The Prolyl Isomerase Pin1 Is a Novel Target of 6,7,4'-Trihydroxyisoflavone for Suppressing Esophageal Cancer Growth

The role of the master cancer regulator Pin1 in the development and treatment of cancer

This review examines the complex role of Pin1 in the development and treatment of cancer. Pin1 is the only peptidyl-prolyl isomerase (PPIase) that can recognize and isomerize phosphorylated Ser/Thr-Pro peptide bonds. Pin1 catalyzes a structural change in phosphorylated Ser/Thr-Pro motifs that can modulate protein function and thereby impact cell cycle regulation and tumorigenesis. The molecular mechanisms by which Pin1 contributes to oncogenesis are reviewed, including Pin1 overexpression and its correlation with poor cancer prognosis, and the contribution of Pin1 to aggressive tumor phenotypes involved in therapeutic resistance is discussed, with an emphasis on cancer stem cells, the epithelial-to-mesenchymal transition (EMT), and immunosuppression. The therapeutic potential of Pin1 inhibition in cancer is discussed, along with the promise and the difficulties in identifying potent, drug-like, small-molecule Pin1 inhibitors. The available evidence supports the efficacy of targeting Pin1 as a novel cancer therapeutic by analyzing the role of Pin1 in a complex network of cancer-driving pathways and illustrating the potential of synergistic drug combinations with Pin1 inhibitors for treating aggressive and drug-resistant tumors.

Recent advances of Pin1 inhibitors as potential anticancer agents

Pin1 (proline isomerase peptidyl-prolyl isomerase NIMA-interacting-1), as a member of PPIase family, catalyzes cis-trans isomerization of pThr/Ser-Pro amide bonds of its substrate proteins, further regulating cell proliferation, division, apoptosis, and transformation. Pin1 is overexpressed in various cancers and is positively correlated with tumor initiation and progression. Pin1 inhibition can effectively reduce tumor growth and cancer stem cell expansion, block metastatic spread, and restore chemosensitivity, suggesting that targeting Pin1 may be an effective strategy for cancer treatment. Considering the promising therapeutic effects of Pin1 inhibitors on cancers, we herein are intended to comprehensively summarize the reported Pin1 inhibitors, mainly highlighting their structures, biological functions and binding modes, in hope of providing a reference for the future drug discovery.

PIN1 and PIN4 inhibition via parvulin impeders Juglone, PiB, ATRA, 6,7,4'-THIF, KPT6566, and EGCG thwarted hepatitis B virus replication

Introduction

Human parvulin peptidyl prolyl cis/trans isomerases PIN1 and PIN4 play important roles in cell cycle progression, DNA binding, protein folding and chromatin remodeling, ribosome biogenesis, and tubulin polymerization. In this article, we found that endogenous PIN1 and PIN4 were upregulated in selected hepatocellular carcinoma (HCC) cell lines.

Methods

In this study, we inhibited PIN1 and PIN4 via parvulin inhibitors (Juglone, PiB, ATRA, 6,7,4'-THIF, KPT6566, and EGCG). The native agarose gel electrophoresis (NAGE) immunoblotting analysis revealed that upon PIN1 and/ or PIN4 inhibition, the HBc protein expression and core particle or capsid synthesis reduced remarkably. The effects of PIN4 inhibition on hepatitis B virus (HBV) replication were more pronounced as compared to that of PIN1. The Northern and Southern blotting revealed reduced HBV RNA and DNA levels.

Results

During the HBV course of infection, Juglone, PiB, ATRA, 6,7,4'-THIF, KPT6566, and EGCG-mediated inhibition of PIN1 and PIN4 significantly lowered HBV transcriptional activities without affecting total levels of covalently closed circular DNA (cccDNA). Similar to the inhibitory effects of PIN1 and PIN4 on HBV replication, the knockdown of PIN1 and PIN4 in HBV infection cells revealed significantly reduced amounts of intracellular HBc, HBs, HBV pgRNA, SmRNAs, core particles, and HBV DNA synthesis. Similarly, PIN1 and PIN4 KD abrogated extracellular virion release, naked capsid levels, and HBV DNA levels. In comparison with PIN1 KD, the PIN4 KD showed reduced HBc and/or core particle stabilities, indicating that PIN4 is more critically involved in HBV replication. Chromatin immunoprecipitation (ChIP) assays revealed that in contrast to DNA binding PIN4 proteins, the PIN1 did not show binding to cccDNA. Similarly, upon PIN1 KD, the HBc recruitment to cccDNA remained unaffected. However, PIN4 KD significantly abrogated PIN4 binding to cccDNA, followed by HBc recruitment to cccDNA and restricted HBV transcriptional activities. These effects were more pronounced in PIN4 KD cells upon drug treatment in HBV-infected cells.

Conclusion

The comparative analysis revealed that in contrast to PIN1, PIN4 is more critically involved in enhancing HBV replication. Thus, PIN1 and PIN4 inhibition or knockdown might be novel therapeutic targets to suppress HBV infection. targets to suppress HBV infection.

