Upregulation of protein tyrosine phosphatase type IVA member 3 (PTP4A3/PRL-3) is associated with tumor differentiation and a poor prognosis in human hepatocellular carcinoma

SNHG19 promotes the proliferation and metastasis of hepatocellular carcinoma through regulating the miR-137/protein tyrosine phosphatase 4A3 axis

Objectives

Long noncoding RNAs plays the important part in tumor biology. SNHG19 was found to be a new oncogenic lncRNA in some malignant tumors. However, the effect of SNHG19 in hepatocellular carcinoma has not been reported.

Methods

The expression of SNHG19 in hepatocellular carcinoma tissues were detected by using quantitative Real-Time Reverse Transcription Polymerase Chain Reaction (qRT-PCR). Melanoma cases from The Cancer Genome Atlas were included in this study. cell counting kit-8 assay, Transwell, and scratch wound assay were used to explore the role of SNHG19 in melanoma cells. Luciferase reporter assays and RNA pull-down assay were used to explore the molecular mechanism of SNHG19 in hepatocellular carcinoma.

Results

Here, we found that SNHG19 level was upregulated in hepatocellular carcinoma. Hepatocellular carcinoma patients with high levels of SNHG19 have shorter Disease-Free Survival (RFS). SNHG19 promotes the Protein Tyrosine Phosphatase 4A3 expression by sponging miR-137 to liberate Protein Tyrosine Phosphatase 4A3 mRNA transcripts. SNHG19 enhances the development of hepatocellular carcinoma by affecting miR-137/Protein Tyrosine Phosphatase 4A3 axis.

Conclusion

These results demonstrated the effect of SNHG19 in the occurrence and progression of hepatocellular carcinoma. SNHG19 may be used as the specific molecular target in patients with hepatocellular carcinoma.

The PACT Network: PRL, ARL, CNNM, and TRPM Proteins in Magnesium Transport and Disease

Magnesium, the most abundant divalent metal within the cell, is essential for physiological function and critical in cellular signaling. To maintain cellular homeostasis, intracellular magnesium levels are tightly regulated, as dysregulation is linked to numerous diseases, including cancer, diabetes, cardiovascular disorders, and neurological conditions. Over the past two decades, extensive research on magnesium-regulating proteins has provided valuable insight into their pathogenic and therapeutic potential. This review explores an emerging mechanism of magnesium homeostasis involving proteins in the PRL (phosphatase of regenerating liver), ARL (ADP ribosylation factor-like GTPase family), CNNM (cyclin and cystathionine β-synthase domain magnesium transport mediator), and TRPM (transient receptor potential melastatin) families, collectively termed herein as the PACT network. While each PACT protein has been studied within its individual signaling and disease contexts, their interactions suggest a broader regulatory network with therapeutic potential. This review consolidates the current knowledge on the PACT proteins' structure, function, and interactions and identifies research gaps to encourage future investigation. As the field of magnesium homeostasis continues to advance, understanding PACT protein interactions offers new opportunities for basic research and therapeutic development targeting magnesium-related disorders.

SERPING1 Reduces Cell Migration via ERK-MMP2-MMP-9 Cascade in Sorafenib- Resistant Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary hepatic malignant tumor, and it ranks 2nd in terms of mortality rate among all malignancies in Taiwan. Sorafenib is a multiple tyrosine kinase inhibitor that suppresses tumor cell proliferation and angiogenesis around tumors via different pathways. However, the survival outcome of advanced HCC patients treated with sorafenib is still unsatisfactory. Unfortunately, there are no clinically applicable biomarkers to predict sorafenib therapeutic efficiency in HCC thus far. We found that serpin peptidase inhibitor, clade G, member 1 (SERPING1) is highly associated with overall and recurrence-free survival rates in HCC patients and is also highly correlated with several clinical parameters. SERPING1 expression was increased with sorafenib in both the HCC cell extract and conditioned medium, which was also observed in sorafenib-resistant HepG2 and Huh7 cells. Sorafenib decreased cell viability and migration, which was similar to the effect of SERPING1 in HCC progression. Moreover, sorafenib inhibited both MMP-2 and MMP-9 activity and enhanced the expression of p-ERK in HCC cells. In summary, sorafenib reduces HCC cancer progression might through the p-ERK-MMP-2-MMP-9 cascade via upregulation of SERPING1. In the present study, the roles and molecular mechanisms of SERPING1 and its value as a marker for predicting sorafenib resistance and progression in HCC patients were examined. The results of the present study provide a deep understanding of the roles of SERPING1 in HCC sorafenib resistance, which can be applied to develop early diagnosis and prognosis evaluation methods and establish novel therapeutic targets for specifically treating HCC.

In silico identification of putative druggable pockets in PRL3, a significant oncology target

Protein tyrosine phosphatases (PTP) have emerged as targets in diseases characterized by aberrant phosphorylations such as cancers. The activity of the phosphatase of regenerating liver 3, PRL3, has been linked to several oncogenic and metastatic pathways, particularly in breast, ovarian, colorectal, and blood cancers. Development of small molecules that directly target PRL3, however, has been challenging. This is partly due to the lack of structural information on how PRL3 interacts with its inhibitors. Here, computational methods are used to bridge this gap by evaluating the druggability of PRL3. In particular, web-based pocket prediction tools, DoGSite3 and FTMap, were used to identify binding pockets using structures of PRL3 currently available in the Protein Data Bank. Druggability assessment by molecular dynamics simulations with probes was also performed to validate these results and to predict the strength of binding in the identified pockets. While several druggable pockets were identified, those in the closed conformation show more promise given their volume and depth. These two pockets flank the active site loops and roughly correspond to pockets predicted by molecular docking in previous papers. Notably, druggability simulations predict the possibility of low nanomolar affinity inhibitors in these sites implying the potential to identify highly potent small molecule inhibitors for PRL3. Putative pockets identified here can be leveraged for high-throughput virtual screening to further accelerate the drug discovery against PRL3 and development of PRL3-directed therapeutics.

Phosphatase and Pseudo-Phosphatase Functions of Phosphatase of Regenerating Liver 3 (PRL-3) Are Insensitive to Divalent Metals In Vitro

Phosphatase of regenerating liver 3 (PRL-3) is associated with cancer metastasis and has been shown to interact with the cyclin and CBS domain divalent metal cation transport mediator (CNNM) family of proteins to regulate the intracellular concentration of magnesium and other divalent metals. Despite PRL-3's importance in cancer, factors that regulate PRL-3's phosphatase activity and its interactions with CNNM proteins remain unknown. Here, we show that divalent metal ions, including magnesium, calcium, and manganese, have no impact on PRL-3's structure, stability, phosphatase activity, or CNNM binding capacity, indicating that PRL-3 does not act as a metal sensor, despite its interaction with CNNM metal transporters. In vitro approaches found that PRL-3 is a broad but not indiscriminate phosphatase, with activity toward di- and tri-nucleotides, phosphoinositols, and NADPH but not other common metabolites. Although calcium, magnesium, manganese, and zinc-binding sites were predicted near the PRL-3 active site, these divalent metals did not specifically alter PRL-3's phosphatase activity toward a generic substrate, its transition from an inactive phospho-cysteine intermediate state, or its direct binding with the CBS domain of CNNM. PRL-3's insensitivity to metal cations negates the possibility of its role as an intracellular metal content sensor for regulating CNNM activity. Further investigation is warranted to define the regulatory mechanisms governing PRL-3's phosphatase activity and CNNM interactions, as these findings could hold potential therapeutic implications in cancer treatment.

