The value and correlation between PRL-3 expression and matrix metalloproteinase activity and expression in human gliomas

Exploiting frequent and specific expression of PRL3 in pediatric solid tumors for first-in-child use of PRL3-zumab humanized antibody

Phosphatase of regenerating liver 3 (PRL3) is a specific tumor antigen overexpressed in a broad range of adult cancer types. However, its physiological expression in pediatric embryonal and mesenchymal tumors and its association with clinical outcomes in children is unknown. We sought to profile the expression of PRL3 in pediatric tumors in relation to survival outcomes, expression of angiogenesis markers, and G-protein-coupled receptor (GPCR)-mitogen-activated protein kinase (MAPK) signaling targets. PRL3-zumab, a first-in-class humanized antibody, was administered in a dose escalation schedule in a first-in-child clinical trial to study toxicity, pharmacokinetics, and clinical outcomes. Among 64 pediatric tumors, PRL3 was most frequently expressed in neuroblastoma (100%), rhabdomyosarcoma and non-rhabdomyosarcoma soft tissue sarcomas (71%), and renal sarcomas (60%) but absent in paired normal tissues. PRL3 was expressed in 75% of relapsed tumors and associated with shorter median event-free survival. Microarray profiling of PRL3-positive tumors showed elevation of angiogenin, TIMP1 and TIMP2, and GPCR-MAPK signaling proteins that commonly interacted with PRL3. The first use of PRL3-zumab in a pediatric patient saw no adverse events. A 28.6% reduction in maximum target lesion diameter was achieved when PRL3-zumab was administered concurrently with hypofractionated radiation. These findings support wider exploration of PRL3 expression in embryonal and mesenchymal tumors and further clinical application of PRL3-zumab in pediatric patients.

PRL-3 and MMP9 Expression and Epithelial-Mesenchymal Transition Markers in Circulating Tumor Cells From Patients With Colorectal Cancer: Potential Value in Clinical Practice

Objective

To evaluate the clinical correlation of epithelial-mesenchymal transition (EMT) with PRL-3 and MMP9 expression in the circulating tumor cells (CTCs) of patients with colorectal cancer (CRC).

Materials and Methods

Between January 2016 and December 2018, the EMT phenotype-based subsets of CTCs and the expression levels of PRL-3 and MMP9 in CTCs were identified, and their clinical values in 172 patients were evaluated. The CTCs were isolated, classified, and counted using the CanPatrol™ CTC filtration system. The CTC subsets (epithelial cells, mesenchymal cells and biphenotypic cells), as well as PRL-3 and MMP9 expression, were detected by RNA in situ hybridization.

Results

CTCs were detected in 93.0% (160/172) of the included patients with CRC. Positive PRL-3 and MMP9 expression in CTC and M-CTC was found in 75.0% (102/136) and 80.8% (97/120) of the patients, respectively. The proportion of patients with positive PRL-3 and MMP9 expression in M-CTC was significantly associated with distant metastasis (p<0.05). The patients with ≥6 CTCs tended to show poorer progression-free survival (PFS) and overall survival (OS) rates (p=0.016, 0.02, respectively), and the patients with ≥3 M-CTC also showed poor PFS (p=0.0013). Additionally, the patients with positive PRL-3 and MMP9 expression in CTCs had significantly poorer PFS (p=0.0024) and OS (p=0.095) than the patients with negative PRL-3 and MMP9 expression. Multivariate Cox analysis uncovered that positive PRL-3 and MMP9 expression in CTCs may be an independent prognostic factor for worse PFS.

Conclusion

EMT phenotypes and CTC numbers can be used as prognostic indicators for metastasis and survival in patients with CRC, and the combination of PRL-3 and MMP9 expression in CTCs is a promising clinical marker for patients with CRC.

The phosphatase of regenerating liver-3 protein(PRL-3)promotes glioma cell invasiveness by interacting with β3 -tubulin

PRL-3 is a tyrosine phosphatase linked with tumor metastasis. It is detected high expression in different kinds of cancers, including colorectal, gastric, ovarian, and liver cancer. Its high expression is positively correlated with the progression of tumors and negatively with survivals of patients. However, the detailed mechanism underlying PRL-3 in tumor metastasis still remains unclear. In the present study, we found that PRL-3 is able to bind to β3-tubulin in pull-down and co-immunoprecipitation assays. Furthermore, overexpression of PRL-3 dephosphorylated β3-tubulin, a component of cytoskeleton, which plays critical role in cell shape formation and migration. Using cell wound healing and matrigel invasion assays, we found that PRL-3 could promote the migration and invasion of glioma cells. Taken together, our study revealed that PRL-3 may be involved in migration and invasion of glioma by dephosphorylating β3-tubulin. It is tempting to speculate that dephosphorylation of β3-tubulin by PRL-3 results in assembly of the cytoskeleton and facilitates cell migration and/or tumor metastasis.

