Progress in the discovery and development of anticancer agents from marine cyanobacteria.

Covering 2010-April 2024There have been tremendous new discoveries and developments since 2010 in anticancer research based on marine cyanobacteria. Marine cyanobacteria are prolific sources of anticancer natural products, including the tubulin agents dolastatins 10 and 15 which were originally isolated from a mollusk that feeds on cyanobacteria. Decades of research have culminated in the approval of six antibody-drug conjugates (ADCs) and many ongoing clinical trials.

Probing a distinct druggable tubulin binding site with gatorbulins 1-7, their metabolic and physicochemical properties, and pharmacological consequences.

Microtubules, consisting of α/β-tubulin heterodimers, are prime targets for anticancer drug discovery. Gatorbulin-1 (GB1, 1a) is a recently described marine natural product that targets tubulin at a new, seventh pharmacological site at the tubulin intradimer interface. Using our previously developed robust route towards GB1 (1a), we synthesized simplified, first-generation gatorbulins, GB2-7 (1b-1g) of this highly modified cyclodepsipeptide (GB1) that does not contain any proteinogenic amino acid.

Small molecular weight epigenetic inhibitors modulate the extracellular matrix during pancreatic acinar ductal metaplasia.

The pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment is distinguished by a high degree of fibrosis and inflammation, known as desmoplasia. Desmoplasia increases the stromal deposition and extracellular matrix (ECM) stiffness observed in the tumor microenvironment, contributing to the dampened penetration of pharmacological agents. The molecular and biophysical composition of the ECM during the earliest cellular changes in the development of PDAC, i.

Discovery of small molecule guanylyl cyclase B receptor positive allosteric modulators.

Myocardial fibrosis is a pathological hallmark of cardiovascular disease (CVD), and excessive fibrosis can lead to new-onset heart failure and increased mortality. Currently, pharmacological therapies for myocardial fibrosis are limited, highlighting the need for novel therapeutic approaches. The particulate guanylyl cyclase B (GC-B) receptor possesses beneficial antifibrotic actions through the binding of its natural ligand C-type natriuretic peptide (CNP) and the generation of the intracellular second messenger, cyclic guanosine 3',5'-monophosphate (cGMP).

Chemical Genetics in Identifies Anticancer Mycotoxins Chaetocin and Chetomin as Potent Inducers of a Nuclear Metal Homeostasis Response.

(clear-localized etal-esponsive) is an identical gene pair encoding a nuclear protein previously shown to be activated by cadmium and disruption of the integrator RNA metabolism complex. We took a chemical genetic approach to further characterize regulation of this novel metal response by screening 41,716 compounds and extracts for activation. The most potent activator was chaetocin, a fungal 3,6-epidithiodiketopiperazine (ETP) with promising anticancer activity.

VCP/p97 mediates nuclear targeting of non-ER-imported prion protein to maintain proteostasis.

Mistargeting of secretory proteins in the cytosol can trigger their aggregation and subsequent proteostasis decline. We have identified a VCP/p97-dependent pathway that directs non-ER-imported prion protein (PrP) into the nucleus to prevent the formation of toxic aggregates in the cytosol. Upon impaired translocation into the ER, PrP interacts with VCP/p97, which facilitates nuclear import mediated by importin-ß.

Epigenetic small-molecule screen for inhibition and reversal of acinar ductal metaplasia in mouse pancreatic organoids.

Acinar ductal metaplasia (ADM) is among the earliest initiating events in pancreatic ductal adenocarcinoma (PDAC) development. We developed a novel morphology-based screen using organoids from wildtype and (Cre) mice to discover epigenetic modulators that inhibit or reverse pancreatic ADM more effectively than the broad-spectrum HDAC inhibitor trichostatin A (TSA). Of the 144 compounds screened, nine hits and two additional natural product HDAC inhibitors were validated by dose-response analysis.

Biosynthesis of Dolastatin 10 in Marine Cyanobacteria, a Prototype for Multiple Approved Cancer Drugs.