Phosphatase regenerating liver 3 participates in Integrinβ1/FAK-Src/MAPK signaling pathway and contributes to the regulation of malignant behaviors in hepatocellular carcinoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the leading cause of mortality worldwide. Phosphatase regenerating liver 3 (PRL-3) was associated with cancer metastasis. However, the significance of PRL-3 in the prognosis of HCC remains elusive. The aim of this study was to elucidate the role of PRL-3 in HCC metastasis and its prognosis.

METHODS

The expressions of PRL-3 in cancer tissues isolated from 114 HCC patients, who underwent curative hepatectomy from May to November in 2008, were analyzed by immunohistochemistry, and its prognostic significance was evaluated. Thereafter, the migration, invasion, and metastatic alterations in MHCC97H cells with PRL-3 overexpression or knockdown were explored and compared with the tumor size and lung metastasis in orthotopic HCC model of nude mice derived from MHCC97H cells with PRL-3 overexpression or knockdown. The underlying mechanism involving PRL-3-mediated effect on HCC migration, invasion, and metastasis was further examined.

RESULTS

Univariate and multivariate analysis demonstrated PRL-3 overexpression was an independent prognostic factor for poor overall survival (OS) and progression-free survival (PFS) of the HCC patients. Increased PRL-3 expression in MHCC97H cells was in accordance with the enhanced metastasis potential. PRL-3 knockdown inhibited the migration, invasiveness, and clone forming ability in MHCC97H cells, whereas PRL-3 overexpression reverted the above behavior. The growth of xenograft tumor in the liver was suppressed, and the lung metastasis in nude mice was inhibited by PRL-3 downregulation. The knockdown of PRL-3 could downregulate the expressions of Integrinβ1 and p-Src (Tyr416), p-Erk (Thr202/Tyr204) activation, and reduce MMP9 expression. Both MEK1/2 inhibitor (U0126) and Src inhibitor could repress PRL-3-induced invasiveness and migration in MHCC97H cells.

CONCLUSIONS

PRL-3 was significantly overexpressed and an independent prognostic factor to predict the death of HCC patients. Mechanically, PRL-3 plays a critical role in HCC invasive and metastasis via Integrinβ1/FAK-Src/RasMAPK signaling. Validation of PRL-3 as a clinical prediction marker in HCC warrants further research.

Cisplatin or Doxorubicin Reduces Cell Viability via the PTPIVA3-JAK2-STAT3 Cascade in Hepatocellular Carcinoma

Introduction

Hepatocellular carcinoma (HCC) accounts for 80% of all liver cancers and is the 2nd leading cause of cancer-related death in Taiwan. Various factors, including rapid cell growth, a high recurrence rate and drug resistance, make HCC difficult to cure. Moreover, the survival rate of advanced HCC patients treated with systemic chemotherapy remains unsatisfactory. Hence, the identification of novel molecular targets and the underlying mechanisms of chemoresistance in HCC and the development more effective therapeutic regimens are desperately needed.

Methods

An MTT assay was used to determine the cell viability after cisplatin or doxorubicin treatment. Western blotting, qRT‒PCR and immunohistochemistry were utilized to examine the protein tyrosine phosphatase IVA3 (PTP4A3) level and associated signaling pathways. ELISA was utilized to analyze the levels of the inflammatory cytokine IL-6 influenced by cisplatin, doxorubicin and PTP4A3 silencing.

Results

In this study, we found that PTP4A3 in the cisplatin/doxorubicin-resistant microarray was closely associated with the overall and recurrence-free survival rates of HCC patients. Cisplatin or doxorubicin significantly reduced cell viability and decreased PTP4A3 expression in hepatoma cells. IL-6 secretion increased with cisplatin or doxorubicin treatment and after PTP4A3 silencing. Furthermore, PTP4A3 was highly expressed in tumor tissues versus adjacent normal tissues from HCC patients. In addition, we evaluated the IL-6-associated signaling pathway involving STAT3 and JAK2, and the levels of p-STAT3, p-JAK2, STAT3 and JAK2 were obviously reduced with cisplatin or doxorubicin treatment in HCC cells using Western blotting and were also decreased after silencing PTP4A3. Collectively, we suggest that cisplatin or doxorubicin decreases HCC cell viability via downregulation of PTP4A3 expression through the IL-6R-JAK2-STAT3 cascade.

Discussion

Therefore, emerging evidence provides a deep understanding of the roles of PTP4A3 in HCC cisplatin/doxorubicin chemoresistance, which can be applied to develop early diagnosis strategies and reveal prognostic factors to establish novel targeted therapeutics to specifically treat HCC.

Characterizing PTP4A3/PRL-3 as the Potential Prognostic Marker Gene for Liver Hepatocellular Carcinoma

Background

A large number of cancer-related deaths in the world can be attributed to liver hepatocellular carcinoma (LIHC). The purpose of this study is to explore protein tyrosine phosphatase type IV A member 3 (PTP4A3/PRL-3) as a new and reliable biomarker to predict the prognosis of LIHC and determine the potential therapeutic targets or drugs that can be used for treating LIHC.

Methods

We included three LIHC datasets with clinical information and expression profiles from public databases. The expression level of PTP4A3 was analyzed, and based on the results, the samples were divided into high- and low-expression groups. The Kaplan–Meier survival analysis method was used to determine the relationship between PTP4A3 and prognosis. The enrichment differences among the functional pathways associated with the high- and low-expression groups were determined using the gene set enrichment analysis (GSEA) method. Five methods were used to determine the differences among the tumor microenvironment in the low- and high-expression groups. The sensitivity of the low- and high-expression groups toward different drug treatment methods was predicted by analyzing the Tumor Immune Dysfunction and Exclusion (TIDE) scores and determining the biochemical half-maximal inhibitory concentration (IC50).

Results

The expression levels of the LIHC and adjacent samples were analyzed, and it was observed that the expression level of PTP4A3 in tumor tissue was significantly higher than the expression level of the same gene in the adjacent samples. It was also inferred that it might be a cancer-promoting gene. It was concluded that high-expression results in a significantly poor prognosis. The high-expression group was significantly enriched in the tumor-related pathways, such as the PI3K-AKT signaling pathway. In addition, the results obtained by conducting immune infiltration analysis revealed a significant positive correlation between some immune scores and the gene PTP4A3. The drug KIN001−135 and gene PTP4A3 were also found to correlate positively with each other. CP466722, Pyrimethamine, AKT inhibitor VIII, Embelin, Cisplatin, QS11, Bexarotene, and Midostaurin negatively correlated with PTP4A3 associated with the three datasets. Moreover, the drugs Cisplatin, QS11, Midostaurin, and CP466722 were more sensitive toward the high-expression group than the low PTP4A3 expression group. Significant differences were observed in these cases.

Conclusion

PTP4A3/PRL-3 is potentially associated with the progression, metastasis, and invasion of LIHC. The prognosis of LIHC patients is negatively impacted by the high-expression levels of the gene. The results indicate that PTP4A3/PRL-3 is an important prognostic factor for LIHC and is a new potential prognostic detection target. The discovery of the 8 drugs that were negatively associated with PTP4A3 provided a new direction that can be developed in the future for the treatment of LIHC.