Deregulation of lncRNA-AC078883.3 and microRNA-19a is involved in the development of chemoresistance to cisplatin via modulating signaling pathway of PTEN/AKT

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer death worldwide. As a platinum-based chemotherapeutic drug, cisplatin has been used in the NSCLC treatment for over 30 years, and its effects are impaired by drug resistance. This study aimed to investigate the potential role of lncRNA-AC078883.3 in the development of chemoresistance against cisplatin. Real-time PCR, Western blot analysis, Immunohistochemistry (IHC) assay, bioinformatic analysis, and luciferase assay were collaboratively used to establish the lncRNA-AC078883.3/miR-19a/PTEN/AKT pathway. Also, the effect of cisplatin on cell proliferation was observed via an MTT assay. Furthermore, Cox regression and Kaplan-Meier analyses were used to study whether lncRNA-AC078883.3 is involved in the survival of NSCLC. Compared with the Cisplatin-Sensitive group, the Cisplatin-Resistance group exhibited lower levels of lncRNA-AC078883.3 and PTEN and higher levels of miR-19a and p-Akt. The growth rate of A549 and H460 cells and the IC ₅₀ of DPP in the Cisplatin-Resistance group were higher than those in the Cisplatin-S group. miR-19a contains a putative binding site of lncRNA-AC078883.3, which enabled the luciferase activity of wild-type lncRNA-AC078883.3 to be reduced by miR-19a. In addition, by directly targeting PTEN 3'-untranslated region (UTR), miR-19a repressed the luciferase activity of wild-type PTEN 3'-UTR. The median OS of patients with reduced lncRNA-AC078883.3 expression was longer than that of patients with higher lncRNA-AC078883.3 expression. Finally, compared with low lncRNA-AC078883.3-expression patients, the high lncRNA-AC078883.3-expression patients were associated with lower miR-19a expression and higher PTEN expression. Therefore, we suggested for the first time that the low expression of lncRNA-AC078883.3 contributed to the development of chemoresistance against cisplatin.

Protein tyrosine phosphatase 4A3 (PTP4A3/PRL-3) promotes the aggressiveness of human uveal melanoma through dephosphorylation of CRMP2

Uveal melanoma (UM) is an aggressive tumor in which approximately 50% of patients develop metastasis. Expression of the PTP4A3 gene, encoding a phosphatase, is predictive of poor patient survival. PTP4A3 expression in UM cells increases their migration in vitro and invasiveness in vivo. Here, we show that CRMP2 is mostly dephosphorylated on T514 in PTP4A3 expressing cells. We also demonstrate that inhibition of CRMP2 expression in UM cells expressing PTP4A3 increases their migration in vitro and invasiveness in vivo. This phenotype is accompanied by modifications of the actin microfilament network, with shortened filaments, whereas cells with a inactive mutant of the phosphatase do not show the same behavior. In addition, we showed that the cell cytoplasm becomes stiffer when CRMP2 is downregulated or PTP4A3 is expressed. Our results suggest that PTP4A3 acts upstream of CRMP2 in UM cells to enhance their migration and invasiveness and that a low level of CRMP2 in tumors is predictive of poor patient survival.

Protein Phosphatases-A Touchy Enemy in the Battle Against Glioblastomas: A Review

Glioblastoma (GBM) is the most common malignant tumor arising from brain parenchyma. Although many efforts have been made to develop therapies for GBM, the prognosis still remains poor, mainly because of the difficulty in total resection of the tumor mass from brain tissue and the resistance of the residual tumor against standard chemoradiotherapy. Therefore, novel adjuvant therapies are urgently needed. Recent genome-wide analyses of GBM cases have clarified molecular signaling mechanisms underlying GBM biology. However, results of clinical trials targeting phosphorylation-mediated signaling have been unsatisfactory to date. Protein phosphatases are enzymes that antagonize phosphorylation signaling by dephosphorylating phosphorylated signaling molecules. Recently, the critical roles of phosphatases in the regulation of oncogenic signaling in malignant tumor cells have been reported, and tumorigenic roles of deregulated phosphatases have been demonstrated in GBM. However, a detailed mechanism underlying phosphatase-mediated signaling transduction in the regulation of GBM has not been elucidated, and such information is necessary to apply phosphatases as a therapeutic target for GBM. This review highlights and summarizes the phosphatases that have crucial roles in the regulation of oncogenic signaling in GBM cells.

PRL-3 is a potential glioblastoma prognostic marker and promotes glioblastoma progression by enhancing MMP7 through the ERK and JNK pathways

Purpose: Glioblastoma is the most common and aggressive type of primary brain malignancy and is associated with a poor prognosis. Previously, we found that phosphatase of regenerating liver-3 (PRL-3) was significantly up-regulated in glioblastoma as determined by a microarray analysis. However, the function of PRL-3 in glioblastoma remains unknown. We aimed to investigate the clinical relationship between PRL-3 and glioblastoma, and uncover the mechanisms of PRL-3 in the process of glioblastoma.

Methods: PRL-3 expression was evaluated in 61 glioblastoma samples and 4 cell lines by RT-qPCR and immunohistochemistry. Kaplan-Meier analysis was performed to evaluate the prognostic value of PRL-3 for overall survival (OS) and progression-free survival (PFS) for glioblastoma patients. Proliferation was evaluated by Cell Counting Kit-8 (CCK-8) assay and EdU proliferation assay, migration and invasion by wound-closure/Transwell assays, and qRT-PCR/immunoblotting/IHC were used for both in vivo and in vitro investigations.

Result: A high PRL-3 expression level was closely correlated with unfavorable OS and PFS for glioblastoma patients, and was also significantly correlated with Ki-67 expression. Down-regulation of PRL-3 inhibited glioma cell proliferation, invasion and migration through ERK/JNK/matrix metalloproteinase 7 (MMP7) in vitro and in vivo.

