A Fluorogenic Probe for γ-Glutamyl Cyclotransferase: Application of an Enzyme-Triggered O-to-N Acyl Migration-Type Reaction

γ-Glutamyl cyclotransferase contributes to endometrial carcinoma malignant progression and upregulation of PD-L1 expression during activation of epithelial-mesenchymal transition

Recent increases in the incidence of endometrial carcinoma represent a significant risk to women's health. We found that γ-glutamyl cyclotransferase (GGCT) was significantly up-regulated in endometrial carcinoma tissues and cells, which suggested that it may be a potential target for treatment of endometrial carcinoma. Furthermore, the impact of GGCT on proliferation, migration, and invasion of endometrial carcinoma has been demonstrated in vitro and in vivo using GGCT silencing and overexpression techniques. In addition, the epithelial-mesenchymal transition (EMT) was significantly inhibited in response to GGCT knockdown, which indicated that GGCT may contribute endometrial carcinoma malignancy during activation of the EMT. We also found that GGCT regulated PD-L1 expression during EMT activation. Furthermore, co-culture of endometrial carcinoma cells with CD8⁺ T lymphocytes showed that downregulation of PD-L1 expression following GGCT knockdown contributed to the killing activity of CD8⁺ T lymphocytes on endometrial carcinoma cells. In conclusion, our study showed that GGCT contributed to malignant progression and upregulation of PD-L1 expression of endometrial carcinoma, and may be a potential target for treatment of endometrial carcinoma.

HAP-01, the first chromogenic substrate forAspergillus oryzaeacid protease

HAP-01 was developed as an activity-based probe forA. oryzaeacid protease important for production ofsake, a Japanese rice wine.

Mechanisms of Tumor Growth Inhibition by Depletion of γ-Glutamylcyclotransferase (GGCT): A Novel Molecular Target for Anticancer Therapy

γ-Glutamylcyclotransferase (GGCT), which is one of the major enzymes involved in glutathione metabolism, is upregulated in a wide range of cancers—glioma, breast, lung, esophageal, gastric, colorectal, urinary bladder, prostate, cervical, ovarian cancers and osteosarcoma—and promotes cancer progression; its depletion leads to the suppression of proliferation, invasion, and migration of cancer cells. It has been demonstrated that the suppression or inhibition of GGCT has an antitumor effect in cancer-bearing xenograft mice. Based on these observations, GGCT is now recognized as a promising therapeutic target in various cancers. This review summarizes recent advances on the mechanisms of the antitumor activity of GGCT inhibition.

Self-immolative versatile fluorogenic probes for screening of hydrolytic enzyme activity

Enzyme triggered probes with a self-immolative linker for rapid and sensitive hydrolase detection through a cascade reaction have been reported. Their utility was proved by the preparation of three model compounds and their evaluation as enzyme substrates and demonstration of their applicability as fluorogenic probes for screening lipase, esterase and protease activities. These probes represent a new class of fluorogenic compounds, are stable under aqueous conditions and not susceptible to nonspecific degradation. The utilization of the carbamate cleavable linkage in a probe structure allows moving away of the bulky fluorophore from the enzyme recognition unit and targets different classes of enzymes with the same substrate.

A Novel Prodrug of a γ-Glutamylcyclotransferase Inhibitor Suppresses Cancer Cell Proliferation in vitro and Inhibits Tumor Growth in a Xenograft Mouse Model of Prostate Cancer

γ-Glutamylcyclotransferase (GGCT) depletion inhibits cancer cell proliferation. However, whether the enzymatic activity of GGCT is critical for the regulation of cancer cell growth remains unclear. In this study, a novel diester-type cell-permeable prodrug, pro-GA, was developed based on the structure of N-glutaryl-l-alanine (GA), by structure optimization using temporary fluorophore-tagged prodrug candidates. The antiproliferative activity of pro-GA was demonstrated using GGCT-overexpressing NIH-3T3 cells and human cancer cells including MCF7, HL-60, and PC3 cells. By contrast, normal cells were not significantly affected by pro-GA treatment. Moreover, pro-GA administration exhibited anticancer effects in a xenograft model using immunocompromised mice inoculated with PC3 cells. These results indicate that the enzymatic activity of GGCT accelerates tumor growth and that GGCT inhibition is a promising therapeutic strategy for the treatment of GGCT-overexpressing tumors.

Gamma-Glutamylcyclotransferase: A Novel Target Molecule for Cancer Diagnosis and Treatment

Gamma-glutamylcyclotransferase (GGCT) is one of the major enzymes involved in glutathione metabolism. However, its gene locus was unknown for many years. Recently, the gene for GGCT was found to be identical to C7orf24, which is registered as a hypothetical protein. Orthologs have been found in bacteria, plants, and nematodes as well as higher organisms, and the GGCT gene is highly preserved among a wide range of species. GGCT (C7orf24) was also reported as an upregulated protein in various cancers. Although the function of GGCT in cancer cells has not been determined, the following important activities have been reported: (1) high expression in various cancer tissues and cancer cell lines, (2) low expression in normal tissues, (3) inhibition of cancer cell proliferation via anti-GGCT RNAi, (4) inhibition of cancer cell invasion and migration via anti-GGCT RNAi, (5) an epigenetic transcriptional regulation in cancer cells, and (6) an antitumor effect in cancer-bearing xenograft mice. Therefore, GGCT is promising as a diagnostic marker and a therapeutic target for various cancers. This review summarizes these interesting findings.

A GGCT fluorogenic probe: design, synthesis and application to cancer-related cells

Cancer-related γ-glutamyl cyclotransferase (GGCT) specifically decomposes γ-glutamyl amino acids. Here we report a novel GGCT fluorogenic probe “LISA-101”.