COVID-19 therapies: do we see substantial progress?

The appearance of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its spread all over the world is the cause of the coronavirus disease 2019 (COVID-19) pandemic, which has recently resulted in almost 400 million confirmed cases and 6 million deaths, not to mention unknown long-term or persistent side effects in convalescent individuals. In this short review, we discuss approaches to treat COVID-19 that are based on current knowledge of the mechanisms of viral cell receptor recognition, virus–host membrane fusion, and inhibition of viral RNA and viral assembly. Despite enormous progress in antiviral therapy and prevention, new effective therapies are still in great demand.

Attempts to use statins in cancer therapy: An update

Although it could be speculated that almost everything has been said concerning the use of statins in cancer therapy, statins as anticancer drugs have both committed supporters and opponents, for whom the dispute about the legitimacy of statin use in cancer treatment seems never to be clearly resolved; every year more than 300 reports which deepen the knowledge about statins and their influence on cancer cells are published. In this mini-review, we focus on the latest (since 2015) outcomes of cohort studies and meta-analyses indicating statin effectiveness in cancer treatment. We discuss attempts to improve the bioavailability of statins using nanocarriers and review the effectiveness of statins in combined therapies. We also summarise the latest results regarding the development of mechanisms of resistance to statins by cancer cells and, on the other hand, give a few examples where statins could potentially be used to overcome resistance to commonly used chemotherapeutics. Finally, special attention is paid to new reports on the effect of statins on epithelial-mesenchymal transition.

EGFR-targeted immunoliposomes as a selective delivery system of simvastatin, with potential use in treatment of triple-negative breast cancers

A promising strategy for treatment of EGFR-dependent tumours is EGFR signal transduction suppression via inhibition of HMG-CoA reductase using high doses of statins, popular cholesterol-lowering drugs. The main purpose of this study was to obtain targeted long circulating immunoliposomes containing simvastatin (tLCLS) with anti-EGFR antibody attached to their surface and to test whether they can be effective in treatment of TNBC. The designed tLCLS were characterized in terms of physicochemical properties and long-term stability. In vitro experiments conducted on MDA-MB-231 cells demonstrated that tLCLS induced apoptosis and are characterized by IC₅₀ of 7.5 µM. Treatment of studied cells with tLCLS led to a decrease in membrane order and inhibited PI3K/Akt signalling. Analyses of efficacy of the tLCLS in in vivo experiments in model animals indicate that immunoliposomes were effectively delivered to tumours. Our results showed that regardless of whether tLCLS were administered before or after tumour formation, at the tested dose they inhibited tumour growth by an average of 25% in comparison to the control. However, the results were not statistically significant. The experiments described above allowed us to test the possibility of using immunoliposomes as simvastatin carriers delivering increased amounts of the drug to tumour cells.

[Liposomes as non-viral carriers for genetic drugs]

Methods in cancer therapy particularly in recent years, are rapidly changing, due to the need of design of new, more effective therapeutic strategies. Very promising approach to treatment of the neoplastic diseases is antisense gene therapy. Due to the low toxicity of treatment and eliminating not only the symptoms but also the molecular causes of the disease it may represent a breakthrough in cancer therapies. Delivery of a therapeutic DNA or RNA oligonucleotides to the target cells in vivo requires suitable carrier system. Non-viral drug carriers are increasingly used in new systems of targeted gene therapy. This review presents new generation of non-viral carriers, and is focused on immunoliposomes finding potential application in targeted gene therapy.

Novel antisense therapeutics delivery systems: In vitro and in vivo studies of liposomes targeted with anti-CD20 antibody

Antisense gene therapy using molecules such as antisense oligodeoxynucleotides, siRNA or miRNA is a very promising strategy for the treatment of neoplastic diseases. It can be combined with other treatment strategies to enhance therapeutic effect. In acute leukemias, overexpression of the antiapoptotic gene BCL2 is observed in more than 70% of cases. Therefore, reduction of the Bcl-2 protein level could, in itself, prevent the development of cancer or could possibly help sensitize cancer cells to apoptosis inducers. The main objective of our work is to develop therapeutic liposome formulations characterized by high transfection efficiency, stability in the presence of serum, as well as specificity and toxicity for target (leukemic) cells. Each of our liposomal formulations consists of a core composed of antisense oligonucleotides complexed by either cationic lipid, DOTAP, or a synthetic polycation, polyethyleneimine, encapsulated within liposomes modified with polyethylenoglycol. In addition, the liposomal shells are enriched with covalently-bound antibodies recognizing a well characterized bio-marker, CD20, exposed on the surface of leukemia cells. The resulting immunoliposomes selectively and effectively reduced the expression of BCL2 in target cells. Model animal experiments carried out on mice-engrafted tumors expressing the specific marker showed high efficiency of the liposome formulations against specific tumor development. In conclusion, we show that lipid formulations based on a polyplex or lipoplex backbone additionally equipped with antibodies are promising non-viral vectors for specific oligonucleotide transfer into human tumor cells.

The effect of statins on cancer cells--review

Statins [3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase, abbreviated HMGCR) inhibitors], are well-known cholesterol-depleting agents. Since the early 1990 s, it has been known that statins could be successfully used in cancer therapy, but the exact mechanism(s) of statin activity remains unclear and is now an extensive focus of investigation. So far, it was proven that there are several mechanisms that are activated by statins in cancer cells; some of them are leading to cell death. Statins exert different effects depending on cell line, statin concentration, duration of exposure of cells to statins, and the type of statin being used. It was shown that statins may inhibit the cell cycle by influence on both expression and activity of proteins involved in cell-cycle progression such as cyclins, cyclin-dependent kinases (CDK), and/or inhibitors of CDK. Also, statins may induce apoptosis by both intrinsic and extrinsic pathways. Statin treatment may lead to changes in molecular pathways dependent on the EGF receptor, mainly via inhibition of isoprenoid synthesis. By inhibition of the synthesis of cholesterol, statins may destabilize the cell membrane. Moreover, statins may change the arrangement of transporter OATP1, the localization of HMGCR, and could induce conformational changes in GLUT proteins. In this review, we have tried to gather and compare most of the recent outcomes of the research in this field. We have also attempted to explain why hydrophilic statins are less effective than hydrophobic statins. Finally, we have gathered results from in vivo experiments, presenting the use of statins in combined therapies and discussed a number of molecular targets that could serve as biomarkers predisposing to statin therapy.

Toward a magic or imaginary bullet? Ligands for drug targeting to cancer cells: principles, hopes, and challenges

There are many problems directly correlated with the systemic administration of drugs and how they reach their target site. Targeting promises to be a hopeful strategy as an improved means of drug delivery, with reduced toxicity and minimal adverse side effects. Targeting exploits the high affinity of cell-surface-targeted ligands, either directly or as carriers for a drug, for specific retention and uptake by the targeted diseased cells. One of the most important parameters which should be taken into consideration in the selection of an appropriate ligand for targeting is the binding affinity (K D). In this review we focus on the importance of binding affinities of monoclonal antibodies, antibody derivatives, peptides, aptamers, DARPins, and small targeting molecules in the process of selection of the most suitable ligand for targeting of nanoparticles. In order to provide a critical comparison between these various options, we have also assessed each technology format across a range of parameters such as molecular size, immunogenicity, costs of production, clinical profiles, and examples of the level of selectivity and toxicity of each. Wherever possible, we have also assessed how incorporating such a targeted approach compares with, or is superior to, original treatments.