Conclusions: PRL-3 expression enhances the invasion and proliferation of glioma cells, highlighting this phosphatase as a novel prognostic candidate and an attractive target for future therapy in glioblastoma.

Antibody Array Revealed PRL-3 Affects Protein Phosphorylation and Cytokine Secretion

Phosphatase of regenerating liver 3 (PRL-3) promotes cancer metastasis and progression via increasing cell motility and invasiveness, however the mechanism is still not fully understood. Previous reports showed that PRL-3 increases the phosphorylation of many important proteins and suspected that PRL-3-enhanced protein phosphorylation may be due to its regulation on cytokines. To investigate PRL-3's impact on protein phosphorylation and cytokine secretion, we performed antibody arrays against protein phosphorylation and cytokines separately. The data showed that PRL-3 could enhance tyrosine phosphorylation and serine/threonine phosphorylation of diverse signaling proteins. Meanwhile, PRL-3 could affect the secretion of a subset of cytokines. Furthermore, we discovered the PRL-3-increased IL-1α secretion was regulated by NF-κB and Jak2-Stat3 pathways and inhibiting IL-1α could reduce PRL-3-enhanced cell migration. Therefore, our result indicated that PRL-3 promotes protein phosphorylation by acting as an 'activator kinase' and consequently regulates cytokine secretion.

Elevated phosphatase of regenerating liver 3 (PRL-3) promotes cytoskeleton reorganization, cell migration and invasion in endometrial stromal cells from endometrioma

STUDY QUESTION

Is phosphatase of regenerating liver-3 (PRL-3) associated with increased motility of endometriotic cells from endometrioma?

SUMMARY ANSWER

Elevated PRL-3 promotes cytoskeleton reorganization, cell migration and invasion of endometrial stromal cells (ESCs) from endometrioma.

WHAT IS KNOWN ALREADY

Overexpression of PRL-3 is associated with cancer cell migration, invasion and metastatic phenotype.

STUDY DESIGN, SIZE, DURATION

Primary human ESCs were isolated from eutopic endometrium of women without endometriosis (EuCo, n = 10), with histologically proven endometrioma (EuEM, n = 19) and from the cyst wall of ovarian endometriosis (OvEM, n = 26).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The expression of PRL-3 in ESCs derived from EuCo, EuEM and OvEM at different phases of menstrual cycle were compared. The protein and mRNA levels of PRL-3 were examined by western blot and RT-qPCR, respectively. ESCs from OvEM were transfected with/without short hairpin RNA (shRNA) or small interfering RNA (siRNA). Additionally, a plasmid-mediated delivery system was used to achieve PRL-3 overexpression in ESCs from EuEM. The cellular distribution of F-actin and α-tubulin were examined by immunocytochemistry. Cell motility was evaluated by a transwell migration/invasion assay.

MAIN RESULTS AND THE ROLE OF CHANCE

The protein and mRNA levels of PRL-3 are significantly elevated in ESCs from OvEM compared with EuCo and EuEM. The expression of PRL-3 was not altered between proliferative phase and secretory phase in ESCs from all groups. Knockdown of PRL-3 significantly modified the distribution of F-actin and α-tubulin cytoskeleton, inhibited cell migration and invasion. Endogenous inhibition of PRL-3 attenuated the expression of Ras homolog gene family members A and C (RhoA, RhoC), Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) and matrix metalloproteinase (MMP) 9, but not MMP2 in ESCs from OvEM. Additionally, overexpression of PRL-3 in ESCs from EuEM up-regulates cell migration and invasion, and increases the expression of RhoA, RhoC, ROCK1 and MMP9.

LIMITATIONS, REASONS FOR CAUTION

Lack of in vivo animal studies is the major limitation of our report. Our results should be further confirmed in a larger cohort of patients and extended to include eutopic and ectopic endometrium from patients with peritoneal endometriosis at different stages of the disease.

WIDER IMPLICATIONS OF THE FINDINGS

Our study describes that elevated expression of PRL-3 contributes to the cell motility of ESCs from endometrioma. The results emphasize the importance of metastatic-related factor PRL-3 in the pathogenesis of endometrioma.

STUDY FUNDING/COMPETING INTEREST

This work was supported by National Natural Science Foundation of China (No. 81170546) and Zhejiang Medicine Science and Technology Projects (No. Y13H040003). The authors declare no conflict of interest.

Girdin, an actin-binding protein, is critical for migration, adhesion, and invasion of human glioblastoma cells

Girdin, an actin-binding protein, possesses versatile functions in a multitude of cellular processes. Although several studies have shown that Girdin is involved in the cell DNA synthesis, actin cytoskeleton rearrangement, and cell motility, the molecular mechanisms of Girdin in tumor development and progression remain elusive. In this study, through over-expression and siRNA experiments, we found that Girdin increased migration of LN229 human glioblastoma cells. On the other hand, reducing Girdin impaired F-actin polymerization, which is essential for cell morphogenesis and motility. Matrix metalloproteinase 2, critical in human glioma migration and invasion, was down-regulated upon Girdin reduction and led to decreased invasion in vitro and in vivo. In addition, silencing Girdin expression impaired the phosphorylation of two important adhesion molecules, integrin β1 and focal adhesion kinase, resulting in cell adhesion defects. Our immunohistochemical study on human gliomas tissue sections indicated that Girdin expression was positively related with glioma malignancy, supporting the in vitro and in vivo results from cell lines. Collectively, our findings suggest a critical role for Girdin in glioma infiltration. We show that reduction of Girdin, an actin-binding protein, leads to impaired F-actin polymerization and down-regulated expression of matrix metallopeptidase protein 2 (MMP-2), phosphorylated integrin β1, and phosphorylated focal adhesion kinase (FAK), which resulted in decreased migration, adhesion, and invasion of glioblastoma cells. Girdin was positively correlated with glioma malignancy and negatively associated with clinical prognosis, suggesting Girdin as a critical regulator in glioma infiltration.

