COT phosphorylates prolyl-isomerase Pin1 to promote tumorigenesis in breast cancer

The molecular mechanisms of peptidyl-prolyl cis/trans isomerase Pin1 and its relevance to kidney disease

Pin1 is a member of the peptidyl-prolyl cis/trans isomerase subfamily and is widely expressed in various cell types and tissues. Alterations in Pin1 expression levels play pivotal roles in both physiological processes and multiple pathological conditions, especially in the onset and progression of kidney diseases. Herein, we present an overview of the role of Pin1 in the regulation of fibrosis, oxidative stress, and autophagy. It plays a significant role in various kidney diseases including Renal I/R injury, chronic kidney disease with secondary hyperparathyroidism, diabetic nephropathy, renal fibrosis, and renal cell carcinoma. The representative therapeutic agent Juglone has emerged as a potential treatment for inhibiting Pin1 activity and mitigating kidney disease. Understanding the role of Pin1 in kidney diseases is expected to provide new insights into innovative therapeutic interventions and strategies. Consequently, this review delves into the molecular mechanisms of Pin1 and its relevance in kidney disease, paving the way for novel therapeutic approaches.

Overexpression of TPL2 may be a predictor of good prognosis in patients with breast invasive ductal carcinoma

The objective of this study was to investigate the clinical significance and roles of tumor progression locus 2 (TPL2) and peptidyl-prolyl cis-trans isomerase 1 (Pin1) in the occurrence and development of breast invasive ductal carcinoma (IDC). Immunohistochemistry was used to detect the expression of TPL2 and Pin1 in human breast tissues, which included normal breast tissues (Normal), tissues with fibrocystic changes (FCC), ductal carcinoma in situ (DCIS), and IDC. The roles of TPL2 and Pin1 in the occurrence and development of IDC, as well as the correlation between their expression levels and clinicopathological parameters, were analyzed. Compared with Normal and FCC groups, the overexpression of TPL2 and Pin1 was significantly increased in DCIS and IDC groups (DCIS vs Normal: P = 0.002/P < 0.001; IDC vs Normal: P = 0.007/P = 0.003; DCIS vs. FCC: P = 0.008/P = 0.004; IDC vs. FCC: P = 0.04/P = 0.043). The expression levels of TPL2 and Pin1 were positively correlated in DCIS and IDC groups (P = 0.001, P = 0.011). In the IDC group, the Ki67 level in the TPL2 overexpression group was significantly lower than that in the TPL2 low expression group (P = 0.02). The TPL2 overexpression rate was significantly higher in IDC with histological grades 1-2 than that in IDC with histological grade 3 (P = 0.029). The TPL2 overexpression rate in IDC with tumor-node-metastasis (TNM) stage I was significantly higher than that in IDC with TNM stages II-III (P = 0.035). We conclude that TPL2 and Pin1 may synergistically promote the occurrence and development of IDC, but TPL2 overexpression may be an early molecular event in IDC development. TPL2 overexpression is significantly related with IDC with lower malignancy or earlier TNM stage, suggesting that the prognosis of IDC patients with TPL2 overexpression may be better and TPL2 overexpression may be a predictor of good prognosis in IDC.

Function and regulation of cis P-tau in the pathogenesis and treatment of conventional and nonconventional tauopathies

Conventional tauopathies are a group of disease characterized by tau inclusions in the brains, including Alzheimer's disease (AD), Pick's disease (PiD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and certain types of frontotemporal dementia (FTD), among which AD is the most prevalent. Extensive post-translational modifications, especially hyperphosphorylation, and abnormal aggregation of tau protein underlie tauopathy. Cis-trans isomerization of protein plays an important role in protein folding, function, and degradation, which is regulated by peptidyl-proline isomerases (PPIases). Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1), the only PPIase found to isomerize Pro following phosphorylated Ser or Thr residues, alters phosphorylated tau protein conformation at pT231-P motif. The cis P-tau but not trans P-tau serves as an early driver of multiple neurodegenerative disease, encompassing AD, traumatic brain injury (TBI), chronic traumatic encephalopathy (CTE), and vascular contributions to cognitive impairment and dementia (VCID). Cis but not trans P-tau is resistant to protein dephosphorylation and degradation, and also prone to protein aggregation. Cis P-tau loses its ability to stabilize microtubule, causing and spreading tauopathy mainly in axons, a pathological process called cistauosis. The conformation-specific monoclonal antibody that targets only the cis P-tau serves as a very early diagnosis method and a potential treatment of not only conventional tauopathies but also nonconventional tauopathies such as VCID, with clinical trials ongoing. Notably, cis P-tau antibody is the only clinical-stage Alzheimer's therapeutic that has shown the efficacy in animal models of not only AD but also TBI and stroke, which are very early stages of dementia. Here we review the identification and pathological consequences of cis pt231-tau, the role of its regulator Pin1, as well as the clinical implication of cis pt231-tau conformation-specific antibody in conventional and nonconventional tauopathies.

