Phosphatase Of Regenerating Liver Research Articles

Can dehydroepiandrostenedione (DHEA) target PRL-3 to prevent colon cancer metastasis?

Colorectal cancer (CRC) is a frequently diagnosed cancer and causing significant mortality in the patients. Metastasis caused by CRC is mainly responsible for this cancer-related deaths. Despite recent advancements in the treatment methods, prognosis remains poor. Therefore, effective treatment strategies need to be designed for successful management of this disease. Dehydroepiandrostenedione (DHEA), a 17-ketosteroid hormone produced by adrenal glands, gonads and including gastrointestinal tract is required for several physiological processes. Deregulation of DHEA levels leads to various disease conditions including cancer. In fact, several experimental studies strongly suggest that DHEA could be used as a chemopreventive agent against colon cancer. Prenlyation of certain membrane proteins such as phosphatase of regenerating liver-3 (PRL-3) is crucial for metastatic progression of colon cancer cells. The ability of DHEA to target prenylation pathway could be utilized to inhibit PRL-3 prenylation for successful prevention of CRC metastases. As DHEA is a widely consumed drug for various ailments, incorporation of DHEA in the treatment regimen may be beneficial to prevent or delay the occurrence of metastasis resulting from CRC.

PRL-3 suppresses c-Fos and integrin α2 expression in ovarian cancer cells

BackgroundPhosphatase of regenerating liver-3 (PRL-3), a protein tyrosine phosphatase, is highly expressed in multiple human cancers and strongly implicated in tumor progression and cancer metastasis. However, the mechanisms by which PRL-3 promotes cancer cell migration, invasion, and metastasis are not very well understood. In this study, we investigated the contribution and molecular mechanisms of PRL-3 in ovarian cancer progression.MethodsPRL-3 protein expression was detected on ovarian cancer tissue microarrays using immunohistochemistry. Stable PRL-3 depleted cell lines were generated using short hairpin RNA (shRNA) constructs. The migration and invasion potential of these cells were analyzed using Transwell and Matrigel assays, respectively. Immunoblotting and immunofluorescence were used to detect protein levels and distribution in PRL-3-ablated cells and the control cells. Cell morphology was observed with hematoxylin-eosin staining and transmission electron microscopy. Finally, PRL-3-ablated and control cells were injected into nude mice for xenograft tumorigenicity assays.ResultsElevated PRL-3 expression was detected in 19% (26 out of 135) of human ovarian cancer patient samples, but not in normal ovary tissues (0 out of 14). Stable depletion of PRL-3 in A2780 ovarian cancer cells resulted in decreased migration ability and invasion activity compared with control parental A2780 cells. In addition, PRL-3-ablated cells also exhibited flattened morphology and extended lamellipodia. To address the possible molecular basis for the altered phenotypes associated with PRL-3 down-regulation, we assessed the expression profiles of various proteins involved in cell-matrix adhesion. Depletion of PRL-3 dramatically enhanced both RNA and protein levels of the cell surface receptor integrin α2, but not its heterologous binding partner integrin β1. Inhibition of PRL-3 also correlated with elevated expression and phosphorylation of paxillin. A pronounced increase in the expression and activation of c-fos, a transcriptional activator of integrin α2, was observed in these PRL-3 knock-down cells. Moreover, forced expression of EGFP-PRL-3 resulted in the suppression of both integrin α2 and c-fos expression in A2780 cells. Significantly, using a xenograft tumor model, we observed a greatly reduced tumorigenicity of A2780 PRL-3 knock-down cells in vivo.ConclusionsThese results suggest that PRL-3 plays a critical role in ovarian cancer tumorigenicity and maintaining the malignant phenotype. PRL-3 may inhibit c-fos transcriptional regulation of integrin α2 signaling. Our results strongly support a role for PRL-3 as a promising therapeutic target and potential early biomarker in ovarian cancer progression.

