The prognostic role of Skp2 and the tumor suppressor protein p27 in colorectal cancer.

PURPOSE: This study aimed at exploring the role of Skp2, p27 and Cks1 expression as prognostic factors for colorectal cancer (CRC) patients, and to identify a correlation between their expression and the cell proliferation marker Ki67.

METHODS: We conducted a retrospective study on 130 patients with CRC treated with surgery and adjuvant treatment at the Oncology Institute Cluj-Napoca between 2006- 2010. The Skp2, p27, Cks1 and Ki67 immunoexpression was grouped from 1 to 4, according to percents of tumor cells with nuclear reactivity. Their correlation with overall survival (OS), recurrence free survival (RFS) and with the classical histopathological prognostic factors were analyzed. All patients had 5-year follow-up.

RESULTS: The majority of patients had locally advanced TNM stages II and III. More than a half of the tumors had low immunoexpression of Skp2 and Cks1, and high and moderate p27 and Ki67 expression. Skp2 overexpression negatively influenced the p27 (p=0.002). Both OS and RFS were significantly higher in patients with moderate and high expression of p27 (p=0.005). Skp2 and Cks1 overexpression negatively influenced OS and RFS. Skp2 overexpression positively correlated with TNM stage (p<0.001), node capsular invasion (p=0.002) and lymphovascular invasion (p=0.042). Ki67 expression did not correlate with Skp2 (p=0.88), Cks1 (p=0.67) and p27 (p=0.40), neither with OS (p=0.841) and RFS (p=0.84).

CONCLUSIONS: The most important prognostic factor was the Skp2 overexpression. It was the only protein we studied that correlated with the other well-known prognostic factors in CRC. The expression of Ki67 did not bring any novel prognostic information regarding CRC.