Pin1 and Alzheimer's disease

Alzheimer's disease (AD) is an immense and growing public health crisis. Despite over 100 years of investigation, the etiology remains elusive and therapy ineffective. Despite current gaps in knowledge, recent studies have identified dysfunction or loss-of-function of Pin1, a unique cis-trans peptidyl prolyl isomerase, as an important step in AD pathogenesis. Here I review the functionality of Pin1 and its role in neurodegeneration.

Regulation of eukaryotic protein kinases by Pin1, a peptidyl-prolyl isomerase

The peptidyl-prolyl isomerase Pin1 cooperates with proline-directed kinases and phosphatases to regulate multiple oncogenic pathways. Pin1 specifically recognizes phosphorylated Ser/Thr-Pro motifs in proteins and catalyzes their cis-trans isomerization. The Pin1-catalyzed conformational changes determine the stability, activity, and subcellular localization of numerous protein substrates. We conducted a survey of eukaryotic protein kinases that are regulated by Pin1 and whose Pin1 binding sites have been identified. Our analyses reveal that Pin1 target sites in kinases do not fall exclusively within the intrinsically disordered regions of these enzymes. Rather, they fall into three groups based on their location: (i) within the catalytic kinase domain, (ii) in the C-terminal kinase region, and (iii) in regulatory domains. Some of the kinases downregulated by Pin1 activity are tumor-suppressing, and all kinases upregulated by Pin1 activity are functionally pro-oncogenic. These findings further reinforce the rationale for developing Pin1-specific inhibitors as attractive pharmaceuticals for cancer therapy.

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.

Potential Anti-Tumor Activity of Kefir-Induced Juglone and Resveratrol Fractions Against Ehrlich Ascites Carcinoma-Bearing BALB/C Mice

We investigated the potential influence of kefir-induced juglone and resveratrol fractions (JRK) against Ehrlich Ascites Carcinoma (EAC) bearing BALB/c male mice. Kefir yeast was grown in the cell culture supplemented with juglone and resveratrol (1:2). After 48 h incubation, JRK solution was applied (0.1 mL/day i.p.) to the EAC-bearing mice throughout five days. Molecular regulatory mechanisms of apoptotic and anti-apoptotic pathway components were evaluated in the plasma of mice and isolated EAC cells with ELISA, qRT-PCR, and immunocytchemical experiments. EAC-induced upregulation in Bcl-2 and downregulation in Caspase-3 were normalized with JRK in the plasma of mice. Additionally, JRK upregulated the expression levels of apoptotic Bax, p53, Caspase-3,8,9, and APAF-1 proteins together with BAX, CASPASE-8, and CASPASE-9 genes in isolated EAC cells. These changes were also associated with decreased expression levels of anti-apoptotic Bcl-2 and Bcl-xl proteins. Immunocytochemical studies also confirmed the activation of apoptotic pathways and repression of anti-apoptotic proteins in EAC cells with JRK treatment. JRK activates apoptotic pathway and inhibits anti-apoptotic genes and proteins in Ehrlich ascites carcinoma- bearing BALB/c mice that could be beneficial in cancer treatment.