Sorafenib inhibits ovarian cancer cell proliferation and mobility and induces radiosensitivity by targeting the tumor cell epithelial–mesenchymal transition

Sorafenib, a pan-protein kinase inhibitor, inhibits the activity of various kinases (like vascular endothelial growth factor, platelet-derived growth factor, and rapidly accelerated fibrosarcoma) and clinically has been used to treat different human cancers. This study investigated its antitumor activity in ovarian cancer and the underlying molecular events. To achieve that, ovarian cancer SKOV-3 cells were treated with or without sorafenib (10 µM), transforming growth factor (TGF)-β1 (10 ng/mL), sorafenib (10 µM) + TGF-β1 (10 ng/mL), and TGF-β1 (10 ng/mL) + Ly2157299 (5 µM), followed by 8-Gy radiation. The cells were then subjected to cell viability, wound healing, Transwell, caspase-3 activity, and western blot assays. TGF-β1 treatment enhanced ovarian cancer cell epithelial–mesenchymal transition (EMT), whereas sorafenib and a selective TGF-β1 inhibitor Ly2157299 reversed tumor cell EMT, invasion, and expression of EMT markers (E-cadherin and vimentin). Sorafenib and Ly2157299 treatment also significantly reduced the tumor cell viability. Furthermore, both sorafenib and Ly2157299 significantly enhanced ovarian cancer cell radiosensitivity, as assessed by a caspase-3 activity assay. In conclusion, sorafenib inhibited ovarian cancer cell proliferation and mobility and induced tumor cell radiosensitivity. Molecularly, sorafenib could inhibit the TGF-β1-mediated EMT. Future studies will assess sorafenib anti-ovarian cancer activity plus TGF-β1 inhibitors in ovarian cancer in vivo.

A novel role of PRL in regulating epithelial cell density by inducing apoptosis at confluence

Maintaining proper epithelial cell density is essential for the survival of multicellular organisms. While regulation of cell density through apoptosis is well known, its mechanistic details remain elusive. Here, we report the involvement of membrane-anchored phosphatase of regenerating liver (PRL), originally known for its role in cancer malignancy, in this process. In epithelial MDCK cells, upon confluence, doxycycline-induced expression of PRL upregulated apoptosis, reducing the cell density. This could be circumvented by artificially reducing the cell density via stretching the cell-seeded silicon chamber. Moreover, siRNA-mediated knockdown of endogenous PRL blocked apoptosis, leading to greater cell density. Mechanistically, PRL promoted apoptosis by upregulating the translation of E-cadherin and activating TGF-β pathway. Morpholino-mediated inhibition of PRL expression in zebrafish embryos caused developmental defect with reduced apoptosis and increased epithelial cell density during convergent extension. This study revealed a novel role of PRL in regulating density-dependent apoptosis in vertebrate epithelium.

Identification of Therapeutic Targets for the Selective Killing of HBV-Positive Hepatocytes

The hepatitis B virus (HBV) infection is a major risk factor for cirrhosis and hepatocellular carcinoma. Most infected individuals become lifelong carriers of HBV as the drugs currently used to treat the patients can only control the disease, thereby achieving functional cure (loss of the hepatitis B surface antigen) but not complete cure (elimination of infected hepatocytes). Therefore, we aimed to identify the target genes for the selective killing of HBV-positive hepatocytes to develop a novel therapy for the treatment of HBV infection. Our strategy was to recognize the conditionally essential genes that are essential for the survival of HBV-positive hepatocytes, but non-essential for the HBV-negative hepatocytes. Using microarray gene expression data curated from the Gene Expression Omnibus database and the known essential genes from the Online GEne Essentiality database, we used two approaches, comprising the random walk with restart algorithm and the support vector machine approach, to determine the potential targets for the selective killing of HBV-positive hepatocytes. The final candidate genes list obtained using these two approaches consisted of 36 target genes, which may be conditionally essential for the cell survival of HBV-positive hepatocytes; however, this requires further experimental validation. Therefore, the genes identified in this study can be used as potential drug targets to develop novel therapeutic strategies for the treatment of HBV, and may ultimately help in achieving the elusive goal of a complete cure for hepatitis B.

A screen of FDA-approved drugs identifies inhibitors of protein tyrosine phosphatase 4A3 (PTP4A3 or PRL-3)

Protein tyrosine phosphatase 4A3 (PTP4A3 or PRL-3) is highly expressed in a variety of cancers, where it promotes tumor cell migration and metastasis leading to poor prognosis. Despite its clinical significance, small molecule inhibitors of PRL-3 are lacking. Here, we screened 1443 FDA-approved drugs for their ability to inhibit the activity of the PRL phosphatase family. We identified five specific inhibitors for PRL-3 as well as one selective inhibitor of PRL-2. Additionally, we found nine drugs that broadly and significantly suppressed PRL activity. Two of these broad-spectrum PRL inhibitors, Salirasib and Candesartan, blocked PRL-3-induced migration in human embryonic kidney cells with no impact on cell viability. Both drugs prevented migration of human colorectal cancer cells in a PRL-3 dependent manner and were selective towards PRLs over other phosphatases. In silico modeling revealed that Salirasib binds a putative allosteric site near the WPD loop of PRL-3, while Candesartan binds a potentially novel targetable site adjacent to the CX₅R motif. Inhibitor binding at either of these sites is predicted to trap PRL-3 in a closed conformation, preventing substrate binding and inhibiting function.

PRL-3 facilitates Hepatocellular Carcinoma progression by co-amplifying with and activating FAK

Background: In addition to protein tyrosine kinases, accumulating evidence has shown that protein tyrosine phosphatases (PTPs) are suitable therapeutic targets in cancer. PRL-3 is a PTP member that has been well studied in many malignant tumours. The goal of the present study was to elucidate the role of PRL-3 in hepatocellular carcinoma (HCC), which remains largely unknown. Methods: Bioinformatic and immunohistochemical analyses were performed to analyse PRL-3 expression in HCC tissue samples and determine its clinical relevance. PRL-3 gene copy number variations were evaluated by bioinformatic analysis and quantitative-genomic polymerase chain reaction. The biological functions of PRL-3 were investigated in vivo and vitro. Gene microarray assays, RT-qPCR, western blotting and luciferase experiments were performed to identify the downstream effectors of PRL-3 that mediate its functions in HCC. Results: PRL-3 expression was upregulated in HCC samples from public databases and in cohort samples from our centre. High PRL-3 expression was associated with poor prognosis. Copy number gains and amplification of chromosome 8q24.3 in HCC were determined to be positively correlated with the PRL-3 overexpression. PRL-3 overexpression promoted HCC cell proliferation, migration and adhesion, while its loss had the opposite effects. Further study showed that focal adhesion kinase (FAK) was co-amplified and co-expressed with PRL-3 in HCC. Interestingly, PRL-3 also promoted the phosphorylation of FAK, which subsequently mediated the oncogenic functions of PRL-3 in HCC cells. Moreover, TGFB1 was identified as a downstream molecule of PRL-3. TGF-β signalling was shown to mediate the PRL-3-induced activation of FAK. Furthermore, the p38 and PI3K/AKT pathways were observed to mediate the PRL-3-induced expression of TGFB1 and the subsequent activation of FAK, while the activation of FAK in turn stimulated activation of the p38 and PI3K/AKT pathways, forming a PRL-3-triggered AKT/p38/TGFB1/FAK positive feedback loop. Conclusion: Collectively, our findings indicate that the PTP PRL-3 plays a crucial role in the progression of HCC and provides an example of how co-amplified genes work together in HCC.

lncRNA PCBP1-AS1 Aggravates the Progression of Hepatocellular Carcinoma via Regulating PCBP1/PRL-3/AKT Pathway

Background

Hepatocellular carcinoma (HCC) is a very belligerent primary liver tumor with high metastatic potential. Aberrant expression of lncRNAs drives tumorous invasion and metastasis. Whether lncRNAs engage mechanisms of liver cancer metastasis remains largely unexplored.