The regulatory role of Pin1 in neuronal death

Regulated cell death predominantly involves apoptosis, autophagy, and regulated necrosis. It is vital that we understand how key regulatory signals can control the process of cell death. Pin1 is a cis-trans isomerase that catalyzes the isomerization of phosphorylated serine or threonine-proline motifs of a protein, thereby acting as a crucial molecular switch and regulating the protein functionality and the signaling pathways involved. However, we know very little about how Pin1-associated pathways might play a role in regulated cell death. In this paper, we review the role of Pin1 in regulated cell death and related research progress and summarize Pin1-related pathways in regulated cell death. Aside from the involvement of Pin1 in the apoptosis that accompanies neurodegenerative diseases, accumulating evidence suggests that Pin1 also plays a role in regulated necrosis and autophagy, thereby exhibiting distinct effects, including both neurotoxic and neuroprotective effects. Gaining an enhanced understanding of Pin1 in neuronal death may provide us with new options for the development of therapeutic target for neurodegenerative disorders.

Molecular action of larvicidal flavonoids on ecdysteroidogenic glutathione S-transferase Noppera-bo in Aedes aegypti

Background

Mosquito control is a crucial global issue for protecting the human community from mosquito-borne diseases. There is an urgent need for the development of selective and safe reagents for mosquito control. Flavonoids, a group of chemical substances with variable phenolic structures, such as daidzein, have been suggested as potential mosquito larvicides with less risk to the environment. However, the mode of mosquito larvicidal action of flavonoids has not been elucidated.

Results

Here, we report that several flavonoids, including daidzein, inhibit the activity of glutathione S-transferase Noppera-bo (Nobo), an enzyme used for the biosynthesis of the insect steroid hormone ecdysone, in the yellow fever mosquito Aedes aegypti. The crystal structure of the Nobo protein of Ae. aegypti (AeNobo) complexed with the flavonoids and its molecular dynamics simulation revealed that Glu113 forms a hydrogen bond with the flavonoid inhibitors. Consistent with this observation, substitution of Glu113 with Ala drastically reduced the inhibitory activity of the flavonoids against AeNobo. Among the identified flavonoid-type inhibitors, desmethylglycitein (4′,6,7-trihydroxyisoflavone) exhibited the highest inhibitory activity in vitro. Moreover, the inhibitory activities of the flavonoids correlated with the larvicidal activity, as desmethylglycitein suppressed Ae. aegypti larval development more efficiently than daidzein.

Conclusion

Our study demonstrates the mode of action of flavonoids on the Ae. aegypti Nobo protein at the atomic, enzymatic, and organismal levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01233-2.

Targeting Pin1 for Modulation of Cell Motility and Cancer Therapy

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) specifically binds and isomerizes the phosphorylated serine/threonine-proline (pSer/Thr-Pro) motif, which leads to changes in protein conformation and function. Pin1 is widely overexpressed in cancers and plays an important role in tumorigenesis. Mounting evidence has revealed that targeting Pin1 is a potential therapeutic approach for various cancers by inhibiting cell proliferation, reducing metastasis, and maintaining genome stability. In this review, we summarize the underlying mechanisms of Pin1-mediated upregulation of oncogenes and downregulation of tumor suppressors in cancer development. Furthermore, we also discuss the multiple roles of Pin1 in cancer hallmarks and examine Pin1 as a desirable pharmaceutical target for cancer therapy. We also summarize the recent progress of Pin1-targeted small-molecule compounds for anticancer activity.

Antineuroinflammatory Effects of 7,3',4'-Trihydroxyisoflavone in Lipopolysaccharide-Stimulated BV2 Microglial Cells through MAPK and NF-κB Signaling Suppression

Neuroinflammation—a common pathological feature of neurodegenerative disorders such as Alzheimer’s disease—is mediated by microglial activation. Thus, inhibiting microglial activation is vital for treating various neurological disorders. 7,3’,4’-Trihydroxyisoflavone (THIF)—a secondary metabolite of the soybean compound daidzein—possesses antioxidant and anticancer properties. However, the effects of 7,3’,4’-THIF on microglial activation have not been explored. In this study, antineuroinflammatory effects of 7,3’,4’-THIF in lipopolysaccharide (LPS)-stimulated BV2 microglial cells were examined. 7,3’,4’-THIF significantly suppressed the production of the proinflammatory mediators nitric oxide (NO), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) as well as of the proinflammatory cytokine interleukin-6 (IL-6) in LPS-stimulated BV2 microglial cells. Moreover, 7,3’,4’-THIF markedly inhibited reactive oxygen species (ROS) generation. Western blotting revealed that 7,3’,4’-THIF diminished LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), glycogen synthase kinase-3β (GSK-3β), and nuclear factor kappa B (NF-κB). Overall, 7,3’,4’-THIF exerts antineuroinflammatory effects against LPS-induced microglial activation by suppressing mitogen-activated protein kinase (MAPK) and NF-κB signaling, ultimately reducing proinflammatory responses. Therefore, these antineuroinflammatory effects of 7,3’,4’-THIF suggest its potential as a therapeutic agent for neurodegenerative disorders.

