBA-15) was modified by N-aminoethyl-γ-aminopropyl trimethoxy (R). R-SBA-15 was employed to purify and immobilize recombinant β-glucosidase from Terrabacter ginsenosidimutans (BgpA) in one step for the first time. Optimum pH of the constructed R-SBA-15@BgpA were 7.0, and it has 20 ℃ higher optimal temperature than free enzyme. Relative activity of R-SBA-15@BgpA still retained > 70% at 42 ℃ after 8-h incubation. The investigation on organic reagent resistance revealed that the immobilized enzyme can maintain strong stability in 15% DMSO. In leaching test and evaluation of storage stability, only trace amount of protein was detected in buffer of the immobilized enzyme after storage at 4 ℃ for 33 days, and the immobilized BgpA still maintained > 50% relative activity. It also demonstrated good reusability, with 76.1% relative activity remaining after fourteen successive enzymatic hydrolyses of epimedin A to sagittatoside A. The newly proposed strategy is an effective approach for the purification and immobilization of BgpA concurrently. In addition, R-SBA-15@BgpA was demonstrated to have high efficiency and stability in this application, suggesting its great feasibility and potential to produce bioactive compounds such as secondary glycosides or aglycones from natural products.

Beyond cytotoxic potency: disposition features required to design ADC payload

1. Antibody-drug conjugates (ADCs) have demonstrated impressive clinical usefulness in treating several types of cancer, with the notion of widening of the therapeutic index of the cytotoxic payload through the minimisation of the systemic toxicity. Therefore, choosing the most appropriate payload molecule is a particularly important part of the early design phase of ADC development, especially given the highly competitive environment ADCs find themselves in today.2. The focus of the current review is to describe critical attributes/considerations needed in the discovery and ultimately development of cytotoxic payloads in support of ADC design. In addition to potency, several key dispositional characteristics including solubility, permeability and bystander effect, pharmacokinetics, metabolism, and drug-drug interactions, are described as being an integral part of the integrated activities required in the design of clinically safe and useful ADC therapeutic agents.

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

The Marine Natural Compound Dragmacidin D Selectively Induces Apoptosis in Triple-Negative Breast Cancer Spheroids

Cancer cells grown in 3D spheroid cultures are considered more predictive for clinical efficacy. The marine natural product dragmacidin D induces apoptosis in MDA-MB-231 and MDA-MB-468 triple-negative breast cancer (TNBC) spheroids within 24 h of treatment while showing no cytotoxicity against the same cells grown in monolayers and treated for 72 h. The IC50 for cytotoxicity based on caspase 3/7 cleavage in the spheroid assay was 8 ± 1 µM in MDA-MB-231 cells and 16 ± 0.6 µM in MDA-MB-468 cells at 24 h. No cytotoxicity was seen at all in 2D, even at the highest concentration tested. Thus, the IC50 for cytotoxicity in the MTT assay (2D) in these cells was found to be >75 µM at 72 h. Dragmacidin D exhibited synergy when used in conjunction with paclitaxel, a current treatment for TNBC. Studies into the signaling changes using a reverse-phase protein array showed that treatment with dragmacidin D caused significant decreases in histones. Differential protein expression was used to hypothesize that its potential mechanism of action involves acting as a protein synthesis inhibitor or a ribonucleotide reductase inhibitor. Further testing is necessary to validate this hypothesis. Dragmacidin D also caused a slight decrease in an invasion assay in the MDA-MB-231 cells, although this failed to be statistically significant. Dragmacidin D shows intriguing selectivity for spheroids and has the potential to be a treatment option for triple-negative breast cancer, which merits further research into understanding this activity.