Membrane interaction and functional plasticity of inositol polyphosphate 5-phosphatases

Strategies in Taxol Development: A Review

Taxol is a compound with a rigid, tetracyclic structure of diterpene, which is characterized by significant antitumor properties. Firstly, Taxol has been isolated by extraction from the bark of the yew tree. However, the low level of availability obligated the researchers' world to uncover alternative techniques of Taxol obtainment. In the last few years, many synthetic and semi-synthetic methodologies have been elaborated. Nowadays, many novel biotechnological approaches using cell suspension cultures and biotransformation are initiated and expanded. These processes are very beneficial. The reason is that both the final product and the yield of the process have high levels. Such approaches are very distinctive and they help achieve significant quantities of natural compounds, which often exist in small amounts in plants. Moreover, a very important aspect of Taxol development is nanotechnology. The use of this method has many benefits - the retention time is protracted and the concentration of a drug in tumor tissue is raised. This is due to the specific targeting of nanomolecules. What is essential for patients is that systemic side effects are reduced and the healthy biological systems and tissues do not damage. Also, the paper presents new directions with the application of Artificial Intelligence methods. Every year, new concepts are created for obtaining Taxol and developing methods to significantly increase its bioavailability.

Repurposing approved drugs for cancer therapy

BACKGROUND

Many drugs approved for other indications can control the growth of tumor cells and limit adverse events (AE).

DATA SOURCES

Literature searches with keywords 'repurposing and cancer' books, websites: https://clinicaltrials.gov/, for drug structures: https://pubchem.ncbi.nlm.nih.gov/.

AREAS OF AGREEMENT

Introducing approved drugs, such as those developed to treat diabetes (Metformin) or inflammation (Thalidomide), identified to have cytostatic activity, can enhance chemotherapy or even replace more cytotoxic drugs. Also, anti-inflammatory compounds, cytokines and inhibitors of proteolysis can be used to control the side effects of chemo- and immuno-therapies or as second-line treatments for tumors resistant to kinase inhibitors (KI). Drugs specifically developed for cancer therapy, such as interferons (IFN), the tyrosine KI abivertinib TKI (tyrosine kinase inhibitor) and interleukin-6 (IL-6) receptor inhibitors, may help control symptoms of Covid-19.

AREAS OF CONTROVERSY

Better knowledge of mechanisms of drug activities is essential for repurposing. Chemotherapies induce ER stress and enhance mutation rates and chromosome alterations, leading to resistance that cannot always be related to mutations in the target gene. Metformin, thalidomide and cytokines (IFN, tumor necrosis factor (TNF), interleukin-2 (IL-2) and others) have pleiomorphic activities, some of which can enhance tumorigenesis. The small and fragile patient pools available for clinical trials can cloud the data on the usefulness of cotreatments.

GROWING POINTS

Better understanding of drug metabolism and mechanisms should aid in repurposing drugs for primary, adjuvant and adjunct treatments.

AREAS TIMELY FOR DEVELOPING RESEARCH

Optimizing drug combinations, reducing cytotoxicity of chemotherapeutics and controlling associated inflammation.

Targeting SHIP1 and SHIP2 in Cancer

Simple Summary

Phosphoinositol signaling pathways and their dysregulation have been shown to have a fundamental role in health and disease, respectively. The SH2-containing 5′ inositol phosphatases, SHIP1 and SHIP2, are regulators of the PI3K/AKT pathway that have crucial roles in cancer progression. This review aims to summarize the role of SHIP1 and SHIP2 in cancer signaling and the immune response to cancer, the discovery and use of SHIP inhibitors and agonists as possible cancer therapeutics.

