Gastric cancer: modern approaches and prospects of treatment for peritoneal carcinomatosis (literature review)

Gastric cancer (gc) is one of the most common cancers worldwide. The majority of newly diagnosed gastric cancer cases present with distant metastases. Peritoneal carcinomatosis (pc) is the most unfavorable type of progression of primary gc, which occurs in 14–43 % of patients. The purpose of the study was to highlight modern approaches to the treatment of gc with pc. Material and methods. We analyzed 136 publications available from pubmed, medline, cochrane library, and elibrary databases. The final analysis included 46 studies that met the specified parameters. Results. The modern approaches to the treatment of gc with peritoneal carcinomatosis were reviewed, namely: cytoreductive surgery (crs), combination of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (crs/hipec); neoadjuvant intraperitoneal/systemic chemotherapy (nips) and pressurized intraperitoneal aerosol chemotherapy (pipac). The results of large randomized trials and meta-analyses were analyzed. Benefits and limitations of these trials were assessed. Conclusion. The peritoneal cancer index (pci) and the level of cytoreduction are two key prognostic factors for increasing the median overall survival. By reducing tumor volume through cytoreductive surgery, it is possible to allow tumor cells to re-enter the proliferative phase of the cell cycle and make them more sensitive to antitumor agents. The hematoperitoneal barrier is the main reason that prevents the effective delivery of drugs from the systemic bloodstream to the abdominal cavity, which is why the effect of systemic chemotherapy on peritoneal metastases is extremely limited. Intraperitoneal chemotherapy offers a more effective and intensive regional therapy, creating a so-called «depot» of a chemotherapy drug, thereby prolonging the effect of the administered drugs. Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (crs + hipec) using the combination of surgical resection, cytotoxic chemotherapy, hyperthermic ablation of the tumor and hydrodynamic flushing, is a promising approach in the treatment of gc with peritoneal carcinomatosis.

Comparative Molecular Mechanisms of Biosynthesis of Naringenin and Related Chalcones in Actinobacteria and Plants: Relevance for the Obtention of Potent Bioactive Metabolites

Naringenin and its glycosylated derivative naringin are flavonoids that are synthesized by the phenylpropanoid pathway in plants. We found that naringenin is also formed by the actinobacterium Streptomyces clavuligerus, a well-known microorganism used to industrially produce clavulanic acid. The production of naringenin in S. clavuligerus involves a chalcone synthase that uses p-coumaric as a starter unit and a P450 monoxygenase, encoded by two adjacent genes (ncs-ncyP). The p-coumaric acid starter unit is formed by a tyrosine ammonia lyase encoded by an unlinked, tal, gene. Deletion and complementation studies demonstrate that these three genes are required for biosynthesis of naringenin in S. clavuligerus. Other actinobacteria chalcone synthases use caffeic acid, ferulic acid, sinapic acid or benzoic acid as starter units in the formation of different antibiotics and antitumor agents. The biosynthesis of naringenin is restricted to a few Streptomycess species and the encoding gene cluster is present also in some Saccharotrix and Kitasatospora species. Phylogenetic comparison of S. clavuligerus naringenin chalcone synthase with homologous proteins of other actinobacteria reveal that this protein is closely related to chalcone synthases that use malonyl-CoA as a starter unit for the formation of red-brown pigment. The function of the core enzymes in the pathway, such as the chalcone synthase and the tyrosine ammonia lyase, is conserved in plants and actinobacteria. However, S. clavuligerus use a P450 monooxygenase proposed to complete the cyclization step of the naringenin chalcone, whereas this reaction in plants is performed by a chalcone isomerase. Comparison of the plant and S. clavuligerus chalcone synthases indicates that they have not been transmitted between these organisms by a recent horizontal gene transfer phenomenon. We provide a comprehensive view of the molecular genetics and biochemistry of chalcone synthases and their impact on the development of antibacterial and antitumor compounds. These advances allow new bioactive compounds to be obtained using combinatorial strategies. In addition, processes of heterologous expression and bioconversion for the production of naringenin and naringenin-derived compounds in yeasts are described.

