Triterpene saponosides from Lysimachia ciliata differentially attenuate invasive potential of prostate cancer cells

NMR-guided isolation of undescribed triterpenoid saponins from Lysimachia atropurpurea L

Phytochemical investigation on aerial parts of Lysimachia atropurpurea L. (Myrsinaceae), guided by NMR methods, resulted in the isolation and characterization of three previously undescribed triterpenoid saponins named stralysaponins A-C along with five known compounds. Their structures were elucidated by 1D and 2D NMR spectroscopy and HR-ESI-MS. Stralysaponins A-C were categorized into 13β-28-epoxyoleanane-type triterpenoid saponins, reaffirming their prevalent presence of this type in the Myrsinaceae family and the genus Lysimachia. The identified derivatives share a common four-unit branched sugar chain, with rhamnose as the terminal sugar linked at C-3 of the aglycone. The presence of triterpenoid saponins in L. atropurpurea is reported herein for the first time. This study enriched the chemical diversity of triterpenoid saponins of the genus Lysimachia. Additionally, it demonstrates the effectiveness of NMR-profiling in isolating previously undescribed triterpenoid saponins from Lysimachia spp.

The interaction between titanium dioxide nanoparticles and light can have dualistic effects on the physiological responses of plants

The model plant Arabidopsis thaliana was exposed to combined stress factors, i.e., titanium dioxide nanoparticles (TiNPs) and high light. The concentrations of TiNPs used for irrigation were 250, 500, and 1000 μg/mL. This study shows that TiNPs alter the morphology and nanomechanical properties of chloroplasts in A. thaliana, which leads to a decrease in membrane elasticity. We found that TiNPs contributed to a delay in the thermal response of A. thaliana under dynamic light conditions, as revealed by non-invasive thermal imaging. The thermal time constants of TiNP-treated plants under excessive light are determined, showing a shortening in comparison to control plants. The results indicate that TiNPs may contribute to an alleviation of temperature stress experienced by plants under exposure to high light. In this research, we observed a decline in photosystem II photochemical efficiency accompanied by an increase in energy dissipation upon exposure to TiNPs. Interestingly, concentrations exceeding 250 µg/mL TiNPs appeared to mitigate the effects of high light, as shown by reduced differences in the values of specific OJIP parameters (FV/FM, ABS/RC, DI0/RC, and Pi_Abs) before and after light exposure.

Hypoxia enhances anti-fibrotic properties of extracellular vesicles derived from hiPSCs via the miR302b-3p/TGFβ/SMAD2 axis

BACKGROUND

Cardiac fibrosis is one of the top killers among fibrotic diseases and continues to be a global unaddressed health problem. The lack of effective treatment combined with the considerable socioeconomic burden highlights the urgent need for innovative therapeutic options. Here, we evaluated the anti-fibrotic properties of extracellular vesicles (EVs) derived from human induced pluripotent stem cells (hiPSCs) that were cultured under various oxygen concentrations.

METHODS

EVs were isolated from three hiPSC lines cultured under normoxia (21% O2; EV-N) or reduced oxygen concentration (hypoxia): 3% O2 (EV-H3) or 5% O2 (EV-H5). The anti-fibrotic activity of EVs was tested in an in vitro model of cardiac fibrosis, followed by a detailed investigation of the underlying molecular mechanisms. Sequencing of EV miRNAs combined with bioinformatics analysis was conducted and a selected miRNA was validated using a miRNA mimic and inhibitor. Finally, EVs were tested in a mouse model of angiotensin II-induced cardiac fibrosis.

RESULTS

We provide evidence that an oxygen concentration of 5% enhances the anti-fibrotic effects of hiPS-EVs. These EVs were more effective in reducing pro-fibrotic markers in activated human cardiac fibroblasts, when compared to EV-N or EV-H3. We show that EV-H5 act through the canonical TGFβ/SMAD pathway, primarily via miR-302b-3p, which is the most abundant miRNA in EV-H5. Our results show that EV-H5 not only target transcripts of several profibrotic genes, including SMAD2 and TGFBR2, but also reduce the stiffness of activated fibroblasts. In a mouse model of heart fibrosis, EV-H5 outperformed EV-N in suppressing the inflammatory response in the host and by attenuating collagen deposition and reducing pro-fibrotic markers in cardiac tissue.

