Abstract
Bladder cancer is one of the most malignant tumors closely associated with macrophages. Polyporus polysaccharide (PPS) has shown excellent efficacy in treating bladder cancer with minimal side effects. However, the molecular mechanisms underlying the effects of PPS in inhibiting bladder cancer remain unclear. In this study, we used macrophages cultured alone or with T24 human bladder cancer cell culture supernatant as study models. We found that PPS enhanced the activities of IFN-γ-stimulated RAW 264.7 macrophages, as shown by the release of inducible nitric oxide synthase (INOS), secretion of tumor necrosis factor (TNF)-α and interleukin (IL)-6, phagocytosis activity, as well as expression of M1 phenotype indicators, such as CD40, CD284 and CD86. PPS acted upstream in activation cascade of nuclear factor (NF)-κB signaling pathways by interfering with IκB phosphorylation. In addition, PPS regulated NF-κB (P65) signaling by interfering with Toll-like receptor (TLR)-4, INOS and cyclooxygenase (COX)-2. Our results indicate that PPS activates macrophages through TLR4/NF-κB signaling pathways.
Highlights
Bladder cancer is one of the most commonly diagnosed diseases and is characterized by a high recurrence rate [1,2]
We found that Polyporus polysaccharide (PPS) could suppress the growth of tumor cell through TLR4/nuclear factor (NF)-κB pathway [15], and it could enhance the secretion of nitric oxide (NO) in vitro [16]
Radio-immunoprecipitation Assay (RIPA) Lysis Buffer and antibodies used in Western blot analysis, including anti-phospho-P65-NF-κB, anti- P65-NF-κB, anti-phospho-IκB, anti-IκB, anti-inducible nitric oxide synthase (INOS), anti-cyclooxygenase (COX)-2, anti-IL-6, anti-tumor necrosis factor (TNF)-α, and anti-GAPDH were purchased from Cell Signaling Technologies (Pickering, ON, CAN), and secondary antibodies were purchased from Sigma
Summary
Bladder cancer is one of the most commonly diagnosed diseases and is characterized by a high recurrence rate [1,2]. Intravesical instillations of bacillus Calmette-Guerin (BCG) are the most effective treatment to prevent recurrence and progression, whereas approximately 30–40% of patients fail to respond to BCG immunotherapy [3]. It is found that tumor-associated macrophages (TAMs) are one of the most important promoters of tumor progression, angiogenesis and metastasis[4]. Polyporus has been frequently used in Chinese Medicine to treat edema and various kidney diseases, and importantly, no side effects or toxicities have yet been. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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