Dolastatin 10, a potent tubulin-targeting marine anticancer natural product, provided the basis for the development of six FDA-approved antibody-drug conjugates. Through the screening of cyanobacterial environmental DNA libraries and metagenome sequencing, we identified its biosynthetic gene cluster. Functional prediction of 10 enzymes encoded in the 39 kb cluster supports the dolastatin 10 biosynthesis.

Phenethylammonium bromide interlayer for high-performance red quantum-dot light emitting diodes.

Interfacial modification is vital to boost the performance of colloidal quantum-dot light-emitting diodes (QLEDs). We introduce phenethylammonium bromide (PEABr) as an interlayer to reduce the trap states and exciton quenching at the interface between the emitting layer (EML) with CdSe/ZnS quantum-dots and the electron transport layer (ETL) with ZnMgO. The presence of PEABr separates the EML and the ETL and thus passivates the surface traps of ZnMgO.

Epigenetic Small-Molecule Screen for Inhibition and Reversal of Acinar Ductal Metaplasia in Mouse Pancreatic Organoids.

Background: Acinar ductal metaplasia (ADM) is among the earliest initiating events in pancreatic ductal adenocarcinoma (PDAC) development.

Methods: We developed a novel morphology-based screen using organoids from wildtype and p48 (Cre) mice to discover epigenetic modulators that inhibit or reverse pancreatic ADM more effectively than the broad-spectrum HDAC inhibitor trichostatin A (TSA).

Results: Of the 144 compounds screened, nine hits and two additional natural product HDAC inhibitors were validated by dose-response analysis.

Triazolothiadiazine derivative positively modulates CXCR4 signaling and improves diabetic wound healing.

Development of specific therapies that target and accelerate diabetic wound repair is an urgent need to alleviate pain and suffering and the huge socioeconomic burden of this debilitating disease. C-X-C Motif Chemokine Ligand 12 (CXCL12) also know an stromal cell-derived factor 1α (SDF-1α) is a chemokine that binds the CXC chemokine receptor type 4 (CXCR4) and activates downstream signaling resulting in recruitment of hematopoietic cells to locations of tissue injury and promotes tissue repair. In diabetes, low expression of CXCL12 correlates with impaired wound healing.

Heterologous Production of the C33-C45 Polyketide Fragment of Anticancer Apratoxins in a Cyanobacterial Host.

A polyketide synthase subcluster of cytotoxic apratoxin A was isolated from a environmental DNA library and engineered with a thioesterase II domain for heterologous expression in the filamentous cyanobacterium sp. PCC7120. Further engineering with a rhamnose-inducible promoter led to the production of (2,3,5,7)-3,7-dihydroxy-2,5,8,8-tetramethylnonanoic acid, a stereogenically rich chiral building block that is important to the efficient synthesis of apratoxin analogues, representing the first synthetic biology attempt for this type of polyketide fragment.

Discovery, Synthesis, and Biological Evaluation of Anaenamides C and D from a New Marine Cyanobacterium, sp.

Our ongoing efforts to explore the chemical space associated with marine cyanobacteria from coral reefs of Guam have yielded two new members of the anaenamide family of natural products, anaenamides C ( and D (). These compounds were isolated from a novel sp. (VPG16-58).

Inhibition of cotranslational translocation by apratoxin S4: Effects on oncogenic receptor tyrosine kinases and the fate of transmembrane proteins produced in the cytoplasm.

Receptor tyrosine kinases (RTKs) have become major targets for anticancer therapy. However, resistance and signaling pathway redundancy has been problematic. The marine-derived apratoxins act complementary to direct kinase inhibitors by downregulating the levels of multiple of these receptors and additionally prevent the secretion of growth factors that act on these receptors by targeting Sec61α, therefore interfering with cotranslational translocation.

Largazole Inhibits Ocular Angiogenesis by Modulating the Expression of VEGFR2 and p21.

Ocular angiogenic diseases, characterized by abnormal blood vessel formation in the eye, are the leading cause of blindness. Although Anti-VEGF therapy is the first-line treatment in the market, a substantial number of patients are refractory to it or may develop resistance over time. As uncontrolled proliferation of vascular endothelial cells is one of the characteristic features of pathological neovascularization, we aimed to investigate the role of the class I histone deacetylase (HDAC) inhibitor Largazole, a cyclodepsipeptide from a marine cyanobacterium, in ocular angiogenesis.