CONCLUSIONS

In this work, we provide evidence of superior anti-fibrotic properties of EV-H5 over EV-N or EV-H3. Our study uncovers that fine regulation of oxygen concentration in the cellular environment may enhance the anti-fibrotic effects of hiPS-EVs, which has great potential to be applied for heart regeneration.

Saponin Fraction CIL1 from Lysimachia ciliata L. Enhances the Effect of a Targeted Toxin on Cancer Cells

Saponins are plant metabolites that possess multidirectional biological activities, among these is antitumor potential. The mechanisms of anticancer activity of saponins are very complex and depend on various factors, including the chemical structure of saponins and the type of cell they target. The ability of saponins to enhance the efficacy of various chemotherapeutics has opened new perspectives for using them in combined anticancer chemotherapy. Co-administration of saponins with targeted toxins makes it possible to reduce the dose of the toxin and thus limit the side effects of overall therapy by mediating endosomal escape. Our study indicates that the saponin fraction CIL1 of Lysimachia ciliata L. can improve the efficacy of the EGFR-targeted toxin dianthin (DE). We investigated the effect of cotreatment with CIL1 + DE on cell viability in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, on proliferation in a crystal violet assay (CV) and on pro-apoptotic activity using Annexin V/7 Actinomycin D (7-AAD) staining and luminescence detection of caspase levels. Cotreatment with CIL1 + DE enhanced the target cell-specific cytotoxicity, as well as the antiproliferative and proapoptotic properties. We found a 2200-fold increase in both the cytotoxic and antiproliferative efficacy of CIL1 + DE against HER14-targeted cells, while the effect on control NIH3T3 off-target cells was less profound (6.9- or 5.4-fold, respectively). Furthermore, we demonstrated that the CIL1 saponin fraction has a satisfactory in vitro safety profile with a lack of cytotoxic and mutagenic potential.

Natural Compounds in Sex Hormone-Dependent Cancers: The Role of Triterpenes as Therapeutic Agents

Sex hormone-dependent cancers currently contribute to the high number of cancer-related deaths worldwide. The study and elucidation of the molecular mechanisms underlying the progression of these tumors was a double-edged sword, leading to the expansion and development of new treatment options, with the cost of triggering more aggressive, therapy resistant relapses. The interaction of androgen, estrogen and progesterone hormones with specific receptors (AR, ER, PR) has emerged as a key player in the development and progression of breast, ovarian, prostate and endometrium cancers. Sex hormone-dependent cancers share a common and rather unique carcinogenesis mechanism involving the active role of endogenous and exogenous sex hormones to maintain high mitotic rates and increased cell proliferation thus increasing the probability of aberrant gene occurrence and accumulation highly correlated with abnormal cell division and the occurrence of malignant phenotypes. Cancer related hormone therapy has evolved, currently being associated with the blockade of other signaling pathways often associated with carcinogenesis and tumor progression in cancers, with promising results. However, despite the established developments, there are still several shortcomings to be addressed. Triterpenes are natural occurring secondary metabolites biosynthesized by various pathways starting from squalene cyclization. Due to their versatile therapeutic potential, including the extensively researched antiproliferative effect, these compounds are most definitely a cornerstone in the research and development of new natural/semisynthetic anticancer therapies. The present work thoroughly describes the ongoing research related to the antitumor activity of triterpenes in sex hormone-dependent cancers. Also, the current review highlights both the biological activity of various triterpenoid compounds and their featured mechanisms of action correlated with important chemical structural features.

