Toxins

Extract of Indigofera spicata Exerts Antiproliferative Effects on Human Colorectal and Ovarian Carcinoma Cells

Metabolic anticancer therapy based on enzymatic arginine (Arg) deprivation (ADT) is currently being evaluated in clinical trials. The combination of ADT with low doses of the plant cytotoxic analogs of Arg, canavanine (Cav) or indospicine (Isp), have been proposed as being more efficient and selective against malignant cells. The leguminous plant Indigofera spicata contains one of the highest known amounts of Isp. Here we demonstrate for the first time that the Isp-containing ethanolic extract from I. spicata is growth-inhibiting and toxic for cultured human colorectal and ovarian carcinoma cells. The extract reduces the viability of colorectal carcinoma cells two-fold under Arg-deficient conditions and entirely abrogates their residual proliferative potential (growth recovery) after the treatment. Pre-exposure of the extract to recombinant human arginase I (rhARGI) as a therapeutic Arg-depleting agent did not impact the extract’s efficacy. Further development of Isp as a component of combinatorial anticancer metabolic targeting strategies is discussed.

The Possible Role of Mycotoxins in the Pathogenesis of Endometrial Cancer

Endometrial cancer is one of the most common cancer types among women. Many factors can contribute to the development of this disease, including environmental factors and, thus, eating habits. Our study aims to determine the levels of various mycotoxins and their metabolites in the blood serum and endometrial tissue samples of participants with previously proven endometrial cancer and to find possible contributions to cancer development. In the cohort clinical trial, 52 participants aged between 44 and 86 were studied. The participants were divided into two groups: patients or matched controls. All patients had previously histologically diagnosed endometrial cancer. The cancer patients were divided into low-grade endometrioid and low- plus high-grade endometrioid groups. Controls had no history of endometrial malignancy or premalignancy. Blood serum and endometrial tissue samples were obtained from all study patients. We compared the concentrations of total Aflatoxins (Afs), Deoxynivalenol (DON), Ochratoxin-A (OTA), T2-toxin and HT2 toxin (T2/HT2 toxin), Zearalenone (ZEN), alpha-Zearalenol (α-ZOL), and Fumonisin B1 (FB1) in the serum and endometrium between the different study groups. As a result, we can see a significant correlation between the higher levels of Afs and zearalenone and the presence of endometrial cancer. In the case of Afs, DON, OTA, T2/HT2 toxins, ZEN, and alpha-ZOL, we measured higher endometrial concentrations than in serum. Considering the effect of mycotoxins and eating habits on cancer development, our results might lead to further research exploring the relationship between certain mycotoxins and endometrium cancer.

Wide-Targeted Metabolome Analysis Identifies Potential Biomarkers for Prognosis Prediction of Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is a fatal gynecologic cancer, and its poor prognosis is mainly due to delayed diagnosis. Therefore, biomarker identification and prognosis prediction are crucial in EOC. Altered cell metabolism is a characteristic feature of cancers, and metabolomics reflects an individual’s current phenotype. In particular, plasma metabolome analyses can be useful for biomarker identification. In this study, we analyzed 624 metabolites, including uremic toxins (UTx) in plasma derived from 80 patients with EOC using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Compared with the healthy control, we detected 77 significantly increased metabolites and 114 significantly decreased metabolites in EOC patients. Especially, decreased concentrations of lysophosphatidylcholines and phosphatidylcholines and increased concentrations of triglycerides were observed, indicating a metabolic profile characteristic of EOC patients. After calculating the parameters of each metabolic index, we found that higher ratios of kynurenine to tryptophan correlates with worse prognosis in EOC patients. Kynurenine, one of the UTx, can affect the prognosis of EOC. Our results demonstrated that plasma metabolome analysis is useful not only for the diagnosis of EOC, but also for predicting prognosis with the variation of UTx and evaluating response to chemotherapy.

Shiga Toxin Uptake and Sequestration in Extracellular Vesicles Is Mediated by Its B-Subunit

Shiga toxin (Stx)-stimulated blood cells shed extracellular vesicles (EVs) which can transfer the toxin to the kidneys and lead to hemolytic uremic syndrome. The toxin can be taken up by renal cells within EVs wherein the toxin is released, ultimately leading to cell death. The mechanism by which Stx is taken up, translocated, and sequestered in EVs was addressed in this study utilizing the B-subunit that binds to the globotriaosylceramide (Gb3) receptor. We found that Stx1B was released in EVs within minutes after stimulation of HeLa cells or red blood cells, detected by live cell imaging and flow cytometry. In the presence of Retro-2.1, an inhibitor of intracellular retrograde trafficking, a continuous release of Stx-positive EVs occurred. EVs from HeLa cells possess the Gb3 receptor on their membrane, and EVs from cells that were treated with a glycosylceramide synthase inhibitor, to reduce Gb3, bound significantly less Stx1B. Stx1B was detected both on the membrane and within the shed EVs. Stx1B was incubated with EVs derived from blood cells, in the absence of cells, and was shown to bind to, and be taken up by, these EVs, as demonstrated by electron microscopy. Using a membrane translocation assay we demonstrated that Stx1B was taken up by blood cell- and HeLa-derived EVs, an effect enhanced by chloropromazine or methyl-ß-cyclodextrin, suggesting toxin transfer within the membrane. This is a novel mechanism by which EVs derived from blood cells can sequester their toxic content, possibly to evade the host response.