OBJECTIVETo investigate the expression of phosphatase of regeneration liver-3(PRL-3) protein and its relationship with tumor invasion and metastasis in human colorectal carcinoma,and elucidate prognostic value.

METHODSImmunohistochemistry method was applied to detect the PRL-3 expression in the primary tumor specimens and paired paratumor normal tissues from 46 colorectal carcinoma patients, the adenoma tissues from 6 patients with colorectal adenoma, all the metastatic lymph nodes from 29 cases and the metastatic liver lesions from 6 cases. The relationship between PRL-3 expression and clinicopathologic parameters was analyzed and a survival curve was achieved according to Kaplan-Meier method.

RESULTSNo or weak PRL-3 protein expression was detected in normal colorectal mucosa and colorectal adenoma. In colorectal carcinoma tissues, PRL-3 expression was confirmed in 26 of 46 cases (56.5%) of primary colorectal carcinomas (with lymph node metastasis 63.0%, without lymph node metastasis 37.0%, P=0.001), 26 of 29 (89.7%) lymph node metastases, and 5 of 6 liver metastases. The expression of PRL-3 was assembled in the cytoplasm of carcinoma cells and more intensively on the cell membrane.Analysis of the relationship between PRL-3 expression and the clinicopathologic features showed that PRL-3 expression was closely associated with tumor stage (P=0.019), lymph node metastasis (P=0.026), but no relationship with age, sex, tumor size, degree of differentiation was founded (P<0.05). The mean follow-up time was 41.4 months and results showed that patients with positive expression of PRL-3 had a significantly poorer prognosis than those with negative PRL-3 expression group(P=0.032).

CONCLUSIONSPRL-3 protein plays a novel role in tumor progression and metastasis of colorectal carcinoma. PRL-3 can be expected to be a potential predictive biomarker for identifying the prognosis in colorectal carcinoma patients.