Her2 promotes early dissemination of breast cancer by suppressing the p38 pathway through Skp2-mediated proteasomal degradation of Tpl2

While mechanisms for metastasis were extensively studied in cancer cells from patients with detectable tumors, pathways underlying metastatic dissemination from early lesions before primary tumors appear are poorly understood. Her2 promotes breast cancer early dissemination by suppressing p38, but how Her2 downregulates p38 is unclear. Here, we demonstrate that in early lesion breast cancer models, Her2 inhibits p38 by inducing Skp2 through Akt-mediated phosphorylation, which promotes ubiquitination and proteasomal degradation of Tpl2, a p38 MAP3K. The early disseminating cells are Her2⁺Skp2^highTpl2^lowp-p38^lowE-cadherin^low in the MMTV-Her2 breast cancer model. In human breast carcinoma, high Skp2 and low Tpl2 expression are associated with the Her2⁺ status; Tpl2 expression positively correlates with that of activated p38; Skp2 expression negatively correlates with that of Tpl2 and activated p38. Moreover, the Her2-Akt-Skp2-Tpl2-p38 axis plays a key role in the disseminating phenotypes in early lesion breast cancer cells; inhibition of Tpl2 enhances early dissemination in vivo. These findings identify the Her2-Akt-Skp2-Tpl2-p38 cascade as a novel mechanism mediating breast cancer early dissemination and a potential target for novel therapies targeting early metastatic dissemination.

The Peptidyl-prolyl Isomerase Pin1 in Neuronal Signaling: from Neurodevelopment to Neurodegeneration

The peptidyl-prolyl isomerase Pin1 is a unique enzyme catalyzing the isomerization of the peptide bond between phosphorylated serine-proline or threonine-proline motifs in proteins, thereby regulating a wide spectrum of protein functions, including folding, intracellular signaling, transcription, cell cycle progression, and apoptosis. Pin1 has been reported to act as a key molecular switch inducing cell-type-specific effects, critically depending on the different phosphorylation patterns of its targets within different biological contexts. While its implication in proliferating cells, and, in particular, in the field of cancer, has been widely characterized, less is known about Pin1 biological functions in terminally differentiated and post-mitotic neurons. Notably, Pin1 is widely expressed in the central and peripheral nervous system, where it regulates a variety of neuronal processes, including neuronal development, apoptosis, and synaptic activity. However, despite studies reporting the interaction of Pin1 with neuronal substrates or its involvement in specific signaling pathways, a more comprehensive understanding of its biological functions at neuronal level is still lacking. Besides its implication in physiological processes, a growing body of evidence suggests the crucial involvement of Pin1 in aging and age-related and neurodegenerative diseases, including Alzheimer's disease, Parkinson disease, frontotemporal dementias, Huntington disease, and amyotrophic lateral sclerosis, where it mediates profoundly different effects, ranging from neuroprotective to neurotoxic. Therefore, a more detailed understanding of Pin1 neuronal functions may provide relevant information on the consequences of Pin1 deregulation in age-related and neurodegenerative disorders.

Development of Pin1 Inhibitors and their Potential as Therapeutic Agents

The prolyl isomerase Pin1 is a unique enzyme, which isomerizes the cis-trans conformation between pSer/pThr and proline and thereby regulates the function, stability and/or subcellular distribution of its target proteins. Such regulations by Pin1 are involved in numerous physiological functions as well as the pathogenic mechanisms underlying various diseases. Notably, Pin1 deficiency or inactivation is a potential cause of Alzheimer's disease, since Pin1 induces the degradation of Tau. In contrast, Pin1 overexpression is highly correlated with the degree of malignancy of cancers, as Pin1 controls a number of oncogenes and tumor suppressors. Accordingly, Pin1 inhibitors as anti-cancer drugs have been developed. Interestingly, recent intensive studies have demonstrated Pin1 to be responsible for the onset or development of nonalcoholic steatosis, obesity, atherosclerosis, lung fibrosis, heart failure and so on, all of which have been experimentally induced in Pin1 deficient mice. In this review, we discuss the possible applications of Pin1 inhibitors to a variety of diseases including malignant tumors and also introduce the recent advances in Pin1 inhibitor research, which have been reported.