Suppression of breast tumor growth by DNA vaccination against phosphatase of regenerating liver 3

Phosphatase of regenerating liver (PRL)-3 is highly expressed in multiple cancers and has important roles in cancer development. Some small-molecule inhibitors and antibodies targeting PRL-3 have been recently reported to inhibit tumor growth effectively. To determine whether PRL-3-targeted DNA vaccination can induce immune response to prevent or inhibit the tumor growth, we established mouse D2F2 breast cancer cells expressing PRL-3 (D2F2/PRL-3) and control cells (D2F2/NC) with lentivirus, and constructed pVAX1-Igκ-PRL-3 plasmid (named as K-P3) as DNA vaccine to immunize BALB/c mice. We found that the K-P3 vaccine delivered by gene gun significantly prevented the growth of D2F2/PRL-3 compared with pVAX1-vector (P<0.01), but not of D2F2/NC, and improved the survival of D2F2/PRL-3-innoculated mice. Both PRL-3-targeted cytotoxic T lymphocytes (CTLs) and T-helper type 1 cell immune response (production of high levels of interferon-γ and tumor necrosis factor-α) were found to be involved in the preventive effect. Furthermore, PRL-3-targeted DNA immunization inhibited tumor growth of D2F2/PRL-3 cells in mice. We also evaluated the potential of immunization with PRL-3 protein, but no significant therapeutic or preventive effect was obtained on tumor growth. To enhance the immunity of PRL-3, we incorporated different molecular adjuvants, such as Mycobacterium tuberculosis heat-shock protein, CTL antigen 4 and M. tuberculosis T-cell stimulatory epitope (MT), into K-P3 vaccine for expressing the fusion proteins. We found that these adjuvant molecules did not significantly improve the antitumor activity of PRL-3 vaccine, but enhanced the production of PRL-3 antibodies in immunized mice. Summarily, our findings demonstrate that PRL-3-targeted DNA vaccine can generate significantly preventive and therapeutic effects on the growth of breast cancer expressing PRL-3 through the induction of cellular immune responses to PRL-3.

Influence of phosphatase of regenerating liver-3 on the biological behavior of prostate cancer LNCaP cells

Objective To investigate influence of phosphatase of regenerating liver-3 (PRL-3)gene silencing with small interference RNA (siRNA) on biological behaviors of human prostate cancer LNCaP cells,including proliferation and invasion.Methods The method of silencing PRL-3 was established by lentivirus-mediated RNAi.The cells were divided into 3 groups.In experimental group,the expression of PRL-3 in LNCaP cells was stably blocked by lentivirus-mediated RNAi.In negative control group,the cells were transfected with lentivirus-mediated control RNAi (without any interference to PRL-3).The normal LNCaP cells served as blank control group.Methyl thiazol tetrazolium (MTT) assay was used to measure the proliferation of LNCaP cells,and Transwell assay was used to observe invasion potency.Results The experimental group showed significantly lower levels of PRL-3 mRNA and protein than those in negative control and blank control groups after transfection (P ＜ 0.05).The invasion potency of LNCaP cells was significantly suppressed after transfection (P ＜ 0.05),but there was no significant difference among the three groups on proliferation.Conclusion Down-regulation of PRL-3 expression can weaken invasion potency of LNCaP cells,but it had no effect on proliferation. Key words: Prostate cancer; Phosphatase of regenerating liver-3 ; RNA interference

