Autophagic-lysosomal damage induced by swainsonine is protected by trehalose through activation of TFEB-regulated pathway in renal tubular epithelial cells.

Swainsonine (SW) is the main toxic component of locoweed. Previous studies have shown that kidney damage is an early pathologic change in locoweed poisoning in animals. Trehalose induces autophagy and alleviates lysosomal damage, while its protective effect and mechanism against the toxic injury induced by SW is not clear. Based on the published literature, we hypothesize that transcription factor EB(TFEB) -regulated is targeted by SW and activating TFEB by trehalose would reverse the toxic effects. In this study, we investigate the mechanism of protective effects of trehalose using renal tubular epithelial cells. The results showed that SW induced an increase in the expression level of microtubule-associated protein light chain 3-II and p62 proteins and a decrease in the expression level of ATPase H+ transporting V1 Subunit A, Cathepsin B, Cathepsin D, lysosome-associated membrane protein 2 and TFEB proteins in renal tubular epithelial cells in a time and dose-dependent manner suggesting TFEB-regulated lysosomal pathway is adversely affected by SW. Conversely, treatment with trehalose, a known activator of TFEB promote TFEB nuclear translocation suggesting that TFEB plays an important role in protection against SW toxicity. We demonstrated in lysosome staining that SW reduced the number of lysosomes and increased the luminal pH, while trehalose could counteract these SW-induced effects. In summary, our results demonstrated for the first time that trehalose could alleviate the autophagy degradation disorder and lysosomal damage induced by SW. Our results provide an interesting method for reversion of SW-induced toxicity in farm animals and furthermore, activation of TFEB by trehalose suggesting novel mechanism of treating lysosomal storage diseases.

Ipomoea carnea alkaloid extract vs swainsonine: A comparative study on cytotoxic activity against glial cells.

The consumption of Ipomoea carnea produces a neurological syndrome in animals. The toxic principles of I. carnea are the alkaloids swainsonine (SW) and calystegines B1, B2, B3 and C1. In this study, we investigated the cytotoxicity of an alkaloid extract of Ipomoea carnea (AEE) and natural swainsonine (SW) isolated from Astragalus lentiginosus (25-1000 µM of SW) for 48 h in a glioma cell line. Although the natural SW did not induce any changes in cell viability, the AEE exhibited a dose dependent cytotoxic effect and release of lactate dehydrogenase (LDH) indicative of cytolysis. In order to evaluate the morphological changes involved, cells were examined using phase contrast and fluorescence microscopy with acridine orange-ethidium bromide staining. The AEE caused a cell death compatible with necrosis, whereas exposure to 1000 µM of SW resulted in cytoplasmic vacuolation. Immunocytochemical studies revealed that astrocytes treated with 150 µM of AEE from I. carnea or 1000 µM of SW exhibited morphological characteristics of cell activation. These findings suggest that swainsonine would not be the only component present in the AEE of I. carnea responsible for in vitro cytotoxicity. Calystegines might also play a role in acting synergistically and triggering cell death through necrosis.

Swainsonine-induced vacuolar degeneration is regulated by mTOR-mediated autophagy in HT22 cells.

The indolizidine alkaloid, swainsonine (SW), is the main toxic component of locoweed, which can cause locoism in animals with characteristic neurological dysfunction. Pathological manifestations at cellular level include extensive vacuolar degeneration. Studies have shown that SW can induces autophagy, but the role and mechanism of autophagy in SW-induced vacuolar degeneration is unclear. In this study, we analyzed the role of autophagy in SW-induced cell injury in mouse hippocampal neurons cell line (HT22) using western blotting, qRT-PCR, transmission electron microscopy and immunofluorescence microscopy. The results showed that the expressions of LC3-II, ATG5, Beclin1 and p62 proteins and their mRNAs in HT22 cells were induced by SW treatment. The SW treatment increased the number of autophagosomes with enhanced fluorescence intensity of monodansylcadaverine (MDC) and LC3-II in a time-dose dependent manner. The results of lysosome staining showed that SW could increase the number of lysosomes, increase the intraluminal pH. Transmission electron microscopy results indicate that SW induced autophagosomes, and Baf A1 could effectively alleviate SW-induced vacuolar degeneration. At the molecular level, SW treatment inhibited the expression of p-PI3K, p-AKT, p-ERK, p-AMPK, p-mTOR, p-p70S6K and p-4EBP1 and promoted the expression of p53. Our results collectively suggest, PI3K/AKT/mTOR, ERK/mTOR and p53/mTOR signaling pathways are involved in the regulation of SW-induced autophagy in HT22 cells, while the AMPK/mTOR signaling pathway is not involved in this regulation. Inhibition of autophagic degradation can effectively alleviate SW-induced vacuolar degeneration.

