Pin1 is overexpressed and correlates with poor prognosis in gastric cancer

Association of polymorphisms in PIN1 with progression and susceptibility in gastric cancer

Background: High expression of PIN1 is associated with gastric cancer progression and risk. Patients & methods: Two single-nucleotide polymorphisms in PIN1, rs2233678 and rs2233679, were examined in gastric cancer patients using PCR-restriction fragment length polymorphism. Results: The rs2233678 GC genotype and C alleles correlated with a decreased susceptibility to gastric cancer. The stratification analysis indicated that the rs2233678 GC genotype was inversely related to gastric cancer risk in never smokers, never drinkers and patients with stage I/II disease. Males and ever drinkers carrying the rs2233679 CT genotype had a mildly elevated susceptibility to gastric cancer. Conclusion: The PIN1 single-nucelotide polymorphisms rs2233678 and rs2233679 correlate with the risk of gastric cancer.

Impact of PIN1 Inhibition on Tumor Progression and Chemotherapy Sensitivity in Colorectal Cancer

BACKGROUND

Deregulated PIN1 is associated with cancer development and progression. Herein, for the first time, we evaluate the roles that PIN1 in tumorigenic characteristics of colorectal cancer (CRC) cells.

METHODS

In this study, PIN1 expression was knocked down in SW-48 cells by synthetic small interfering RNA (siRNA). After confirming the knockdown of PIN1, cell viability, colony formation, apoptosis, autophagy, cancer stem cell (CSC)-related genes, CSC-related signaling pathways, cell migration, and 5-FU chemosensitivity were evaluated in vitro.

RESULTS

Transfection of PIN1 siRNA into SW-48 cells inhibited cancer cell proliferation, migration, and increased apoptosis and autophagy. Transfected SW-48 cells had lower properties of CSCs through the inhibition of β-catenin and Notch1 gene expression. Moreover, inhibition of PIN1 enhanced the inhibitory effect of 5-FU on SW-48 cell proliferation.

CONCLUSION

Our results indicated that targeting of PIN1 serves as a promising therapeutic solution for the suppression of tumor progression processes in CRC.

Roles of peptidyl-prolyl isomerase Pin1 in disease pathogenesis

Pin1 belongs to the peptidyl-prolyl cis-trans isomerases (PPIases) superfamily and catalyzes the cis-trans conversion of proline in target substrates to modulate diverse cellular functions including cell cycle progression, cell motility, and apoptosis. Dysregulation of Pin1 has wide-ranging influences on the fate of cells; therefore, it is closely related to the occurrence and development of various diseases. This review summarizes the current knowledge of Pin1 in disease pathogenesis.

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.

PIN1 Inhibition Sensitizes Chemotherapy in Gastric Cancer Cells by Targeting Stem Cell-like Traits and Multiple Biomarkers

Gastric cancer is the third leading cause of cancer-related death worldwide. Diffuse type gastric cancer has the worst prognosis due to notorious resistance to chemotherapy and enrichment of cancer stem-like cells (CSC) associated with the epithelial-to-mesenchymal transition (EMT). The unique proline isomerase PIN1 is a common regulator of oncogenic signaling networks and is important for gastric cancer development. However, little is known about its roles in CSCs and drug resistance in gastric cancer. In this article, we demonstrate that PIN1 overexpression is closely correlated with advanced tumor stages, poor chemo-response and shorter recurrence-free survival in diffuse type gastric cancer in human patients. Furthermore, shRNA-mediated genetic or all-trans retinoic acid-mediated pharmaceutical inhibition of PIN1 in multiple human gastric cancer cells potently suppresses the EMT, cell migration and invasion, and lung metastasis. Moreover, PIN1 genetic or pharmaceutical inhibition potently eliminates gastric CSCs and suppresses their self-renewal and tumorigenicity in vitro and in vivo Consistent with these phenotypes, are that PIN1 biochemically targets multiple signaling molecules and biomarkers in EMT and CSCs and that genetic and pharmaceutical PIN1 inhibition functionally and drastically enhances the sensitivity of gastric cancer to multiple chemotherapy drugs in vitro and in vivo These results demonstrate that PIN1 inhibition sensitizes chemotherapy in gastric cancer cells by targeting CSCs, and suggest that PIN1 inhibitors may be used to overcome drug resistance in gastric cancer.