Patients and Methods

We collected HCC tissues from the tumors and their adjacent normal samples in the Chinese population and analyzed the levels of lncRNAs by microarray analysis. The gain- and loss-of-function analysis demonstrated that PCBP1-AS1 accelerated tumorous growth and metastasis in vivo and in vitro. Moreover, we used RNA-pulldown assay to show that PCBP1-AS1 physically interacted with polyC-RNA-binding protein 1 (PCBP1); meanwhile, PCBP1-AS1 was indeed detected in RIP with the PCBP1 antibody. Mechanistically, we first explored the relationship between PCBP1‐AS1 and PCBP1 in HCC cell lines.

Results

Here we show that PCBP1-AS1, identified by microarray analysis on pre- and post-operative HCC plasma specimens, was highly expressed in human HCC, clinically verified as a prometastatic factor and markedly associated with poor prognosis in patients with hepatocellular carcinoma. PCBP1‐AS1 was negatively related with PCBP1 at the messenger RNA and protein expression levels. PCBP1-AS1 triggered PRL-3 and AKT in HCC tumor cells. Additionally, the double knockout of PCBP1 and PCBP1-AS1 abolished the PCBP1-AS1-induced PRL-3-AKT signalling pathway activation.

Conclusion

The upregulation of PCBP1-AS1 enhances proliferation and metastasis in HCC, thus regulating the PCBP1-PRL-3-AKT signalling pathway.

Protein tyrosine phosphatase 4A3 (PTP4A3/PRL-3) drives migration and progression of T-cell acute lymphoblastic leukemia in vitro and in vivo

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive blood cancer. There are no immunotherapies and few molecularly targeted therapeutics available for treatment of this malignancy. The identification and characterization of genes and pathways that drive T-ALL progression are critical for the development of new therapies for T-ALL. Here, we determined that the protein tyrosine phosphatase 4A3 (PTP4A3 or PRL-3) plays a critical role in T-ALL initiation and progression by promoting leukemia cell migration. PRL-3 is highly expressed in patient T-ALL samples at both the mRNA and protein levels compared to normal lymphocytes. Knock-down of PRL-3 expression using short-hairpin RNA (shRNA) in human T-ALL cell lines significantly impeded T-ALL cell migration capacity in vitro and reduced their ability to engraft and proliferate in vivo in xenograft mouse models. Additionally, PRL-3 overexpression in a Myc-induced zebrafish T-ALL model significantly accelerated disease onset and shortened the time needed for cells to enter blood circulation. Reverse-phase protein array (RPPA) and gene set enrichment analysis (GSEA) revealed that the SRC signaling pathway is affected by PRL-3. Immunoblot analyses validated that manipulation of PRL-3 expression in T-ALL cells affected the SRC signaling pathway, which is directly involved in cell migration, although Src was not a direct substrate of PRL-3. More importantly, T-ALL cell growth and migration were inhibited by small molecule inhibition of PRL-3, suggesting that PRL-3 has potential as a therapeutic target in T-ALL. Taken together, our study identifies PRL-3 as an oncogenic driver in T-ALL both in vitro and in vivo and provides a strong rationale for targeted therapies that interfere with PRL-3 function.

Loss of alanine-glyoxylate and serine-pyruvate aminotransferase expression accelerated the progression of hepatocellular carcinoma and predicted poor prognosis

BACKGROUND

Accumulated studies reported abnormal gene expression profiles of hepatocellular carcinoma (HCC) by cDNA microarray. We tried to merge cDNA microarray data from different studies to search for stably changed genes, and to find out better diagnostic and prognostic markers for HCC.

METHODS

A systematic review was performed by searching publications indexed in Pubmed from March 1, 2001 to July 1, 2016. Studies that reporting cDNA microarray profiles in HCC, containing both tumor and nontumor data and published in English-language were retrieved. The differentially expressed genes from eligible studies were summarized and ranked according to the frequency. High frequency genes were subjected to survival analyses. The expression and prognostic value of alanine-glyoxylate and serine-pyruvate aminotransferase (AGXT) was further evaluated in HCC datasets in Oncomine and an independent HCC tissue array cohort. The role of AGXT in HCC progression was evaluated by proliferation and migration assays in a human HCC cell line.

RESULTS

A total of 43 eligible studies that containing 1917 HCC patients were included, a list of 2022 non redundant abnormally expressed genes in HCC were extracted. The frequencies of reported genes were ranked. We finally obtained a list of only five genes (AGXT; ALDOB; CYP2E1; IGFBP3; TOP2A) that were differentially expressed in tumor and nontumor tissues across studies and were significantly correlated to HCC prognosis. Only AGXT had not been reported in HCC. Reduced expression of AGXT reflected poor differentiation of HCC and predicts poor survival. Knocking down of AGXT enhanced cell proliferation and migration of HCC cell line.

CONCLUSIONS

The present study supported the feasibility and necessity of systematic review on discovering new and reliable biomarkers for HCC. We also identified a list of high frequency prognostic genes and emphasized a critical role of AGXT deletion during HCC progression.

Up-Regulation of Phosphatase in Regenerating Liver-3 (PRL-3) Contributes to Malignant Progression of Hepatocellular Carcinoma by Activating Phosphatase and Tensin Homolog Deleted on Chromosome Ten (PTEN)/Phosphoinositide 3-Kinase (PI3K)/AKT Signaling Pathway

BACKGROUND The purpose of the study was to investigate the functional roles of phosphatase in regenerating liver-3 (PRL-3) in hepatocellular carcinoma (HCC), as well as the related molecular mechanisms. MATERIAL AND METHODS HCC tissues and adjacent normal tissues were collected from 124 HCC patients. The mRNA and protein levels of PRL-3 were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assays, respectively. The relationship between PRL-3 expression and clinical characteristics of HCC patients was evaluated by chi-square test. MTT and Transwell assays were performed to estimate cell proliferation and motility, respectively. RESULTS The expression of PRL-3 was significantly increased in HCC tissues and cells at both protein and mRNA levels (P<0.01 for all). Furthermore, the up-regulation of PRL-3 was positively correlated with hepatic vascular invasion (P=0.019), lymph node metastasis (P=0.012), and TNM stage (P=0.001). The knockdown of PRL-3 suppressed HCC cell proliferation, migration, and invasion, and PR3K/AKT pathway activity was also obviously inhibited in HCC cells with PRL-3 deficiency. The levels of PTEN were negatively associated with PRL-3 expression. PRL-3 might inhibit the protein level of PTEN through enhancing its phosphorylation level. The transfection of si-PTEN can reverse the anti-tumor action caused by PRL-3 knockdown in HCC cells. CONCLUSIONS Up-regulation of PRL-3 may activate the PI3K/AKT signaling pathway and enhance malignant progression of HCC through targeting PTEN.