PRL-3 Regulates Myeloma Cell Survival, Proliferation, Adhesion and Migration

AbstractAbstract 1321 Introduction:Multiple myeloma (MM) is a neoplastic monoclonal proliferation of bone marrow plasma cells. Despite advances in treatment in recent years, MM is still a fatal disease. Phosphatase of regenerating liver-3 (PRL-3) is a protein expressed in primary MM cells and MM cell lines, but not in normal plasma cells. A recent study showed that siRNA against PRL-3 suppresses MM-cell migration (Fagerli et al, 2008) and another study has identified PRL-3 as a marker gene for a subgroup of patients with MM (Broyl et al, 2010). Methods:The human myeloma cell lines INA-6, ANBL-6, IH-1, OH-2 and RPMI-8226 were used in this study. Apoptosis was measured by Annexin V-FITC binding by flow cytometry, proliferation was measured by methyl-3H-thymidine incorporation, migration against a stromal cell derived factor-1α (SDF-1α) gradient was studied in a Transwell two-chamber assay and adhesion was measured as percentage adhered cells to fibronectin after stimulation with the pro-adhesive cytokines hepatocyte growth factor (HGF), insulin like growth factor-1 (IGF-1) and SDF-1α. RT-PCR and Western blotting were used to measure expression of pro- and anti-apoptotic proteins. Western blotting was used to map intracellular signaling pathways. INA-6 cells stably expressing exogenous PRL-3 were generated using retroviral transduction. The small molecular inhibitor PRL-3 Inhibitor I was used for PRL-3 inhibition. Results:PRL-3 inhibitor I reduced survival of the myeloma cell lines INA-6, ANBL-6, IH-1, OH-2 and RPMI-8226. IC50 was between 15 and 50 μM depending on cell line. Treatment with the inhibitor down-regulated the anti-apoptotic protein Mcl-1 and led to activation of the intrinsic apoptotic pathway. Inhibition of PRL-3 reduced interleukin (IL)-6-induced phosphorylation of STAT-3. Treatment with 10 μM of PRL-3 inhibitor I also significantly reduced migration against a SDF-1α gradient and HGF-, IGF-1- and SDF-1α -mediated adhesion of the cell line INA-6. By retroviral transduction we made PRL-3-overexpressing INA-6 cells. INA-6 cells are dependent on IL-6 to grow, but overexpression of PRL-3 led to a major increase in cell proliferation even in the absence of IL-6 as well as increased survival at suboptimal concentrations of IL-6. Conclusion:PRL-3 is expressed in MM cells but not in normal plasma cells and can represent a cancer-specific target. Overexpression of PRL-3 in the IL-6-dependent human myeloma cell line INA-6 renders the cells less dependent of IL-6 and increases survival and proliferation. On the other hand, the use of an inhibitor against PRL-3 significantly decreases survival of five MM-cell lines and reduces adhesion and migration of the cell line INA-6. IL-6-STAT3 signaling is important in MM cell survival and proliferation and we here show that PRL-3 possibly influences cell survival as a positive regulator of this signaling pathway. This study indicates that PRL-3 could be important in the pathogenesis of MM and a potential target in the treatment of MM. Disclosures:No relevant conflicts of interest to declare.

The significance of the aberrant expression of phosphatase of regenerating liver-3 and microRNA-17-92 family in colon cancer cells

Objective To explore the significance of the aberrant expression phosphatase of regenerating liver-3 (PRL-3) and microRNA (miR)-17-92 family in colon cancer cells.Methods We stablely transfected PRL-3 expressing plasmid and empty plasmid into LoVo colon cancer cells and established two cell lines:LoVo-PRL-3 and LoVo-VC.MicroRNA chipset was used to investigate the aberrant expression of some oncomiRs.Two important members of miR-17-92 family:miR-17 and miR-19a were selected.quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was used to validate the expression of miR-17 and miR-19a in LoVo cells.RNA interference was used to knocked down STAT3 in LoVo-PRL-3 cells,after that the expression miR-17 and miR-19a were detected.Transient transfection of miR-17 and miR-19a mimic into LoVo-VC cells or transient transfection of miR-17 and miR-19a inhibitor into LoVo-PRL-3 cells were performed to evaluate the proliferation and invasive ability of these cells by cell counting kit-8 (CCK-8) proliferating assay and Transwell chamber assay.In 13 paired primary colon cancer tissues and metastatic lesions,immunohistochemistry was used to detect the expression of PRL-3 and pSTAT3 protein,while qRT-PCR was used to investigate the expression of PRL-3,miR-17 and miR-19a.Results In LoVo-PRL-3 cells,miR-17 and miR-19 were up-regulated significantly (P ＜ 0.05).Knockdown of STAT3 mRNA decreased the expression of miR-17 and miR-19.Over-expression of miR-17 and miR-19 promoted proliferation (P ＜0.05 and P ＜0.01) and invasion (P ＜0.01) of LoVo-VC cells,while knocking down of miR-17 and miR-19 inhibited proliferation and invasion of LoVo-PRL-3 cells (P ＜0.05).PRL-3 was elevated in metastatic lesions of colon cancer and positively correlated with pSTAT3,miR-17 and miR-19a.Conclusion PRL-3 promotes proliferation and invasion of colon cancer cells by up-regulation of the expression of miR-17 and miR-19a. Key words: Colon cancer; Phosphatase of regenerating liver-3; microRNA-17; microRNA-19a