Structure and backbone dynamics of vanadate-bound PRL-3: comparison of 15N nuclear magnetic resonance relaxation profiles of free and vanadate-bound PRL-3

Phosphatases of regenerating liver (PRLs) constitute a novel class of small, prenylated phosphatases with oncogenic activity. PRL-3 is particularly important in cancer metastasis and represents a potential therapeutic target. The flexibility of the WPD loop as well as the P-loop of protein tyrosine phosphatases is closely related to their catalytic activity. Using nuclear magnetic resonance spectroscopy, we studied the structure of vanadate-bound PRL-3, which was generated by addition of sodium orthovanadate to PRL-3. The WPD loop of free PRL-3 extended outside of the active site, forming an open conformation, whereas that of vanadate-bound PRL-3 was directed into the active site by a large movement, resulting in a closed conformation. We suggest that vanadate binding induced structural changes in the WPD loop, P-loop, helices α4-α6, and the polybasic region. Compared to free PRL-3, vanadate-bound PRL-3 has a longer α4 helix, where the catalytic R110 residue coordinates with vanadate in the active site. In addition, the hydrophobic cavity formed by helices α4-α6 with a depth of 14-15 Å can accommodate a farnesyl chain at the truncated prenylation motif of PRL-3, i.e., from R169 to M173. Conformational exchange data suggested that the WPD loop moves between open and closed conformations with a closing rate constant k(close) of 7 s(-1). This intrinsic loop flexibility of PRL-3 may be related to their catalytic rate and may play a role in substrate recognition.

Expression of phosphatase of regenerating liver-3 (PRL-3) in endometrioid cancer and lymph nodes metastases

PURPOSE

We identify the expression of PRL-3 in primary endometrioid endometrial cancer and metastases in relation to the clinicopathological characteristics.

MATERIAL/METHODS

The study involved 30 patients with type I endometrial cancer. Twelve of them were diagnosed with metastases in various localization of abdomen. The PRL-3 expression was evaluated on the basis of immunohistochemistry results by the use of monoclonal antibody anti-PRL3 clone 3B6.

RESULTS

The intensity of PRL-3 expression in correlation with tumor stage was statistically significant (p = 0.024). The strongest reaction was noted in cases classified as a 1a and 1b stage defined by FIGO. The strength of PRL-3 expression is significantly associated with the degree of histological tumor grade (p = 0.035).

CONCLUSIONS

The strong expression of PRL-3 in the primary tumor that was significantly correlated with the grade and clinical stage suggest that PTP4A3 participates in the process of endometrial carcinogenesis.

Phosphatase of regenerating liver-3 induces angiogenesis by increasing extracellular signal-regulated kinase phosphorylation in endometrial adenocarcinoma

OBJECTIVE

The aim of this study was to investigate the mechanism by which phosphatase of regenerating liver-3 (PRL-3) induces angiogenesis in endometrial adenocarcinoma tissues and cells.

METHODS

We investigated the expression of PRL-3 and vascular endothelial growth factor (VEGF) in samples from 124 patients with endometrial adenocarcinoma using immunohistochemical staining. The relationship between PRL-3 expression and microvessel density (MVD), clinicopathological factors and surgical treatment outcome was also studied. Following this, we studied the effect on cell lines of blocking or upregulating PRL-3.

RESULTS

PRL-3 expression in endometrial adenocarcinoma was high, and this overexpression is correlated with advanced clinical stage (p=0.008), lymph node metastasis (p=0.016) and poor postoperative survival. PRL-3 overexpression was associated with VEGF (p=0.001) expression and MVD (p=0.005). Upregulating PRL-3 expression promoted VEGF and phosphorylated extracellular signal-regulated kinase (pERK) expression. Blocking PRL-3 expression inhibited VEGF and pERK expression. Following inhibition of pERK, VEGF expression was downregulated.

CONCLUSIONS

PRL-3 induces microvascular vessel formation by facilitating VEGF expression in endometrial adenocarcinoma tissues. PRL-3 upregulates pERK expression and activity, facilitating VEGF expression and accelerating angiogenesis.

Drosophila PRL-1 is a growth inhibitor that counteracts the function of the Src oncogene

Phosphatase of Regenerating Liver (PRL) family members have emerged as molecular markers that significantly correlate to the ability of many cancers to metastasize. However, contradictory cellular responses to PRL expression have been reported, including the inhibition of cell cycle progression. An obvious culprit for the discrepancy is the use of dozens of different cell lines, including many isolated from tumors or cultured cells selected for immortalization which may have missing or mutated modulators of PRL function. We created transgenic Drosophila to study the effects of PRL overexpression in a genetically controlled, organismal model. Our data support the paradigm that the normal cellular response to high levels of PRL is growth suppression and furthermore, that PRL can counter oncogenic activity of Src. The ability of PRL to inhibit growth under normal conditions is dependent on a CAAX motif that is required to localize PRL to the apical edge of the lateral membrane. However, PRL lacking the CAAX motif can still associate indiscriminately with the plasma membrane and retains its ability to inhibit Src function. We propose that PRL binds to other membrane-localized proteins that are effectors of Src or to Src itself. This first examination of PRL in a model organism demonstrates that PRL performs as a tumor suppressor and underscores the necessity of identifying the conditions that enable it to transform into an oncogene in cancer.

