二甲双胍阻断乳腺癌细胞-间质细胞的交互作用:基于抑制肿瘤相关成纤维细胞缺氧诱导因子-1α的表达

Metformin suppresses hypoxia-inducible factor-1αexpression in cancer-associated fibroblasts to block tumor-stromal cross-talk in breast cancer

目的探讨二甲双胍(Met)对乳腺癌肿瘤-间质细胞交互作用的影响及机制。方法将肿瘤相关成纤维细胞(CAFs)与乳腺癌细胞共培养,运用二甲双胍进行干预,分为对照组和Met干预组,ELISA及RT-qPCR检测Met对CAFs中HIF-1α、p-AMPK、基质衍生因子-1(SDF-1)和白细胞介素-8(IL-8)等因子的表达变化以及Transwell检测肿瘤细胞侵袭能力的变化。运用外源性SDF-1、IL-8干预后,Transwell检测肿瘤细胞侵袭能力的变化。运用缺氧诱导因子-1α(HIF-1α)shRNA或过表达质粒调节CAFs-HIF-1α的表达,以及AMPK-shRNA抑制AMPK的表达,并运用OG和2-OXO调节脯氨酸羟化酶的表达,及运用外源性TGF-β1干预后,Western blot及RT-qPCR检测CAFs中p-AMPK、HIF-1α、SDF-1、IL-8的表达,Transwell检测肿瘤细胞侵袭能力的变化。结果相较于对照组,Met干预组中CAFs的p-AMPK、SDF-1和IL-8的表达水平升高(P<0.05),HIF-1α表达水平下降(P<0.05),AMPK的表达水平差异无统计学意义(P>0.05),Met组中乳腺癌细胞侵袭能力下降(P<0.05)。外源性SDF-1、IL-8干预可降低Met对乳腺癌细胞侵袭的抑制作用,增加乳腺癌细胞的侵袭能力(P<0.05)。过表达HIF-1α及运用脯氨酸羟化酶抑制剂OG提高HIF-1α的表达后,可降低Met对CAFs中HIF-1α、SDF-1及IL-8表达的抑制作用,并可降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05);运用HIF-1α-shRNA及运用脯氨酸羟化酶激活剂2-OXO抑制HIF-1α的表达后,降低乳腺癌细胞的侵袭能力(P<0.05);运用AMPK-shRNA抑制p-AMPK的表达后,可降低Met对CAFs中HIF-1α表达的抑制作用,并可降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05);加入外源性TGF-β1后,可部分降低Met对CAFs中HIF-1α表达的抑制作用,并可部分降低Met对乳腺癌细胞侵袭的抑制作用(P<0.05)。结论Met通过抑制CAFs-HIF-1α的表达进而发挥阻断乳腺癌细胞-间质细胞交互作用。

Objective To investigate the mechanism of metformin for regulating tumor-stromal cell cross-talk in breast cancer.Methods Tumor associated fibroblasts(CAFs)co-cultured with breast cancer cells were treated with metformin,and the changes in expressions of hypoxia-inducible factor-1α(HIF-1α),p-AMPK,stroma-derived factor-1(SDF-1)and interleukin-8(IL-8)in the CAFs were detected using ELISA,RT-qPCR or Western blotting;Transwell assay was used to evaluate the invasiveness of the tumor cells and its changes following treatment with exogenous SDF-1,IL-8 and TGF-β1.The effects of HIF-1αshRNA or overexpression plasmid,AMPK shRNA,and treatment with OG(a proline hydroxylase inhibitor)or 2-OXO(a proline hydroxylase activator)were examined on p-AMPK,HIF-1α,SDF-1 and IL-8 expressions and invasiveness of the CAFs.Results Metformin treatment significantly increased the expression levels of p-AMPK,SDF-1 and IL-8(P<0.05)and decreased HIF-1αexpression(P<0.05)without affecting AMPK expression level(P>0.05)in the CAFs.The invasion ability of metformintreated breast cancer cells was significantly decreased(P<0.05).Exogenous SDF-1 and IL-8,HIF-1αoverexpression,and OGinduced upregulation of HIF-1αall significantly attenuated the inhibitory effects of metformin on breast cancer cell invasion(P<0.05)and HIF-1α,SDF-1 and IL-8 expressions in CAFs(P<0.05).Transfection with HIF-1αshRNA or treatment with 2-OXO significantly decreased the invasiveness of breast cancer cells(P<0.05).P-AMPK knockdown significantly suppressed the inhibitory effect of metformin on HIF-1αexpression in CAFs and on invasion of breast cancer cells(P<0.05).Treatment with TGF-β1 partially decreased the inhibitory effect of metformin on HIF-1αexpression in CAFs and invasiveness of the breast cancer cells(P<0.05).Conclusion Metformin suppresses HIF-1αexpression in CAFs to block tumor-stromal cross talk in breast cancer.