Prognostic value of peptidyl-prolyl cis-trans isomerase 1 (PIN1) in human malignant tumors

BACKGROUND

PIN1, a peptidyl-prolyl cis-trans isomerase, specifically can regulate phosphorylation of proteins on serine/threonine residues that precede proline and has critical roles in cell proliferation and transformation. Many studies have revealed that overexpression of PIN1 is involved in the malignant biological behavior of various cancers, but to date, no meta-analyses have evaluated PIN1 clinical and prognostic value in patients with malignant tumors.

METHODS

We retrieved related articles from PubMed, Web of Science and Scopus databases up to April 20, 2019. Pooled odds ratios (ORs) and hazard ratios (HRs) with 95% CIs were used to estimate the correlation of PIN1 expression with clinicopathological characteristics and survival outcomes. The methodology was according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Cochrane Collaboration guidelines.

RESULTS

A total of 20 studies containing 2574 patients with various tumors were included in this analysis. Pooled results showed that PIN1 overexpression was significantly associated with the advanced clinical stages of cancer (OR = 1.37, 95% CI 1.06-1.78), positive lymph node metastasis (OR = 1.65, 95% CI 1.15-2.37) and poor prognosis (HR = 2.40, 95% CI 1.55-3.74), although no correlation with poor differentiation was found.

CONCLUSIONS

These results suggest that high expression of PIN1 can be considered as a risk factor for progression and invasion of malignant tumors and thus may serve as a promising therapeutic target and prognostic biomarker for human solid tumors.

Targeting PIN1 exerts potent antitumor activity in pancreatic ductal carcinoma via inhibiting tumor metastasis

The human prolyl isomerase PIN1, best known for its association with carcinogenesis, has recently been indicated in the disease of pancreatic ductal adenocarcinoma (PDAC). However, the functions of PIN1 and the feasibility of targeting PIN1 in PDAC remain elusive. For this purpose, we examined the expression of PIN1 in cancer, related paracarcinoma and metastatic cancer tissues by immunohistochemistry and analyzed the associations with the pathogenesis of PDAC in 173 patients. The functional roles of PIN1 in PDAC were explored in vitro and in vivo using both genetic and chemical PIN1 inhibition. We showed that PIN1 was upregulated in pancreatic cancer and metastatic tissues. High PIN1 expression is significantly association with poor clinicopathological features and shorter overall survival and disease‐free survival. Further stratified analysis showed that PIN1 phenotypes refined prognostication in PDAC. Inhibition of PIN1 expression with RNA interference or with all trans retinoic acid decreased not only the growth but also the migration and invasion of PDAC cells through regulating the key molecules of multiple cancer‐driving pathways, simultaneously resulting in cell cycle arrest and mesenchymal‐epithelial transition in vitro. Furthermore, genetic and chemical PIN1 ablation showed dramatic inhibition of the tumorigenesis and metastatic spread and then reduced the tumor burden in vivo. We provided further evidence for the use of PIN1 as a promising therapeutic target in PDAC. Genetic and chemical PIN1 ablation exerted potent antitumor effects through blocking multiple cancer‐driving pathways in PDAC. More potent and specific PIN1 targeted inhibitors could be exploited to treat this aggressive cancer.