High bisphenol A concentrations augment the invasiveness of tumor cells through Snail-1/Cx43/ERRγ-dependent epithelial-mesenchymal transition

Bisphenol A (BPA) is commonly present in plastics used for food storage and preservation. The release of BPA from these products results in a permanent human exposition to BPA; however, the quality and quantity of BPA adverse effects remain a matter of controversy. The common presence of BPA in the human environment and the controversies concerning the relations of human exposition to BPA and cancer incidence justify the research on the interactions between BPA and pro-metastatic signaling in cancer cells. Here, we describe a novel BPA-reactive signaling axis that induces the epithelial-mesenchymal transition (EMT) in lung adenocarcinoma A549 cells. BPA exerted negligible effects on their properties in a wide range of concentrations (10 nM - 100 nM), whereas it considerably induced A549 invasiveness at high concentrations (10 μM). The BPA-induced EMT was illustrated by morphologic changes, E/N-cadherin switch and vimentin/Snail-1/connexin(Cx)43 up-regulation in A549 populations. It was followed by enhancement of A549 drug-resistance. Corresponding effects of BPA were observed in prostate cancer cell populations. Concomitantly, we observed increased levels and perinuclear accumulation of estrogen-related receptor gamma (ERRγ) in BPA-treated cells, its interactions with Cx43/Snail-1, and the corresponding effects of phenol red on A549 cells. Collectively, these data identify a novel, pro-metastatic Snail-1/Cx43/ERRγ signaling pathway. Its reactivity to BPA underlies the induction of cancer cells' invasiveness in the presence of high BPA concentrations in vitro. Thus, the chronic exposition of cancer cells to extrinsic and intrinsic BPA should be considered as a potential obstacle in a cancer therapy.

Cytoprotective Compounds Interfere with the Nutraceutical Potential of Bread Supplemented with Green Coffee Beans

The proliferation and motile activity of prostate epithelial (Pnt2) and cancer cells (DU-145; PC-3) in the presence of bioavailable compounds from green coffee beans (GCB), wholemeal wheat bread (WMWB), and its GCB-fortified variant were analyzed. The considerable cytostatic and anti-invasive activity of GCB extracts was correlated with its phenolic contents. WMWB extract contained significantly lower levels of phenolics but still displayed relatively high cytostatic activity. However, the cytostatic properties of WMWB compounds were hardly augmented by 3% GCB flour supplementation. The cytoprotective activity of the WMWB compounds exerts a negative impact on the cytostatic activity of GCB compounds. These data confirm the relatively high chemopreventive potential of GCB. However, they also indicate that subtle interactions between bioavailable compounds in GCB and WMWB can negatively affect the nutraceutic potential of the fortified bread. Apparently, gastrointestinal processing differentially regulates the availability of individual compounds and affects the balance between the cytostatic and cytoprotective activity of the whole product. Our data show that comprehensive research is necessary before the fortification of a specific carrier with a specific supplement can be recommended.

Melanin presence inhibits melanoma cell spread in mice in a unique mechanical fashion

Melanoma is a highly aggressive cancer that exhibits metastasis to various critical organs. Unlike any other cancer cells, melanoma cells can synthesize melanin in large amounts, becoming heavily pigmented. Until now the role of melanin in melanoma, particularly the effect of melanin presence on the abilities of melanoma cells to spread and metastasize remains unknown. Recently, we have shown that melanin dramatically modified elastic properties of melanoma cells and inhibited the cells invasive abilities in vitro. Here, we inoculated human melanoma cells with different melanin content into nude mice and tested the hypothesis that cell elasticity is an important property of cancer cells for their efficient spread in vivo. The obtained results clearly showed that cells containing melanin were less capable to spread in mice than cells without the pigment. Our findings indicate that the presence of melanin inhibits melanoma metastasis, emphasizing possible clinical implications of such an inhibitory effect.

