Inhibitory effect and mechanism of total flavonoids from Melicope pteleifolia on transplanted tumor of colorectal cancer in nude mice / 中国药房

ABSTRACT

OBJECTIVE To study the inhibitory effect and mechanism of total flavonoids from Melicope pteleifolia （TF-MPL） on transplanted tumor of colorectal cancer in nude mice. METHODS The transplanted tumor model of colorectal cancer was induced by injecting 0.2 mL colorectal cancer cell LoVo subcutaneously via the right armpit of nude mice. After successful modeling， nude mice were randomly divided into model group， 5-fluorouracil group （positive control， 10 mg/kg）， TF-MPL high- dose and low-dose groups （25， 12.5 mg/kg）； a normal group （normal saline containing 0.3% carboxymethyl cellulose sodium） without modeling was additionally set up， with 6 mice in each group. Each group was intraperitoneally injected with the corresponding drug solution/solvent for 21 consecutive days. The inhibitory rate of the transplanted tumor， liver and spleen index， and the levels of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6） in serum were detected after the last medication； the morphological changes of tumor tissue were observed； immunohistochemical staining was used to detect protein expressions of Toll- like receptor 4 （TLR4） and nuclear factor-κB subunit p65 （NF-κB p65） in tumor tissue of nude mice. Western blot assay was used to detect protein expressions of TLR4， myeloid differentiation factor 88 （MyD88）， TNF receptor-associated factor 6 （TRAF6）， interleukin-1 receptor-associated kinase 1 （IRAK-1）， NF-κB p65 and caspase-3 in tumor tissue of nude mice. RESULTS Compared with the model group， TF-MPL high-dose group showed a significant decrease in tumor weight （inhibitory rate of 36.91%）， liver and spleen index， serum levels of TNF-α and IL-6 and protein expressions of TLR4， MyD88， TRAF6，IRAK-1 and NF- κB p65 （P＜0.05 or P＜0.01）； the expression of caspase-3 protein was increased significantly （P＜0.05）， and more tumor cell shrinkage and deformation， nuclear pyknosis and fragmentation were observed. CONCLUSIONS TF-MPL can significantly inhibit the growth of transplanted tumor of colorectal cancer in nude mice， the mechanism of which may be associated with reducing inflammatory response， inhibiting TLR4/MyD88/NF-κB signaling pathway， and promoting apoptosis in colorectal cancer cells.