Evaluation of the context of downstream N- and free N-glycomic alterations induced by swainsonine in HepG2 cells.

Swainsonine (SWA), a potent inhibitor of class II α-mannosidases, is present in a number of plant species worldwide and causes severe toxicosis in livestock grazing these plants. The mechanisms underlying SWA-induced animal poisoning are not fully understood. In this study, we analyzed the alterations that occur in N- and free N-glycomic upon addition of SWA to HepG2 cells to understand better SWA-induced glycomic alterations. After SWA addition, we observed the appearance of SWA-specific glycomic alterations, such as unique fucosylated hybrid-type and fucosylated M5 (M5F) N-glycans, and a remarkable increase in all classes of Gn1 FNGs. Further analysis of the context of these glycomic alterations showed that (fucosylated) hybrid type N-glycans were not the precursors of these Gn1 FNGs and vice versa. Time course analysis revealed the dynamic nature of glycomic alterations upon exposure of SWA and suggested that accumulation of free N-glycans occurred earlier than that of hybrid-type N-glycans. Hybrid-type N-glycans, of which most were uniquely core fucosylated, tended to increase slowly over time, as was observed for M5F N-glycans. Inhibition of swainsonine-induced unique fucosylation of hybrid N-glycans and M5 by coaddition of 2-fluorofucose caused significant increases in paucimannose- and fucosylated paucimannose-type N-glycans, as well as paucimannose-type free N-glycans. The results not only revealed the gross glycomic alterations in HepG2 cells induced by swainsonine, but also provide information on the global interrelationships between glycomic alterations.

Swainsonine producing performance of Alternaria oxytropis was improved by heavy-ion mutagenesis technology.

Swainsonine, an indolizidine alkaloid, is a promising anti-tumorigenic compound. Biological production of swainsonine was prospective, but the low swainsonine yield of wild type Alternaria oxytropis limited its production on a large scale. In present work, a stable A. oxytropis mutant UO1 with swanisonine yield of 14.84% higher than the wild-type strain was successfully obtained after heavy-ion irradiation. The A. oxytropis mutant UO1 and original wild-type strain were futher evaluated for SW concentrations under different factors. Results showed that the optimum culture temperature was 25°C. The optimum initial medium pH was 6.5 and the optimum inoculum size was 2 mL per 200 mL. Addition of the biosynthetic precursor L-pipecolic acids and L-lysine appropriately could increase the SW synthesis. These findings provided a theoretical basis and scientific data for the industrial production of swainsonine.

Swainsonine promotes apoptosis by impairing lysosomal function and inhibiting autophagic degradation in rat primary renal tubular epithelial cells.

Swainsonine (SW), an indolizidine alkaloid, is the primary toxin in locoweeds that causes toxicity syndrome in livestock. Current research shows that SW can induce both apoptosis and autophagy. However, the relationship between, and regulatory mechanism of, autophagy and apoptosis in SW-mediated cytotoxicity remain unclear. In this study, we investigated the role of autophagy and apoptosis in SW-induced cytotoxicity in rat primary renal tubular epithelial cells (RTECs). We examined the effect of SW on lysosomal function using western blotting, transmission electron microscopy, fluorescent microscopy, and flow cytometry. The results showed that SW induced both autophagy and apoptosis, and autophagy protected RTECs from cellular damage. Activating autophagy using rapamycin (Rapa) inhibited apoptosis, while suppressing autophagy using bafilomycin A1 (Baf A1) greatly enhanced SW-induced apoptosis. SW treatment suppressed the expression of lysosomal-related proteins, and co-incubation with SW and aloxistatin (E64d) further promoted apoptosis and LC3-II accumulation in RTECs. These results suggest that SW causes toxicity by disrupting lysosomal dysfunction, inhibiting autophagic degradation, and promoting apoptosis.