Therapeutic potential of monoterpene α-thujone, the main compound of Thuja occidentalis L. essential oil, against malignant glioblastoma multiforme cells in vitro

Thuja occidentalis L. is indigenous for Northern America and commonly cultivated in Europe. Raw materials obtained from this tree are widely applied in the ethnomedicine and phytotherapy of numerous ailments, incl. scurvy, cystitis, rheumatism and cancer. Despite wide medicinal applications of Thuja occidentalis, still little is known on its therapeutic potential in tumor treatment. α-thujone is the main component of Thuja occidentalis essential oil, which has been suggested to possess anti-tumor activities. This monoterpene easily penetrates the blood-brain barrier. Therefore, we examined its effects on the malignancy of glioblastoma multiforme (GBM) cells, with the special emphasis on the mechanisms of its effect on cell viability and invasiveness. α-thujone exerted the attenuating effect on the viability and proliferation of GBM cells when administered at the concentrations between 100 and 500 μg/ml (660 μM - 3.2 mM). This effect was correlated with the induction of apoptosis in GBM cell populations and with considerable inhibition of GBM cells motility. Mechanistic analyses demonstrated the induction of oxidative stress and autophagy in α-thujone-treated tumor cells, whereas normal astrocytes displayed considerably lower sensitivity to α-thujone. Our observations demonstrate that α-thujone exerts pro-apoptotic and anti-invasive effects on GBM cells. They confirm the potential of α-thujone for the treatment of glioblastoma multiforme.

Fenofibrate Augments the Sensitivity of Drug-Resistant Prostate Cancer Cells to Docetaxel

Metronomic agents reduce the effective doses and adverse effects of cytostatics in cancer chemotherapy. Therefore, they can enhance the treatment efficiency of drug-resistant cancers. Cytostatic and anti-angiogenic effects of fenofibrate (FF) suggest that it can be used for the metronomic chemotherapy of drug-resistant prostate tumors. To estimate the effect of FF on the drug-resistance of prostate cancer cells, we compared the reactions of naïve and drug-resistant cells to the combined treatment with docetaxel (DCX)/mitoxantrone (MTX) and FF. FF sensitized drug-resistant DU145 and PC3 cells to DCX and MTX, as illustrated by their reduced viability and invasive potential observed in the presence of DCX/MTX and FF. The synergy of the cytostatic activities of both agents was accompanied by the inactivation of P-gp-dependent efflux, dysfunction of the microtubular system, and induction of polyploidy in DCX-resistant cells. Chemical inhibition of PPARα- and reactive oxygen species (ROS)-dependent pathways by GW6471 and N-acetyl-L-cysteine, respectively, had no effect on cell sensitivity to combined DCX/FF treatment. Instead, we observed the signs of adenosine triphosphate (ATP) deficit and autophagy in DCX/FF-treated drug-resistant cells. Furthermore, the cells that had been permanently propagated under DCX- and DCX/FF-induced stress did not acquire DCX/FF-resistance. Instead, relatively slow proliferation of DCX-resistant cells was efficiently inhibited by FF. Collectively, our observations show that FF reduces the effective doses of DCX by interfering with the drug resistance and energy metabolism of prostate cancer cells. Concomitantly, it impairs the chemotherapy-induced microevolution and expansion of DCX/FF-resistant cells. Therefore, FF can be applied as a metronomic agent to enhance the efficiency of palliative chemotherapy of prostate cancer.

Nanomechanical Phenotype of Melanoma Cells Depends Solely on the Amount of Endogenous Pigment in the Cells

Cancer cells have unique nanomechanical properties, i.e., they behave as if they were elastic. This property of cancer cells is believed to be one of the main reasons for their facilitated ability to spread and metastasize. Thus, the so-called nanomechanical phenotype of cancer cells is viewed as an important indicator of the cells’ metastatic behavior. One of the most highly metastatic cancer cells are melanoma cells, which have a very unusual property: they can synthesize the pigment melanin in large amounts, becoming heavily pigmented. So far, the role of melanin in melanoma remains unclear, particularly the impact of the pigment on metastatic behavior of melanoma cells. Importantly, until recently the potential mechanical role of melanin in melanoma metastasis was completely ignored. In this work, we examined melanoma cells isolated from hamster tumors containing endogenous melanin pigment. Applying an array of advanced microscopy and spectroscopy techniques, we determined that melanin is the dominating factor responsible for the mechanical properties of melanoma cells. Our results indicate that the nanomechanical phenotype of melanoma cells may be a reliable marker of the cells’ metastatic behavior and point to the important mechanical role of melanin in the process of metastasis of melanoma.

