Cancer Stem Cells in Ovarian Cancer—A Source of Tumor Success and a Challenging Target for Novel Therapies

Ovarian cancer is the most lethal neoplasm of the female genital organs. Despite indisputable progress in the treatment of ovarian cancer, the problems of chemo-resistance and recurrent disease are the main obstacles for successful therapy. One of the main reasons for this is the presence of a specific cell population of cancer stem cells. The aim of this review is to show the most contemporary knowledge concerning the biology of ovarian cancer stem cells (OCSCs) and their impact on chemo-resistance and prognosis in ovarian cancer patients, as well as to present the treatment options targeted exclusively on the OCSCs. The review presents data concerning the role of cancer stem cells in general and then concentrates on OCSCs. The surface and intracellular OCSCs markers and their meaning both for cancer biology and clinical prognosis, signaling pathways specifically activated in OCSCs, the genetic and epigenetic regulation of OCSCs function including the recent studies on the non-coding RNA regulation, cooperation between OCSCs and the tumor microenvironment (ovarian cancer niche) including very specific environment such as ascites fluid, the role of shear stress, autophagy and metabolic changes for the function of OCSCs, and finally mechanisms of OCSCs escape from immune surveillance, are described and discussed extensively. The possibilities of anti-OCSCs therapy both in experimental settings and in clinical trials are presented, including the recent II phase clinical trials and immunotherapy. OCSCs are a unique population of cancer cells showing a great plasticity, self-renewal potential and resistance against anti-cancer treatment. They are responsible for the progression and recurrence of the tumor. Several completed and ongoing clinical trials have tested different anti-OCSCs drugs which, however, have shown unsatisfactory efficacy in most cases. We propose a novel approach to ovarian cancer diagnosis and therapy.     

Glycosylation of Methylflavonoids in the Cultures of Entomopathogenic Filamentous Fungi as a Tool for Obtaining New Biologically Active Compounds

Flavonoid compounds are secondary plant metabolites with numerous biological activities; they naturally occur mainly in the form of glycosides. The glucosyl moiety attached to the flavonoid core makes them more stable and water-soluble. The methyl derivatives of flavonoids also show increased stability and intestinal absorption. Our study showed that such flavonoids can be obtained by combined chemical and biotechnological methods with entomopathogenic filamentous fungi as glycosylation biocatalysts. In the current paper, two flavonoids, i.e., 2′-hydroxy-4-methylchalcone and 4′-methylflavone, have been synthesized and biotransformed in the cultures of two strains of entomopathogenic filamentous fungi Isaria fumosorosea KCH J2 and Beauveria bassiana KCH J1.5. Biotransformation of 2′-hydroxy-4-methylchalcone resulted in the formation of two dihydrochalcone glucopyranoside derivatives in the culture of I. fumosorosea KCH J2 and chalcone glucopyranoside derivative in the case of B. bassiana KCH J1.5. 4′-Methylflavone was transformed in the culture of I. fumosorosea KCH J2 into four products, i.e., 4′-hydroxymethylflavone, flavone 4′-methylene-O-β-d-(4″-O-methyl)-glucopyranoside, flavone 4′-carboxylic acid, and 4′-methylflavone 3-O-β-d-(4″-O-methyl)-glucopyranoside. 4′-Methylflavone was not efficiently biotransformed in the culture of B. bassiana KCH J1.5. The computer-aided simulations based on the chemical structures of the obtained compounds showed their improved physicochemical properties and antimicrobial, anticarcinogenic, hepatoprotective, and cardioprotective potential.     

Protein Prenyltransferases and Their Inhibitors: Structural and Functional Characterization

Protein prenylation is a post-translational modification controlling the localization, activity, and protein–protein interactions of small GTPases, including the Ras superfamily. This covalent attachment of either a farnesyl (15 carbon) or a geranylgeranyl (20 carbon) isoprenoid group is catalyzed by four prenyltransferases, namely farnesyltransferase (FTase), geranylgeranyltransferase type I (GGTase-I), Rab geranylgeranyltransferase (GGTase-II), and recently discovered geranylgeranyltransferase type III (GGTase-III). Blocking small GTPase activity, namely inhibiting prenyltransferases, has been proposed as a potential disease treatment method. Inhibitors of prenyltransferase have resulted in substantial therapeutic benefits in various diseases, such as cancer, neurological disorders, and viral and parasitic infections. In this review, we overview the structure of FTase, GGTase-I, GGTase-II, and GGTase-III and summarize the current status of research on their inhibitors.     

