cyanoginosin-lr and Colorectal-Neoplasms

Microcystin-LR (MC-LR) is an extremely poisonous cyanotoxin that poses a threat to ecosystems and human health. MC-LR has been reported as an enterotoxin. The objective of this study was to determine the effect and the mechanism of subchronic MC-LR toxicity on preexisting diet-induced colorectal damage. C57BL/6J mice were given either a regular diet or a high-fat diet (HFD) for 8 weeks. After 8 weeks of feeding, animals were supplied with vehicle or 120 μg/L MC-LR via drinking water for another 8 weeks, and their colorectal were stained with H&E to detect microstructural alterations. Compared with the CT group, the HFD and MC-LR + HFD-treatment group induced a significant weight gain in the mice. Histopathological findings showed that the HFD- and MC-LR + HFD-treatment groups caused epithelial barrier disruption and infiltration of inflammatory cells. The HFD- and MC-LR + HFD-treatment groups raised the levels of inflammation mediator factors and decreased the expression of tight junction-related factors compared to the CT group. The expression levels of p-Raf/Raf and p-ERK/ERK in the HFD- and MC-LR + HFD-treatment groups were significantly increased compared with the CT group. Additionally, treated with MC-LR + HFD, the colorectal injury was further aggravated compared with the HFD-treatment group. These findings suggest that by stimulating the Raf/ERK signaling pathway, MC-LR may cause colorectal inflammation and barrier disruption. This study suggests that MC-LR treatment may exacerbate the colorectal toxicity caused by an HFD. These findings offer unique insights into the consequences and harmful mechanisms of MC-LR and provide strategies for preventing and treating intestinal disorders.

Topics: Animals; Colorectal Neoplasms; Ecosystem; Humans; Inflammation; Mice; Mice, Inbred C57BL; Mice, Obese; Microcystins; Signal Transduction

Microcystin-LR (MC-LR) is a toxic secondary metabolite produced by cyanobacteria that has been demonstrated to promote colorectal cancer (CRC). However, the mechanism by which MC-LR enhances CRC in the tumor microenvironment (TME) is poorly understood. To elucidate its role in TME, a co-culture system was established using CRC cells and M2 macrophages in a Transwell chamber. The study found that MC-LR promotes CRC cell migration by upregulating TGF-β1 expression and secretion in M2 macrophages and downregulating CST3 in CRC cells. Neutralizing TGF-β1 increased CST3 expression in CRC cells, while overexpressing CST3 in CRC cells suppressed TGF-β1 expression in M2 macrophages, both of which weakened MC-LR-induced cellular motility in the co-culture system. In vivo, the mice in the MC-LR/AOM/DSS group had more tumor nodules, deeper tumor invasion, and higher M2 macrophage infiltration compared to the AOM/DSS group, and the expression of TGF-β1 and CST3 in tumors was consistent with the cellular level. Overall, this study provides insights into the regulatory mechanism of MC-LR on TME, revealing that MC-LR upregulates the expression and secretion of TGF-β1 in M2 macrophages, which in turn inhibits the expression of CST3 in CRC cells to promote migration.

Topics: Animals; Cell Line, Tumor; Cell Movement; Colorectal Neoplasms; Mice; Transforming Growth Factor beta1; Tumor Microenvironment; Tumor-Associated Macrophages

Microcystin-LR (MC-LR) contamination is a worldwide environmental problem that poses a grave threat to the water ecosystem and public health. Exposure to MC-LR has been associated with the development of intestinal injury, but there are no effective treatments for MC-LR-induced intestinal disease. Probiotics are "live microorganisms that are beneficial to the health of the host when administered in sufficient quantities". It has been demonstrated that probiotics can prevent or treat a variety of human diseases; however, their ability to mitigate MC-LR-induced intestinal harm has not yet been investigated. The objective of this study was to determine whether probiotics can mitigate MC-LR-induced intestinal toxicity and its underlying mechanisms. We first evaluated the pathological changes in colorectal tissues using an animal model with sub-chronic exposure to low-dose MC-LR, HE staining to assess colorectal histopathologic changes, qPCR to detect the expression levels of inflammatory factors in colorectal tissues, and WB to detect the alterations on CSF1R signaling pathway proteins in colorectal tissues. Microbial sequencing analysis and screening of fecal microorganisms differential to MC-LR treatment in mice. To investigate the role of microorganisms in MC-LR-induced colorectal injury, an in vitro model of MC-LR co-treatment with microorganisms was developed. Our findings demonstrated that MC-LR treatment induced an inflammatory response in mouse colorectal tissues, promoted the expression of inflammatory factors, activated the CSF1R signaling pathway, and significantly decreased the abundance of

Topics: Animals; Colorectal Neoplasms; Ecosystem; Humans; Inflammation; Limosilactobacillus fermentum; Mice

