Protective Effects of Fucoidan on Aß25-35 and d-Gal-Induced Neurotoxicity in PC12 Cells and d-Gal-Induced Cognitive Dysfunction in Mice.

Alzheimer's disease (AD) is a chronic neurodegenerative disease which contributes to memory loss and cognitive decline in the elderly. Fucoidan, extracted from brown algae, is a complex sulfated polysaccharide and potential bioactive compound. In this study, we investigated whether fucoidan protects PC12 cells from apoptosis induced by a combination of beta-amyloid 25-35 (Aß25-35) and d-galactose (d-Gal), and improves learning and memory impairment in AD model mice. The results indicated that fucoidan could inhibit the release of cytochrome c from the mitochondria to cytosol and activation of caspases, and increase the expression of apoptosis inhibitor proteins (IAPs), including livin and X-linked IAP (XIAP) in PC12 cells damaged by Aß25-35 and d-Gal-induction. Fucoidan reversed the decreased activity of acetylcholine (ACh) and choline acetyl transferase (ChAT), as well as the increased activity of acetylcholine esterase (AChE), in AD model mice induced by infusion of d-Gal. Furthermore, fucoidan improved antioxidant activity in vitro and in vivo by activation of superoxide dismutase (SOD) and glutathione (GSH). These results suggested that fucoidan could protect PC12 cells from apoptosis and ameliorate the learning and memory impairment in AD model mice, which appeared to be due to regulating the cholinergic system, reducing oxidative stress, and inhibiting the caspase-dependent apoptosis pathway.

Fucoidan Suppresses Hypoxia-Induced Lymphangiogenesis and Lymphatic Metastasis in Mouse Hepatocarcinoma.

Metastasis, the greatest clinical challenge associated with cancer, is closely connected to multiple biological processes, including invasion and adhesion. The hypoxic environment in tumors is an important factor that causes tumor metastasis by activating HIF-1α. Fucoidan, extracted from brown algae, is a sulfated polysaccharide and, as a novel marine biological material, has been used to treat various disorders in China, Korea, Japan and other countries. In the present study, we demonstrated that fucoidan derived from Undaria pinnatifida sporophylls significantly inhibits the hypoxia-induced expression, nuclear translocation and activity of HIF-1α, the synthesis and secretion of VEGF-C and HGF, cell invasion and lymphatic metastasis in a mouse hepatocarcinoma Hca-F cell line. Fucoidan also suppressed lymphangiogenesis in vitro and in vivo. In addition, accompanied by a reduction in the HIF-1α nuclear translocation and activity, fucoidan significantly reduced the levels of p-PI3K, p-Akt, p-mTOR, p-ERK, NF-κB, MMP-2 and MMP-9, but increased TIMP-1 levels. These results indicate strongly that the anti-metastasis and anti-lymphangiogenesis activities of fucoidan are mediated by suppressing HIF-1α/VEGF-C, which attenuates the PI3K/Akt/mTOR signaling pathways.

Natural killer cell-related prognostic risk model predicts prognosis and treatment outcomes in triple-negative breast cancer.

Background: Natural killer (NK) cells are crucial to the emergence, identification, and prognosis of cancers. The roles of NK cell-related genes in the tumor immune microenvironment (TIME) and immunotherapy treatment are unclear. Triple-negative breast cancer (TNBC) is a highly aggressive malignant tumor. Hence, this study was conducted to develop a reliable risk model related to NK cells and provide a novel system for predicting the prognosis of TNBC. Methods: NK cell-related genes were collected from previous studies. Based on TCGA and GEO database, univariate and LASSO cox regression analysis were used to establish the NK cell-related gene signature. The patients with TNBC were separated to high-risk and low-risk groups. After that, survival analysis was conducted and the responses to immunotherapies were evaluated on the basis of the signature. Moreover, the drug sensitivity of some traditional chemotherapeutic drugs was assessed by using the "oncoPredict" R package. In addition, the expression levels of the genes involved in the signature were validated by using qRT-PCR in TNBC cell lines. Results: The patients with TNBC were divided into high- and low-risk groups according to the median risk score of the 5-NK cell-related gene signature. The low-risk group was associated with a better clinical outcome. Besides, the differentially expressed genes between the different risk groups were enriched in the biological activities associated with immunity. The tumor immune cells were found to be highly infiltrated in the low-risk groups. In accordance with the TIDE score and immune checkpoint-related gene expression analysis, TNBC patients in the low-risk groups were suggested to have better responses to immunotherapies. Eventually, some classical anti-tumor drugs were shown to be less effective in high-risk groups than in low-risk groups. Conclusion: The 5-NK cell-related gene signature exhibit outstanding predictive performance and provide fresh viewpoints for evaluating the success of immunotherapy. It will provide new insights to achieve precision and integrated treatment for TNBC in the future.

Identification of an exosome-related signature associated with prognosis and immune infiltration in breast cancer.

Exosomes, nanosized vesicles, play a vital role in breast cancer (BC) occurrence, development, and drug resistance. Hence, we proceeded to study the potential prognostic value of exosome-related genes and their relationship to the immune microenvironment in BC. 121 exosome-related genes were provided by the ExoBCD database, and 7 final genes were selected to construct the prognostic signature. Besides, the expression levels of the 7 exosome-related genes were validated by the experiment in BC cell lines. Based on the signature, BC patients from the training and validation cohorts were separated into low- and high-risk groups. Subsequently, the R clusterProfiler package was applied to identify the distinct enrichment pathways between high-risk groups and low-risk groups. The relevance of the tumor immune microenvironment and exosome-related gene risk score were analyzed in BC. Eventually, the different expression levels of immune checkpoint-related genes were compared between the two risk groups. Based on the risk model, the low-risk groups were identified with a higher survival rate both in the training and validation cohorts. A better overall survival was revealed in patients with higher scores evaluated by the estimation of stromal and immune cells in malignant tumor tissues using expression (ESTIMATE) algorithm. Subsequently, BC patients with lower risk scores were indicated by higher expression levels of some immune checkpoint-related genes and immune cell infiltration. Exosomes are closely associated with the prognosis and immune cell infiltration of BC. These findings may contribute to improving immunotherapy and provide a new vision for BC treatment strategies.