Curcumin Derivative GT863 Inhibits Amyloid-Beta Production via Inhibition of Protein N-Glycosylation.

Amyloid-ß (Aß) peptides play a crucial role in the pathogenesis of Alzheimer's disease (AD). Aß production, aggregation, and clearance are thought to be important therapeutic targets for AD. Curcumin has been known to have an anti-amyloidogenic effect on AD. In the present study, we performed screening analysis using a curcumin derivative library with the aim of finding derivatives effective in suppressing Aß production with improved bioavailability of curcumin using CHO cells that stably express human amyloid-ß precursor protein and using human neuroblastoma SH-SY5Y cells. We found that the curcumin derivative GT863/PE859, which has been shown to have an inhibitory effect on Aß and tau aggregation in vivo, was more effective than curcumin itself in reducing Aß secretion. We further found that GT863 inhibited neither ß- nor γ-secretase activity, but did suppress γ-secretase-mediated cleavage in a substrate-dependent manner. We further found that GT863 suppressed N-linked glycosylation, including that of the γ-secretase subunit nicastrin. We also found that mannosidase inhibitors that block the mannose trimming step of N-glycosylation suppressed Aß production in a similar fashion, as was observed as a result of treatment with GT863. Collectively, these results suggest that GT863 downregulates N-glycosylation, resulting in suppression of Aß production without affecting secretase activity.

Swainsonine protects H9c2 cells against lipopolysaccharide-induced apoptosis and inflammatory injury via down-regulating miR-429.

Pediatric myocarditis (PM) is usually related to myocardial dysfunction. Generally, 30% of PM patients will die or undergo heart transplantation. Swainsonine (SW) is a natural alkaloid and an anti-cancer substance. Our goal was to determine the roles of SW in PM in current study. H9c2 cells were pre-treated by lipopolysaccharide (LPS). Viability and apoptosis were evaluated utilizing CCK-8 assay and flow cytometry. Inflammatory cytokines' mRNA expression and production were assessed by western blot and ELISA. Western blot was utilized to distinguish apoptosis and immune-related factors expression. Sequentially, the abovementioned parameters were reassessed when miR-429 was overexpressed. LPS declined viability as well as raised apoptosis and inflammatory injury in H9c2 cells. SW alleviated apoptosis and inflammatory injury induced by LPS. MiR-429 expression was elevated by LPS and suppressed by SW. SW-induced the increasing of viability and the reduction of inflammatory injury were reversed by overexpression of miR-429. Eventually, SW inhibited p38MAPK/NF-κB pathway which activated by LPS via overexpressing miR-429. SW exerted its anti-apoptosis and anti-inflammatory function in LPS-treated H9c2 cells through p38MAPK/NF-κB pathway and down-regulation of miR-429.

Swainsonine induces autophagy via PI3K/AKT/mTOR signaling pathway to injure the renal tubular epithelial cells.

Swainsonine is a major toxic ingredients of locoweed plants, ingestion of these plants may cause locoism in livestock characterized by extensive cellular vacuolar degeneration of multiple tissues. However, so far, the mechanisms responsible for vacuolar degeneration induced by SW are not known. In this study, we investigated the role of autophagy in SW-induced TCMK-1 cells using Western blotting, transmission electron microscopy, immunofluorescent microscopy and qRT-PCR. The results showed that SW treatment increased the levels of LC3-II. The co-localization of LC3-II and lysosomal protein LAMP-2 results suggested that SW treatment does not interfere with fusion between autophagosome and lysosome. TEM results indicated that SW induced aggregation of the lysosome around the autophagosome. In addition, SW treatment suppressed p-PI3K, p-Akt, p-mTOR, p-p70S6K and p-4EBP1 level. In conclusion, SW induced autophagy via pI3K/AKT/mTOR signaling pathway and revealed the role of autophagy in causing the SW toxicity characterized by the vacuolar degeneration.

Swainsonine inhibits proliferation and collagen synthesis of NIH-3T3 cells by declining miR-21.