Tumor progression locus 2 (TPL2) in tumor-promoting Inflammation, Tumorigenesis and Tumor Immunity

Over the years, tumor progression locus 2 (TPL2) has been identified as an essential modulator of immune responses that conveys inflammatory signals to downstream effectors, subsequently modulating the generation and function of inflammatory cells. TPL2 is also differentially expressed and activated in several cancers, where it is associated with increased inflammation, malignant transformation, angiogenesis, metastasis, poor prognosis and therapy resistance. However, the relationship between TPL2-driven inflammation, tumorigenesis and tumor immunity has not been addressed. Here, we reconcile the function of TPL2-driven inflammation to oncogenic functions such as inflammation, proliferation, apoptosis resistance, angiogenesis, metastasis, immunosuppression and immune evasion. We also address the controversies reported on TPL2 function in tumor-promoting inflammation and tumorigenesis, and highlight the potential role of the TPL2 adaptor function in regulating the mechanisms leading to pro-tumorigenic inflammation and tumor progression. We discuss the therapeutic implications and limitations of targeting TPL2 for cancer treatment. The ideas presented here provide some new insight into cancer pathophysiology that might contribute to the development of more integrative and specific anti-inflammatory and anti-cancer therapeutics.

Post-translational Modifications of the Peptidyl-Prolyl Isomerase Pin1

The peptidyl-prolyl cis/trans isomerase (PPIase) Pin1 is a unique enzyme that only binds to Ser/Thr-Pro peptide motifs after phosphorylation and regulates the conformational changes of the bond. The Pin1-catalyzed isomerization upon phosphorylation can have profound effects on substrate biological functions, including their activity, stability, assembly, and subcellular localization, affecting its role in intracellular signaling, transcription, and cell cycle progression. The functions of Pin1 are regulated by post-translational modifications (PTMs) in many biological processes, which include phosphorylation, ubiquitination, SUMOylation and oxidation. Phosphorylation of different Pin1 sites regulates Pin1 enzymatic activity, binding ability, localization, and ubiquitination by different kinases under various cellular contexts. Moreover, SUMOylation and oxidation have been shown to downregulate Pin1 activity. Although Pin1 is tightly regulated under physiological conditions, deregulation of Pin1 PTMs contributes to the development of human diseases including cancer and Alzheimer's disease (AD). Therefore, manipulating the PTMs of Pin1 may be a promising therapeutic option for treating various human diseases. In this review, we focus on the molecular mechanisms of Pin1 regulation by PTMs and the major impact of Pin1 PTMs on the progression of cancer and AD.

ATF-2 and Tpl2 regulation of endothelial cell cycle progression and apoptosis

Cells respond to soluble and membrane-bound factors to activate signalling cascades that control cell proliferation and cell death. Vascular endothelial growth factor A (VEGF-A) is a soluble ligand that modulates a variety of cellular responses including cell proliferation and apoptosis. It is not well understood how VEGF-A signalling pathways regulate cell proliferation and cell death. To address this, we examined VEGF-A-regulated signalling pathways in the cytosol and nucleus and functional requirement for such cellular responses. The VEGF-A-regulated transcription factor, ATF-2, is required for cell cycle proteins such as p53, p21 and Cyclin D1. A cytosolic serine/threonine protein kinase (Tpl2) modulates ATF-2-regulated effects on the endothelial cell cycle. Such regulatory effects impact on endothelial cell proliferation, cell viability and apoptosis. These cellular effects influence complex cell-based organisation such as endothelial tubulogenesis. Our study now provides a framework for incorporating VEGF-A-stimulated signalling events from the cytosol to the nucleus which helps to understand how cell proliferation and apoptosis are controlled.

ABIN-2, of the TPL-2 Signaling Complex, Modulates Mammalian Inflammation

Mammalian TPL-2 kinase (MAP3K8) mediates Toll-like receptor activation of ERK1/2 and p38α MAP kinases and is critical for regulating immune responses to pathogens. TPL-2 also has an important adaptor function, maintaining stability of associated ABIN-2 ubiquitin-binding protein. Consequently, phenotypes detected in Map3k8^-/- mice can be caused by lack of TPL-2, ABIN-2, or both proteins. Recent studies show that increased inflammation of Map3k8^-/- mice in allergic airway inflammation and colitis results from reduced ABIN-2 signaling, rather than blocked TPL-2 signaling. However, Map3k8^-/- mice have been employed extensively to evaluate the potential of TPL-2 as an anti-inflammatory drug target. We posit that Map3k8^D270A/D270A mice, expressing catalytically inactive TPL-2 and physiologic ABIN-2, should be used to evaluate the potential effects of TPL-2 inhibitors in disease.