Bmi-1 promotes the aggressiveness of glioma via activating the NF-kappaB/MMP-9 signaling pathway

Background

The prognosis of human glioma is poor, and the highly invasive nature of the disease represents a major impediment to current therapeutic modalities. The oncoprotein B-cell-specific Moloney murine leukemia virus integration site 1 protein (Bmi-1) has been linked to the development and progression of glioma; however, the biological role of Bmi-1 in the invasion of glioma remains unclear.

Methods

A172 and LN229 glioma cells were engineered to overexpress Bmi-1 via stable transfection or to be silenced for Bmi-1 expression using RNA interfering method. Migration and invasiveness of the engineered cells were assessed using wound healing assay, Transwell migration assay, Transwell matrix penetration assay and 3-D spheroid invasion assay. MMP-9 expression and activity were measured using real-time PCR, ELISA and the gelatin zymography methods. Expression of NF-kappaB target genes was quantified using real-time PCR. NF-kappaB transcriptional activity was assessed using an NF-kappaB luciferase reporter system. Expression of Bmi-1 and MMP-9 in clinical specimens was analyzed using immunohistochemical assay.

Results

Ectopic overexpression of Bmi-1 dramatically increased, whereas knockdown of endogenous Bmi-1 reduced, the invasiveness and migration of glioma cells. NF-kappaB transcriptional activity and MMP-9 expression and activity were significantly increased in Bmi-1-overexpressing but reduced in Bmi-1-silenced cells. The reporter luciferase activity driven by MMP-9 promoter in Bmi-1-overexpressing cells was dependent on the presence of a functional NF-kappaB binding site, and blockade of NF-kappaB signaling inhibited the upregulation of MMP-9 in Bmi-1 overexpressing cells. Furthermore, expression of Bmi-1 correlated with NF-kappaB nuclear translocation as well as MMP-9 expression in clinical glioma samples.

Conclusions

Bmi-1 may play an important role in the development of aggressive phenotype of glioma via activating the NF-kappaB/MMP-9 pathway and therefore might represent a novel therapeutic target for glioma.

Transcriptional profiling of human glioblastoma vessels indicates a key role of VEGF-A and TGFβ2 in vascular abnormalization

Glioblastoma are aggressive astrocytic brain tumours characterized by microvascular proliferation and an abnormal vasculature, giving rise to brain oedema and increased patient morbidity. Here, we have characterized the transcriptome of tumour-associated blood vessels and describe a gene signature clearly associated with pleomorphic, pathologically altered vessels in human glioblastoma (grade IV glioma). We identified 95 genes differentially expressed in glioblastoma vessels, while no significant differences in gene expression were detected between vessels in non-malignant brain and grade II glioma. Differential vascular expression of ANGPT2, CD93, ESM1, ELTD1, FILIP1L and TENC1 in human glioblastoma was validated by immunohistochemistry, using a tissue microarray. Through qPCR analysis of gene induction in primary endothelial cells, we provide evidence that increased VEGF-A and TGFβ2 signalling in the tumour microenvironment is sufficient to invoke many of the changes in gene expression noted in glioblastoma vessels. Notably, we found an enrichment of Smad target genes within the distinct gene signature of glioblastoma vessels and a significant increase of Smad signalling complexes in the vasculature of human glioblastoma in situ. This indicates a key role of TGFβ signalling in regulating vascular phenotype and suggests that, in addition to VEGF-A, TGFβ2 may represent a new target for vascular normalization therapy.

miR-21, miR-17 and miR-19a induced by phosphatase of regenerating liver-3 promote the proliferation and metastasis of colon cancer

Background:

Phosphatase of regenerating liver-3 (PRL-3) is an oncogene known to promote tumour metastasis, especially in colorectal cancer (CRC). Here, we demonstrate that the miR-21, miR-17 and miR-19a expressions induced by PRL-3 are involved in the proliferation and metastasis of colon cancer.

Methods:

Microarray analysis and quantitative reverse-transcription polymerase chain reactions (qRT–PCR) were used to investigate the changes in miRNA expression due to the overexpression of PRL-3. Transwell chamber invasion assays, CCK-8 proliferation assays and RNA interference assays were used to explore the effects of PRL-3 on miR-21, miR-17 and miR-19a expression in colon cancer cells. Immunohistochemistry and qRT–PCR were performed in colon cancer tissues to evaluate the expression of PRL-3, signal transducer and activator of transcription 3 (STAT3), miR-21, miR-17 and miR-19a.

Results:

Our study demonstrated that the overexpression of PRL-3 in colon cancer cells induced the expression of miR-21, miR-17 and miR-19a by activating STAT3. Subsequently, these microRNAs contributed to the increased proliferation and invasiveness of the colon cancer cells. Positive correlations between PRL-3 and these microRNAs were also observed in matched primary colon cancer tissues and metastatic lesions.

Conclusion:

miR-21, miR-17 and miR-19a induced by PRL-3 contribute to the proliferation and invasion of colon cancer.

