Protective effect of mussel polysaccharide on cyclophosphamide-induced intestinal oxidative stress injury via Nrf2-Keap1 signaling pathway.

The hard-shelled mussel (Mytilus coruscus) has been used as a traditional Chinese medicine and health food in China for centuries. Polysaccharides from mussel has been reported to have multiple biological functions, however, it remains unclear whether mussel polysaccharide (MP) exerts protective effects in intestinal functions, and the underlying mechanisms of action remain unclear. The aim of this study was to investigate the protective effects and mechanism of MP on intestinal oxidative injury in mice. In this study, 40 male BALB/C mice were used, with 30 utilized to produce an animal model of intestinal oxidative injury with intraperitoneal injection of cyclophosphamide (Cy) for four consecutive days. The protective effects of two different doses of MP (300 and 600 mg/kg) were assessed by investigating the change in body weight, visceral index, and observing colon histomorphology. Moreover, the underlying molecular mechanisms were investigated by measuring the antioxidant enzymes and related signaling molecules through ELISA, real-time PCR, and western blot methods. The results showed that MP pretreatment effectively protected the intestinal from Cy-induced injury: improved the colon tissue morphology and villus structure, increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, and reduced malondialdehyde (MDA) content in serum and colon tissues. Meanwhile, MP also significantly increased the expression levels of SOD, GSH-Px, heme oxygenase-1 (HO-1), and nuclear factor E2-related factor 2 (Nrf2) mRNA in colon tissues. Further, western blot results showed that the expression of Nrf2 protein was significantly upregulated while kelch-like ECH-associated protein 1 (Keap1) was significantly downregulated by MP in the colonic tissues. This study indicates that MP can ameliorate Cy-induced oxidative stress injury in mice, and Nrf2-Keap1 signaling pathway may mediate these protective effects.

Overexpression of Stat3 increases circulating cfDNA in breast cancer.

PURPOSE: Current studies on circulating cell-free DNA (cfDNA) have been focusing on its potential as biomarkers in liquid biopsy by detecting its content or genetic and epigenetic changes for the evaluation of tumor burden and therapeutic efficacy. However, the regulatory mechanism of cfDNA release remains unclear. Stat3 has been documented as an oncogene for the development and metastasis of breast cancer cells. In this study, we investigated whether Stat3 affects the release of cfDNA into blood and its association with the number of circulating tumor cells (CTCs). METHODS: The cfDNA level in plasma of patients with breast cancer and healthy volunteers were determined by quantitative real-time PCR. Three mouse breast cancer models with different Stat3 expression were generated and used to established three breast cancer orthotopic animal models to examine the effect of Stat3 on cfDNA release in vivo. Stat3 mediated Epithelial-mesenchymal phenotype transition of CTCs was determined by immunofluorescence assay and Western blot assay. RESULTS: The data showed that Stat3 increased circulating cfDNA, which is correlated with the increased volume of primary tumors and number of CTCs, accompanied with the dynamic EMT changes regulated by Snail induction. Furthermore, the high level of total circulating cfDNA and Stat3-cfDNA in patients with breast cancer were detected by quantitative real-time PCR using GAPDH and Stat3 primers. CONCLUSION: Our results suggested that Stat3 increases the circulating cfDNA and CTCs in breast cancer.

Stat3/Oct-4/c-Myc signal circuit for regulating stemness-mediated doxorubicin resistance of triple-negative breast cancer cells and inhibitory effects of WP1066.

Doxorubicin (Dox) is widely used in the treatment of triple-negative breast cancer cells (TNBCs), however resistance limits its effectiveness. Cancer stem cells (CSCs) are associated with Dox resistance in MCF-7 estrogen receptor positive breast cancer cells. Signal transducer and activator of transcription 3 (Stat3) may functionally shift non-CSCs towards CSCs. However, whether Stat3 drives the formation of CSCs during the development of resistance in TNBC, and whether a Stat3 inhibitor reverses CSC-mediated Dox resistance, remains to be elucidated. In the present study, human MDA-MB-468 and murine 4T1 mammary carcinoma cell lines with the typical characteristics of TNBCs, were compared with estrogen receptor-positive MCF-7 cells as a model system. The MTT assay was used to detect cytotoxicity of Dox. In addition, the expression levels of CSC-specific markers and transcriptional factors were measured by western blotting, immunofluorescence staining and flow cytometry. The mammosphere formation assay was used to detect stem cell activity. Under long-term continuous treatment with Dox at a low concentration, TNBC cultures not only exhibited a drug-resistant phenotype, but also showed CSC properties. These Dox-resistant TNBC cells showed activation of Stat3 and high expression levels of pluripotency transcription factors octamer-binding transcription factor-4 (Oct-4) and c-Myc, which was different from the high expression of superoxide dismutase 2 (Sox2) in Dox-resistant MCF-7 cells. WP1066 inhibited the phosphorylation of Stat3, and decreased the expression of Oct-4 and c-Myc, leading to a reduction in the CD44-positive cell population, and restoring the sensitivity of the cells to Dox. Taken together, a novel signal circuit of Stat3/Oct-4/c-Myc was identified for regulating stemness-mediated Dox resistance in TNBC. The Stat3 inhibitor WP1066 was able to overcome the resistance to Dox through decreasing the enrichment of CSCs, highlighting the therapeutic potential of WP1066 as a novel sensitizer of Dox-resistant TNBC.

Research on protein thermal condensation detection based on phase modulation SPR imaging.

This article presents a novel SPR imaging biomolecular interaction detection method based on time domain phase modulation. An experimental apparatus of SPR imaging biomolecular interaction detection based on TDPM is established to detect biomolecular interaction. During the experimental pretreatment process, we prepared the 2×2 lysozyme array chip and detected lysozyme thermal condensation state with the experimental apparatus. Using the Stoilov algorithm, we were able to extract the changed phase information as well as obtain the interactive SPR curves and calculate kinetic parameters. This method can sensitively acquire real-time phase change caused by biomolecular interaction based on interference imaging and resolve the related bioinformation, which is a potential tool for proteomics research.