Induction of EnR stress by Melatonin enhances the cytotoxic effect of Lapatinib in HER2-positive breast cancer.

Despite HER2-targeted cancer treatments have provided considerable clinical benefits, resistance to HER2-targeted agents will inevitably develop. Targeting non-oncogene vulnerabilities including endoplasmic reticulum (EnR) stress has emerged as an attractive alternative approach to improve the efficacy of existing targeted cancer therapies. In the current study, we find that Melatonin sensitizes HER2-positive breast cancer cells to the dual tyrosine kinase inhibitor Lapatinib in vitro. Mechanistically, Melatonin enhances the cytotoxic effects of Lapatinib through promoting excessive EnR stress-induced unfolded protein response (UPR) and ROS overaccumulation. Consistently, the antioxidant N-acetylcysteine remarkably reverses the effects of the drug combination on ROS production, DNA damage and cytotoxicity. Furthermore, Melatonin significantly enhances the anti-tumor effect of Lapatinib in an HCC1954 xenograft model. Meanwhile, Lapatinib resistant HER2-positive breast cancer cells (LapR) display lower basal expression levels of UPR genes and enhanced tolerance to EnR stress with attenuated response to Brefeldin A and Tunicamycin. Importantly, Melatonin also increases the sensitivity of HCC1954 LapR cells to Lapatinib. Together, our findings highlight the potential utility of Melatonin as an adjuvant in the treatment of primary or therapy resistant HER2-positive breast cancer via EnR stress-mediated mechanisms.

Melatonin potentiates the cytotoxic effect of Neratinib in HER2+ breast cancer through promoting endocytosis and lysosomal degradation of HER2.

Complete blockade of the HER2 protein itself and HER signaling network is critical to achieving effective HER2-targeted therapies. Despite the success of HER2-targeted therapies, the diseases will relapse in a significant fraction of patients with HER2+ breast cancers. How to improve the therapeutic efficacy of existing HER2-targeted agents remains an unmet clinical need. Here, we uncover a role of Melatonin in diminishing HER2-mediated signaling by destruction of HER2 protein. Mechanistically, Melatonin treatment attenuated the protective effect of the HSP90 chaperone complex on its client protein HER2, triggering ubiquitylation and subsequent endocytic lysosomal degradation of HER2. The inhibitory effect of Melatonin on HER2 signaling substantially enhanced the cytotoxic effects of the pan-HER inhibitor Neratinib in HER2+ breast cancer cells. Lastly, we demonstrate that dual inhibition of HER2 by combined use of Melatonin and Neratinib effectively blocked the growth of HER2+ breast tumor xenografts in vivo. Our findings shed light on the potential use of Melatonin in a novel dual HER2 blockade strategy for HER2+ breast cancer treatment.

Inhibition of BTF3 sensitizes luminal breast cancer cells to PI3Kα inhibition through the transcriptional regulation of ERα.

Selective phosphatidylinositol 3 kinase (PI3K) inhibitors are being actively tested in clinical trials for ERα-positive (ER+) breast cancer due to the presence of activating PIK3CA mutations. However, recent studies have revealed that increased ERα transcriptional activity limits the efficacy of PI3K inhibitor monotherapy for ER + breast cancers. Herein, we report the identification of BTF3 as an oncogenic transcription factor that regulates ERα expression in luminal breast cancers. Our TCGA analysis reveals high expression levels of BTF3 in luminal/ER + breast cancer and cell line models harboring ERα overexpression. Concordantly, BTF3 expression is highly and strongly associated with ESR1 expression in multiple breast cancer cohorts. We further show that BTF3 promotes the proliferation, survival and migration of ER + breast cancer cells by modulating ESR1 expression and ERα-dependent transcription. Moreover, BTF3 knockdown sensitizes ER + breast cancer cells to the PI3Kα inhibitor BYL-719 in both in vitro and in vivo models. Together, our findings highlight a novel role of BTF3 in modulation of ERα-dependent transcriptional activity and its potential as a predictive marker for the response to PI3K-targeted therapy in ER + breast cancer.

Fucoidan inhibits lymphangiogenesis by downregulating the expression of VEGFR3 and PROX1 in human lymphatic endothelial cells.

Lymphangiogenesis is one of the promoters of tumor lymphatic metastasis. Fucoidan which is a fucose-enriched sulfated polysaccharide has effect on various pharmacological activities including anti-metastasis activity. However, the inhibitory effect of fucoidan on lymphangiogenesis remains unclear. Here, fucoidan extracted from U. pinnatifida sporophylls suppressed HLECs proliferation, migration and tube-like structure formation, and had inhibitory effect of tumor-induced lymphangiogenesis in vitro. Additionally, we found that fucoidan had a dose-dependent depressive effect on the expressions of PROX1, vascular endothelial growth factor receptor 3 (VEGFR3), NF-κB, phospho-PI3K and phospho-Akt in HLECs. Moreover, anti-lymphangiogenesis effect of fucoidan was assessed by using mouse tumor model. In summary, fucoidan inhibit tumor lymphangiogenesis and lymphatic metastasis by suppressing the NF-κB/PI3K/Akt signaling pathway through reduced levels of PROX1 and VEGFR3.