Crosstalk between RON and androgen receptor signaling in the development of castration resistant prostate cancer

Castrate-resistant prostate cancer (CRPC) is the fatal form of prostate cancer. Although reactivation of androgen receptor (AR) occurs following androgen deprivation, the precise mechanism involved is unclear. Here we show that the receptor tyrosine kinase, RON alters mechanical properties of cells to influence epithelial to mesenchymal transition and functions as a transcription factor to differentially regulate AR signaling. RON inhibits AR activation and subset of AR-regulated transcripts in androgen responsive LNCaP cells. However in C4-2B, a castrate-resistant sub-line of LNCaP and AR-negative androgen independent DU145 cells, RON activates subset of AR-regulated transcripts. Expression of AR in PC-3 cells leads to activation of RON under androgen deprivation but not under androgen proficient conditions implicating a role for RON in androgen independence. Consistently, RON expression is significantly elevated in castrate resistant prostate tumors. Taken together our results suggest that RON activation could aid in promoting androgen independence and that inhibition of RON in combination with AR antagonist(s) merits serious consideration as a therapeutic option during hormone deprivation therapy.

Chemopreventive and Anticancer Activities of Bacopa Monnieri Extracted from Artificial Digestive Juices

Bacopa monnieri (L.) Pennell (water hyssop) from the Scrophulariaceae family represents one of the best known plants of the Ayurveda system, with reported procognitive, antioxidant, anti-inflammatory, neuroprotective, and anticonvulsant activity. It is considered to be a central nervous system modulating agent. However, recent studies have indicated its potential use in cancer prevention and treatment. Here we report the findings from a study of the effects of B. monnieri extracts derived from artificial digestive juices on physiological traits of prostate cancer cells (DU 145), such as viability and migratory activity. The safety profile and chemopreventive potential of B. monnieri extracts were investigated in Vibrio harveyi mutagenicity assays. Additionally, in this study for the first time the content of phenolic compounds and bacosides released from B. monnieri biomass to artificial digestive juices was determined. The investigated extracts were cytotoxic to DU 145; however, in non-cytotoxic concentrations, they significantly reduced cancer cell motility, thereby demonstrated anti-invasive activity. All extracts under study exhibited very strong antimutagenic activity against nitroquinoline- N-oxide. Bacoside A and phenolic acids were determined, but qualitative and quantitative differences between extracts were found.

HyPer Family Probes: State of the Art

SIGNIFICANCE

Hydrogen peroxide (H2O2) is not only a key mediator of oxidative stress but also one of the most important cellular second messengers. This small short-lived molecule is involved in the regulation of a wide range of different biological processes, including regulation of cellular signaling pathways. Studying the role of H2O2 in living systems would be challenging without modern approaches. A genetically encoded fluorescent biosensor, HyPer, is one of the most effective tools for this purpose.

RECENT ADVANCES

HyPer has been used by many investigators of redox signaling in various models of different scales: from cytoplasmic subcompartments and single cells to tissues of whole organisms. In many studies, the results obtained using HyPer have enabled a better understanding of the roles of H2O2 in these biological processes. However, much remains to be learned.

CRITICAL ISSUES

In this review, we focus on the uses of HyPer. We provide a general description of HyPer and its improved versions. Separate chapters are devoted to the results obtained by various groups who have used this biosensor for their experiments in living cells and organisms.

FUTURE DIRECTIONS

HyPer is an effective tool for H2O2 imaging in living systems as indicated by the increasing numbers of publications each year since its development. However, this biosensor requires further improvements. In particular, much brighter and more pH-stable versions of HyPer are necessary for imaging in mammalian tissues. Antioxid. Redox Signal. 24, 731-751.

