Correlation between Liver Metastases and the Level of PRL-3 mRNA Expression in Patients with Primary Colorectal Cancer

Colorectal liver metastasis: molecular mechanism and interventional therapy

Colorectal cancer (CRC) is one of the most frequently occurring malignancy tumors with a high morbidity additionally, CRC patients may develop liver metastasis, which is the major cause of death. Despite significant advances in diagnostic and therapeutic techniques, the survival rate of colorectal liver metastasis (CRLM) patients remains very low. CRLM, as a complex cascade reaction process involving multiple factors and procedures, has complex and diverse molecular mechanisms. In this review, we summarize the mechanisms/pathophysiology, diagnosis, treatment of CRLM. We also focus on an overview of the recent advances in understanding the molecular basis of CRLM with a special emphasis on tumor microenvironment and promise of newer targeted therapies for CRLM, further improving the prognosis of CRLM patients.

A retrospective cohort study of clinical value of PRL-3 in stage III human colorectal cancer

ABSTRACT

The aim of this study was to investigate the expression of phosphatase of regenerating live-3 (PRL-3) in human stage III colorectal cancer (CRC) and to evaluate its correlation with metachronous liver metastasis (MLM) and prognosis.The retrospective cohort study included 116 stage III CRC primary tumors and 60 normal colorectal tissues. PRL-3 expression was measured by immunohistochemistry. We investigated the correlation of PRL-3 with clinicopathologic features by the chi-square test. The association of PRL-3 expression with MLM was assessed by binary logistic regression. Overall survival (OS) and disease-free survival (DFS) between patients with positive PRL-3 expression and those with negative PRL-3 expression were compared by the Kaplan-Meier method and Cox proportional hazards regression model.We found that 32.8% of stage III CRC primary tumors were PRL-3 positive, and 15.0% of normal colorectal epithelia showed high PRL-3 expression (P = .012). Seventeen tumors (47.2%) among 36 cases that developed MLM were PRL-3 positive, and only 21 tumors (26.3%) in the 80 cases that did not develop MLM had positive PRL-3 expression (P = .026). PRL-3 expression was associated with MLM (P = .028). Patients with positive expression of PRL-3 showed a significantly shorter OS (40.32 ± 3.97 vs 53.96 ± 2.77 months, P = .009) and DFS (34.97 ± 4.30 vs 44.48 ± 2.89 months, P = .036). A multivariate analysis indicated that PRL-3 expression was an independent unfavorable prognostic factor for OS (P = .007).Our study suggested that high PRL-3 expression is an independent risk factor for MLM and poor prognosis. PRL-3 is expected to be a promising biomarker for predicting the incidence of MLM and prognosis in patients with stage III CRC.

Biomarkers for predicting future metastasis of human gastrointestinal tumors

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

MiR495- and miR551a-mediated down-regulation of PRL-3 expression inhibits peritoneal metastasis in a mouse model of gastric cancer

AIM: To investigate the effect of miR495 and miR551 on PRL-3 expression in gastric cancer SGC7901 cells to explore gene interference therapies for gastric cancer.

METHODS: SGC7901 cells stably transfected with miR495 or miR551a and non-transfected SGC7901 cells were inoculated intraperitoneally in BALB/CA (nu/nu) nude mice. One month after inoculation, the mice were killed to observe the rate of tumor formation, tumor growth and migration. Real-time PCR was performed to quantify mRNA levels of miR495, miR551a and PRL-3.

RESULTS: Compared to nude mice inoculated with non-transfected cells, miR495 and miR551a levels were increased, PRL-3 level was decreased, and migration of gastric cancer was suppressed in mice inoculated with SGC7901 cells stably transfected with miR495 or miR551a.

CONCLUSION: MiR495 and miR551a can suppress the migration of gastric cancer by inhibiting PRL-3 expression in mice.

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

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