How Are the Flower Structure and Nectar Composition of the Generalistic Orchid Neottia ovata Adapted to a Wide Range of Pollinators?

Plant-pollinator interactions significantly influence reproductive success (RS) and drive the evolution of pollination syndromes. In the context of RS, mainly the role of flower morphology is touched. The importance of nectar properties is less studied, despite its significance in pollination effectiveness. Therefore, the aim of this study was to test selection on flower morphology and nectar chemistry in the generalistic orchid Neottia ovata. In 2019–2020, we measured three floral displays and six flower traits, pollinaria removal (PR), female reproductive success (FRS), and determined the soil properties. The sugars and amino acids (AAs) were analyzed using the HPLC method. Data were analyzed using multiple statistical methods (boxplots, ternary plot, one-way ANOVA, Kruskal-Wallis test, and PCA). Variation of flower structure and nectar chemistry and their weak correlation with RS confirms the generalistic character of N. ovata. In particular populations, different traits were under selection. PR was high and similar in all populations in both years, while FRS was lower and varied among populations. Nectar was dominated by glucose, fructose, and included 28 AAs (Ala and Glu have the highest content). Sugars and AAs influenced mainly FRS. Among soil parameters, carbon and carbon:nitrogen ratio seems to be the most important in shaping flower structure and nectar chemistry.     

Effects of quinoa and amaranth on zinc,magnesium and calcium content in beer wort

Pseudocereals such as quinoa and amaranth can be used as partial replacements for malt in the production of new beers. Quinoa and amaranth are of interest due to their high levels of nutrients and micronutrients, including minerals which can significantly improve the performance of brewing yeast and the fermentation rate. In this study, we investigated whether the use of quinoa or amaranth as partial replacements for malt affected the concentration of ions such as zinc and magnesium in beer wort. The use of amaranth, and in particular quinoa, increased the content of both zinc and magnesium ions substantially, even when only 10% of the barley malt was replaced. With 10% quinoa, Zn²⁺ and Mg²⁺ content increased by 41% and 49%, respectively, while the ratio of Mg²⁺ to Ca²⁺ rose from 1.4:1 to 1.9:1. Use of unmalted quinoa and amaranth appears a good way of enriching wort with essential metal ions.     

A Human Cellular Model for Colorectal Anastomotic Repair: The Effect of Localization and Transforming Growth Factor-β1 Treatment on Collagen Deposition and Biomarkers

Anastomotic leakage (AL) is a devastating complication after colorectal surgery, possibly due to the loss of stabilizing collagen fibers in the submucosa. Our aim was to assess the formation of collagen in the colon versus the rectum with or without transforming growth factor (TGF)-β1 exposure in a human cellular model of colorectal repair. Primary fibroblasts were isolated by an explant procedure from clinically resected tissue rings during anastomosis construction in 19 consecutive colorectal patients who underwent laparoscopy. The cells, identified as fibroblasts by morphologic characteristics and flow cytometry analysis (CD90⁺), were cultured for 8 days and in 12 patients in the presence of 1 ng/mL TGF-β1. Total collagen deposition was measured colorimetrically after Sirius red staining of fixed cell layers, and type I, III, and VI collagen biosynthesis and degradation were specifically determined by the biomarkers PINP, PRO-C3, PRO-C6, and C3M in conditioned media by competitive enzyme-linked immunosorbent assays. Total collagen deposition by fibroblasts from the colon and rectum did not significantly differ. TGF-β1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-β1 treatment increased COL1A1 and ACTA2 (encoding α-smooth muscle actin), and decreased COL6A1 and MMP2 mRNA levels in colorectal fibroblasts. In conclusion, we found no effect of anatomic localization on collagen production by fibroblasts derived from the large intestine. TGF-β1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.     

Solvates of New Arylpiperazine Salicylamide Derivative-a Multi-Technique Approach to the Description of 5 HTR Ligand Structure and Interactions

A new ligand for 5-HT1A and 5-HT7 receptors, an arylpiperazine salicylamide derivative with an inflexible spacer, is investigated to identify preferred fragments capable of creating essential intermolecular interactions in different solvates. To fully identify and characterize the obtained crystalline materials, various methods including powder and single-crystal X-ray diffraction, solid-state NMR, and thermal analysis were employed, supplemented by periodic ab initio calculations. The molecular conformation in different solvates, types, and hierarchy of intermolecular interactions as well as the crystal packing were investigated to provide data for future research focused on studying protein–ligand interactions. Based on various methods of crystal structure analysis, including the interaction energy calculation and programs using an artificial neural network, a salicylamide fragment was found to be crucial for intermolecular contacts, mostly of dispersion and electrostatic character. A supramolecular 2D kite-type layer of {4,4} topology was found to form in crystals. The closed voids between layers contain disordered solvents, very weakly interacting with the molecule and the layer. It has been postulated that the separation of the layers might be influenced by an increase in temperature or the size of the solvent; hence, only methanol and ethanol hemi-solvates could be obtained from a series of various alcohols.     