Extremophilic Fungi from Marine Environments: Underexplored Sources of Antitumor, Anti-Infective and Other Biologically Active Agents

Marine environments are underexplored terrains containing fungi that produce a diversity of natural products given unique environmental pressures and nutrients. While bacteria are commonly the most studied microorganism for natural products in the marine world, marine fungi are also abundant but remain an untapped source of bioactive metabolites. Given that their terrestrial counterparts have been a source of many blockbuster antitumor agents and anti-infectives, including camptothecin, the penicillins, and cyclosporin A, marine fungi also have the potential to produce new chemical scaffolds as leads to potential drugs. Fungi are more phylogenetically diverse than bacteria and have larger genomes that contain many silent biosynthetic gene clusters involved in making bioactive compounds. However, less than 5% of all known fungi have been cultivated under standard laboratory conditions. While the number of reported natural products from marine fungi is steadily increasing, their number is still significantly lower compared to those reported from their bacterial counterparts. Herein, we discuss many varied cytotoxic and anti-infective fungal metabolites isolated from extreme marine environments, including symbiotic associations as well as extreme pressures, temperatures, salinity, and light. We also discuss cultivation strategies that can be used to produce new bioactive metabolites or increase their production. This review presents a large number of reported structures though, at times, only a few of a large number of related structures are shown.

Synthetic Approaches Towards the Total synthesis of tubulysin and its fragments: A review

Background: Tubulysins, linear tetrapeptides show extraordinary cytotoxicity against various cancer cells, with IC50 values in nano or picomolar range. Due to their extremely vigorous anti-proliferative and antiangiogenic characteristics, tubulysins exhibit captivating prospects in the development of anticancer drugs. This review focuses on diverse routes for the total synthesis of natural and synthetic tubulysins as well as their fragments. Objective: The purpose of this review is to present the synthetic strategies for the development of antitumor agents, tubulysins. Conclusion: A range of synthetic pathways adopted for the total synthesis of tubulysins and their fragments have been described in this review. Synthesis of fragments, Tuv, Tup, and Tut can be accomplished by adopting appropriate strategies such as Manganese-mediated synthesis, Ireland-Claisen rearrangement, Mukaiyama aldol reaction, and Mannich process etc. Tubulysin B, D, U, V, and N14-desacetoxytubulysin H have been prepared through Mitsunobu reaction, tert-butanesulfinamide method, Tandem reaction, aza-Barbier reaction, Evans aldol reaction, and C-H activation strategies etc. The remarkable anticancer potential of tubulysins toward a substantiate target make them prominent leads for developing novel drugs against multidrug-resistant cancers.

Platelets, thrombo-inflammation and cancer

It has long been recognized a crucial role played by platelets in thrombosis and hemostasis. Along with that, laboratory and clinical data suggest that platelets contribute to tumor progression and metastasis through a variety of interactions with cancer cells. During oncological process, the platelet function becomes modulated via their activation and increased aggregation being one of the risk factors for developing thrombosis in cancer patients. The platelets per se enhance tumor cell dissemination, activate endothelial cells, and attract immune cells to the primary and metastatic tumor sites. In this review, we summarize the current knowledge about the complex interactions between platelets and tumor cells, as well as cells of the microenvironment, and discuss the development of new antitumor agents aimed at various arms in platelet functioning.

An Easily Expandable Multi-Drug LC-MS Assay for the Simultaneous Quantification of 57 Oral Antitumor Drugs in Human Plasma

Oral anticancer drugs have led to significant improvements in the treatment of multiple tumor entities. However, in patients undergoing oral antitumor therapy, plasma concentrations are highly variable, resulting in risks of reduced therapeutic effects or an increase in side effects. One important tool to reduce this variability is therapeutic drug monitoring. In this work we describe a method to simultaneously quantify the plasma concentrations of 57 oral antitumor agents. Quantification of these drugs was achieved using liquid chromatography coupled to an Orbitrap mass spectrometer. The method was fully validated according to the FDA guidelines and constitutes a simple and robust way for exposure monitoring of a wide variety of oral anticancer drugs. Applicability to clinical routine was demonstrated by the analysis of 71 plasma samples taken from 39 patients. In summary, this new multi-drug method allows simultaneous quantification of 57 oral antitumor drugs, which can be applied to exposure monitoring in clinical studies, taking into account the broad variety of oral antitumor drugs prescribed in clinical routine.