Rational design of PIN1 inhibitors for cancer treatment based on conformational diversity analysis and docking based virtual screening

The parvulin PIN1 (peptidyl-prolyl cis-trans isomerase NIMA-interacting 1), is the only enzyme capable of isomerizing prolines of phospho-Serine/Threonine-Proline motifs. PIN1 binds to a subset of proteins and plays an essential role in regulating protein function post-phosphorylation control. Furthermore, the activity of PIN1 regulates the outcome of the signalling of proline-directed kinases (e.g. MAPK, CDK, or GSK3) and thus regulates cell proliferation and cell survival. For these reasons, PIN1 inhibitors are interesting since they may have therapeutic implications for cancer. Several authors have already reported that the non-structural point mutation Trp34Ala prevents PIN1 from interacting with its downstream effector proteins. In this work, we characterized PIN1 structurally, intending to explore new inhibition targets for the rational design of pharmacological activity compounds. Through a conformational diversity analysis of PIN1, we identified and characterized a highly specific druggable pocket around the residue Trp34. This pocket was used in a high-throughput docking screening of 450,000 drug-like compounds, and the top 10 were selected for re-docking studies on the previously used conformers. Finally, we evaluated the binding of each compound by thermal shift assay and found four molecules with a high affinity for PIN1 and potential inhibitory activity. Through this strategy, we achieved novel drug candidates with the ability to interfere with the phosphorylation-dependent actions of PIN1 and with potential applications in the treatment of cancer.Communicated by Ramaswamy H. Sarma.

Function of PIN1 in Cancer Development and Its Inhibitors as Cancer Therapeutics

Peptidyl-prolyl isomerase (PIN1) specifically binds and isomerizes the phosphorylated serine/threonine-proline (pSer/Thr-Pro) motif, which results in the alteration of protein structure, function, and stability. The altered structure and function of these phosphorylated proteins regulated by PIN1 are closely related to cancer development. PIN1 is highly expressed in human cancers and promotes cancer as well as cancer stem cells by breaking the balance of oncogenes and tumor suppressors. In this review, we discuss the roles of PIN1 in cancer and PIN1-targeted small-molecule compounds.

Protective effects of 6,7,4'-trihydroxyisoflavone, a major metabolite of daidzein, on 6-hydroxydopamine-induced neuronal cell death in SH-SY5Y human neuroblastoma cells

Daidzein, one of the important isoflavones, is extensively metabolized in the human body following consumption. In particular, 6,7,4'-trihydroxyisoflavone (THIF), a major metabolite of daidzein, has been the focus of recent investigations due to its various health benefits, such as anti-cancer and anti-obesity effects. However, the protective effects of 6,7,4'-THIF have not yet been studied in models of Parkinson's disease (PD). Therefore, the present study aimed to investigate the protective activity of 6,7,4'-THIF on 6-hydroxydopamine (OHDA)-induced neurotoxicity in SH-SY5Y human neuroblastoma cells. Pretreatment of SH-SY5Y cells with 6,7,4'-THIF significantly inhibited 6-OHDA-induced neuronal cell death, lactate dehydrogenase release, and reactive oxygen species production. In addition, 6,7,4'-THIF significantly attenuated reductions in 6-OHDA-induced superoxide dismutase activity and glutathione content. Moreover, 6,7,4'-THIF attenuated alterations in Bax and Bcl-2 expression and caspase-3 activity in 6-OHDA-induced SH-SY5Y cells. Furthermore, 6,7,4'-THIF significantly reduced 6-OHDA-induced phosphorylation of c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and extracellular signal-regulated kinase 1/2. Additionally, 6,7,4'-THIF effectively prevented 6-OHDA-induced loss of tyrosine hydroxylase. Taken together, these results suggest that 6,7,4'-THIF, a major metabolite of daidzein, may be an attractive option for treating and/or preventing neurodegenerative disorders such as PD.

Prolyl isomerase Pin1: a promoter of cancer and a target for therapy

Pin1 is the only known peptidyl-prolyl cis–trans isomerase (PPIase) that specifically recognizes and isomerizes the phosphorylated Serine/Threonine-Proline (pSer/Thr-Pro) motif. The Pin1-mediated structural transformation posttranslationally regulates the biofunctions of multiple proteins. Pin1 is involved in many cellular processes, the aberrance of which lead to both degenerative and neoplastic diseases. Pin1 is highly expressed in the majority of cancers and its deficiency significantly suppresses cancer progression. According to the ground-breaking summaries by Hanahan D and Weinberg RA, the hallmarks of cancer comprise ten biological capabilities. Multiple researches illuminated that Pin1 contributes to these aberrant behaviors of cancer via promoting various cancer-driving pathways. This review summarized the detailed mechanisms of Pin1 in different cancer capabilities and certain Pin1-targeted small-molecule compounds that exhibit anticancer activities, expecting to facilitate anticancer therapies by targeting Pin1.