Phosphatase of regenerating liver-3 promotes migration and invasion by upregulating matrix metalloproteinases-7 in human colorectal cancer cells

Phosphatase of regenerating liver (PRL)-3, a member of a subgroup of protein tyrosine phosphatases that can stimulate the degradation of the extracellular matrix, is over-expressed in metastatic colorectal cancer (CRC) relative to primary tumors. To determine whether PRL-3-induced enhancement of migration and invasion is dependent on the expression of matrix metalloproteinases (MMPs), PRL-3 was expressed in DLD-1 human CRC cells. The motility, migration and invasion characteristics of the cells were examined, and metastasis to the lung was confirmed in a nude mouse using PRL-3-overexpressing DLD-1 cells [DLD-1 (PRL-3)]. Migration and invasion of the cells were inhibited by phosphatase and farnesyltransferase inhibitors. Expression of MMPs was enhanced 3- to 10-fold in comparison to control cells, and migration and invasion were partially inhibited by small interfering RNA (siRNA) knockdown of MMP-2, -13 or -14. Importantly, siRNA knockdown of MMP-7 completely inhibited the migration and invasion of DLD-1 (PRL-3) cells, whereas overexpression of MMP-7 increased migration. The expression of MMP-7 was also downregulated by phosphatase and farnesyltransferase inhibitors. It was found that PRL-3 induced MMP-7 through oncogenic pathways including PI3K/AKT and ERK and that there is a relationship between the expression of PRL-3 and MMP-7 in human tumor cell lines. The expression of MMP-13 and -14 was very sensitive to the inhibition of farnesyltransferase; however, the migration and invasion of DLD-1 (PRL-3) cells did not strongly depend on the expression of MMP-13 or -14. These results suggest that the migration and invasion of PRL-3-expressing CRC cells depends primarily on the expression of MMP-7.

VEGF promotes the transcription of the human PRL-3 gene in HUVEC through transcription factor MEF2C

Phosphatase of regenerating liver 3 (PRL-3) is known to be overexpressed in many tumors, and its transcript level is high in the vasculature and endothelial cells of malignant tumor tissue. However, the mechanism(s) underlying its enhanced expression and its function in endothelial cells remain unknown. Here, we report that vascular endothelial growth factor (VEGF) can induce PRL-3 transcription in human umbilical vein endothelial cells (HUVEC). An analysis of its 5′UTR revealed that PRL-3 transcription is initiated from two distinct sites, which results in the formation of the two transcripts, PRL-3-iso1 and PRL-3-iso2, but only the latter is up-regulated in HUVEC by VEGF. The PRL-3-iso2 promoter region includes two functional MEF2 (myocyte enhancer factor2) binding sites. The over-expression of the constitutively active form of MEF2C promotes the abundance of the PRL-3-iso2 transcript in a number of human cell lines. The siRNA-induced knockdown of MEF2C abolished the stimulative effect of VEGF on PRL-3 transcript in HUVEC, indicating that the VEGF-induced promotion of PRL-3 expression requires the presence of MEF2C. Finally, blocking PRL-3 activity or expression suppresses tube formation by HUVEC. We suggest that PRL-3 functions downstream of the VEGF/MEF2C pathway in endothelial cells and may play an important role in tumor angiogenesis.

Discriminant analysis to classify glioma grading using dynamic contrast-enhanced MRI and immunohistochemical markers

INTRODUCTION

The purpose of the present study was to look for the possible predictors which might discriminate between high- and low-grade gliomas by pooling dynamic contrast-enhanced (DCE)-perfusion derived indices and immunohistochemical markers.

METHODS

DCE-MRI was performed in 76 patients with different grades of gliomas. Perfusion indices, i.e., relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), permeability (k (trans) and k (ep)), and leakage (v (e)) were quantified. MMP-9-, PRL-3-, HIF-1α-, and VEGF-expressing cells were quantified from the excised tumor tissues. Discriminant function analysis using these markers was used to identify discriminatory variables using a stepwise procedure. To look for correlations between immunohistochemical parameters and DCE metrics, Pearson's correlation coefficient was also used.

RESULTS

A discriminant function for differentiating between high- and low-grade tumors was constructed using DCE-MRI-derived rCBV, k (ep), and v (e). The form of the functions estimated are "D (1) = 0.642 × rCBV + 0.591 × k (ep) - 1.501 × v (e) - 1.550" and "D (2) = 1.608 × rCBV + 3.033 × k (ep) + 5.508 × v (e) - 8.784" for low- and high-grade tumors, respectively. This function classified overall 92.1% of the cases correctly (89.1% high-grade tumors and 100% low-grade tumors). In addition, VEGF expression correlated with rCBV and rCBF, whereas MMP-9 expression correlated with k (ep). A significant positive correlation of HIF-1α with rCBV and VEGF expression was also found.

CONCLUSION

DCE-MRI may be used to differentiate between high-grade and low-grade brain tumors non-invasively, which may be helpful in appropriate treatment planning and management of these patients. The correlation of its indices with immunohistochemical markers suggests that this imaging technique is useful in tissue characterization of gliomas.