Chemotherapy induced PRL3 expression promotes cancer growth via plasma membrane remodeling and specific alterations of caveolae-associated signaling

BACKGROUND

The outcome of cancer therapy is greatly defined by the ability of a tumor cell to evade treatment and re-establish its bulk mass after medical interventions. Consequently, there is an urgent need for the characterization of molecules affecting tumor reoccurrence. The phosphatase of regenerating liver 3 (PRL3) protein was recently emerged among the targets that could affect such a phenomenon.

METHODS

The expression induction of PRL3 in melanoma cells treated with chemotherapeutic agents was assessed by western blotting. The effect of PRL3 expression on cancer growth was investigated both in vitro and in vivo. The association of PRL3 with the caveolae structures of the plasma membrane was analyzed by detergent free raft purification. The effect of PRL3 expression on the membrane organization was assayed by electron microscopy and by membrane biophysical measurements. Purification of the plasma membrane fraction and co-immunoprecipitation were used to evaluate the altered protein composition of the plasma membrane upon PRL3 expression.

RESULTS

Here, we identified PRL3 as a genotoxic stress-induced oncogene whose expression is significantly increased by the presence of classical antitumor therapeutics. Furthermore, we successfully connected the presence of this oncogene with increased tumor growth, which implies that tumor cells can utilize PRL3 effects as a survival strategy. We further demonstrated the molecular mechanism that is connected with the pro-growth action of PRL3, which is closely associated with its localization to the caveolae-type lipid raft compartment of the plasma membrane. In our study, PRL3 was associated with distinct changes in the plasma membrane structure and in the caveolar proteome, such as the dephosphorylation of integrin β1 at Thr788/Thr789 and the increased partitioning of Rac1 to the plasma membrane. These alterations at the plasma membrane were further associated with the elevation of cyclin D1 in the nucleus.

CONCLUSIONS

This study identifies PRL3 as an oncogene upregulated in cancer cells upon exposure to anticancer therapeutics. Furthermore, this work contributes to the existing knowledge on PRL3 function by characterizing its association with the caveolae-like domains of the plasma membrane and their resident proteins.

Targeting phosphatases of regenerating liver (PRLs) in cancer

The phosphatase of regenerating liver (PRL) family, also known as protein tyrosine phosphatase 4A (PTP4A), are dual-specificity phosphatases with largely unknown cellular functions. However, accumulating evidence indicates that PRLs are oncogenic across a broad variety of human cancers. PRLs are highly expressed in advanced tumors and metastases compared to early stage cancers or matched healthy tissue, and high expression of PRLs often correlates with poor patient prognosis. Consequentially, PRLs have been considered potential therapeutic targets in cancer. Persistent efforts have been made to define their role and mechanism in cancer progression and to create specific PRL inhibitors for basic research and drug development. However, targeting PRLs with small molecules remains challenging due to the highly conserved active site of protein tyrosine phosphatases and a high degree of sequence similarity between the PRL protein families. Here, we review the current PRL inhibitors, including the strategies used for their identification, their biological efficacy, potency, and selectivity, with a special focus on how PRL structure can inform future efforts to develop specific PRL inhibitors.

PRL-3 promotes gastric cancer peritoneal metastasis via the PI3K/AKT signaling pathway in vitro and in vivo

The peritoneal metastasis-associated phosphatase of regenerating liver-3 (PRL-3) is upregulated in gastric cancer. The phosphatidylinositol 3-kinase (PI3K)/RAC serine/threonine-protein kinase (AKT) signaling pathway acts downstream of PRL-3 in gastric cancer. However, the exact PRL-3 signaling mechanisms are poorly understood. The present study investigated whether PRL-3 facilitates the peritoneal metastasis of gastric cancer via the PI3K/AKT pathway in vivo and in vitro. Nude mouse models of peritoneal metastasis were established using SGC7901/PRL-3 cell lines. The results confirmed that the invasion and migration abilities of SGC7901/PRL-3 cells were significantly increased in these models. Furthermore, western blotting demonstrated that the expression of p-AKT, matrix metallopeptidase-2 (MMP-2) and -9 proteins increased in SGC7901/PRL-3 cells. These effects were suppressed in SGC7901 cell lines when PI3K was inhibited by LY294002. Furthermore, tumors derived from the peritoneal injection of SGC7901/PRL-3 cells were significantly smaller when the cells were grown in the presence of LY249002, compared with cells grown in its absence. These results indicated that targeted inhibition of the PI3K/AKT signaling pathway decreased the effects of PRL-3 on metastasis in vivo. Collectively, the results of the present study indicated that PRL-3 acts via the PI3K/AKT pathway to promote peritoneal metastasis and invasion of gastric cancer cells in vitro and in vivo.

The Roles of Protein Tyrosine Phosphatases in Hepatocellular Carcinoma

The protein tyrosine phosphatase (PTP) family is involved in multiple cellular functions and plays an important role in various pathological and physiological processes. In many chronic diseases, for example cancer, PTP is a potential therapeutic target for cancer treatment. In the last two decades, dozens of PTP inhibitors which specifically target individual PTP molecules were developed as therapeutic agents. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors and is the second most lethal cancer worldwide due to a lack of effective therapies. Recent studies have unveiled both oncogenic and tumor suppressive functions of PTP in HCC. Here, we review the current knowledge on the involvement of PTP in HCC and further discuss the possibility of targeting PTP in HCC.

Expression of phosphatase of regenerating liver (PRL)-3, is independently associated with biochemical failure, clinical failure and death in prostate cancer

Background

Prostate cancer (PC) stratification needs new prognostic tools to reduce overtreatment. Phosphatase of regenerating liver (PRL-3) is a phosphatase found at high levels in several cancer types, where its expression is associated with survival. A recent PC cell line study has shown it to be involved in PC growth and migration.

Methods

We used a monoclonal antibody to evaluate the expression of PRL-3 in PC tissue of patients in an unselected cohort of 535 prostatectomy patients. We analyzed associations between PRL-3 expression and biochemical failure-free survival (BFFS), clinical failure-free survival (CFFS) and PC death-free survival (PCDFS).

Results

Cytoplasmic PRL-3 staining in tumor cells was significantly correlated to expression of molecules in the VEGFR-axis, but not to the clinicopathological variables. High PRL-3 was not significantly associated with survival in the univariate analysis for BFFS (p = 0.131), but significantly associated with CFFS (p = 0.044) and PCDFS (p = 0.041). In multivariate analysis for the various end points, PRL-3 came out as an independent and significant indicator of poor survival for BFFS (HR = 1.53, CI95% 1.10–2.13, p = 0.012), CFFS (HR = 2.41, CI95% 1.17–4.98, p = 0.017) and PCDFS (HR = 3.99, CI95% 1.21–13.1, p = 0.023).

Conclusions

PRL-3 is independently associated with all PC endpoints in this study. Since high PRL-3 expression also correlates with poor prognosis in other cancers and functional studies in PC support these findings, PRL-3 emerges as a potential treatment target in PC.

