Department of General, Visceral and Vascular Surgery, Campus Benjamin Franklin, Charité Universitätsmedizin Berlin, Hindenburgdamm 30, 12203, Berlin, Germany.
Department of General, Visceral and Transplantation Surgery, Hospital of the University of Munich, Munich, Germany.
Cell Oncol (Dordr). 2021 Feb;44(1):167-177. doi: 10.1007/s13402-020-00559-9. Epub 2020 Sep 17.
Currently, the exact role of estrogen receptor (ER) signaling in pancreatic cancer is unknown. Recently, we showed that expression of phosphorylated ERβ correlates with a poor prognosis in patients with pancreatic ductal adenocarcinoma (PDAC). Here, we hypothesized that raloxifene, a FDA-approved selective ER modulator (SERM), may suppress PDAC tumor growth by interfering with ERβ signaling. To test this hypothesis, we studied the impact of raloxifene on interleukin-6/glycoprotein-130/signal transducer and activator of transcription-3 (IL-6/gp130/STAT3) signaling.
Human PDAC cell lines were exposed to raloxifene after which growth inhibition was assessed using a BrdU assay. ER knockdown was performed using siRNAs specific for ERα and ERβ. The effects of raloxifene on IL-6 expression and STAT3 phosphorylation in PDAC cells were assessed by ELISA and Western blotting, respectively. In addition, raloxifene was administered to an orthotopic PDAC tumor xenograft mouse model, after which tumor growth was monitored and immunohistochemistry was performed.
Raloxifene inhibited the in vitro growth of PDAC cells, and this effect was reversed by siRNA-mediated knockdown of ERβ, but not of ERα, indicating ER isotype-specific signaling. We also found that treatment with raloxifene inhibited the release of IL-6 and suppressed the phosphorylation of STAT3 in PDAC cells. In vivo, we found that orthotopic PDAC tumor growth, lymph node and liver metastases as well as Ki-67 expression were reduced in mice treated with raloxifene.
Inhibition of ERβ and the IL-6/gp130/STAT3 signaling pathway by raloxifene leads to potent reduction of PDAC growth in vitro and in vivo. Our results suggest that ERβ signaling and IL-6/gp130 interaction may serve as promising drug targets for pancreatic cancer and that raloxifene may serve as an attractive therapeutic option for PDAC patients expressing the ERβ isotype.
目前，雌激素受体（ER）信号在胰腺癌中的确切作用尚不清楚。最近，我们发现磷酸化 ERβ的表达与胰腺导管腺癌（PDAC）患者的预后不良相关。在这里，我们假设他莫昔芬，一种 FDA 批准的选择性 ER 调节剂（SERM），通过干扰 ERβ信号可能抑制 PDAC 肿瘤生长。为了验证这一假设，我们研究了他莫昔芬对白细胞介素 6/糖蛋白 130/信号转导和转录激活因子 3（IL-6/gp130/STAT3）信号的影响。
用他莫昔芬处理人 PDAC 细胞系，然后用 BrdU 测定法评估生长抑制情况。使用针对 ERα 和 ERβ 的 siRNA 进行 ER 敲低。通过 ELISA 和 Western blot 分别评估他莫昔芬对 PDAC 细胞中 IL-6 表达和 STAT3 磷酸化的影响。此外，将他莫昔芬给予原位 PDAC 肿瘤异种移植小鼠模型，然后监测肿瘤生长并进行免疫组织化学分析。
他莫昔芬抑制 PDAC 细胞的体外生长，这种作用可被 ERβ 的 siRNA 介导的敲低逆转，但 ERα 的 siRNA 介导的敲低不能逆转，表明 ER 同种型特异性信号。我们还发现，用他莫昔芬处理可抑制 PDAC 细胞中 IL-6 的释放并抑制 STAT3 的磷酸化。在体内，我们发现用他莫昔芬治疗可减少小鼠的原位 PDAC 肿瘤生长、淋巴结和肝转移以及 Ki-67 的表达。
他莫昔芬抑制 ERβ 和 IL-6/gp130/STAT3 信号通路导致 PDAC 在体外和体内生长的强烈减少。我们的结果表明，ERβ 信号和 IL-6/gp130 相互作用可能是胰腺癌有前途的药物靶点，他莫昔芬可能是表达 ERβ 同种型的 PDAC 患者的一种有吸引力的治疗选择。