Juglone in Oxidative Stress and Cell Signaling

Juglone (5-hydroxyl-1,4-naphthoquinone) is a phenolic compound found in walnuts. Because of the antioxidant capacities of phenolic compounds, juglone may serve to combat oxidative stress, thereby protecting against the development of various diseases and aging processes. However, being a quinone molecule, juglone could also act as a redox cycling agent and produce reactive oxygen species. Such prooxidant properties of juglone may confer health effects, such as by killing cancer cells. Further, recent studies revealed that juglone influences cell signaling. Notably, juglone is an inhibitor of Pin1 (peptidyl-prolyl cis/trans isomerase) that could regulate phosphorylation of Tau, implicating potential effects of juglone in Alzheimer’s disease. Juglone also activates mitogen-activated protein kinases that could promote cell survival, thereby protecting against conditions such as cardiac injury. This review describes recent advances in the understanding of the effects and roles of juglone in oxidative stress and cell signaling.

Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 as a molecular target in breast cancer: a therapeutic perspective of gynecological cancer

Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1) induces conformational and functional changes to numerous key signaling molecules following proline-directed phosphorylation and its deregulation contributes to disease, particularly cancer. PIN1 is overexpressed in breast cancer, promoting cell proliferation and transformation in collaboration with several oncogenic signaling pathways, and is correlated with a poor clinical outcome. PIN1 level is also increased in certain gynecological cancers such as cervical, ovarian, and endometrial cancers. Although women with breast cancer are at risk of developing a second primary gynecological malignancy, particularly of the endometrium and ovary, the common oncogenic signaling pathway mediated by PIN1 has not been noted to date. This review discusses the roles of PIN1 in breast tumorigenesis and gynecological cancer progression, as well as the clinical effect of targeting this enzyme in breast and gynecological cancers.

The Multiple Roles of Peptidyl Prolyl Isomerases in Brain Cancer

Peptidyl prolyl isomerases (PPIases) are broadly expressed enzymes that accelerate the cis-trans isomerization of proline peptide bonds. The most extensively studied PPIase family member is protein interacting with never in mitosis A1 (PIN1), which isomerizes phosphorylated serine/threonine–proline bonds. By catalyzing this specific cis-trans isomerization, PIN1 can alter the structure of its target proteins and modulate their activities in a number of different ways. Many proteins are targets of proline-directed phosphorylation and thus PIN1-mediated isomerization of proline bonds represents an important step in the regulation of a variety of cellular mechanisms. Numerous other proteins in addition to PIN1 are endowed with PPIase activity. These include other members of the parvulin family to which PIN1 belongs, such as PIN4, as well as several cyclophilins and FK506-binding proteins. Unlike PIN1, however, these other PPIases do not isomerize phosphorylated serine/threonine–proline bonds and have different substrate specificities. PIN1 and other PPIases are overexpressed in many types of cancer and have been implicated in various oncogenic processes. This review will discuss studies providing evidence for multiple roles of PIN1 and other PPIases in glioblastoma and medulloblastoma, the most frequent adult and pediatric primary brain tumors.

Pin1 Modulation in Physiological Status and Neurodegeneration. Any Contribution to the Pathogenesis of Type 3 Diabetes?

