Prognostic and metastatic value of phosphatase of regenerating liver-3 in invasive breast cancer

Establishment of tumor protein p53 mutation-based prognostic signatures for acute myeloid leukemia

PURPOSE

The tumor protein p53 gene (TP53) mutations are associated with poor prognosis of patients with acute myeloid leukemia (AML). This study aimed to establish TP53 mutation-based prognostic risk signatures.

PATIENTS AND METHODS

The transcriptomes and clinical characteristics of AML patients were acquired from The Cancer Genome Atlas database, including 11 TP53-mutant samples and 114 TP53-wildtype samples. Differentially expressed mRNAs and long non-coding RNAs (lncRNA) in TP53-mutant samples were identified. Weighted gene correlation network analysis was performed to generate survival-associated co-expression modules. LASSO regression analysis was conducted to build mRNA- and lncRNA-based prognostic risk signatures. Kaplan-Meier curve analysis and multivariate regression analysis were carried out to assess the prognostic values of the risk signatures. Receiver operating characteristic (ROC) analysis was performed to evaluate the accuracy of the signatures.

RESULTS

Based on the co-expression modules, a 5-mRNA risk signature and a 13-lncRNA risk signature were constructed to predict the overall survival for AML patients. Kaplan-Meier curves revealed that the high-risk patients had significantly shorter overall survival than the low-risk patients. ROC analysis yielded 1-, 3-, and 5-year AUCs of 0.681, 0.783, and 0.827 for mRNA signature and 0.85, 0.835, and 0.908 for lncRNA signature. Multivariate regression analysis revealed that both mRNA (HR = 1.45, P< 0.001) and lncRNA (HR = 1.19, P< 0.001) risk scores were independent prognostic factors for AML patients.

CONCLUSION

We provided a potential patients stratification tool for AML prognosis prediction and management, which established by effective TP53 mutation-related gene signatures.

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.

A chemical genetics approach identifies PTP4A3 as a regulator of colon cancer cell adhesion

Dysregulation of the tightly controlled protein phosphorylation networks that govern cellular behavior causes cancer. The membrane-associated, intracellular protein tyrosine phosphatase PTP4A3 is overexpressed in human colorectal cancer and contributes to cell migration and invasion. To interrogate further the role of PTP4A3 in colorectal cancer cell migration and invasion, we deleted the Ptp4a3 gene from murine colorectal tumor cells. The resulting PTP4A3^-/- cells exhibited impaired colony formation, spheroid formation, migration, and adherence compared with the paired PTP4A3^fl/fl cells. We replicated these phenotypic changes using the new small-molecule, allosteric PTP4A3 inhibitor JMS-053. A related structure, JMS-038, which lacked phosphatase inhibition, displayed no cellular activity. Reduction in cell viability and colony formation by JMS-053 occurred in both mouse and human colorectal cell lines and required PTP4A3 expression. Ptp4a3 deletion increased the expression of extracellular matrix (ECM) and adhesion genes, including the tumor suppressor Emilin 1. JMS-053 also increased Emilin 1 gene expression. Moreover, The Cancer Genome Atlas genomic database revealed human colorectal tumors with high Ptp4a3 expression had low Emilin 1 expression. These chemical and biologic reagents reveal a previously unknown communication between the intracellular PTP4A3 phosphatase and the ECM and support efforts to pharmacologically target PTP4A3.-McQueeney, K. E., Salamoun, J. M., Ahn J. G., Pekic, P., Blanco, I. K., Struckman, H. L., Sharlow, E. R., Wipf, P., Lazo, J. S. A chemical genetics approach identifies PTP4A3 as a regulator of colon cancer cell adhesion.