Swainsonine (SW) is an indolizidine alkaloid first discovered in Swainsona canescens. This study explored the effects of SW on mouse embryo fibroblast NIH-3T3 cell proliferation and collagen synthesis, as well as potential molecule mechanisms. We discovered that SW exposure lowered the viability and proliferation of NIH-3T3 cells. The collagen synthesis was reduced after SW exposure, as evidenced by declines of the mRNA and protein levels of collagen I (CoI I), collagen III (CoI III) and α-smooth muscle actin (α-SMA) in NIH-3T3 cells, as well as reduction of collagen concentration in the culture supernatant of NIH-3T3 cells. Mechanically, transforming growth factor ß1 (TGF-ß1) stimulation elevated the microRNA-21 (miR-21) expression in NIH-3T3 cells. SW reversed the TGF-ß1-caused elevation of miR-21. Up-regulation of miR-21 attenuated the inhibitory influences of SW on NIH-3T3 cell viability, proliferation and collagen synthesis. Silence of miR-21 had converse influence. Besides, SW inactivated PI3K/AKT and NF-κB pathways via declining miR-21. Altogether, SW inhibited the proliferation and collagen synthesis of fibroblast NIH-3T3 might be through declining miR-21 and then suppressing PI3K/AKT and NF-κB pathways. SW may be an effective therapeutic medicine for scar hyperplasia.

Sesquiterpenoids and mycotoxin swainsonine from the locoweed endophytic fungus Alternaria oxytropis.

Oxytropiols A-J, ten undescribed guaiane-type sesquiterpenoids, and the mycotoxin swainsonine (SW) were isolated from the locoweed endophytic fungus Alternaria oxytropis. The chemical structures of these sesquiterpenoids were elucidated on the basis of HR-ESI-MS and NMR data including 1H, 13C, HSQC, 1H-1H COSY, HMBC, and NOESY spectra, and the absolute configurations of these compounds were determined using a modified Mosher's method and X-ray diffraction spectroscopy. A possible biosynthetic pathway of these guaiane-type sesquiterpenoids is discussed, and proposed that post-modification oxidative enzymes might form these highly polyhydroxylated structures. Compound 1 displayed biological effects on the root growth of Arabidopsis thaliana, and SW displayed cytotoxicity against A549 and HeLa cancer cell lines.

Swainsonine represses glioma cell proliferation, migration and invasion by reduction of miR-92a expression.

BACKGROUND: Swainsonine is a natural indolizidine alkaloid, its anti-tumor activity has been widely reported in varied cancers. This study aimed to investigate whether Swainsonine exerted anti-tumor impact on glioma cells, likewise uncovered the relative molecular mechanisms. METHODS: After administration with diverse concentrations of Swainsonine, cell growth, migration and invasion in U251 and LN444 cells were appraised by the common-used CCK-8, BrdU, flow cytometry and Transwell assays. MiR-92a mimic, inhibitor and the correlative NC were transfected into U251 and LN444 cells, and assessment of miR-92a expression was by utilizing qRT-PCR. Functions of miR-92a in above-mentioned cell biological processes were analyzed again in Swainsonine-treated cells. The momentous proteins of cell cycle, apoptosis and PI3K/AKT/mTOR pathway were ultimately examined by western blot. RESULTS: Swainsonine significantly hindered cell proliferation through decreasing cell viability, declining the percentage of BrdU cells, down-regulating CyclinD1 and up-regulating p16 expression. Enhancement of percentage of apoptotic cells was presented in Swainsonine-treated cells via activating cleaved-Caspase-3 and cleaved-Caspase-9. Additionally, Swainsonine impeded the abilities of migration and invasion by decreasing MMP-2, MMP-9, Vimentin and E-cadherin. Repression of miR-92a was observed in Swainsonine-treated cells, and miR-92a overexpression overturned the anti-tumor activity of Swainsonine in glioma cells. Finally, western blot assay displayed that Swainsonine hindered PI3K/AKT/mTOR pathway via regulating miR-92a. CONCLUSIONS: These discoveries corroborated that Swainsonine exerted anti-tumor impacts on glioma cells via repression of miR-92a, and inactivation of PI3K/AKT/mTOR signaling pathway.

Complex N-glycan promotes CD133 mono-ubiquitination and secretion.