Prolyl isomerases (Peptidylprolyl isomerase, PPIases) are enzymes that catalyze the isomerization between the cis/trans Pro conformations. Three subclasses belong to the class: FKBP (FK506 binding protein family), Cyclophilin and Parvulin family (Pin1 and Par14). Among Prolyl isomerases, Pin1 presents as distinctive feature, the ability of binding to the motif pSer/pThr-Pro that is phosphorylated by kinases. Modulation of Pin1 is implicated in cellular processes such as mitosis, differentiation and metabolism: The enzyme is dysregulated in many diverse pathological conditions, i.e., cancer progression, neurodegenerative (i.e., Alzheimer’s diseases, AD) and metabolic disorders (i.e., type 2 diabetes, T2D). Indeed, Pin1 KO mice develop a complex phenotype of premature aging, cognitive impairment in elderly mice and neuronal degeneration resembling that of the AD in humans. In addition, since the molecule modulates glucose homeostasis in the brain and peripherally, Pin1 KO mice are resistant to diet-induced obesity, insulin resistance, peripheral glucose intolerance and diabetic vascular dysfunction. In this review, we revise first critically the role of Pin1 in neuronal development and differentiation and then focus on the in vivo studies that demonstrate its pivotal role in neurodegenerative processes and glucose homeostasis. We discuss evidence that enables us to speculate about the role of Pin1 as molecular link in the pathogenesis of type 3 diabetes i.e., the clinical association of dementia/AD and T2D.

Structure and function of the human parvulins Pin1 and Par14/17

Parvulins belong to the family of peptidyl-prolyl cis/trans isomerases (PPIases) assisting in protein folding and in regulating the function of a broad variety of proteins in all branches of life. The human representatives Pin1 and Par14/17 are directly involved in processes influencing cellular maintenance and cell fate decisions such as cell-cycle progression, metabolic pathways and ribosome biogenesis. This review on human parvulins summarizes the current knowledge of these enzymes and intends to oppose the well-studied Pin1 to its less well-examined homolog human Par14/17 with respect to structure, catalytic and cellular function.

Pin1 Promotes Regulated Necrosis Induced by Glutamate in Rat Retinal Neurons via CAST/Calpain2 Pathway

The purpose of the current study was to investigate whether peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (Pin1) can interact with calpastatin (CAST) and regulate CAST/calpain2, under excessive glutamate conditions, and subsequently regulate necrosis in rat retinal neurons. Glutamate triggered CAST/calpain2-mediated necrosis regulation in primary cultured retinal neurons, as demonstrated by propidium iodide-staining and lactate dehydrogenase assay. Co-IP results and a computer simulation suggested that Pin1 could bind to CAST. Western blot, real-time quantitative polymerase chain reaction, immunofluorescence, and phosphorylation analysis results demonstrated that CAST was regulated by Pin1, as proven by the application of juglone (i.e., a Pin1 specific inhibitor). The retinal ganglion cell 5 cell line, combined with siRNA approach and flow cytometry, was then used to verify the regulatory pathway of Pin1 in CAST/calpain2-modulated neuronal necrosis that was induced by glutamate. Finally, in vivo studies further confirmed the role of Pin1 in CAST/calpain2-modulated necrosis following glutamate excitation, in the rat retinal ganglion cell and inner nuclear layers. In addition, a flash electroretinogram study provided evidence for the recovery of impaired visual function, which was induced by glutamate, with juglone treatment. Our work aims to investigate the involvement of the Pin1-CAST/calpain2 pathway in glutamate-mediated excitotoxicity.

Physiological and Pathogenic Roles of Prolyl Isomerase Pin1 in Metabolic Regulations via Multiple Signal Transduction Pathway Modulations

Prolyl isomerases are divided into three groups, the FKBP family, Cyclophilin and the Parvulin family (Pin1 and Par14). Among these isomerases, Pin1 is a unique prolyl isomerase binding to the motif including pSer/pThr-Pro that is phosphorylated by kinases. Once bound, Pin1 modulates the enzymatic activity, protein stability or subcellular localization of target proteins by changing the cis- and trans-formations of proline. Several studies have examined the roles of Pin1 in the pathogenesis of cancers and Alzheimer's disease. On the other hand, recent studies have newly demonstrated Pin1 to be involved in regulating glucose and lipid metabolism. Interestingly, while Pin1 expression is markedly increased by high-fat diet feeding, Pin1 KO mice are resistant to diet-induced obesity, non-alcoholic steatohepatitis and diabetic vascular dysfunction. These phenomena result from the binding of Pin1 to several key factors regulating metabolic functions, which include insulin receptor substrate-1, AMPK, Crtc2 and NF-κB p65. In this review, we focus on recent advances in elucidating the physiological roles of Pin1 as well as the pathogenesis of disorders involving this isomerase, from the viewpoint of the relationships between signal transductions and metabolic functions.

