The Inhibitory Effects of Hesperetin, a Natural Flavonoid, against Substance P-induced Inflammatory Responses in Glioblastoma Cells

Objectives: As a key inflammatory neuropeptide, substance P (SP) is involved in Glioblastoma multiforme (GBM) carcinogenesis and tumor progression. Thus, the proinflammatory effects of SP must be strictly regulated in GBM patients. The purpose of the study is to examine whether Hesperetin, a natural flavonoid found in citrus fruits with strong anti-inflammatory and anticancer effects, can regulate SP-induced inflammation in GBM primary human cells Methods: The primary human cells were derived from fresh surgically resected tissue samples of GBM patients and characterized by immunocytochemical analysis of Ki-67. MTT assay was used to evaluate cell proliferation. Apoptosis was detected by an Annexin-V/propidium iodide assay kit using flow cytometry. The levels of the specific inflammatory mediators were measured by western blotting and enzyme-linked immunosorbent assay. Results: We observed that Hesperetin effectively reduced GBM cell viability in a dose- dependent manner, which was associated with the induction of apoptosis. Obtained findings indicated SP increased the protein expression of phosphorylated-NF-κB, the main regulator of inflammatory processes, and the pro-inflammatory cytokines (IL-1β, TNF-α), while Hesperetin treatment reduced the effects of SP. Conclusion: Taken together, our findings highlight the role of SP-induced inflammatory responses in GBM pathology and suggest that Hesperetin could be an effective therapeutic strategy in attenuating SP-associated inflammation.