Pin1 inhibition potently suppresses gastric cancer growth and blocks PI3K/AKT and Wnt/β-catenin oncogenic pathways

Gastric cancer is the second leading cause of cancer-related mortality and the fourth most common cancer globally. High intratumor heterogeneity of advanced gastric cancer poses great challenges to targeted therapy due to simultaneous activation of many redundant cancer-driving pathways. A central common signaling mechanism in cancer is proline-directed phosphorylation, which is further regulated by the unique proline isomerase Pin1. Pin1 inhibition exerts anticancer activity by blocking multiple cancer-driving pathways in some cancers, but its role in gastric cancer is not fully understood. Here we detected Pin1 protein expression in 1065 gastric cancer patients and paired normal tissues using immunohistochemistry and Western blot, and then examined the effects of Pin1 overexpression, and genetic and chemical Pin1 inhibition using Pin1 short hairpin RNA or small molecule inhibitor all-trans retinoic acid (ATRA) on tumorigenesis of human gastric cancer in vitro and in vivo, followed by biochemical analyses to elucidate Pin1 regulated oncogenic pathways. We found that Pin1 was significantly overexpressed in primary and metastasized tumors, with Pin1 overexpression being correlated with advanced stage and poor prognosis. Furthermore, whereas Pin1 overexpression promoted the transformed phenotype in immortalized and nontransformed human gastric cells, either genetic or chemical Pin1 inhibition in multiple human gastric cancer cells potently suppressed cell growth, G1/S transition and colony formation in vitro, as well as tumor growth in xenograft tumor models in vivo, which were further supported by downregulation of multiple key oncoproteins in PI3K/AKT and Wnt/β-catenin signaling pathways. These results not only provide the first evidence for a critical role of Pin1 in the tumorigenesis of gastric cancer but also suggest that targeting Pin1 using ATRA or other inhibitors offers an effective new therapeutic approach for treating advanced gastric cancer.

Identification of Prolyl isomerase Pin1 as a novel positive regulator of YAP/TAZ in breast cancer cells

The Hippo signalling pathway plays very important roles in tumorigenesis, metastasis, organ size control, and drug resistance. Although, it has been shown that the two major components of Hippo pathway, YAP and TAZ, play very crucial role in tumorigenesis and drug resistance, the exact molecular mechanisms are still unknown. Recently, we have shown that the prolyl isomerase Pin1 regulates the activity of Hippo pathway through interaction with Hippo component LATS kinase. Thus we asked if Pin1 is also able to interact with other Hippo pathway components. Therefore, in order to investigate whether Pin1 can interacts with other components of the Hippo pathway, we performed GST-pull down and co-immunoprecipitation (Co-IP) assays and have identified two Hippo components YAP and TAZ oncoproteins as novel binding partner of Pin1. We found that Pin1 interacts with YAP/TAZ in a phosphorylation-independent manner and WW domain of Pin1 is necessary for this interaction. Moreover, by using real time qRT-PCR, Cycloheximide chase, luciferase reporter, cell viability and soft agar assays, we have shown that Pin1 increases the tumorigenic and drug-resistant activity of YAP/TAZ through stabilization of YAP/TAZ at protein levels. Together, we have identified Pin1 as a novel positive regulator of YAP/TAZ in tumorigenesis and drug resistance of breast cancer cells. These findings will provide a significant contribution for targeting the Pin1-YAP/TAZ signaling for the successful treatment of tumorigenesis and drug resistance of breast and other cancers in the future.

Cytoplasmic Pin1 expression is increased in human cutaneous melanoma and predicts poor prognosis