The isomerase PIN1 controls numerous cancer-driving pathways and is a unique drug target

Targeted drugs have changed cancer treatment but are often ineffective in the long term against solid tumours, largely because of the activation of heterogeneous oncogenic pathways. A central common signalling mechanism in many of these pathways is proline-directed phosphorylation, which is regulated by many kinases and phosphatases. The structure and function of these phosphorylated proteins are further controlled by a single proline isomerase: PIN1. PIN1 is overactivated in cancers and it promotes cancer and cancer stem cells by disrupting the balance of oncogenes and tumour suppressors. This Review discusses the roles of PIN1 in cancer and the potential of PIN1 inhibitors to restore this balance.

Tumor progression locus 2 ablation suppressed hepatocellular carcinoma development by inhibiting hepatic inflammation and steatosis in mice

Background

Tumor progression locus 2 (TPL2), a serine-threonine kinase, functions as a critical regulator of inflammatory pathways and mediates oncogenic events. The potential role of Tpl2 in nonalcoholic fatty liver disease (NAFLD) associated hepatocellular carcinoma (HCC) development remains unknown.

Methods

Both wild-type and Tpl2 knockout male mice were initiated by a hepatic carcinogen (diethylnitrosamine, i.p. with a single dose of 25 mg.kg⁻¹)at 2 weeks of age, and then were given the high carbohydrate diet feeding to induce hepatic steatosis, inflammation, adenoma and HCC for 24 weeks.

Results

Tpl2 knockout mice had significantly lower incidences of liver tumor and developed hepatocellular adenoma only, which is contrast to wild-type mice where they all developed HCC. Tpl2 knockout mice had significantly down-regulated phosphorylation of JNK and ERK, and levels of mRNA expression of pro-inflammatory cytokines (Il-1β, Il-18, Mcp-1 and Nalp3), which correlated with the reduced incidence and number of hepatic inflammatory foci. Furthermore, Tpl2 ablation resulted in decreased hepatic steatosis and expression of de novo lipogenesis related markers (ACC, SCD1, SREBP1C and AKT phosphorylation), as well as reduction of endoplasmic reticulum stress biomarkers PERK and eIF-2a.

Conclusion

The study revealed for the first time that Tpl2 plays a significant role in promoting HCC development by its pro-inflammatory effect, which suggested that Tpl2 could be a molecular target for HCC prevention.

Tumor progression locus 2 (Tpl2) kinase as a novel therapeutic target for cancer: double-sided effects of Tpl2 on cancer

Tumor progression locus 2 (Tpl2) is a mitogen-activated protein kinase (MAPK) kinase kinase (MAP3K) that conveys various intra- and extra-cellular stimuli to effector proteins of cells provoking adequate adoptive responses. Recent studies have elucidated that Tpl2 is an indispensable signal transducer as an MAP3K family member in diverse signaling pathways that regulate cell proliferation, survival, and death. Since tumorigenesis results from dysregulation of cellular proliferation, differentiation, and apoptosis, Tpl2 participates in many decisive molecular processes of tumor development and progression. Moreover, Tpl2 is closely associated with cytokine release of inflammatory cells, which has crucial effects on not only tumor cells but also tumor microenvironments. These critical roles of Tpl2 in human cancers make it an attractive anti-cancer therapeutic target. However, Tpl2 contradictorily works as a tumor suppressor in some cancers. The double-sided effects of Tpl2 originate from the specific upstream and downstream signaling environment of each tumor, since Tpl2 interacts with various signaling components. This review summarizes recent studies concerning the possible roles of Tpl2 in human cancers and considers its possibility as a therapeutic target, against which novel anti-cancer agents could be developed.