Phosphatase of regenerating liver-3-signal transducer and activators of transcription 3-miR-21 sighal pathway promotes proliferation and invasion of colon cancer cells

Objective To explore the effect of phosphatase of regenerating liver-3-signal transducer and activators of transcription 3-microRNA-21 (PRL-3-STAT3-miR-21) signal pathway on proliferation and invasion of colon cancer cellsMethods We stablely transfected PRL-3 expressing plasmid and empty plasmid into LoVo colon cancer cells and established two cell lines:LoVo-PRL-3 and LoVo-VC.We used quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) to detect the expression of miR-21 in LoVo cells.We also performed transient transfection of PRL-3 into SW480 and CACO2 cells to validate the expression of miR-21.Western blotting was used to detect the effect of PRL-3 on the expression of STAT3.RNA interference was used to knocked down STAT3 in LoVo-PRL-3 cells,after that miR-21 expression was detected.Transient transfection of miR-21mimic into LoVo-VC cells or transient transfection of miR-21 inhibitor into LoVo-PRL-3 cells were performed to evaluate the proliferation and invasive ability of these cells by CCK8 proliferating assay and Transwell chamber assay.Results PRL-3 promoted proliferation of LoVo-PRL-3 cells at 72 h,96 h and invasion of LoVo-PRL-3 cells after 24 h compared with LoVo-VC cells (P＜0.01).In LoVo-PRL-3 cells,pSTAT3 and miR-21 were up-regulated.Knock-down of STAT3 mRNA decreased the expression of miR-21 (P ＜ 0.05).Over-expression of miR-21 promoted proliferation and invasion of LoVo-VC cells (P ＜ 0.01),while knocking down of miR-21 inhibited proliferation and invasion of LoVo-PRL-3 cells (P ＜ 0.05).Conclusion PRL-3-STAT3-miR-21 signal pathway promotes proliferation and invasion of colon cancer cells. Key words: Phosphatase of regenerating liver-3; Signal transducer and activators of transcription 3 ; MicroRNA-21

