BackgroundCdk1 (cyclin-dependent kinase 1) is critical regulator of the G2-M checkpoint. Cyclin-dependent kinase pathways are considered possible targets for cancer treatment; however, the prognostic role of Cdk1 in colorectal cancer is still controversial. Therefore, we attempted to determine the impact of Cdk1 on the clinical outcome of colorectal cancer patients to further identify its role in colorectal cancer.MethodsCdk1 immunoreactivity was analyzed by immunohistochemistry (IHC) in 164 cancer specimens from primary colorectal cancer patients. The medium follow-up time after surgery was 3.7 years (range: 0.01 to 13.10 years). The prognostic value of Cdk1 on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models.ResultsAll samples displayed detectable Cdk1 expression with predominant location in the cytoplasm and nucleus. A high Cdk1 nuclear/cytoplasmic (N/C) expression ratio was correlated with poor overall survival (5-year survival rate: 26.3% vs 46.9%, N/C ratio ≥1.5 vs N/C ratio <1.5, log-rank p = 0.027). Accordingly, a Cdk1 N/C expression ratio ≥1.5 was identified as an independent risk factor by multivariate analysis (hazard ratio = 1.712, P = 0.039).ConclusionsWe suggest that Cdk1 N/C expression ratio determined by IHC staining could be an independent prognostic marker for colorectal cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-951) contains supplementary material, which is available to authorized users.

ObjectivePDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK) regulates components of the cell cycle, including cell growth, immune responses, DNA damage repair, apoptosis, and inflammation. PBK/TOPK may also accelerate tumorigenesis in colorectal cancer.MethodsWe investigated the impact of PBK/TOPK on the clinical outcome of colorectal cancer patients to further identify its role in colorectal cancer. PBK/TOPK immunoreactivity was analyzed by immunohistochemistry in 162 cancer specimens from primary colorectal cancer patients.ResultsThe mean follow-up time after surgery was 5.4 years (medium: 3.9 years; range 0.01 to 13.1 years). The prognostic value of PBK/TOPK on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models. PBK/TOPK was expressed in both the cytoplasm and nucleus. High PBK/TOPK expression in tumor cells was significantly associated with advanced T value. The 5-year survival rate was greater for patients with high total PBK/TOPK expression than with low PBK/TOPK expression (58.3% vs 34.4%, P = 0.005). Multivariate analyses showed that low-scoring cytoplasmic PBK/TOPK, negative nuclear PBK/TOPK, low total PBK/TOPK, and advanced tumor stage were correlated with poor overall patient survival.ConclusionsWe suggest that PBK/TOPK expression, detected by IHC staining, could be used as an independent prognostic marker for colorectal cancer patients.

STEAP1 (six transmembrane epithelial antigen of the prostate 1) is a transmembrane protein that functions as a potential channel or transporter protein. It is overexpressed in certain cancers and is viewed as a promising therapeutic target. However, the prognostic role of STEAP1 is still controversial, and no role for STEAP1 has yet been indicated in colorectal cancer. The aim of this study was to investigate the possible association of STEAP1 expression with colorectal cancer prognosis. STEAP1 expression was analyzed by immunohistochemical staining of a tissue array of 165 cancer specimens from primary colorectal cancer patients. The mean and medium follow-up times after surgery were 5.1 and 3.9 years, respectively. A total of 139 patients died during the 13 years of follow-up in the survey period. The prognostic value of STEAP1 with respect to overall survival was analyzed by Kaplan-Meier analysis and Cox proportional hazard models. In total, 164 samples displayed detectable STEAP1 expression in the cytoplasm and membrane. Low STEAP1 expression was correlated with poor overall survival (five-year survival: 33.7% vs. 57.0%, low expression vs. high expression, p = 0.020). Accordingly, multivariate analysis identified low STEAP1 expression as an independent risk factor (hazard ratio = 1.500, p = 0.018), especially in elderly patients or those with late stage cancers, late T values, and early N values. We suggest that analysis of STEAP1 expression by immunohistochemical staining could serve as an independent prognostic marker for colorectal patients. This finding should be validated by other investigative groups.

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