Inside the human cancer tyrosine phosphatome

Members of the protein tyrosine phosphatase (Ptp) family dephosphorylate target proteins and counter the activities of protein tyrosine kinases that are involved in cellular phosphorylation and signalling. As such, certain PTPs might be tumour suppressors. Indeed, PTPs play an important part in the inhibition or control of growth, but accumulating evidence indicates that some PTPs may exert oncogenic functions. Recent large-scale genetic analyses of various human tumours have highlighted the relevance of PTPs either as putative tumour suppressors or as candidate oncoproteins. Progress in understanding the regulation and function of PTPs has provided insights into which PTPs might be potential therapeutic targets in human cancer.

Stathmin, a new target of PRL-3 identified by proteomic methods, plays a key role in progression and metastasis of colorectal cancer

To better understand the role of PRL-3 in progression and metastasis of colorectal cancer (CRC), we searched for PRL-3 associated proteins using proteomic methods. We identified 39 PRL-3 associated proteins based on proteomic strategy. Stathmin, a key oncoprotein, was proved to be a new PRL-3 associated protein. Notably, co-immunoprecipitation assays in both endogenous CRC cell lines and CRC tissues indicated that PRL-3 could interact with stathmin. And, both stathmin and PRL-3 contributed to microtubule (MT) destabilization of CRC cells. Moreover, gain-of-function and loss-of-function analyses revealed that stathmin promoted proliferation, cell adhesion, and migration of human CRC cells. Immunohistochemical analysis of 149 colorectal tumor samples showed that overexpression of stathmin was strongly correlated with tumor differentiation (P = 0.035), tumor invasion (P = 0.024), lymph node status (P < 0.001), Dukes classification (P < 0.001), and TNM staging (P < 0.001) of CRC patients. Univariate and multivariate survival analyses further supported that overexpression of stathmin protein was a potential independent poor prognostic factor for CRC. Our results reveal many PRL-3 associated proteins for the first time. The oncoprotein stathmin plays a key role in CRC as a new target of PRL-3. Interaction between PRL-3 and stathmin leads to MT destabilization of CRC cells, which contributes to progression and metastasis of CRC.

The significance of CD14+ monocytes in peripheral blood stem cells for the treatment of rat liver cirrhosis

BACKGROUND AIMS

Circulating monocytes have been exploited as an important progenitor cell resource for hepatocytes in vitro and are instrumental in the removal of fibrosis. We investigated the significance of monocytes in peripheral blood stem cells (PBSC) for the treatment of liver cirrhosis.

METHODS

Rat CD14+ monocytes in PBSC were mobilized with granulocyte-colony-stimulating factor (G-CSF) and harvested by magnetic cell sorting (MACS). Female rats with carbon tetrachloride (CCl₄-induced liver cirrhosis were injected CM-DiI-labeled monocytes, CD14⁻ cells (1 x 10⁷ cells/rat) or saline via the portal vein.

RESULTS

Rat CD14+ and CD11b+ monocytes in PBSC were partly positive for CD34, CD45, CD44, Oct3/4 and Sox2, suggesting monocytes with progenitor capacity. Compared with CD14⁻ cell-infused and saline-injected rats, rats undergoing monocyte transplantation showed a gradually increased serum albumin level and decreased portal vein pressure, resulting in a significantly improved survival rate. Meanwhile, monocyte transplantation apparently attenuated liver fibrosis by analysis for fibronectin, α2-(1)-procollagen, α-smooth muscle aorta (SMA) and transforming growth factor (TGF)-β. Transplanted monocytes mainly clustered in periportal areas of liver, in which 1.8% cells expressed hepatocyte marker albumin and CK18. The expression level of hepatocyte growth factor (HGF), TGF-α, extracellular matrix (EGF) and vascular endothelial growth factor (VEGF) increased, while monocyte transplantation enhanced hepatocyte proliferation. On the other hand, the activities and expression of matrix metalloproteinases (MMP) increased while tissue inhibitor of metalloproteinase (TIMP)-1 expression significantly reduced in monocyte-transplanted livers. Some transplanted monocytes expressed MMP-9 and -13.

CONCLUSIONS

The data suggest that CD14+ monocytes in PBSC contribute to hepatocyte regeneration and extracellular matrix (ECM) remodeling in rat liver cirrhosis much more than CD14⁻ cells, and might offer a therapeutic alternative for patients with liver cirrhosis.

Alterations in gene expression profiles correlated with cisplatin cytotoxicity in the glioma U343 cell line

Gliomas are the most common tumors in the central nervous system, the average survival time of patients with glioblastoma multiforme being about 1 year from diagnosis, in spite of harsh therapy. Aiming to study the transcriptional profiles displayed by glioma cells undergoing cisplatin treatment, gene expression analysis was performed by the cDNA microarray method. Cell survival and apoptosis induction following treatment were also evaluated. Drug concentrations of 12.5 to 300 μM caused a pronounced reduction in cell survival rates five days after treatment, whereas concentrations higher than 25 μM were effective in reducing the survival rates to ~1%. However, the maximum apoptosis frequency was 20.4% for 25 μM cisplatin in cells analyzed at 72 h, indicating that apoptosis is not the only kind of cell death induced by cisplatin. An analysis of gene expression revealed 67 significantly (FDR < 0.05) modulated genes: 29 of which down- and 38 up-regulated. These genes belong to several classes (metabolism, protein localization, cell proliferation, apoptosis, adhesion, stress response, cell cycle and DNA repair) that may represent several affected cell processes under the influence of cisplatin treatment. The expression pattern of three genes (RHOA, LIMK2 and TIMP2) was confirmed by the real time PCR method.