Abstract

Membrane-anchored and soluble inositol phospholipid species are critical mediators of intracellular cell signaling cascades. Alterations in their normal production or degradation are implicated in the pathology of a number of disorders including cancer and pro-inflammatory conditions. The SH2-containing 5′ inositol phosphatases, SHIP1 and SHIP2, play a fundamental role in these processes by depleting PI(3,4,5)P₃, but also by producing PI(3,4)P₂ at the inner leaflet of the plasma membrane. With the intent of targeting SHIP1 or SHIP2 selectively, or both paralogs simultaneously, small molecule inhibitors and agonists have been developed and tested in vitro and in vivo over the last decade in various disease models. These studies have shown promising results in various pre-clinical models of disease including cancer and tumor immunotherapy. In this review the potential use of SHIP inhibitors in cancer is discussed with particular attention to the molecular structure, binding site and efficacy of these SHIP inhibitors.

Repurposing approved drugs on the pathway to novel therapies

The time and cost of developing new drugs have led many groups to limit their search for therapeutics to compounds that have previously been approved for human use. Many "repurposed" drugs, such as derivatives of thalidomide, antibiotics, and antivirals have had clinical success in treatment areas well beyond their original approved use. These include applications in treating antibiotic-resistant organisms, viruses, cancers and to prevent burn scarring. The major theoretical justification for reusing approved drugs is that they have known modes of action and controllable side effects. Coadministering antibiotics with inhibitors of bacterial toxins or enzymes that mediate multidrug resistance can greatly enhance their activity. Drugs that control host cell pathways, including inflammation, tumor necrosis factor, interferons, and autophagy, can reduce the "cytokine storm" response to injury, control infection, and aid in cancer therapy. An active compound, even if previously approved for human use, will be a poor clinical candidate if it lacks specificity for the new target, has poor solubility or can cause serious side effects. Synergistic combinations can reduce the dosages of the individual components to lower reactivity. Preclinical analysis should take into account that severely ill patients with comorbidities will be more sensitive to side effects than healthy trial subjects. Once an active, approved drug has been identified, collaboration with medicinal chemists can aid in finding derivatives with better physicochemical properties, specificity, and efficacy, to provide novel therapies for cancers, emerging and rare diseases.

Allosteric inhibitors of Coxsackie virus A24 RNA polymerase

Coxsackie virus A24 (CVA24), a causative agent of acute hemorrhagic conjunctivitis, is a prototype of enterovirus (EV) species C. The RNA polymerase (3D(pol)) of CVA24 can uridylylate the viral peptide linked to the genome (VPg) from distantly related EV and is thus, a good model for studying this reaction. Once UMP is bound, VPgpU primes RNA elongation. Structural and mutation data have identified a conserved binding surface for VPg on the RNA polymerase (3D(pol)), located about 20Å from the active site. Here, computational docking of over 60,000 small compounds was used to select those with the lowest (best) specific binding energies (BE) for this allosteric site. Compounds with varying structures and low BE were assayed for their effect on formation of VPgU by CVA24-3D(pol). Two compounds with the lowest specific BE for the site inhibited both uridylylation and formation of VPgpolyU at 10-20μM. These small molecules can be used to probe the role of this allosteric site in polymerase function, and may be the basis for novel antiviral compounds.

Sequence specificity for uridylylation of the viral peptide linked to the genome (VPg) of enteroviruses

Enteroviruses (EV) uridylylate a peptide, VPg, as the first step in their replication. VPgpUpU, found free in infected cells, serves as the primer for RNA elongation. The abilities of four polymerases (3D(pol)), from EV-species A-C, to uridylylate VPgs that varied by up to 60% of their residues were compared. Each 3D(pol) was able to uridylylate all five VPgs using polyA RNA as template, while showing specificity for its own genome encoded peptide. All 3D(pol) uridylylated a consensus VPg representing the physical chemical properties of 31 different VPgs. Thus the residues required for uridylylation and the enzymatic mechanism must be similar in diverse EV. As VPg-binding sites differ in co-crystal structures, the reaction is probably done by a second 3D(pol) molecule. The conservation of polymerase residues whose mutation reduces uridylylation but not RNA elongation is compared.