Phosphatase of regenerating liver-3 inhibits invasiveness and proliferation in non-small cell lung cancer by regulating the epithelial-mesenchymal transition

Phosphatase of regenerating liver-3 (PRL-3) has been reported to be associated with colon and gastric cancer metastasis. However, the role and function of PRL-3 in human non-small cell lung cancer cells is unknown. Our studies showed that the expression of PRL-3mRNA and protein are higher in less invasive human lung adenocarcinoma cells than in highly invasive cell lines. Ectopic expression of PRL-3 reduced cell capacity for anchorage-dependent growth, anchorage-independent growth, migration, and invasion in vitro, as well as tumorigenesis in vivo. Conversely, catalytic (C104S) and prenylation-site (C170S) mutants enhanced cell invasion. Microarray profiling of PRL-3 transfectants revealed the pathways potentially involving PRL-3, including the epithelial-mesenchymal transition (EMT), extracellular matrix remodeling, and the WNT signaling pathway. Furthermore, we demonstrated that increased PRL-3 reduced Slug and enhanced E-cadherin gene expression through the AKT/GSK3β/β-catenin pathway. In conclusion, our data suggest that PRL-3 might play a tumor suppressor role in lung cancer, distinct from other cancers, by inhibiting EMT-related pathways.

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.

Expression of PRL-3 regulates proliferation and invasion of breast cancer cells in vitro

PURPOSE

The protein tyrosine phosphatase PRL-3 plays an important role in cancer cell migration, invasion and metastasis. In breast cancer, PRL-3 is overexpressed in 70-75% of tumors and even more frequently in lymph node metastases. Moreover, PRL-3 overexpression in breast cancer is associated with an adverse disease outcome. Aim of this study was to determine the role of PRL-3 in breast cancer cell proliferation, migration and invasion in vitro.

METHODS

PRL-3 mRNA expression was evaluated in 6 breast cancer cell lines by quantitative real-time PCR. To investigate the effect of PRL-3 expression in breast cancer cells in vitro we both up- and downregulated PRL-3 expression in breast cancer cells and performed in vitro wound repair cell motility assays and invasion assays. The influence of PRL-3 knockdown in MCF-7 cells on the expression of several gene products involved in cell invasion and cytoskeletal function was evaluated with real-time PCR.

RESULTS

PRL-3 mRNA expression was demonstrated in all breast cancer cell lines evaluated. Knockdown of PRL-3 in MCF-7 cells resulted in decreased proliferation, wound healing and invasion. PRL-3 knockdown in MCF-7 cells resulted in a significant reduction of heparanase, MMP-9, actin gamma-2 and Myosin 9 expression, and significant elevation of E-cadherin.

CONCLUSIONS

We conclude that PRL-3 is an important regulatory factor for breast cancer cell proliferation and invasion. Loss of PRL-3 function induces an antimetastatic gene expression profile in breast cancer cells. Due to its role in tumor growth and metastasis, PRL-3 emerges as a new therapeutic target in breast cancer therapy.

Risk factors for the Long-Term Efficacy, Recurrence, and Metastasis in Small Hepatocellular Carcinomas

We tried to determine the risk factors for the long-term efficacy, recurrence, and metastasis of small hepatocellular carcinoma (HCC, diameter <5 cm). One hundred sixty-eight small liver cancer patients received percutaneous cryoablation therapy by argon-helium superconducting surgery system under the ultrasound guidance. Clinical parameter and the efficacy were analyzed after follow-up. After cryoablation treatment, the median follow-up time for the 168 patients was 36 (7-41) months. Liver functions were impaired as indicated by increased alanine aminotransferase, total bilirubin, total protein, albumin, and prothrombin activity. The difference of VEGF expression in liver cancer and the surrounding tissue is significant. 1-, 2-, and 3-year overall survival were 92.9, 83.9, and 65.5 %, respectively. Relapse-free survival was 76.8, 53.0, and 41.1 %. Less tumor number, higher tumor differentiation, and low VEGF expression predict higher metastasis-free and relapse-free survival rate. Lower Child-Pugh classification is correlated with the higher overall survival after cryoablation. There was no statistical significance in in situ intrahepatic recurrence patients, but VEGF changes were statistically significant for metastasis in other parts of liver or extrahepatic metastasis. Tumor number, differentiation, VEGF expression, large vessel invasion, lymph node, and extrahepatic metastasis all affect the overall and relapse-free survival. VEGF expression can be a predictable factor for liver cancer recurrence and metastasis.