Regulator of G-protein signaling 5 enhances portal vein invasion in hepatocellular carcinoma

Portal vein invasion (PVI) is a major prognostic factor in hepatocellular carcinoma (HCC). The aim of the present study was to identify molecules that regulate PVI. Sections of cancerous tissue, paired noncancerous tissue and the PVI area were collected from 3 frozen HCC sections, using laser microdissection. The present study focused on 3 upregulated molecules, integrin β3 (ITGB3), secreted phosphoprotein 1 (SPP1) and regulator of G-protein signaling 5 (RGS5), and 2 molecules that were downregulated in PVI tissue compared with cancer tissue, metallothionein 1G (MT1G) and metallothionein 1H (MT1H), as determined by cDNA microarray analysis. Reverse transcription-quantitative polymerase chain reaction analysis of 32 HCC cases revealed that RGS5 mRNA levels were significantly increased and MT1 G and MT1H mRNA levels were significantly decreased in cancerous tissue compared with noncancerous tissue. However, there was no significant difference in ITGB3 and SPP1 expression. There were no significant differences between the expression of these molecules and any clinicopathologic factors, including PVI. Immunohistochemical staining for RGS5 in 60 HCC cases demonstrated that RGS5 protein levels were higher in cancerous tissue compared with paired noncancerous tissue in 63.3% of HCC cases. Furthermore, high expression of RGS5 in cancerous tissue was significantly associated with PVI and tended to be associated with intrahepatic metastasis. Confluent multinodular type was significantly more frequent in cases with high expression of RGS5 in the cancerous tissue. Therefore, RGS5 may be a useful prognostic biomarker as well as a potential target of molecular therapy to treat HCC.

A systematic comparison of copy number alterations in four types of female cancer

Background

Detection and localization of genomic alterations and breakpoints are crucial in cancer research. The purpose of this study was to investigate, in a methodological and biological perspective, different female, hormone-dependent cancers to identify common and diverse DNA aberrations, genes, and pathways.

Methods

In this work, we analyzed tissue samples from patients with breast (n = 112), ovarian (n = 74), endometrial (n = 84), or cervical (n = 76) cancer. To identify genomic aberrations, the Circular Binary Segmentation (CBS) and Piecewise Constant Fitting (PCF) algorithms were used and segmentation thresholds optimized. The Genomic Identification of Significant Targets in Cancer (GISTIC) algorithm was applied to the segmented data to identify significantly altered regions and the associated genes were analyzed by Ingenuity Pathway Analysis (IPA) to detect over-represented pathways and functions within the identified gene sets.

Results and Discussion

Analyses of high-resolution copy number alterations in four different female cancer types are presented. For appropriately adjusted segmentation parameters the two segmentation algorithms CBS and PCF performed similarly. We identified one region at 8q24.3 with focal aberrations that was altered at significant frequency across all four cancer types. Considering both, broad regions and focal peaks, three additional regions with gains at significant frequency were revealed at 1p21.1, 8p22, and 13q21.33, respectively. Several of these events involve known cancer-related genes, like PPP2R2A, PSCA, PTP4A3, and PTK2. In the female reproductive system (ovarian, endometrial, and cervix [OEC]), we discovered three common events: copy number gains at 5p15.33 and 15q11.2, further a copy number loss at 8p21.2. Interestingly, as many as 75% of the aberrations (75% amplifications and 86% deletions) identified by GISTIC were specific for just one cancer type and represented distinct molecular pathways.

Conclusions

Our results disclose that some prominent copy number changes are shared in the four examined female, hormone-dependent cancer whereas others are definitive to specific cancer types.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2899-4) contains supplementary material, which is available to authorized users.

PRL-3 promotes the peritoneal metastasis of gastric cancer through the PI3K/Akt signaling pathway by regulating PTEN

Peritoneal metastasis is the most frequent cause of death in patients with advanced gastric carcinoma (GC). The phosphatase of regenerating liver-3 (PRL-3) is recognized as an oncogene and plays an important role in GC peritoneal metastasis. However, the mechanism of how PRL-3 regulates GC invasion and metastasis is unknown. In the present study, we found that PRL-3 presented with high expression in GC with peritoneal metastasis, but phosphatase and tensin homologue (PTEN) was weakly expressed. The p-PTEN/PTEN ratio was also higher in GC with peritoneal metastasis than that in the normal gastric tissues. We also found the same phenomenon when comparing the gastric mucosa cell line with the GC cell lines. After constructing a wild-type and a mutant-type plasmid without enzyme activity and transfecting them into GC SGC7901 cells, we showed that only PRL-3 had enzyme activity to downregulate PTEN and cause PTEN phosphorylation. The results also showed that PRL-3 increased the expression levels of MMP-2/MMP-9 and promoted the migration and invasion of the SGC7901 cells. Knockdown of PRL-3 decreased the expression levels of MMP-2/MMP-9 significantly, which further inhibited the migration and invasion of the GC cells. PRL-3 also increased the expression ratio of p-Akt/Akt, which indicated that PRL-3 may mediate the PI3K/Akt pathway to promote GC metastasis. When we transfected the PTEN siRNA plasmid into the PRL-3 stable low expression GC cells, the expression of p-Akt, MMP-2 and MMP-9 was reversed. In conclusion, our results provide a bridge between PRL-3 and PTEN; PRL-3 decreased the expression of PTEN as well as increased the level of PTEN phosphorylation and inactivated it, consequently activating the PI3K/Akt signaling pathway, and upregulating MMP-2/MMP-9 expression to promote GC cell peritoneal metastasis.

Ubiquitin-Specific Protease 4-Mediated Deubiquitination and Stabilization of PRL-3 Is Required for Potentiating Colorectal Oncogenesis

Ubiquitin specific protease 4 (USP4) is a deubiquitinating enzyme with key roles in the regulation of p53 and TGFβ signaling, suggesting its importance in tumorigenesis. However, the mechanisms and regulatory roles of USP4 in cancer, including colorectal cancer, remain largely elusive. Here, we present the first evidence that USP4 regulates the growth, invasion, and metastasis of colorectal cancer. USP4 expression was significantly elevated in colorectal cancer tissues and was significantly associated with tumor size, differentiation, distant metastasis, and poor survival. Knockdown of USP4 diminished colorectal cancer cell growth, colony formation, migration, and invasion in vitro and metastasis in vivo. Importantly, we found that phosphatase of regenerating liver-3 (PRL-3) is indispensable for USP4-mediated oncogenic activity in colorectal cancer. Mechanistically, we observed that USP4 interacted with and stabilized PRL-3 via deubiquitination. This resulted in activation of Akt and reduction of E-cadherin, critical regulators of cancer cell growth and metastasis. Examination of clinical samples confirmed that USP4 expression positively correlates with PRL-3 protein expression, but not mRNA transcript levels. Taken together, our results demonstrate that aberrant expression of USP4 contributes to the development and progression of colorectal cancer and reveal a critical mechanism underlying USP4-mediated oncogenic activity. These observations suggest that the potential of harnessing proteolytic degradation processes for therapeutic manipulation may offer a much-needed new approach for improving colorectal cancer treatment strategies.