Development and Validation of a Rapid and Simple UPLC-ESI-MS Method for Pharmacokinetics and Tissue Distribution of Astragaloside III in Rats

A rapid and simple ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS) method for the determination of astragaloside III was developed and used in a pharmacokinetic and tissue distribution study in rats following the oral administration 95% ethanol extraction of Zhenqi Fuzheng capsules. Although astragaloside III and astragaloside IV have the same molecular weight and very similar structures, they were successfully separated using this method. Quantification was performed using low-energy collision tandem mass spectrometry (CID-MS-MS) with the multiple reaction monitoring scan mode of the following precursor ion → product ion atm/z807.61→335.22 for astragaloside III and atm/z633.18→331.18 for the internal standard (hesperidin). Both astragaloside III and astragaloside IV in rat plasma were best fit to a two-compartment model. The tissue distribution study showed the overall trend of disposition of astragaloside III were C thymus > C spleen > C stomach > C liver > C heart > C kidney > C lung > C testicle The high levels of astragaloside III in thymus and spleen indicated an accumulation in organs involved in immune responses and showed that these organs are major target sites in vivo The results in the article will provide valuable information for use in clinical applications of astragaloside III.

Cell elasticity is an important indicator of the metastatic phenotype of melanoma cells

The relationship between melanin pigmentation and metastatic phenotype of melanoma cells is an intricate issue, which needs to be unambiguously determined to fully understand the process of metastasis of malignant melanoma. Despite significant research efforts undertaken to solve this problem, the outcomes are far from being satisfying. Importantly, none of the proposed explanations takes into consideration biophysical aspects of the phenomenon such as cell elasticity. Recently, we have demonstrated that melanin granules dramatically modify elastic properties of pigmented melanoma cells. This prompted us to examine the mechanical effects of melanosomes on the transmigration abilities of melanoma cells. Here, we show for the first time that melanin granules inhibit transmigration abilities of melanoma cells in a number of granules dependent manner. Moreover, we demonstrate that the inhibitory effect of melanosomes is mechanical in nature. Results obtained in this study demonstrate that cell elasticity may play a key role in the efficiency of melanoma cells spread in vivo. Our findings may also contribute to better understanding of the process of metastasis of malignant melanoma.

The roles of cellular nanomechanics in cancer

The biomechanical properties of cells and tissues may be instrumental in increasing our understanding of cellular behavior and cellular manifestations of diseases such as cancer. Nanomechanical properties can offer clinical translation of therapies beyond what are currently employed. Nanomechanical properties, often measured by nanoindentation methods using atomic force microscopy, may identify morphological variations, cellular binding forces, and surface adhesion behaviors that efficiently differentiate normal cells and cancer cells. The aim of this review is to examine current research involving the general use of atomic force microscopy/nanoindentation in measuring cellular nanomechanics; various factors and instrumental conditions that influence the nanomechanical properties of cells; and implementation of nanoindentation methods to distinguish cancer cells from normal cells or tissues. Applying these fundamental nanomechanical properties to current discoveries in clinical treatment may result in greater efficiency in diagnosis, treatment, and prevention of cancer, which ultimately can change the lives of patients.

Research Progress on Natural Triterpenoid Saponins in the Chemoprevention and Chemotherapy of Cancer

Triterpenoid saponins are glycosides with remarkable structural and bioactive diversity. They are becoming increasingly significant in the treatment of cancer due to their efficacy and safety. This chapter provides an update on the sources, pharmacological effects, structure-activity relationships, and clinical studies of anticancer triterpenoid saponins with a particular focus on the molecular mechanisms underlying their therapeutic properties. The correlative references and study reports described were collected through PubMed. The anticancer triterpenoid saponins enable the inhibition of cancer formation and progression by modulating multiple signaling targets related to cellular proliferation, apoptosis, autophagy, metastasis, angiogenesis, inflammation, oxidative stress, multidrug resistance, cancer stem cells, and microRNAs. This review provides new insights into the molecular basis of triterpenoid saponins in the chemoprevention and chemotherapy of cancer.