Phosphatase PTP4A3 Promotes Triple-Negative Breast Cancer Growth and Predicts Poor Patient Survival

Triple-negative breast cancer (TNBC) has the worst prognosis of all breast cancers, and women diagnosed with TNBC currently lack targeted treatment options. To identify novel targets for TNBC, we evaluated phosphatase expression in breast tumors and characterized their contributions to in vitro and in vivo growth of TNBC. Using Affymetrix microarray analysis of 102 breast cancers, we identified 146 phosphatases that were significantly differentially expressed in TNBC compared with estrogen receptor (ER)-positive tumors. Of these, 19 phosphatases were upregulated (0.66-fold; FDR = 0.05) in TNBC compared with ER-positive breast cancers. We knocked down 17 overexpressed phosphatases in four triple-negative and four ER-positive breast cancer lines using specific siRNAs and found that depletion of six of these phosphatases significantly reduced growth and anchorage-independent growth of TNBC cells to a greater extent than ER-positive cell lines. Further analysis of the phosphatase PTP4A3 (also known as PRL-3) demonstrated its requirement for G1-S cell-cycle progression in all breast cancer cells, but PTP4A3 regulated apoptosis selectively in TNBC cells. In addition, PTP4A3 inhibition reduced the growth of TNBC tumors in vivo Moreover, in silico analysis revealed the PTP4A3 gene to be amplified in 29% of basal-like breast cancers, and high expression of PTP4A3 could serve as an independent prognostic indicator for worse overall survival. Collectively, these studies define the importance of phosphatase overexpression in TNBC and lay the foundation for the development of new targeted therapies directed against phosphatases or their respective signaling pathways for TNBC patients. Cancer Res; 76(7); 1942-53. ©2016 AACR.

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.

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.

Genomic gain of the PRL-3 gene may represent poor prognosis of primary colorectal cancer, and associate with liver metastasis

PRL-3 genomic copy number is increased in colorectal cancer (CRC), and PRL-3 expression is closely associated with lymph node and liver metastasis of CRC. However, the clinical significance of PRL-3 genomic gain for CRC remains obscure. Here, PRL-3 genomic status in 109 primary CRC tumors and in 44 CRC tumors that had metastasized to the liver, was quantified using real time PCR. Association of PRL-3 genomic status with clinicopathological factors and prognosis was assessed in detail. PRL-3 genomic gain was identified in 31 primary CRC (27.4 %) and was more frequently seen in stage III than in stage II (p = 0.025). Among the clinicopathological factors assessed, PRL-3 genomic gain was significantly associated with poorly differentiated histology (p = 0.0039). Moreover, CRC patients with PRL-3 genomic gain exhibited poorer prognosis than those with no gain in stage II-IV CRC (p = 0.017). PRL-3 genomic gain was identified in 18 (41 %) of the liver metastasis tumors, and this frequency of gain was significantly increased as compared to that of the corresponding primary CRCs (11 %) (p = 0.001). Our findings suggested that PRL-3 genomic gain may represent an aggressive phenotype of primary CRC, and may associate with liver metastasis.

Overexpression of PTP4A3 is associated with metastasis and unfavorable prognosis in bladder cancer

PURPOSE

Bladder cancer (BC) is the most common malignancy in urinary system. The prognosis of metastatic BC is poor, but there remains no reliable marker to early detect metastasis. Dysregulated prenylated protein tyrosine phosphatases (PTPs) are commonly associated with cancer metastasis. From a published BC transcriptome, we identified that PTP IVA3 (PTP4A3) was the most significantly upregulated gene implicated in tumor progression among genes related to prenylated PTPs. We therefore analyzed PTP4A3 expression in our well-characterized cohort of BC.

