Wang Yue, Langley Ries J, Harms Julia, Portlock Theo, Jamieson Stephen M F, Perry Jo K
Liggins Institute, University of Auckland, Auckland, New Zealand.
Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand.
Protein Sci. 2025 Aug;34(8):e70211. doi: 10.1002/pro.70211.
Aberrant human growth hormone (GH) expression has been increasingly linked to poor outcomes in certain cancers and reduced health span. GH receptor (GHR) signal transduction activates signaling pathways that promote cell proliferation and survival, contributing to tumor progression. Consequently, there has been growing interest in creating antagonists that target GH signaling for anticancer applications. Pegvisomant is the only clinically available GHR antagonist (GHA). It is a protein antagonist that consists of a mutated GH protein (B2036) conjugated to polyethylene glycol (PEG). While pegvisomant is a potent human GHR antagonist, it has lower efficacy in mice, necessitating the use of higher doses in preclinical models. Here, we describe two antagonists, GHA2 and GHA3, based on an earlier reported antagonist, B2024, that have improved efficacy in mice. Recombinant GHA2 and GHA3 were produced in E. coli and then conjugated to multiple 5 kDa amine-reactive mPEG (GHA2-PEG5K) or site-specifically PEGylated with 40 kDa mPEG at amino acid site 144 (GHA3-PEG40K). When compared with B2036, GHA2 and GHA3 had significantly improved in vitro activity against the mouse GHR in a Ba/F3 cell viability assay, and GHA2 more effectively reduced GH-dependent signal transduction in the mouse melanoma cell line, B16-F10. A single dose of 30 mg/kg of amine-PEGylated GHA2-PEG5K or site-specific conjugate, GHA3-PEG40K, reduced serum IGF-1 in mice at 24 h by 40.7% and 45.8%, respectively. In contrast, amine-PEGylated B2036-PEG5K did not significantly reduce serum IGF-I levels. In conclusion, we demonstrate here that GHA2-PEG5K and GHA3-PEG40K are more potent inhibitors than B2036-PEG5K in mouse models.
异常的人生长激素（GH）表达与某些癌症的不良预后以及健康寿命缩短的关联日益增加。生长激素受体（GHR）信号转导激活促进细胞增殖和存活的信号通路，从而导致肿瘤进展。因此，针对抗癌应用开发靶向GH信号的拮抗剂的兴趣与日俱增。培维索孟是唯一临床上可用的GHR拮抗剂（GHA）。它是一种蛋白质拮抗剂，由与聚乙二醇（PEG）偶联的突变GH蛋白（B2036）组成。虽然培维索孟是一种有效的人GHR拮抗剂，但它在小鼠中的效力较低，因此在临床前模型中需要使用更高的剂量。在此，我们描述了基于先前报道的拮抗剂B2024的两种拮抗剂GHA2和GHA3，它们在小鼠中具有更高的效力。重组GHA2和GHA3在大肠杆菌中产生，然后与多个5 kDa胺反应性mPEG偶联（GHA2-PEG5K），或在氨基酸位点144处用40 kDa mPEG进行位点特异性聚乙二醇化（GHA3-PEG40K）。与B2036相比，在Ba/F3细胞活力测定中，GHA2和GHA3对小鼠GHR的体外活性显著提高，并且GHA2更有效地降低了小鼠黑色素瘤细胞系B16-F10中GH依赖性信号转导。单剂量30 mg/kg的胺聚乙二醇化GHA2-PEG5K或位点特异性偶联物GHA3-PEG40K在24小时时分别使小鼠血清IGF-1降低40.7%和45.8%。相比之下，胺聚乙二醇化B2036-PEG5K并未显著降低血清IGF-I水平。总之，我们在此证明，在小鼠模型中，GHA2-PEG5K和GHA3-PEG40K是比B2036-PEG5K更有效的抑制剂。