CD133 is a widely used cell surface marker of cancer stem cells that plays an important role in tumor initiation and metastasis. Increasing evidence shows that CD133 is secreted to the extracellular space. However, the underlying mechanisms of CD133 secretion remain largely unknown. In this study, we report that secreted CD133 has a complex-type N-glycosylation and is modified by beta1,6GlcNAc N-glycan. We found that inhibition of CD133 complex-type N-glycosylation by swainsonine does not affect the membrane localization of CD133, but significantly reduces CD133 secretion and promotes its accumulation in early endosomes. Moreover, swainsonine reduces CD133 secretion by reducing its mono-ubiquitination and inhibiting the interaction between CD133 and Tsg101. These findings reveal a new mechanism of glycosylation-dependent secretion of CD133.

Swainsonine, an alpha-mannosidase inhibitor, may worsen cervical cancer progression through the increase in myeloid derived suppressor cells population.

Cervical cancer, caused by high oncogenic risk Human Papillomavirus (HPV) infection, continues to be a public health problem, mainly in developing countries. Using peptide phage display as a tool to identify potential molecular targets in HPV associated tumors, we identified α-mannosidase, among other enriched sequences. This enzyme is expressed in both tumor and inflammatory compartment of the tumor microenvironment. Several studies in experimental models have shown that its inhibition by swainsonine (SW) led to inhibition of tumor growth and metastasis directly and indirectly, through activation of macrophages and NK cells, promoting anti-tumor activity. Therefore, the aim of this work was to test if swainsonine treatment could modulate anti-tumor immune responses and therefore interfere in HPV associated tumor growth. Validation of our biopanning results showed that cervical tumors, both tumor cells and leukocytes, expressed α-mannosidase. Ex vivo experiments with tumor associated macrophages showed that SW could partially modulate macrophage phenotype, decreasing CCL2 secretion and impairing IL-10 and IL-6 upregulation, which prompted us to proceed to in vivo tests. However, in vivo, SW treatment increased tumor growth. Investigation of the mechanisms leading to this result showed that SW treatment significantly induced the accumulation of myeloid derived suppressor cells in the spleen of tumor bearing mice, which inhibited T cell activation. Our results suggested that SW contributes to cervical cancer progression by favoring proliferation and accumulation of myeloid cells in the spleen, thus exacerbating these tumors systemic effects on the immune system, therefore facilitating tumor growth.

Detection of swainsonine and calystegines in Convolvulaceae species from the semiarid region of Pernambuco / Detecção de swainsonina e calisteginas em espécies de Convolvulaceae da região semiárida de Pernambuco

Numerous plant species worldwide including some Ipomoea (Convolvulaceae) and Sida (Malvaceae) species in Brazil cause lysosomal storage disease in herbivores and are known to contain swainsonine and calystegines as the main toxic compounds. The aim of this work was to determine swainsonine and calystegines concentrations in species of Convolvulaceae from the semiarid region of Pernambuco. Seven municipalities in the Moxotó region were visited and nine species were collected and screened for the presence of swainsonine and calystegines using an HPLC-APCI-MS method. The presence and concentration of these alkaloids within the same and in different species were very variable. Seven species are newly reported here containing swainsonine and/or calystegines. Ipomoea subincana contained just swainsonine. Ipomoea megapotamica, I. rosea and Jacquemontia corymbulosa contained swainsonine and calystegines. Ipomoea sericosepala, I. brasiliana, I. nil, I. bahiensis and I. incarnata contained just calystegines. The discovery of six Ipomoea species and one Jacquemontia species containing toxic polyhydroxy alkaloids reinforces the importance of this group of poisonous plants to ruminants and horses in the semiarid region of Pernambuco. Epidemiological surveys should be conducted to investigate the occurrence of lysosomal storage disease associated to these new species.(AU)