METHODS

By immunohistochemistry, PTP4A3 expression was determined using H-score. PTP4A3 expression of 295 BCs was compared with clinicopathological parameters, and the effect of PTP4A3 on cancer-specific survival (CSS) and metastasis-free survival (MFS) was also examined. Two independent sets of BCs were used to assess PTP4A3 protein and transcript expression in normal urothelium and different stage tumors.

RESULTS

PTP4A3 overexpression was significantly associated with higher pT stage (P < 0.001), nodal metastasis (P < 0.001), vascular invasion (P < 0.001), and perineural invasion (P = 0.021). In multivariate analysis, PTP4A3 overexpression was an independent predictor for CSS (P < 0.001) and MFS (P = 0.007). Notably, the difference in CSS and MFS between high and low PTP4A3-expressing tumors was also significant in muscle-invasive BCs. PTP4A3 protein expression showed significant and stepwise increments from normal urothelium to noninvasive BC, invasive BC, and metastatic foci (P < 0.001). PTP4A3 transcript was also obviously upregulated in high-stage BC (P < 0.001).

CONCLUSIONS

PTP4A3 may play a role in BC oncogenesis and is a predictive marker of metastasis. PTP4A3 overexpression represents an independent prognosticator for BC, suggesting its potential theranostic value.

Phosphatase of regenerating liver: a novel target for cancer therapy

INTRODUCTION

Phosphatases of regenerating livers (PRLs) are novel oncogenes that interact with many well-established cell signaling pathways that are misregulated in cancer, and are known to drive cancer metastasis when overexpressed.

AREAS COVERED

This review covers basic information of the discovery and characteristics of the PRL family. We also report findings on the role of PRL in cancer, cell functions and cell signaling. Furthermore, PRL's suitability as a novel drug target is discussed along with current methods being developed to facilitate PRL inhibition.

EXPERT OPINION

PRLs show great potential as novel drug targets for anticancer therapeutics. Studies indicate that PRL can perturb major cancer pathways such as Src/ERK1/2 and PTEN/PI3K/Akt. Upregulation of PRLs has also been shown to drive cancer metastasis. However, in order to fully realize its therapeutic potential, a deeper understanding of the function of PRL in normal tissue and in cancer must be obtained. Novel and integrated biochemical, chemical, biological, and genetic approaches will be needed to identify PRL substrate(s) and to provide proof-of-concept data on the druggability of the PRL phosphatases.

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.

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.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

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.

Retroviral integration mutagenesis in mice and comparative analysis in human AML identify reduced PTP4A3 expression as a prognostic indicator

Acute myeloid leukemia (AML) results from multiple genetic and epigenetic aberrations, many of which remain unidentified. Frequent loss of large chromosomal regions marks haplo-insufficiency as one of the major mechanisms contributing to leukemogenesis. However, which haplo-insufficient genes (HIGs) are involved in leukemogenesis is largely unknown and powerful experimental strategies aimed at their identification are currently lacking. Here, we present a new approach to discover HIGs, using retroviral integration mutagenesis in mice in which methylated viral integration sites and neighbouring genes were identified. In total we mapped 6 genes which are flanked by methylated viral integration sites (mVIS). Three of these, i.e., Lrmp, Hcls1 and Prkrir, were up regulated and one, i.e., Ptp4a3, was down regulated in the affected tumor. Next, we investigated the role of PTP4A3 in human AML and we show that PTP4A3 expression is a negative prognostic indicator, independent of other prognostic parameters. In conclusion, our novel strategy has identified PTP4A3 to potentially have a role in AML, on one hand as a candidate HIG contributing to leukemogenesis in mice and on the other hand as a prognostic indicator in human AML.