Inhibition of Dual-specificity Phosphatase 22 (DUSP22) by PRL-3 inhibitor I

Protein phosphorylation is an essential mechanism for human health and disease, which is regulated by the coordinated activities of kinases and phosphatases. Protein phosphorylation occurs predominantly on serine, threonine, and tyrosine residues of eukaryotic proteins and plays critical roles in the regulation of physiological processes including gene expression, proliferation, differentiation, cell cycles arrest, and apoptosis. Mitogen-activated protein (MAP) kinases are critical mediators in signal transduction pathways regulating embryogenesis, cell differentiation, cell proliferation, and cell death in response to extracellular stimuli and stress. Extracellular signal-regulated kinase (ERK), p38, and c-Jun Nterminal kinase (JNK) are the major mammalian MAP kinases that are regulated by some of protein tyrosine phosphatase (PTP) family members. PTP superfamily comprises 107 enzymes. Based on the amino acid sequences of their catalytic domains, the PTPs can be grouped into four main families: (i) classical PTPs and dual-specificity phosphatases (DUSPs), (ii) tyrosine-specific low molecular weight phosphatases, (iii) the cdc25 family, and (iv) Eyes absent (EyA) protein that was recently discovered to be tyrosine-, or dual serineand tyrosine-specific protein phosphatases. DUSPs are a subfamily of mammalian class I cysteine-based PTP superfamily, which dephosphorylate both tyrosine and serine/ threonine residues. Some DUSPs have been characterized for the role in MAPK signaling pathways. Since PTPs play critical roles for cell homeostasis, chemical inhibitors that regulate DUSPs have been extensively investigated to be used as therapeutic reagents. PRL-3 inhibitor I is a rhodanine derivative and inhibits phosphatase of regenerating liver-3 (PRL-3) in vitro. PRL-3 is a nonclassical protein tyrosine phosphtase and overexpression of PRL-3 plays a role in tumorigenesis and metastasis in various types of cancer cells. PRL-3 is associated with promoting cell motility, invasion activity, and metastasis. However, the biological and mechanistic evidence for PRL-3 function has not been understood well. The half maximal inhibitory concentration (IC50) of PRL-3 inhibitor I is known to be 0.9 μM against PRL-3 (Fig. 1(a)). To investigate the role of PRL-3 inhibitor I on other PTPs, we performed in vitro phosphatase assays with purified recombinant PTPs (Table 1). We identified that dualspecificity phosphatase 22 (DUSP22) is inhibited by PRL-3 inhibitor I while other PTPs are not. DUSP22, also called JNK-stimulatory phosphatase 1 (JSP1) and JNK pathway-associated phosphatase (JKAP), positively regulates MAPK signaling pathways in contrast to most phosphatases which negatively regulate MAPK signaling pathways. Overexpression of DUSP22 in HEK 293T cells activated JNK but not p38 and ERK. Activation of JNK by DUSP22 is associated with activation of MKK4 which is an immediate JNK upstream activating kinase. In addition, a kinase inactive form of MKK4 (MKK4KR) abolished DUSP22-induced activation of JNK in COS-1 cells. Furthermore, the inactive mutant of DUSP22 failed to induce JNK activation. This suggests that DUSP22 does not directly activate JNK but supports an enzyme activity of

Phosphatase of Regenerating Liver 2 (PRL2) Is Essential for Placental Development by Down-regulating PTEN (Phosphatase and Tensin Homologue Deleted on Chromosome 10) and Activating Akt Protein

The PRL (phosphatase of regenerating liver) phosphatases are implicated in the control of cell proliferation and invasion. Aberrant PRL expression is associated with progression and metastasis of multiple cancers. However, the specific in vivo function of the PRLs remains elusive. Here we show that deletion of PRL2, the most ubiquitously expressed PRL family member, leads to impaired placental development and retarded growth at both embryonic and adult stages. Ablation of PRL2 inactivates Akt and blocks glycogen cell proliferation, resulting in reduced spongiotrophoblast and decidual layers in the placenta. These structural defects cause placental hypotrophy and insufficiency, leading to fetal growth retardation. We demonstrate that the tumor suppressor PTEN is elevated in PRL2-deficient placenta. Biochemical analyses indicate that PRL2 promotes Akt activation by down-regulating PTEN through the proteasome pathway. This study provides the first evidence that PRL2 is required for extra-embryonic development and associates the oncogenic properties of PRL2 with its ability to negatively regulate PTEN, thereby activating the PI3K-Akt pathway.

Overexpression of phosphatase regenerating liver 3 in oesophageal squamous cell carcinoma associated with metastasis and its comparison with phosphatase regenerating liver 1

Expression of PRL3 (phosphatase of regenerating liver 3) protein was examined with immunohistochemistry in 60 cases of ESCC (oesophageal squamous cell carcinoma) with matched lymph node metastasis (n = 40) and 6 cases of oesophageal adenocarcinoma. Its associations with PRL1 and clinicopathological parameters were analysed. The results showed the frequency of PRL3 protein expression was significantly higher in ESCC (39/60, 65%) than in normal oesophageal mucosa (0/20, P < 0.001); higher in ESCC with lymph node metastasis (30/40, 75%) than in ESCC without lymph node metastasis (9/20, P = 0.022), as well as higher in metastatic ESCC in lymph node (38/40, 95%) than in the primary ESCC (39/60, 65%, P < 0.001). PRL3 was expressed in 1 out of 6 oesophageal adenocarcinomas, but showed no nuclear staining of PRL1. Expression of PRL3 protein was positively associated with the grade and partially with the stage of ESCC. These results suggest that expression of PRL3 protein may be involved in the metastasis of ESCC and serve as a biomarker for prediction of ESCC metastasis.

