Targeted Deletion of the Metastasis-Associated Phosphatase Ptp4a3 (PRL-3) Suppresses Murine Colon Cancer

Ptp4a3 (commonly known as PRL-3) is an enigmatic member of the Ptp4a family of prenylated protein tyrosine phosphatases that are highly expressed in many human cancers. Despite strong correlations with tumor metastasis and poor patient prognosis, there is very limited understanding of this gene family's role in malignancy. Therefore, we created a gene-targeted murine knockout model for Ptp4a3, the most widely studied Ptp4a family member. Mice deficient for Ptp4a3 were grossly normal. Fewer homozygous-null males were observed at weaning, however, and they maintained a decreased body mass. Although Ptp4a3 is normally associated with late-stage cancer and metastasis, we observed increased Ptp4a3 expression in the colon of wildtype mice immediately following treatment with the carcinogen azoxymethane. To investigate the role of Ptp4a3 in malignancy, we used the most commonly studied murine colitis-associated colon cancer model. Wildtype mice treated with azoxymethane and dextran sodium sulfate developed approximately 7-10 tumors per mouse in the distal colon. The resulting tumor tissue had 4-fold more Ptp4a3 mRNA relative to normal colon epithelium and increased PTP4A3 protein. Ptp4a3-null mice developed 50% fewer colon tumors than wildtype mice after exposure to azoxymethane and dextran sodium sulfate. Tumors from the Ptp4a3-null mice had elevated levels of both IGF1Rβ and c-MYC compared to tumors replete with Ptp4a3, suggesting an enhanced cell signaling pathway engagement in the absence of the phosphatase. These results provide the first definitive evidence implicating Ptp4a3 in colon tumorigenesis and highlight the potential value of the phosphatase as a therapeutic target for early stage malignant disease. © 2013 Zimmerman et al

Clinical Significance of Microvessel Count in Patients with Metastatic Liver Cancer Originating from Colorectal Carcinoma.

BACKGROUND: Microvessel count (MVC) has been correlated with patient prognosis in hepatocellular carcinoma. We investigated whether MVC assessed by staining with CD34 antibody was associated with disease-free and overall survival in patients with metastatic liver cancer (MLC). METHODS: We examined relationships between MVC and clinicopathologic factors or postoperative outcomes in 139 MLC patients who underwent hepatectomy between 1990 and 2006. CD34 expression was analyzed by the immunohistochemical method. RESULTS: MVC was associated with fibrous pseudocapsular formation on histological examination. By means of the modern Japanese classification of liver metastasis, poorer survival was associated with higher score, poorly differentiated adenocarcinoma, higher preoperative carcinoembryonic antigen (CEA) level, fibrous pseudocapsular formation, and smaller surgical margin. Shorter disease-free survival was associated with higher score when the Japanese classification of liver metastasis was used, multiple or bilobar tumor, regional lymph node metastasis in primary colon carcinoma, preoperative CEA level, fibrous pseudocapsular formation, and smaller surgical margin (/=406/mm(2)) was associated with decreased disease-free and overall survival by univariate analysis (P = .034 and P = .021, respectively), and higher MVC represented an independently poor prognostic factor in overall survival by Cox multivariate analysis (risk ratio, 2.71; P = .023) in addition to histological differentiation. CONCLUSIONS: Tumor MVC seems to be a useful prognostic marker of MLC patient survival