Decreased expression of methyl methansulfonate and ultraviolet-sensitive gene clone 81 (Mus81) is correlated with a poor prognosis in patients with hepatocellular carcinoma

BACKGROUND. Recent work has demonstrated that methyl methansulfonate and ultraviolet-sensitive gene clone 81 (Mus81) is critical in the maintenance of chromosome stability and tumor suppression in mice. To investigate its role in human hepatocellular carcinoma (HCC), which currently is unknown, the authors examined the correlation between Mus81 expression and prognosis in patients with HCC. METHODS. Reverse transcriptase-polymersase chain reaction and Western blot analyses were used to determine Mus81 expression levels in 41 paired HCC and paracarcinomatous liver tissue (PCLT) specimens. Immunohistochemistry analysis was also performed on 104 HCC specimens from patients with follow-up information. RESULTS. Both Mus81 messenger RNA and protein expression levels were decreased significantly in HCC specimens. Moreover, lower Mus81 expression levels were detected in nodular HCC (NHCC) than in solitary large HCC (SLHCC) specimens. Among 104 specimens of HCC, the positive rate of Mus81 was significantly lower than the rate in PCLT (P =.017), and the decreased Mus81 expression was correlated significantly with high Edmondson-Steiner grade, multiple tumor nodes, and venous invasion. Patients with HCC who had low Mus81 expression had either poorer disease-free survival or poorer overall survival than patients who had with high Mus81 expression (P =.0027 and P =.0001, respectively). Multivariate Cox regression analysis revealed that low Mus81 expression was an independent prognostic factor for patients with HCC (risk ratio, 5.74; P =.012). CONCLUSIONS. Mus81 expression levels were decreased significantly in HCC specimens, and the decreased levels were correlated with a poor prognosis in patients with HCC, implicating Mus81 as a candidate prognostic marker in HCC.