Fucoidan Inhibits Prostate Cancer Growth Through Modulation of Different Cell Deaths

Docetaxel (DOC) is the main chemotherapeutic agent for the treatment of advanced metastatic prostate cancer. Docetaxel shows anticancer effects by preventing the depolymerization of microtubules in the cell, therefore preventing cell division. However, the low survival effect of docetaxel has prompted researchers to search for novel therapeutic agents. Fucoidan (FUC) is a sulfated polysaccharide derived from brown algae. It has many bioactivities which makes fucoidan a promising anticancer agent. In this study, the potential anti-tumorigenic and preventive effects of fucoidan with or without docetaxel in prostate cancer were investigated by analyzing different cell death modalities. The in-vivo six groups (n = 8) were conducted; preventive (Pt), docetaxel treated after preventive (Pt-D), control, fucoidan (FUC), docetaxel (DOC), and FUC and DOC (FUC+DOC) combination. Apoptotic, necroptotic, and autophagic cell death-related protein expressions were assessed in tumor tissues by using immunohistochemical staining. Oxidative stress-related lipid peroxidation, glutathione peroxidase, and glutathione levels were also determined in tumor tissues. Although apoptotic, necroptotic, and autophagic cell deaths were significantly induced in agent-treated groups compared to the control. Apoptotic cell death was more significantly induced in FUC and FUC+DOC-treated groups. Necroptotic cell death was increased considerably by inducing MLKL protein expression in all treatment groups. In the FUC, Pt, and DOC groups, LC3A/B expressions were significantly increased. DOC, FUC+DOC, and Pt-D treatments caused a significant increase in Beclin-1 expression. Oxidative stress-related MDA, GPX, and GSH levels significantly decreased with FUC treatment. The anti-tumorigenic effects of FUC and DOC were also demonstrated through tumor size reduction. According to the findings of this study, FUC inhibited tumor growth temporally and dimensionally, especially in preventive applications. FUC and FUC+DOC combinations in both treatment groups showed anti-tumorigenic effects. The results of this study suggest that fucoidan is a promising anticancer agent against prostate cancer. FUC can be considered as a preventive or treatment agent in prostate cancer therapy with DOC. Further studies are needed to fully elucidate the mechanism of action of fucoidan in metastatic prostate cancer.