Aberrant expression of COT is related to recurrence of papillary thyroid cancer

Aberrant expression of Cancer Osaka Thyroid Oncogene mitogen-activated protein kinase kinase kinase 8 (COT) (MAP3K8) is a driver of resistance to B-RAF inhibition. However, the de novo expression and clinical implications of COT in papillary thyroid cancer (PTC) have not been investigated.The aim of this study is to investigate the expression of A-, B-, C-RAF, and COT in PTC (n = 167) and analyze the clinical implications of aberrant expression of these genes.Quantitative polymerase chain reaction (qPCR) and immunohistochemical staining (IHC) were performed on primary thyroid cancers. Expression of COT was compared with clinicopathological characteristics including recurrence-free survival. Datasets from public repository (NCBI) were subjected to Gene Set Enrichment Analysis (GSEA).qPCR data showed that the relative mRNA expression of A-, B-, C-RAF and COT of PTC were higher than normal tissues (all P < 0.01). In addition, the expression of COT mRNA in PTC showed positive correlation with A- (r = 0.4083, P < 0.001), B- (r = 0.2773, P = 0.0003), and C-RAF (r = 0.5954, P < 0.001). The mRNA expressions of A-, B,- and C-RAF were also correlated with each other (all P < 0.001). In IHC, the staining intensities of B-RAF and COT were higher in PTC than in normal tissue (P < 0.001). Interestingly, moderate-to-strong staining intensities of B-RAF and COT were more frequent in B-RAF-positive PTC (P < 0.001, P = 0.013, respectively). In addition, aberrant expression of COT was related to old age at initial diagnosis (P = 0.045) and higher recurrence rate (P = 0.025). In multivariate analysis, tumor recurrence was persistently associated with moderate-to-strong staining of COT after adjusting for age, sex, extrathyroidal extension, multifocality, T-stage, N-stage, TNM stage, and B-RAF mutation (odds ratio, 4.662; 95% confidence interval 1.066 - 21.609; P = 0.045). Moreover, moderate-to-strong COT expression in PTC was associated with shorter recurrence-free survival (mean follow-up duration, 14.2 ± 4.1 years; P = 0.0403). GSEA indicated that gene sets related to B-RAF-RAS (P < 0.0001, false discovery rate [FDR] q-value = 0.000) and thyroid differentiation (P = 0.048, FDR q-value = 0.05) scores were enriched in lower COT expression group and gene sets such as T-cell receptor signaling pathway and Toll-like receptor signaling pathway are coordinately upregulated in higher COT expression group (both, P < 0.0001, FDR q-value = 0.000).Aberrant expression of A-, B-, and C-RAF, and COT is frequent in PTC; increased expression of COT is correlated with recurrence of PTC.

TPL2 kinase regulates the inflammatory milieu of the myeloma niche

Targeted modulation of microenvironmental regulatory pathways may be essential to control myeloma and other genetically/clonally heterogeneous cancers. Here we report that human myeloma-associated monocytes/macrophages (MAM), but not myeloma plasma cells, constitute the predominant source of interleukin-1β (IL-1β), IL-10, and tumor necrosis factor-α at diagnosis, whereas IL-6 originates from stromal cells and macrophages. To dissect MAM activation/cytokine pathways, we analyzed Toll-like receptor (TLR) expression in human myeloma CD14(+) cells. We observed coregulation of TLR2 and TLR6 expression correlating with local processing of versican, a proteoglycan TLR2/6 agonist linked to carcinoma progression. Versican has not been mechanistically implicated in myeloma pathogenesis. We hypothesized that the most readily accessible target in the versican-TLR2/6 pathway would be the mitogen-activated protein 3 (MAP3) kinase, TPL2 (Cot/MAP3K8). Ablation of Tpl2 in the genetically engineered in vivo myeloma model, Vκ*MYC, led to prolonged disease latency associated with plasma cell growth defect. Tpl2 loss abrogated the "inflammatory switch" in MAM within nascent myeloma lesions and licensed macrophage repolarization in established tumors. MYC activation/expression in plasma cells was independent of Tpl2 activity. Pharmacologic TPL2 inhibition in human monocytes led to dose-dependent attenuation of IL-1β induction/secretion in response to TLR2 stimulation. Our results highlight a TLR2/6-dependent TPL2 pathway as novel therapeutic target acting nonautonomously through macrophages to control myeloma progression.