Numerosas espécies de plantas em todo o mundo, incluindo algumas espécies de Ipomoea (Convolvulaceae) e Sida (Malvaceae) no Brasil, causam doença de armazenamento lisossomal em herbívoros e são conhecidas por conterem swainsonina e calisteginas como princípios tóxicos. O objetivo deste trabalho foi determinar a concentração de swainsonina e calisteginas em espécies de Convolvulaceae da região semiárida de Pernambuco. Sete municípios na região do Sertão do Moxotó foram visitados, onde foram coletadas amostras das folhas de nove espécies de Convolvulaceae para avaliação da presença de swainsonina e calisteginas utilizando-se cromatografia líquida com espectrometria de massa. A presença e concentração destes alcaloides nas folhas de plantas da mesma espécie e dentre as espécies foram muito variáveis. Seis novas espécies de Ipomoea e uma espécie de Jacquemontia contendo swainsonina e/ou calisteginas são relatadas neste estudo. Ipomoea subincana continha apenas swainsonina. Ipomoea megapotamica, I. rosea e Jacquemontia corymbulosa continham swainsonina e calisteginas. Ipomoea sericosepala, I. brasiliana, I. nil, I. bahiensis e I. incarnata continham apenas calisteginas. A descoberta de novas espécies de Ipomoea e Jacquemontia contendo alcaloides polihidroxílicos tóxicos reforçam a importância deste grupo de plantas tóxicas para ruminantes e equinos na região semiárida de Pernambuco. Pesquisas epidemiológicas devem ser realizadas para investigar a ocorrência de doença de depósito lisossomal associada a essas novas espécies.(AU)

Swainsonine induces apoptosis of rat cardiomyocytes via mitochondria­mediated pathway.

Swainsonine is an Astragalus membranaceus extract. It is indole, alkaloid, and soluble in water. Its effect on rat cardiomyocytes apoptosis, and the mechanisms underlying that effect, were investigated by inducing apoptosis in H9c2 cells. This was detected by MTT assay, Annexin V-FITC/propidium iodide double staining and western blotting. Flow cytometry and fluorescence microscopy were used to confirm swainsonine's effect on mitochondrial membrane potential and levels of reactive oxygen species, while an ATP-dependent bioluminescence assay kit served to find the ATP contents. Assessment was also carried out for peroxisome proliferator activated receptor γ co-activator 1α (PGC-1α) expression levels as well as those of such apoptosis-associated proteins as Cytochrome c, Caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax). Overall, indications were that swainsonine may have the potential to inhibit viability of cells, decrease expression of PGC-1α, induce mitochondrial dysfunction, upregulate Cytochrome c, Bax and Caspase-3, and downregulate Bcl-2. The suggestion would be that apoptosis may be induced through signalling pathways in H9c2 cells mediated by mitochondria.

Integrin expression and glycosylation patterns regulate cell-matrix adhesion and alter with breast cancer progression.

Integrins are the major cell adhesion glycoproteins involved in cell-extracellular matrix (ECM) interaction and metastasis. Further, glycosylation on integrin is necessary for its proper folding and functionality. Herein, differential expression of integrins viz., αvß3 and αvß6 was examined in MDA-MB-231, MDA-MB-468 and MCF-10A cells, which signify three different stages of breast cancer development from highly metastatic to non-tumorigenic stage. The expression of αvß3 and αvß6 integrins at mRNA and protein levels was observed in all three cell lines and the results displayed a distinct pattern of expression. Highly metastatic cells showed enhanced expression of αvß3 than moderate metastatic and non-tumorigenic cells. The scenario was reversed in case of αvß6 integrin, which was strongly expressed in moderate metastatic and non-tumorigenic cells. N-glycosylation of αvß3 and αvß6 integrins is required for the attachment of cells to ECM proteins like fibronectin. The cell adhesion properties were found to be different in these cancer cells with respect to the type of integrins expressed. The results testify that αvß3 integrin in highly metastatic cells, αvß6 integrin in both moderate metastatic and non-tumorigenic cells play an important role in cell adhesion. The investigation typify that N-glycosylation on integrins is also necessary for cell-ECM interaction. Further, glycosylation inhibition by Swainsonine is found to be more detrimental to invasive property of moderate metastatic cells. Conclusively, types of integrins expressed as well as their N-glycosylation pattern alter during the course of breast cancer progression.

Swainsonine Inhibits Invasion and the EMT Process in Esophageal Carcinoma Cells by Targeting Twist1.