DNA ADDUCTS OF BENZO[A]PYRENE- AND DIBENZO[A,L]PYRENE-DIOL EPOXIDES IN HUMAN LUNG EPITHELIAL CELLS: KINETICS OF ADDUCT REMOVAL,EFFECTS ON CELL CYCLE CHECKPOINTS,AND GENE EXPRESSION

The fjord-region PAH dibenzo[a,l]pyrene (DBP) is considerably more carcinogenic than the bay-region benzo[a]pyrene (BP). This fact can be ascribed to differences in DNA binding efficiency of their ultimate carcinogenic diol epoxide (DEs) intermediates, differences in structural features of the DNA adducts, and differences in DNA adduct recognition and the subsequent lesion removal by nucleotide excision repair (NER). In order to further substantiate previous findings in cell-free human systems (1 Buterin, T., Hess, M. T., Luneva, N., Geacintov, N. E., Amin, S., Kroth, H., Seidel, A. and Naegeli, H. 2000. Unrepaired Fjord Region Polycyclic Aromatic Hydrocarbon-DNA Adducts in Ras Codon 61 Mutational Hot Spots. Cancer Research, 60: 1849–1856.  [Google Scholar]), cultured cells (2 Luch, A., Kudla, K., Seidel, A., Doehmer, J., Greim, H. and Baird, W. M. 1999. The Level of DNA Modification by (+)-syn-(11S,12R,13S,14R)- and (?)-anti-(11R,12S,13S, 14R)-Dihydrodiol Epoxides of Dibenzo[a,l]pyrene Determined the Effect on the Proteins p53 and p21WAF1 in the Human Mammary Carcinoma Cell Line MCF-7. Carcinogenesis, 20: 859–865.  [Google Scholar]), and in rodents (3 Jankowiak, R., Ariese, F., Hewer, A., Luch, A., Zamzow, D., Hughes, N. C., Phillips, D., Seidel, A., Platt, K. L., Oesch, F. and Small, G. J. 1998. Structure, Conformations, and Repair of DNA Adducts from Dibenzo[a,l]pyrene: 32P-Postlabeling and Fluorescence Studies. Chemical Research in Toxicology, 11: 674–685.  [Google Scholar]) we have studied DNA adduct formation of anti-DE of DBP [(±)-anti-DBPDE], in A549 human epithelial lung carcinoma cells and monitored the levels of adducts as a function of time. A high-performance liquid chromatography (HPLC) procedure that allows monitoring of all cis- and trans-nucleoside adducts of dA and dG was used. Circular dichroism and UV-spectroscopy have been employed to gain information on adduct structural features. Incubation of cells with 0.1 μM (±)-anti-DBPDE resulted in rapid formation of adducts, followed by a decline. After 6 h of incubation about 20% of the adducts remained. Repeating the experiment with 0.01 μM (±)-anti-DBPDE resulted in a correspondingly lower adduct level initially, but in this case a larger proportion (35%) of the adducts remained after 6 h of incubation. Notably, at this time point, similar amounts of adducts are observed with both (±)-anti-DBPDE concentrations studied. Independent of diol epoxide concentration and incubation time, the dA/dG adducts were constant in number (～2.8). However, within the different adduct categories, the adduct distribution seemed to be time dependent. Although the data are preliminary, a selection with regard to adduct removal seems to have taken place. In comparative experiments with (+)-anti-BPDE, no significant difference in rates of adduct removal was evident. Preliminary results from global gene expression analysis, with focus on genes involved in DNA maintenance and cell cycle checkpoints, demonstrate interesting differences in the stress response elicited in the cells following exposure to the distorted and flexible nonplanar DBPDE or the rigid and planar BPDE molecule. As expected some major common induction events were clearly related to the activation of p53-dependent cell cycle checkpoint. However, distinct clusters of gene expression alterations were detected which mark one or other treatment specifically, indicating a high degree of subtlety in the stress response to closely related DNA adduct forming species.