Protein tyrosine phosphatases in glioma biology

Gliomas are a diverse group of brain tumors of glial origin. Most are characterized by diffuse infiltrative growth in the surrounding brain. In combination with their refractive nature to chemotherapy this makes it almost impossible to cure patients using combinations of conventional therapeutic strategies. The drastically increased knowledge about the molecular underpinnings of gliomas during the last decade has elicited high expectations for a more rational and effective therapy for these tumors. Most studies on the molecular pathways involved in glioma biology thus far had a strong focus on growth factor receptor protein tyrosine kinase (PTK) and phosphatidylinositol phosphatase signaling pathways. Except for the tumor suppressor PTEN, much less attention has been paid to the PTK counterparts, the protein tyrosine phosphatase (PTP) superfamily, in gliomas. PTPs are instrumental in the reversible phosphorylation of tyrosine residues and have emerged as important regulators of signaling pathways that are linked to various developmental and disease-related processes. Here, we provide an overview of the current knowledge on PTP involvement in gliomagenesis. So far, the data point to the potential implication of receptor-type (RPTPδ, DEP1, RPTPμ, RPTPζ) and intracellular (PTP1B, TCPTP, SHP2, PTPN13) classical PTPs, dual-specific PTPs (MKP-1, VHP, PRL-3, KAP, PTEN) and the CDC25B and CDC25C PTPs in glioma biology. Like PTKs, these PTPs may represent promising targets for the development of novel diagnostic and therapeutic strategies in the treatment of high-grade gliomas.

PRL-3 promotes the motility, invasion, and metastasis of LoVo colon cancer cells through PRL-3-integrin beta1-ERK1/2 and-MMP2 signaling

BACKGROUND

Phosphatase of regenerating liver-3 (PRL-3) plays a causative role in tumor metastasis, but the underlying mechanisms are not well understood. In our previous study, we observed that PRL-3 could decrease tyrosine phosphorylation of integrin beta1 and enhance activation of ERK1/2 in HEK293 cells. Herein we aim to explore the association of PRL-3 with integrin beta1 signaling and its functional implications in motility, invasion, and metastasis of colon cancer cell LoVo.

METHODS

Transwell chamber assay and nude mouse model were used to study motility and invasion, and metastsis of LoVo colon cancer cells, respectively. Knockdown of integrin beta1 by siRNA or lentivirus were detected with Western blot and RT-PCR. The effect of PRL-3 on integrin beta1, ERK1/2, and MMPs that mediate motility, invasion, and metastasis were measured by Western blot, immunofluorencence, co-immunoprecipitation and zymographic assays.

RESULTS

We demonstrated that PRL-3 associated with integrin beta1 and its expression was positively correlated with ERK1/2 phosphorylation in colon cancer tissues. Depletion of integrin beta1 with siRNA, not only abrogated the activation of ERK1/2 stimulated by PRL-3, but also abolished PRL-3-induced motility and invasion of LoVo cells in vitro. Similarly, inhibition of ERK1/2 phosphorylation with U0126 or MMP activity with GM6001 also impaired PRL-3-induced invasion. In addition, PRL-3 promoted gelatinolytic activity of MMP2, and this stimulation correlated with decreased TIMP2 expression. Moreover, PRL-3-stimulated lung metastasis of LoVo cells in a nude mouse model was inhibited when integrin beta1 expression was interfered with shRNA.

CONCLUSION

Our results suggest that PRL-3's roles in motility, invasion, and metastasis in colon cancer are critically controlled by the integrin beta1-ERK1/2-MMP2 signaling.

PRL-3 facilitates angiogenesis and metastasis by increasing ERK phosphorylation and up-regulating the levels and activities of Rho-A/C in lung cancer

AIMS

The aim of this study was to investigate the mechanism of PRL-3 in inducing angiogenesis and lymphangiogenesis to promote distant and lymph node metastasis in human lung cancer tissues and cells.

METHODS

We investigated the expression of PRL-3, VEGF, and VEGF-C from 94 patients with non-small cell lung cancer (NSCLC) using immunohistochemical staining. The relationship between PRL-3 expression and microvessel density (MVD), lymphatic vessel density (LVD), clinicopathological factors, and surgical treatment outcome was also studied. Following this, we studied the effect on A549 by blocking PRL-3.

RESULTS

PRL-3 expression in NSCLC was high, and this over-expression is correlated with advanced clinical stage (p = 0.019), distant metastasis (p = 0.001), lymph node metastasis (p = 0.001), and poor post-operative survival. PRL-3 over-expression was associated with vascular endothelial growth factor (VEGF; p = 0.000) and VEGF-C (p = 0.008) expressions, MVD and LVD (p = 0.000 and p = 0.000). Blocking PRL-3 expression in A549 cell resulted in decreased cellular proliferative, migratory, and invasive abilities, and VEGF, VEGF-C, pERK, Rho-A, and Rho-C expression was inhibited. Following inhibition of either Rho or pERK, VEGF expression was down-regulated.

CONCLUSIONS

PRL-3 induces microvascular and lymphatic vessel formation by facilitating VEGF and VEGF-C expression in lung cancer tissues, thus promoting distant and lymph node metastasis of lung cancer. PRL-3 up-regulates pERK and Rho expression and activity, facilitating VEGF expression, and accelerating angiogenesis and distant metastasis. How to regulate VEGF-C expression needs to be further studied.