Clinical importance of phosphatase of regenerating liver-3 expression in breast cancer

Several biomarkers have been previously studied for breast cancer to define risk of recurrence and metastasis. Phosphatase of regenerating liver-3 (PRL-3) is one of them. High PRL-3 expression has been found to be correlated with axillary lymph node metastasis and survival in breast cancer. Herein, we evaluated the prognostic significance of PRL-3 expression and the relationship between PRL-3 and other clinicopathological factors. PRL-3 expression was analyzed immunohistochemically in 122 invasive breast cancer tissues. We evaluated the correlation between PRL-3 and other clinicopathological factors by χ² test. Kaplan-Meier test and log rank method were used to define prognostic importance of PRL-3 expression. Of 122 breast cancer tumor samples, 46 (37.7%) were negative while 76 (62.3%) were positive in respect to PRL-3 expression. There was significant correlation between PRL-3 expression and other clinicopathological factors, such as histology, lymphovascular invasion (LVI), necrosis, progesterone receptor (PR) status, and the presence of triple negative disease. Tumors with LVI and necrosis had more positive PRL-3 expression compared to tumors without LVI or necrosis (P=0.05 and 0.03, respectively). Triple negative and cerb-B overexpressed breast cancers were found to be more positive PRL-3 expression than hormone receptor positive with cerb-B negative groups (luminal A) (P=0.02).We could not find any relationship between PRL-3 expression and overall survival (OS) or disease-free survival (DFS) (P>0.05). Although PRL-3 expression was related to LVI or necrosis which is important for tumor invasiveness, we could not find that PRL-3 as an important prognostic factor in breast cancer patients. In addition, triple negative and cerb-B overexpressed tumors, which had worse prognosis compared to hormone receptor positive without cerb-B expressed group, associated with also PRL-3 positivity more than PRL-3 negative group.

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.

Plakophilin3 loss leads to an increase in PRL3 levels promoting K8 dephosphorylation, which is required for transformation and metastasis.

The desmosome anchors keratin filaments in epithelial cells leading to the formation of a tissue wide IF network. Loss of the desmosomal plaque protein plakophilin3 (PKP3) in HCT116 cells, leads to an increase in neoplastic progression and metastasis, which was accompanied by an increase in K8 levels. The increase in levels was due to an increase in the protein levels of the Phosphatase of Regenerating Liver 3 (PRL3), which results in a decrease in phosphorylation on K8. The increase in PRL3 and K8 protein levels could be reversed by introduction of an shRNA resistant PKP3 cDNA. Inhibition of K8 expression in the PKP3 knockdown clone S10, led to a decrease in cell migration and lamellipodia formation. Further, the K8 PKP3 double knockdown clones showed a decrease in colony formation in soft agar and decreased tumorigenesis and metastasis in nude mice. These results suggest that a stabilisation of K8 filaments leading to an increase in migration and transformation may be one mechanism by which PKP3 loss leads to tumor progression and metastasis.

Clinical significance of PRL-3 genomic amplification/expression profiles and preclinical study of PRL-3 inhibitor in human gastrointestinal cancers.

