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We have previously shown that compound-7g inhibits colorectal cancer cell proliferation and survival by inducing cell cycle arrest and PI3K/AKT/mTOR pathway blockage. However, whether it has the ability to exert antitumor activity in other cancer cells and what is the exact molecular mechanism for its antiproliferation effect remained to be determined. In the present study, compound-7g exhibited strong activity in suppressing proliferation and growth of glioblastoma cells. The inhibitor selectively downregulated F-box protein SKP2 expression and upregulated cell cycle inhibitor p27, and then resulted in G1 cell cycle arrest. Mechanism analysis revealed that compound-7g also provokes the down-regulation of E2F-1, which acts as a transcriptional factor of SKP2. Further results indicated that compound-7g induced an increase of LC3B-II and p62, which causes a suppression of fusion between autophagosome and lysosome. Moreover, compound-7g mediated autophagic flux blockage promoted accumulation of ubiquitinated proteins and then led to endoplasmic reticulum stress. Our study thus demonstrated that pharmacological inactivation of E2F-1-SKP2-p27 axis is a promising target for restricting cancer progression. [ABSTRACT FROM AUTHOR]

Fucoidans have been reported to exert anticancer effects with simultaneous low toxicity against healthy tissue. That correlation was observed in several cancer models, however, it has never been investigated in head and neck cancer before. To magnify the efficacy of conventional therapy, the administration of agents like fucoidan could be beneficial. The aim of this study was to evaluate the anticancer effect of Fucus vesiculosus (FV) extract alone and with co-administration of cisplatin in head and neck squamous cell carcinoma (HNSCC) in vitro. MTT assay results revealed an FV-induced inhibition of proliferation in all tested cell lines (H103, FaDu, KB). Flow cytometric cell cycle analysis showed an FV-induced, dose-dependent arrest in either S/G2 phase (H103, FaDu) or G1 arrest (KB). Furthermore, a dose-dependent gain in apoptotic fraction was observed. Western blot analysis confirmed the induction of apoptosis. A significant dose-dependent increase in reactive oxygen species (ROS) production was revealed in the H103 cell line, while FaDu cells remained unresponsive. On the contrary, an HPV-positive cell line, KB, demonstrated a dose-dependent decrease in ROS synthesis. Moreover, fucoidan enhanced the response to cisplatin (synergistic effect) in all cell lines with the HPV-positive one (KB) being the most sensitive. These results have been confirmed by flow-cytometric apoptosis analysis. In conclusion, we confirmed that fucoidan exhibits anticancer properties against HNSCC, which are manifested by the induction of apoptosis, regulation of ROS production, cell cycle arrest, and inhibition of proliferation. [ABSTRACT FROM AUTHOR]