Microcystins-LR (MC-LR), a cyanobacterial toxins, initiate apoptosis in normal and tumor cells. Nitric oxide produced by iNOS is necessary for MC-LR-induced apoptosis. However, the underlying mechanism of NO mediated MC-LR cytotoxicity remains unclear. Here, we performed in vitro experiments on MC-LR cytotoxicity associated with NO induced S-nitrosyation of GAPDH in human colon cancer cells SW480. MTT assay indicated that MC-LR decreased the cellular viability by high concentration (>1 μM). Flow cytometer assay revealed that apoptosis was core mode for MC-LR cytotoxicity. Griess assay showed that MC-LR exposure increased the release of NO through the function of NOS1 and NOS2 in SW480 cells. In turn, NO stress induced the S-nitrosylated modification of GAPDH leading to its nuclear translocation following Siah1 binding. CHIP assay showed that the nuclear GADPH increased P53 transcript of a panner of apoptosis related genes. Moreover, apoptosis induced by MC-LR could be reduced by GAPDH or si-Siah1 or NOSs inhibitor, L-NAME. Thus, our study verified a molecular mechanism of NO/GAPDH/Siah1 cascade in MC-LR mediated apoptosis in colorectal cancer cells, providing a further understanding the in vitro molecular mechanism of MC-LR colorectal toxicity.

Topics: Apoptosis; Bacterial Toxins; Cell Nucleus; Cell Survival; Colonic Neoplasms; Colorectal Neoplasms; Cyanobacteria Toxins; Humans; Marine Toxins; Microcystins; Nitric Oxide; Nitric Oxide Synthase Type II

Increasing evidences suggest that microcystins, a kind of toxic metabolites, produced by cyanobacteria in contaminated water may contribute to the aggravation of the human colorectal carcinoma. Our previous study showed that microcystin-LR (MC-LR) exposure caused significant invasion and migration of colorectal cancer cells. However, the roles of MC-LR in regulating epithelial-mesenchymal transition (EMT) in colorectal cancer cells remain unknown. In our study, we observed that MC-LR treatment decreased epithelial marker E-cadherin expression and up-regulated the levels of mesenchymal markers Vimentin and Snail in colorectal cancer cells. Moreover, MC-LR stimulated protein expression of SMAD2 and phospho-SMAD2 by PI3-K/AKT activation. The activated PI3-K/AKT and SMAD2 signaling largely accounted for MC-LR-induced EMT, which could be reversed by SMAD2 RNA interference or PI3-K/AKT chemical inhibitor in colorectal cancer cells. Our results show that MC-LR could induce SMAD2 expression to promote colorectal cancer cells EMT, which not only provides a mechanistic insight on MC-LR promotes EMT in colorectal cancer cells, but also support to the development of therapies aimed at SMAD2 in colorectal cancer induced by MC-LR.

Topics: Blotting, Western; Cell Culture Techniques; Cell Movement; Colorectal Neoplasms; Epithelial-Mesenchymal Transition; HT29 Cells; Humans; Marine Toxins; Microcystins; Phosphatidylinositol 3-Kinase; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; Signal Transduction; Smad2 Protein; Water Pollutants, Chemical

Microcystin-LR (MC-LR) is an environmental toxin from blooms of cyanobacteria and it has been shown to be one of the environmental carcinogens for the progression of colorectal carcinoma. However, there is no direct evidence that MC-LR can induce colorectal cancer migration and invasion. In the present study, 0.04 or 40 µg/kg/d (human tolerable daily intake value of MC-LR) MC-LR treatment was observed to induce Matrix Metalloproteinase-13 (MMP-13) expression in tumor tissues and local invasion in DLD-1 xenograft model. The results are consistent with those of cell test showing that MC-LR treatment enhanced migration and invasion of DLD-1, HT-29, and SW480 cells and are also correlated with the increased mRNA and protein levels of MMP-13 by Quantitative real-time PCR, Luciferase assay, and Western blot assay respectively in DLD-1 cells and HT-29 cells after MC-LR exposure. In addition, MMP-13 siRNA inhibited MC-LR induced migration and invasion enhancement and MMP-13 over-expression in DLD-1 cells and HT-29 cells. This is the first paper confirming MC-LR-induced MMP-13 expression can promote colorectal cancer invasion and migration. Further investigation revealed that phosphorylation of AKT increased in MC-LR-treated cells, and the phosphatidylinositol 3-kinase/Akt. (PI3-K/AKT) inhibitor LY294002 effectively abolished MC-LR-enhanced migration and invasion and MMP-13 expression. Therefore, based on these observations, we concluded that the activation of PI3K/AKT by MC-LR results in MMP-13 expression, leading to the migration and invasion of DLD-1 cells and HT-29 cells. The study provides a mechanistic insight into the promoting colorectal cancer functions of MC-LR.

Topics: Animals; Cell Line, Tumor; Cell Movement; Colorectal Neoplasms; Gene Expression Regulation, Neoplastic; HT29 Cells; Humans; Marine Toxins; Matrix Metalloproteinase 13; Mice; Microcystins; Neoplasm Invasiveness; Neoplasm Transplantation; Signal Transduction; Up-Regulation