3071 Background: PRL (phosphatase of regenerating liver) is a tyrosine phosphatase that dephosphorylates molecules involved in cancer invasion and metastasis and subsequently activates either PI3 kinase or Src pathway. PRL-3 was initially identified as a gene that is amplified in metastasis of colorectal cancer. We are thinking much of clinical potential of PRL-3 inhibitor as a molecular targeted therapy in GI cancer. Methods: Immunohistochemistry and genomic status were assessed for PRL-3 in esophageal squamous cell carcinoma (ESCC)(n=88), gastric adenocarcinoma (n=173), and colorectal adenocarcinoma (n=107).RNA interference was used to determine its specific functional roles in GI cancers. Preclinical study using PRL-3 inhibitors (1-4-bromo-2-benzylidene rhodanine) was performed in 4 ESCC and 4 gastric cancer cell lines that were intensely expressed for PRL-3, or TE5 which showed basal level expression. Results: (1) PRL-3 expression is associated with lymph node metastasis in primary ESCC (p=0.0012), gastric adenocarcinoma (p&lt;0.0001), and colorectal carcinoma (p&lt;0.0001). In the primary tumors with lymph node metastasis, its expression was recognized in 96, 80, 86%, respectively. (2) If restricted to patients with PRL-3 expression, genomic amplification was found exclusively in stage IV ESCC (30%), and stage III/IV gastric cancer (40%). In colorectal cancer, PRL-3 genomic amplification is found in 35% of stage III/IV, but only in 10% of stage II (p=0.002). (3) PRL-3 RNA interference robustly suppressed metastatic cancer phenotypes. (4) PRL-3 inhibitor suppressed phenotypes as well in a dose dependent manner (0, 1, 10, and 50 mM). Interestingly, 10 mM of the inhibitor could not suppress muscle cell (C2C12) that endogenously express PRL-3, but 50 mM suppressed it. Conclusions: PRL-3 inhibitor has a great clinical potential to suppress tumors with metastatic ability, that was represented by lymph node metastasis or recurrent disease of GI cancers.

Downregulating PRL-3 Inhibit Migration and Invasion of Lung Cancer Cell via RhoA and mDia1

The overexpression of phosphatase of regenerating liver-3 (PRL-3) affects the migration and invasion of epithelial cells. Little is known about the substrates or pathways that PRL-3 interacts with. We studied the action and the mechanism of PRL-3 in migration and invasion of lung cancer. We detected the expression of PRL-3 in lung cancer cell lines and normal human bronchial epithelial cell. We found that PRL-3 expression was high in lung cancer cells. Knockdown of PRL-3 by siRNA inhibited cell migration and invasion and reorganizated the cytoskeleton. Furthermore, blocking PRL-3 decreased RhoA activity and mDia1 expression. Blocking RhoA or mDia1 showed the similar changes of cytoskeleton and suppression of migration and invasion as inhibiting PRL-3 expression. Blocking RhoA inhibited the expression of mDia1. These data indicate that downregulating PRL-3 inhibit cell migration and invasion by inactivating RhoA to downregulate mDia1 to reorganizate cytoskeleton of lung cancer cells.

Molecular mechanisms of the PRL phosphatases

The phosphatases of regenerating liver (PRLs) are an intriguing family of dual specificity phosphatases due to their oncogenicity. The three members are small, single domain enzymes. We provide an overview of the phosphatases of regenerating liver, compare them to related phosphatases, and review recent reports about each phosphatase. Finally, we discuss similarities and differences between the phosphatases of regenerating liver, focusing on their molecular mechanisms and signalling pathways.

Combined Phenotype of 4 Markers Improves Prognostic Value of Patients With Colon Cancer

IntroductionCombination of multiple biomarkers representing distinct aspects of tumor biology will have a better prognostic value. This study was to identify prognostic subgroups of colon adenocarcinoma by combined analysis of synuclein-gamma (SNCG), a human homologue of piwi (Hiwi), phosphatase of regenerating liver-3 (PRL-3), arrest-defective protein 1, homolog A (ARD1) and clinicopathologic features in 225 colon adenocarcinoma specimens. MethodsImmunohistochemistry for 4 tumor markers was performed in whole tissue sections from 225 colon adenocarcinoma patients with complete clinicopathologic data and up to 10-year follow-up. The immunohistochemical expression patterns were examined individually and in multimarker combinations. Univariate and multivariate analyses were performed to identify independent predictive markers of poor outcome. ResultsWith the tumor marker positive rate [32.0% (62/225) for SNCG; 76.9% (173/225) for combined SNCG/Hiwi/PRL-3/ARD1] and the detecting accuracy [61.9% (252/407) for SNCG; 82.6% (336/407) for combined SNCG/Hiwi/PRL-3/ARD1] increasing, incremental value of combined SNCG/Hiwi/PRL-3/ARD1(P <0.001; hazard ratios (HR), 3.2) to poor outcome was found. Stratified by lymph node, Hiwi alone (P= 0.004; HR, 3.2) led to poor outcome in patients without lymph node metastasis (LN—), and SNCG (P< 0.001; HR, 2.5) had independently poor prognostic value for patients with lymph node metastasis (LN+). ConclusionsMultimarker phenotypes improved tumor positive rate, detecting accuracy and prognostic value. In addition, a subgroup of more aggressive tumors can be identified by evaluating Hiwi level in LN— cancer, and SNCG level in LN+ cancer.