The prolyl isomerase Pin1 is widely over-expressed or over-activated in cancers and promotes tumorigenesis. The authors investigated the expression level of Pin1 and analyzed the prognostic value of Pin1 expression using a large-scale melanoma tissue microarray study. Two independent sets of tissue microarrays were employed, including 114 melanoma cases in the discovery set and 424 in the validation set (538 cases in total), 32 normal nevi and 86 dysplastic nevi 118 cases of nevi. The subcellular Pin1 expression in different stages of melanocytic lesions and its prognostic significance were studied. High expression (IRS 0-8) of cytoplasmic Pin1 was observed in 3.13%, 8.33%, 16.49% and 22.76% of the biopsies in normal nevi, dysplastic nevi, primary melanoma and metastatic melanoma, respectively. Significant differences for cytoplasmic Pin1 staining were observed between normal nevi and metastatic melanoma (P = 0.011, χ2 test), between dysplastic nevi and primary melanoma (P = 0.046, χ2 test) and between dysplastic nevi and metastatic melanoma (P = 0.016, χ2 test). Kaplan-Meier survival analysis showed that increased cytoplasmic Pin1 expression was associated with a worse 5-year melanoma-specific survival of melanoma (P < 0.001) and metastatic melanoma patients (P = 0.004). Multivariate Cox regression analysis showed that cytoplasmic Pin1 expression is an independent prognostic factor in melanoma. Our data indicate that cytoplasmic Pin1 plays an important role in melanoma pathogenesis and progression, and serve as a potential prognostic marker for melanoma.

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.

A scoring system based on artificial neural network for predicting 10-year survival in stage II A colon cancer patients after radical surgery

Nearly 20% patients with stage II A colon cancer will develop recurrent disease post-operatively. The present study aims to develop a scoring system based on Artificial Neural Network (ANN) model for predicting 10-year survival outcome. The clinical and molecular data of 117 stage II A colon cancer patients from Sun Yat-sen University Cancer Center were used for training set and test set; poor pathological grading (score 49), reduced expression of TGFBR2 (score 33), over-expression of TGF-β (score 45), MAPK (score 32), pin1 (score 100), β-catenin in tumor tissue (score 50) and reduced expression of TGF-β in normal mucosa (score 22) were selected as the prognostic risk predictors. According to the developed scoring system, the patients were divided into 3 subgroups, which were supposed with higher, moderate and lower risk levels. As a result, for the 3 subgroups, the 10-year overall survival (OS) rates were 16.7%, 62.9% and 100% (P < 0.001); and the 10-year disease free survival (DFS) rates were 16.7%, 61.8% and 98.8% (P < 0.001) respectively. It showed that this scoring system for stage II A colon cancer could help to predict long-term survival and screen out high-risk individuals for more vigorous treatment.

Prolyl isomerase PIN1 regulates the stability, transcriptional activity and oncogenic potential of BRD4

BRD4 has emerged as an important factor in tumorigenesis by promoting the transcription of genes involved in cancer development. However, how BRD4 is regulated in cancer cells remains largely unknown. Here, we report that the stability and functions of BRD4 are positively regulated by prolyl-isomerase PIN1 in gastric cancer cells. PIN1 directly binds to phosphorylated threonine (T) 204 of BRD4 as revealed by peptide binding and crystallographic studies and enhances BRD4’s stability by inhibiting its ubiquitination. PIN1 also catalyses the isomerization of proline 205 of BRD4 and induces its conformational change, which promotes its interaction with CDK9 and increases BRD4’s transcriptional activity. Substitution of BRD4 with PIN1 binding-defective BRD4-T204A mutant in gastric cancer cells reduces BRD4’s stability, attenuates BRD4-mediated gene expression by impairing its interaction with CDK9, and suppresses gastric cancer cell proliferation, migration and invasion, and tumor formation. Our results identify BRD4 as a new target of PIN1 and suggest that interfering with their interaction could be a potential therapeutic approach for cancer treatment.

The role of Pin1 in the development and treatment of cancer

Protein phosphorylation and post-phosphorylation events regulate many cellular signaling pathways. Peptidyl-prolyl isomerase (Pin1) is the only peptidyl-prolyl cis/trans isomerase that interacts with numerous oncogenic or tumor suppressive phosphorylated proteins, causes conformational changes in target proteins, and eventually regulates the activities of such proteins. These alterations in activity play a pivotal role in tumorigenesis. Since Pin1 is overexpressed and/or activated in various types of cancers, and the dysregulation of proline-directed phosphorylation contributes to tumorigenesis, Pin1 represents an attractive target for cancer therapy. This review will describe the role of Pin1 in cancer and the current status of Pin1 inhibitor development.