Esophageal cancer is a common gastrointestinal cancer, with a very high mortality rate in patients with metastasis. Swainsonine, a cytotoxic fungal alkaloid, has been shown to inhibit cell growth in esophageal cancer. In the present study, we explored the effects of swainsonine on cell invasion and metastasis in esophageal cancer cells. Human esophageal carcinoma cells were treated with different doses of swainsonine, and then cell viability, invasion, and apoptosis were measured. The mRNA and protein expressions of Twist1, apoptosis- and EMT-related factors, and PI3K/AKT pathway factors were detected by qRT-PCR and Western blot. Swainsonine had no effect on esophageal cancer cell viability and apoptosis, but it significantly decreased cell invasion in a dose-dependent manner. Swainsonine increased the expression of E-cadherin but decreased the expression of N-cadherin, vimentin, ZEB1, and snail in a dose-dependent manner, thereby inhibiting EMT. Last, we found that swainsonine inhibits cell invasion and EMT in the esophageal carcinoma cells by downregulation of Twist1 and deactivation of the PI3K/AKT signaling pathway.

The Biosynthesis Pathway of Swainsonine, a New Anticancer Drug from Three Endophytic Fungi.

Swainsonine (SW) is the principal toxic ingredient of locoweed plants that causes locoism characterized by a disorder of the nervous system. It has also received widespread attention in the medical field for its beneficial anticancer and antitumor activities. Endophytic fungi, Alternaria sect. Undifilum oxytropis isolated from locoweeds, the plant pathogen Slafractonia leguminicola, and the insect pathogen Metarhizium anisopliae, produce swainsonine. Acquired SW by biofermentation has a certain foreground and research value. This paper mainly summarizes the local and foreign literature published thus far on the swainsonine biosynthesis pathway, and speculates on the possible regulatory enzymes involved in the synthesis pathway within these three fungi in order to provide a new reference for research on swainsonine biosynthesis by endophytic fungi.

Spontaneous poisoning by Sida carpinifolia (Malvaceae) in horses / Intoxicação natural por Sida carpinifolia em equinos

Sida carpinifolia poisoning causes a chronic neurodegenerative disorder associated with lysosomal storage by indolizidine alkaloids (swainsonine). The epidemiological, clinical, pathological and lectin histochemistry findings of an outbreak of natural poisoning by S. carpinifolia in horses in Rio Grande do Sul state, Brazil, are described. Five horses from a total of 15 that were kept on native pasture with large amounts of S. carpinifolia presented during 90 days clinical signs of progressive weight loss, incoordination, stiff gait and ramble, in addition to exacerbated reactions and locomotion difficulty after induced movement. Four horses died, and one of them was submitted for necropsy. At necropsy, no significant gross lesions were observed. Histological findings observed in the central nervous system were characterized by swollen neurons with cytoplasm containing multiple microvacuoles; these abnormalities were more severe in the thalamus, hippocampus, cerebellum and pons. Using lectin histochemistry, the pons and hippocampus sections stained positive for commercial lectin Con-A, sWGA and WGA. This study aimed to detail S. carpinifolia poisoning in horses to be included in the differential diagnoses of neurological diseases of horses.(AU)

A intoxicação por Sida carpinifolia é uma desordem neurodegenerativa crônica associada ao acúmulo lisossomal pelo alcaloide indolizidínico, denominado swainsonina. Descrevem-se os achados epidemiológicos, clínicos, patológicos e de lectina-histoquímica de um surto de intoxicação natural por S. carpinifolia em equinos no Rio Grande do Sul, Brasil. De um total de 15 equinos, cinco equinos mantidos em campo nativo com grande quantidade de S. carpinifolia apresentaram sinais clínicos de emagrecimento progressivo, incoordenação, andar rígido e deambulação, além de dificuldade de locomoção com reações exacerbadas após estímulos ao movimento em um período de 90 dias de evolução clínica. Quatro equinos vieram a óbito e um foi submetido ao exame de necropsia. À necropsia, não foram observadas lesões macroscópicas. Os achados histológicos observados no sistema nervoso central caracterizaram-se por aumento de tamanho dos neurônios, com citoplasma contendo microvacúolos; tais alterações foram observadas com maior intensidade em tálamo, hipocampo, cerebelo e ponte. Na lectina-histoquímica, fragmentos de ponte e hipocampo marcaram positivamente para as lectinas comerciais Con-A, sWGA e WGA. Este trabalho visa alertar a ocorrência da intoxicação por S. carpinifolia em equinos, a qual deve ser incluída como diagnóstico diferencial dentre as doenças neurológicas de equinos.(AU)