PTP4A3 Independently Predicts Metastasis and Survival in Upper Tract Urothelial Carcinoma Treated with Radical Nephroureterectomy

PURPOSE

Increasing evidence has shown that protein tyrosine phosphatases have dominant roles in setting the levels of tyrosine phosphorylation and promoting oncogenic processes. PTP4A3 has been implicated in cancer metastasis but to our knowledge the role of PTP4A3 in upper tract urothelial carcinoma is unknown. The aim of this study was to investigate the association of PTP4A3 with disease characteristics, distant metastasis and prognosis of upper tract urothelial carcinoma.

MATERIALS AND METHODS

The importance of PTP4A3 was initially examined in paired normal urothelium, noninvasive upper tract urothelial carcinoma, invasive upper tract urothelial carcinoma and nodal metastatic tissue. The PTP4A3 transcript level was assessed in another 20 upper tract urothelial carcinoma samples by real-time reverse transcriptase-polymerase chain reaction. PTP4A3 protein expression was determined by immunohistochemistry using the H-score in 340 upper tract urothelial carcinoma samples. It was further correlated with clinicopathological factors, and disease specific and metastasis-free survival.

RESULTS

The expression of PTP4A3 significantly increased from normal urothelium, noninvasive upper tract urothelial carcinoma and invasive upper tract urothelial carcinoma to nodal metastatic tissue (p <0.001). The PTP4A3 transcript level was also markedly up-regulated in higher stage upper tract urothelial carcinoma (p = 0.002). Over expression of PTP4A3 protein was significantly associated with advanced pT status, nodal metastasis, lymphovascular invasion and perineural invasion (each p <0.001) as well as with inferior disease specific and metastasis-free survival on multivariate analysis (each p <0.0001). In addition, it predicted metastasis in patients with pTa, pT1 and pT2 upper tract urothelial carcinoma.

CONCLUSIONS

Results imply that PTP4A3 has a role in the carcinogenesis of upper tract urothelial carcinoma. PTP4A3 over expression independently predicted the metastasis and outcome of upper tract urothelial carcinoma, which was even more important in organ confined disease.

Clinical comparison of laparoscopic and open liver resection after propensity matching selection

BACKGROUND

This study aimed to compare the radicality for and clinical advantages of laparoscopic liver resection, which is increasingly used, and the corresponding open procedure by propensity score matching analysis.

METHODS

We analyzed 260 hepatocellular carcinoma patients who underwent initial liver resection at our department between January 2003 and June 2011, including 60 laparoscopic (the Lap group) and 200 open cases (the Open group). Propensity scores were calculated for each patient via the use of various clinicopathologic features as covariates, and patients' survival was compared.

RESULTS

The Lap group had more women and patients of advanced age (n = 60) than the Open group (n = 200). Tumor size (2.3 cm vs 3.5 cm median), multiple tumors (18.3% vs 41.0%), vascular invasion (15.0% vs 36.5%), poor differentiation status (11.2% vs 24.5%), intraoperative bleeding (110 mL vs 420 mL; median), and operative time (277 minutes vs 312 minutes; median) were significantly more favorable in the Lap group than in the Open group because of a selection bias of the patients (Lap vs Open). The postoperative recurrence-free and overall survival rates were greater in the Lap group than in the Open group; however, when 35 patients from each group were analyzed after propensity score matching of clinicopathologic characteristics of the patients, intraoperative bleeding was lesser in the Lap group. The recurrence-free survival rates at 1, 3, and 5 years were 75.0%, 43.8%, and 43.8%, respectively, in the Lap group and 73.6%, 49.3%, and 37.2%, respectively, in the Open group, which indicated no significant differences (P = .954). Similarly, the overall survival rates at 1, 3, and 5 years were 93.9%, 82.1%, and 82.1%, respectively, in the Lap group and 94.3%, 85.2%, and 61.8%, respectively, in the Open group, indicating no significant differences between the 2 groups (P = .672).

CONCLUSION

Our results indicate that laparoscopic liver resection is comparable with the corresponding open procedure in clinical safety and prognostic efficacy.

PRL-3 promotes migration and invasion and is associated with poor prognosis in salivary adenoid cystic carcinoma

BACKGROUND

PRL-3 had been found to be involved in tumorigenesis in various malignancies. In this study, we investigated the role of PRL-3 in the development, migration, and invasion of salivary adenoid cystic carcinoma (SACC).

METHODS

Immunohistochemistry (IHC) was used to analyze the role of PRL-3 in the development and prognosis of SACC. Then, we overexpressed or inhibited the expression of PRL-3 in paired SACC cells to analyze the role of PRL-3 in the migration and invasion of SACC. In vitro migration and invasion assays were used. Western blotting was used to detect metastasis-related protein levels.

RESULTS

IHC results confirmed that the deregulation of PRL-3 was a frequent event in SACC; the upregulation of PRL-3 was related to clinical stages, vital status, and distant metastasis, which was associated with reduced overall survival and disease-free survival. SACC-LM cells with higher migratory and invasive abilities had more robust PRL-3 protein expression than SACC-83 cells with lower migratory and invasive abilities. PRL-3 overexpression promoted cell migration, invasion, and proliferation, led to simultaneous upregulation of phosphorylated PRL-3, pERK1/2, Slug, vimentin, and downregulation of E-cadherin in SACC-83 cells. However, the inhibition of PRL-3 by PRL-3 inhibitor or PRL-3 siRNA in SACC-LM cells inhibited cell migration, invasion, and proliferation, resulted in simultaneous downregulation of phosphorylated PRL-3, pERK1/2, Slug, vimentin, and upregulation of E-cadherin.

CONCLUSIONS

Our results confirm that PRL-3 plays an important role in the development of SACC and contributes to the migratory and invasive abilities of SACC.

Independent oncogenic and therapeutic significance of phosphatase PRL-3 in FLT3-ITD-negative acute myeloid leukemia

BACKGROUND

Internal tandem duplication of FMS-like tyrosine kinase (FLT3-ITD) is well known to be involved in acute myeloid leukemia (AML) progression, but FLT3-ITD-negative AML cases account for 70% to 80% of AML, and the mechanisms underlying their pathology remain unclear. This study identifies protein tyrosine phophatase PRL-3 as a key mediator of FLT3-ITD-negative AML.

METHODS

A total of 112 FLT3-ITD-negative AML patients were sampled between 2010 and 2013, and the occurrence of PRL-3 hyperexpression in FLT3-ITD-negative AML was evaluated by multivariate probit regression analysis. Overexpression or depletion of endogenous PRL-3 expression with the specific small interfering RNAs was performed to investigate the role of PRL-3 in AML progression. Xenograft models were also used to confirm the oncogenic role of PRL-3.

RESULTS

Compared to healthy donors, PRL-3 is upregulated more than 3-fold in 40.2% of FLT3-ITD-negative AML patients. PRL-3 expression level is adversely correlated to the overall survival of the AML patients, and the AML relapses accompany with re-upregulation of PRL-3. Mechanistically, aberrant PRL-3 expression promoted cell cycle progression and enhanced the antiapoptotic machinery of AML cells to drug cytotoxicity through downregulation of p21 and upregulation of Cyclin D1 and CDK2 and activation of STAT5 and AKT. Depletion of endogenous PRL-3 sensitizes AML cells to therapeutic drugs, concomitant with apoptosis by upregulation of cleaved PARP (poly ADP ribose polymerase) and apoptosis-related caspases. Xenograft assays further confirmed PRL-3's oncogenic role in leukemogenesis.

