Weich Alexander, Rogoll Dorothea, Peschka Melissa, Weich Wolfgang, Pongracz Judit, Brand Markus, Fröhlich Matthias, Serfling Sebastian E, Rowe Steven P, Kosmala Aleksander, Reiter Florian P, Meining Alexander, Werner Rudolf A, Scheurlen Michael
Department of Internal Medicine II, Gastroenterology, University Hospital Würzburg, Würzburg, Germany.
Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, University of Pecs, Pecs, Hungary.
Nucl Med Commun. 2023 Apr 1;44(4):259-269. doi: 10.1097/MNM.0000000000001666. Epub 2023 Feb 21.
Differentiated neuroendocrine tumors (NETs) express somatostatin receptors (SSTRs), targets for therapy with either unlabeled or radioactively labeled somatostatin analogs (SSA). Associated with worse prognosis, dedifferentiated NET loose SSTR expression, which may be linked to deregulation of Wnt/β-catenin signaling on an intracellular level. The aim of the present study was to investigate the effect of Wnt/β-catenin signaling pathway alterations on SSTR expression and its function in NET.
The NET cell lines BON-1 and QGP-1 were incubated with the Wnt-inhibitors 5-aza-2'-deoxycytidine (5-aza-CdR), Quercetin, or Niclosamide, or the Wnt activator lithium chloride (LiCl). Expression of SSTR1, SSTR2, and SSTR5 was determined by quantitative RT-PCR (qRT-PCR), immunocytomicroscopy and western blot. Changes in the Wnt pathway were analyzed by qRT-PCR of selected target genes and the TaqMan Array Human WNT Pathway. Receptor-associated function was determined by measuring the cellular uptake of [125I-Tyr3] octreotide.
The mRNAs of SSTRs 1-5 were expressed in both cell lines. Wnt inhibitors caused downregulation of Wnt target genes, while 5-aza-CdR had the highest inhibitory effect. LiCl lead to an upregulation of Wnt genes, which was more marked in QGP-1 cells. SSTR expression increased in both cell lines upon Wnt inhibition. All three Wnt inhibitors lead to a marked increase in the specific uptake of [125I-Tyr3]octreotide, with 5-aza-CdR showing the greatest effect (increase by more than 50% in BON-1 cells), while a decreased uptake of [125I-Tyr3]octreotide was seen upon activation of Wnt signaling by LiCl.
We demonstrate here that Wnt signaling orchestrates SSTR expression and function in a preclinical NET model. Wnt inhibition increases [125I-Tyr3]octreotide uptake offering an opportunity to enhance the efficacy of SSTR-targeted theranostic approaches.
分化型神经内分泌肿瘤（NETs）表达生长抑素受体（SSTRs），是未标记或放射性标记的生长抑素类似物（SSA）治疗的靶点。去分化型NET与更差的预后相关，其失去SSTR表达，这可能与细胞内Wnt/β-连环蛋白信号通路失调有关。本研究的目的是探讨Wnt/β-连环蛋白信号通路改变对NET中SSTR表达及其功能的影响。
将NET细胞系BON-1和QGP-1与Wnt抑制剂5-氮杂-2'-脱氧胞苷（5-aza-CdR）、槲皮素或氯硝柳胺，或Wnt激活剂氯化锂（LiCl）孵育。通过定量逆转录-聚合酶链反应（qRT-PCR）、免疫细胞显微镜检查和蛋白质印迹法测定SSTR1、SSTR2和SSTR5的表达。通过对选定靶基因的qRT-PCR和TaqMan Array Human WNT Pathway分析Wnt通路的变化。通过测量[125I-Tyr3]奥曲肽的细胞摄取来确定受体相关功能。
SSTRs 1-5的mRNA在两种细胞系中均有表达。Wnt抑制剂导致Wnt靶基因下调，而5-aza-CdR具有最高的抑制作用。LiCl导致Wnt基因上调，在QGP-1细胞中更明显。Wnt抑制后两种细胞系中SSTR表达均增加。所有三种Wnt抑制剂均导致[125I-Tyr3]奥曲肽的特异性摄取显著增加，5-aza-CdR的作用最大（BON-1细胞中增加超过50%），而LiCl激活Wnt信号后[125I-Tyr3]奥曲肽的摄取减少。
我们在此证明，在临床前NET模型中，Wnt信号调节SSTR表达和功能。Wnt抑制增加[125I-Tyr3]奥曲肽摄取，为提高SSTR靶向诊疗方法的疗效提供了机会。