The Expression of the Phosphatase Regenerating Liver 3 Gene is Associated with Outcome in Patients with Colorectal Cancer

The phosphatase of regenerating liver-3 (PRL-3) is over expressed in several human cancers and associated with tumor progression, invasion and metastasis. However, the correlation between PRL-3 expression and clinical outcome in colorectal cancer (CRC) has not been investigated. This study examined the relationship between the relative expression of the PRL-3 gene to the clinicopathological factors and outcomes in patients with CRC. Surgical specimens of cancer tissue and adjacent normal mucosa were obtained from 202 patients with untreated CRC. The relative expression level of PRL-3 mRNA in cancer and in the normal adjacent mucosa was measured using the quantitative real-time reverse-transcriptase PCR. PRL-3 expression was higher in cancer tissue than in the adjacent normal mucosa. The tumor location and liver metastasis were found to be related to the PRL-3 expression level. The overall survival differed significantly between patients with high PRL-3 expression and those with low expression. High expression of the PRL-3 gene might be a useful predictor of poor postoperative outcome in patients with CRC.

Downregulation of phosphatase of regenerating liver-3 is involved in the inhibition of proliferation and apoptosis induced by emodin in the SGC-7901 human gastric carcinoma cell line

Emodin, an anthraquinone derivative isolated mainly from the root and rhizome of the medicinal plant Rheum palmatum L., was found to exert anticancer effects on various cultured cancer cells. Phosphatase of regenerating liver-3 (PRL-3), a novel gene, has been known to play an important role in the promotion of cellular proliferation as well as inhibition of apoptosis in cancer cells. However, there is relatively little information in the published literature with regard to the anticancer mechanism of emodin, and whether emodin is involved in the regulation of PRL-3 in human gastric carcinoma cells is not known. In the present study, we investigated the effects of emodin on SGC-7901 cell proliferation, apoptosis and regulation of PRL-3. The results showed that the proliferation of SGC-7901 cells was inhibited by emodin in a time- and concentration-dependent manner. The results also showed that early apoptosis rates increased in a concentration-dependent manner after emodin treatment. Furthermore, real-time quantitative PCR analysis showed that PRL-3 mRNA was significantly decreased by treatment with emodin. Western blotting showed that PRL-3 protein expression was also downregulated significantly. Overall, the present study demonstrated that emodin inhibited cell growth and induced apoptotic cell death in the SGC-7901 human gastric carcinoma cell line. Downregulation of PRL-3 is involved in the inhibition of proliferation and apoptosis induced by emodin. PRL-3 may be a new potential therapeutic target for gastric cancer using emodin.

Inhibitory activity of a water-soluble morin derivative on phosphatase of regenerating liver-3

Morin sulphate, a novel water-soluble derivative was semi-synthesized from morin as a parent molecule. The aim of the current study was to examine the inhibitory activity of morin sulphate on the phosphatase of regenerating liver-3 (PRL-3), and its role in the metastatic potency of high metastatic ovarian carcinoma cell line (HO-8910PM) in vitro. Morin sulphate significantly inhibited PRL-3 activity in a dose-dependent manner with an IC 50 value of 1.06 μM. Furthermore, morin sulphate inhibited the invasion and migration of HO-8910PM cells, suggesting that it is a PRL-3 inhibitor. Key words: Protein tyrosine phosphatases, PRL-3 protein, enzyme inhibitors, morin hydrate, neoplasms, metastasis.