Gatorbulin-1, a distinct cyclodepsipeptide chemotype, targets a seventh tubulin pharmacological site.

Tubulin-targeted chemotherapy has proven to be a successful and wide spectrum strategy against solid and liquid malignancies. Therefore, new ways to modulate this essential protein could lead to new antitumoral pharmacological approaches. Currently known tubulin agents bind to six distinct sites at α/β-tubulin either promoting microtubule stabilization or depolymerization.

Bifunctional Doscadenamides Activate Quorum Sensing in Gram-Negative Bacteria and Synergize with TRAIL to Induce Apoptosis in Cancer Cells.

New cyanobacteria-derived bifunctional analogues of doscadenamide A, a LasR-dependent quorum sensing (QS) activator in , characterized by dual acylation of the pyrrolinone core structure and the pendant side chain primary amine to form an imide/amide hybrid are reported. The identities of doscadenamides B-J were confirmed through total synthesis and a strategic focused library with different acylation and unsaturation patterns was created. Key molecular interactions for binding with LasR and a functional response through mutation studies coupled with molecular docking were identified.

Ahp-Cyclodepsipeptides as tunable inhibitors of human neutrophil elastase and kallikrein 7: Total synthesis of tutuilamide A, serine protease selectivity profile and comparison with lyngbyastatin 7.

We describe the total synthesis of tutuilamide A, a potent porcine pancreatic elastase (PPE) inhibitor and a representative member of the 3-amino-6-hydroxy-2-piperidone (Ahp) cyclodepsipeptide family, isolated from marine cyanobacteria. The Ahp unit serves as a pharmacophore and the adjacent 2-amino-2-butenoic acid (Abu) is a main driver of the selectivity among serine proteases. We adapted our previous convergent strategy to generate the macrocycle, common with lyngbyastatin 7 and related elastase inhibitors, and then appended the tutuilamide A-specific side chain bearing a vinyl chloride.

Largazole is a Brain-Penetrant Class I HDAC Inhibitor with Extended Applicability to Glioblastoma and CNS Diseases.

Largazole is a potent class I selective histone deacetylase inhibitor prodrug with anticancer activity against solid tumors in preclinical models. Largazole possesses in vitro activity against glioblastoma multiforme (GBM) cells and sufficiently crosses the blood-brain barrier based on measurement of the active species, largazole thiol, to achieve therapeutically relevant concentrations in the mouse brain. The effective dose resulted in pronounced functional responses on the transcript level based on RNA sequencing and quantitative polymerase chain reaction after reverse transcription (RT-qPCR), revealing desirable expression changes of genes related to neuroprotection, including and upregulation, extending the applicability of largazole to the treatment of brain cancer and neurodegenerative disorders.

A dual function-enabled novel zwitterion to stabilize a Pb-I framework and passivate defects for highly efficient inverted planar perovskite solar cells.

A novel zwitterion named bethanechol chloride (BTCC) was introduced to simultaneously stabilize a Pb-I framework and passivate defects for efficient inverted perovskite solar cells. The BTCC-assisted device yielded an elevated power conversion efficiency of 20.45% with an open-circuit voltage of 1.

Discovery, Total Synthesis, and SAR of Anaenamides A and B: Anticancer Cyanobacterial Depsipeptides with a Chlorinated Pharmacophore.

New modified depsipeptides and geometric isomers, termed anaenamides A () and B (), along with the presumptive biosynthetic intermediate, anaenoic acid (), were discovered from a marine cyanobacterium from Guam. Structures were confirmed by total synthesis. The alkylsalicylic acid fragment and the C-terminal α-chlorinated -unsaturated ester are novelties in cyanobacterial natural products.

Circular RNA induced cell apoptosis in urothelial carcinoma via interaction with .

Background: Circular RNAs (circRNAs) play a critical role in cancer. Emerging evidence has shown circ-Foxo3, a circRNA, was dysregulated in a variety of tumor types. However, the exact role of in bladder cancer has never been studied.