ML-7

Thyroid cancer has emerged as the most rapidly proliferating solid neoplasm. In this study, we included a cohort of patients who underwent sonographic assessment and surgical intervention at the Sir Run Run Shaw Hospital, associated with the School of Medicine at Zhejiang University, spanning from January 2019 to June 2020. Stratification of cases was based on a combination of preoperative ultrasonographic evaluations and postoperative histopathological diagnoses, resulting in three distinct groups: high-risk papillary thyroid carcinoma (PTC) labeled as C1, low-risk PTC designated as C2, and a control group (N) composed of benign thyroid tissue adjacent to the carcinoma. Proteomic and phosphoproteomic analyses were conducted on PTC specimens. The comparative assessment revealed that proteins up-regulated in the C1/N and C2/N groups were predominantly involved in functions such as amino acid binding, binding of phosphorylated compounds, and serine protease activity. Notably, proteins like NADH dehydrogenase, ATP synthase, oxidoreductases, and iron ion channels were significantly elevated in the C1 versus C2 comparative group. Through meticulous analysis of differential expression multiples, statistical significance, and involvement in metabolic pathways, this study identified eight potential biomarkers pertinent to PTC metastasis diagnostics, encompassing phosphorylated myosin 10, phosphorylated proline-directed protein kinase, leucine tRNA synthetase, 2-oxo-isovalerate dehydrogenase, succinic semialdehyde dehydrogenase, ADP/ATPtranslocase, pyruvate carboxylase, and fibrinogen. Therapeutic assays employing metformin, an AMP-activated protein kinase (AMPK) activator, alongside the phosphorylation-specific inhibitor ML-7 targeting Myosin10, demonstrated attenuated cellular proliferation, migration, and invasion capabilities in thyroid cancer cells, accompanied by a reduction in amino acid pools. Cellular colocalization and interaction studies elucidated that AMPK activation imposes an inhibitory influence on Myosin10 levels. The findings of this research corroborate the utility of proteomic and phosphoproteomic platforms in the identification of metastatic markers for PTC and suggest that modulation of AMPK activity, coupled with the inhibition of Myosin10 phosphorylation, may forge novel therapeutic avenues in the management of thyroid carcinoma. SIGNIFICANCE: The significance of our research lies in its potential to transform the current understanding and management of thyroid papillary carcinoma (PTC), particularly in its metastatic form. By integrating both proteomic and phosphoproteomic analyses, our study not only sheds light on the molecular alterations associated with PTC but also identifies eight novel biomarkers that could serve as indicators of metastatic potential.

Control of angiogenesis is widely considered a therapeutic strategy, but reliable control methods are still under development. Phosphorylation of myosin light chain 2 (MLC2), which regulates actin-myosin interaction, is critical to the behavior of vascular endothelial cells (ECs) during angiogenesis. MLC2 is phosphorylated by MLC kinase (MLCK) and dephosphorylated by MLC phosphatase (MLCP) containing a catalytic subunit PP1. We investigated the potential role of MLC2 in the pharmacological control of angiogenesis.

We exposed transgenic zebrafish Tg(fli1a:Myr-mCherry)^ncv1 embryos to chemical inhibitors and observed vascular development. PP1 inhibition by tautomycetin increased length of intersegmental vessels (ISVs), whereas MLCK inhibition by ML7 decreased it; these effects were not accompanied by structural dysplasia. ROCK inhibition by Y-27632 also decreased vessel length. An in vitro angiogenesis model of human umbilical vein endothelial cells (HUVECs) showed that tautomycetin increased vascular cord formation, whereas ML7 and Y-27632 decreased it. These effects appear to be influenced by regulation of cell morphology rather than cell viability or motility. Actin co-localized with phosphorylated MLC2 (pMLC2) was abundant in vascular-like elongated-shaped ECs, but poor in non-elongated ECs. pMLC2 was associated with tightly arranged actin, but not with loosely arranged actin. Moreover, knockdown of MYL9 gene encoding MLC2 reduced total MLC2 and pMLC2 protein and inhibited angiogenesis in HUVECs.

The present study found that MLC2 is a pivotal regulator of angiogenesis. MLC2 phosphorylation may be involved in the regulation of of cell morphogenesis and cell elongation. The functionally opposite inhibitors positively or negatively control angiogenesis, probably through the regulating EC morphology. These findings may provide a unique therapeutic target for angiogenesis.