Antitumor Activity of Portulaca Oleracea L. Polysaccharide on HeLa Cells Through Inducing TLR4/NF-κB Signaling
Antitumor Activity of Portulaca Oleracea L. Polysaccharide on HeLa Cells Through Inducing TLR4/NF-κB Signaling
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DOI：
10.1080/01635581.2017.1248294
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发表时间：
2017-01
期刊：
影响因子：
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通讯作者：
R. Zhao;Tao Zhang;B. Ma;Xing Li
中科院分区：
文献类型：
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作者：
R. Zhao;Tao Zhang;B. Ma;Xing Li
在体外和体内实验中，我们已经证明马齿苋多糖（POL-P3b）具有抑制宫颈癌细胞生长的能力。在本研究中，我们探讨了toll样受体4 （TLR4）信号通路与POL-P3b抗肿瘤机制的关系。Western blotting检测TLR4的表达及下游信号通路。采用酶联免疫吸附测定（ELISA）试剂盒定量检测炎症介质水平。采用WST-8法和Hoechst 33342/碘化丙啶（PI）法检测POL-P3b对HeLa细胞增殖和凋亡的影响。我们的研究结果表明，脂多糖（LPS）与肿瘤细胞上的TLR4结合可以增强HeLa细胞的增殖，增加TLR4及其下游分子的表达。POL-P3b处理HeLa细胞后，可抑制HeLa细胞的增殖，上调Bax水平，下调Bcl-2水平，并呈浓度依赖性。POL-P3b抑制HeLa细胞中TLR4、MyD88、TRAF6、激活蛋白1 （AP-1）和核因子-κB （NF-κB）亚基P65的蛋白表达水平。此外，POL-P3b还能减少细胞因子/趋化因子的产生。综上所述，本研究提示POL-P3b的抗肿瘤机制可能是通过下调TLR4下游信号通路，诱导细胞凋亡。我们的研究结果可能提供了直接的证据，表明POL-P3b应该被认为是一种有效的肿瘤治疗营养补充剂。
Abstarct We have previously shown that Portulaca oleracea L. polysaccharide (POL-P3b) possesses the ability to inhibit cervical cancer cell growth in vitro and in vivo. In this study, we explored how toll-like receptor 4 (TLR4) signaling correlated with the antitumor mechanism of POL-P3b. Western blotting was utilized to detect the expression of TLR4 and the downstream signaling pathway. The level of inflammatory mediator was quantified using enzyme-linked immunosorbent assay (ELISA) kits. The effects of POL-P3b on the proliferation and apoptosis in HeLa cells were determined by WST-8 assay and Hoechst 33342/propidium iodide (PI) assay. Our results demonstrated that lipopolysaccharide (LPS) binding to TLR4 on tumor cells could enhance HeLa cell proliferation and increase the expression of TLR4 and the downstream molecules. Treating HeLa cells with POL-P3b could decrease the proliferation of HeLa cells, and upregulate Bax level and downregulate Bcl-2 level in a concentration-dependent manner. In addition, POL-P3b inhibited the protein expression levels of TLR4, MyD88, TRAF6, Activator Protein-1 (AP-1) and nuclear factor-κB (NF-κB) subunit P65 in HeLa cells. Furthermore, POL-P3b also reduced the production of cytokine/chemokine. Taken together, the present work suggested the antitumor mechanism of POL-P3b by downregulating TLR4 downstream signaling pathway and inducing cell apoptosis. Our results may provide direct evidence to suggest that POL-P3b should be considered as a potent nutrient supplement for oncotherapy.