CONCLUSIONS

Our results demonstrated that PRL-3 is a novel independent crucial player in both FLT3-ITD-positive and FLT3-ITD-negative AML and could be a potential therapeutic target.

Novel hepatocellular carcinoma molecules with prognostic and therapeutic potentials

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, is the sixth most common cancer worldwide and the third leading cause of cancer-related death. The difficulty to diagnose early cancer stages, the aggressive behaviors of HCC, and the poor effectiveness of therapeutic treatments, represent the reasons for the quite similar deaths per year and incidence number. Considering the fact that the diagnosis of HCC typically occurs in the advanced stages of the disease when the therapeutic options have only modest efficacy, the possibility to identify early diagnostic markers could be of significant benefit. So far, a large number of biomarkers have been associated to HCC progression and aggressiveness, but many of them turned out not to be of practical utility. This is the reason why active investigations are ongoing in this field. Given the huge amount of published works aimed at the identification of HCC biomarkers, in this review we mainly focused on the data published in the last year, with particular attention to the role of (1) molecular and biochemical cellular markers; (2) micro-interfering RNAs; (3) epigenetic variations; and (4) tumor stroma. It is worth mentioning that a significant number of the HCC markers described in the present review may be utilized also as targets for novel therapeutic approaches, indicating the tight relation between diagnosis and therapy. In conclusion, we believe that integrated researches among the different lines of investigation indicated above should represent the winning strategies to identify effective HCC markers and therapeutic targets.

Phosphatase of regenerating liver-3 (PRL-3) is associated with metastasis and poor prognosis in gastric carcinoma

BACKGROUND

PRL-3 is a member of phosphatases of regenerating liver family, characterized by phosphatase active domain and C-terminal prenylation motif. Overexpression of PRL-3 has been implicated in multiple cancers. Here we examined the clinical significance of PRL-3 in gastric cancer together with its metastatic biological functions utilizing different structural mutants.

METHODS

PRL-3 expression was analyzed immunohistochemically in 196 gastric cancer patients and 21 cases of liver metastasis. A series of wild type PRL-3 or its mutant plasmids were expressed in BGC823 cells to investigate the relationship between its catalytic activity, cellular localization and metastatic potential in vitro.

RESULTS

Positive staining of PRL-3 was observed in 19.4% (38/196) gastric cancer tissues compared with 76.2% (16/21) in liver metastasis. Statistical analysis revealed that PRL-3 expression correlated with lymph node metastasis and vascular invasion (P<0.05). Patients with high PRL-3 expression showed poorer 5-year overall survival (P=0.011). Wild type PRL-3 expressing cells resulted in enhanced migration and invasion ability, which were greatly crippled in form of PRL-3(C104S) or PRL-3(ΔCAAX) mutants accompanied with its alteration in subcellular localization.

CONCLUSIONS

Metastasis associated protein PRL-3 may serve as a potential prognostic biomarker in human gastric cancer. Both the phosphatase catalytic activity and cellular localization are critical for its function.

Poor prognosis of phosphatase of regenerating liver 3 expression in gastric cancer: a meta-analysis

Background

Overexpression of phosphatase of regenerating liver 3 (PRL-3) has been implicated in gastric cancer (GC) metastasis. Epidemiological studies have evaluated the relationship between PRL-3 expression and prognosis in GC. However, results still remains controversial. In this study, a meta-analysis was performed to evaluate the association of PRL-3 expression with overall survival (OS) and clinicopathological characteristics.

Methods

Literature databases were searched to identify eligible studies dated until April 2013. Summary hazard ratios (HRs) or odds ratios (ORs) with 95% confidence interval (95% CI) were calculated to estimate the association.

Results

A total of 1380 GC patients from six studies were included in the meta-analysis. Overall, the combined HR estimate for OS in a random-effect model was 1.89 (95% CI = 1.38–2.60; P<0.001). Results showed that PRL-3 overexpression was significantly associated with OS, indicating that it may be a biomarker for poor prognosis of GC. Both subgroup and sensitivity analyses further identified the prognostic role of PRL-3 expression in GC patients. Moreover, PRL-3 overexpression was significantly associated with tumor stage (OR = 2.25; 95% CI = 1.63–3.12; P<0.001), depth of invasion (OR = 2.03; 95% CI = 1.38–2.98; P<0.001), vascular invasion (OR = 2.52; 95% CI = 1.79–3.56; P<0.001), lymphatic invasion (OR = 3.74; 95% CI = 2.49–5.63; P<0.001), and lymph node metastasis (OR = 4.56; 95% CI = 2.37–8.76; P<0.001). However, when age, sex, tumor size, and tumor differentiation were considered, no obvious association was observed.

Conclusions

This meta-analysis reveals significant association of PRL-3 overexpression with OS and some clinicopathological features in GC. PRL-3 may be a predicative factor of poor prognosis and aggressive tumor behavior in GC patients.

Biomarkers for predicting future metastasis of human gastrointestinal tumors

The recent advances in surgery and radiation therapy have significantly improved the prognosis of patients with primary cancer, and the major challenge of cancer treatment now is metastatic disease development. The 5-year survival rate of cancer patients who have distant metastasis at diagnosis is extremely low, suggesting that prediction and early detection of metastasis would definitely improve their prognosis because suitable patient therapeutic management and treatment strategy can be provided. Cancer cells from a primary site give rise to a metastatic tumor via a number of steps which require the involvement and altered expression of many regulators. These regulators may serve as biomarkers for predicting metastasis. Over the past few years, numerous regulators have been found correlating with metastasis. In this review, we summarize the findings of a number of potential biomarkers that are involved in cadherin-catenin interaction, integrin signaling, PI3K/Akt/mTOR signaling and cancer stem cell identification in gastrointestinal cancers. We will also discuss how certain biomarkers are associated with the tumor microenvironment that favors cancer metastasis.

Src-mediated phosphorylation of the tyrosine phosphatase PRL-3 is required for PRL-3 promotion of Rho activation, motility and invasion

The metastasis-associated tyrosine phosphatase PRL-3/PTP4A is upregulated in numerous cancers, but the mechanisms modulating PRL-3 activity other than its expression levels have not been investigated. Here we report evidence for both Src-dependent tyrosine phosphorylation of PRL-3 and Src-mediated regulation of PRL-3 biological activities. We used structural mutants, pharmacological inhibitors and siRNA to demonstrate Src-dependent phosphorylation of endogenous PRL-3 in SW480 colon cancer cells. We also demonstrated that PRL-3 was not tyrosine phosphorylated in SYF mouse embryo fibroblasts deficient in Src, Yes and Fyn unless Src was re-expressed. Further, we show that platelet-derived growth factor (PDGF) can stimulate PRL-3 phosphorylation in a Src-dependent manner. Finally, we show that PRL-3-induced cell motility, Matrigel invasion and activation of the cytoskeleton-regulating small GTPase RhoC were abrogated in the presence of the phosphodeficient PRL-3 mutant Y53F, or by use of a Src inhibitor. Thus, PRL-3 requires the activity of a Src kinase, likely Src itself, to promote these cancer-associated phenotypes. Our data establish a model for the regulation of PRL-3 by Src that supports the possibility of their coordinate roles in signaling pathways promoting invasion and metastasis, and supports simultaneous use of novel molecularly targeted therapeutics directed at these proteins.