The online version of this article (doi:10.1186/s13000-016-0589-9) contains supplementary material, which is available to authorized users.
The Cks1 protein is an essential factor in regulating cell cycle by mediating the ubiquitination of CDK inhibitor p27kip1. It has been reported that aberrant expression of Cks1 and p27kip1 proteins was found in various tumors and related to initiation and progression of carcinomas. However, the potential roles which Cks1 and p27KIP1 proteins play in NPC remain unclear. This study aims to examine the expression status of Cks1 and p27kip1 and their possible prognostic significance in NPC.
Paraffin-embedded specimens with NPC (n = 168) and non-tumor nasopharyngeal tissues (n = 49) were analyzed by IHC.
Expression of Cks1 increased in NPC tissues compared with non-tumor nasopharyngeal tissues (P < 0.05), whereas p27kip1 protein frequently expressed in non-tumor nasopharyngeal tissues compared with NPC tissues (P < 0.05). There was a significant reverse correlation between Cks1 and p27kip1 protein expression in NPC (r = −0.189, P < 0.05).In addition, Kaplan-Meier survival curve showed that there was a significant tendency of shorter overall survival (OS) in NPC patients with Cks1 positive expression compared to negative ones, especially in patients with lymph node metastasis (P < 0.001, respectively). But there was no significance between p27kip1 expression and survival viability of NPC patients. Multivariate Cox regression analysis further identified increased expression of Cks1 was the independent poor prognostic factor for NPC (p = 0.13).
Our research found expression of Cks1 increased and was inverse to the expression of p27KIP1. High expression of Cks1 was significantly associated with lymph node metastasis and survival status in NPC. In addition, the abnormally high level of Cks1 protein was proved to be an independent poor prognostic factor in NPC. These results may provide novel clue for NPC therapy method.
Additional file 1: The original data of IHC scoring. The expression of CKS1 and p27KIP1 had been tested in 168 cases of paraffin-embedded tissue from the primary NPC patients and 49 cases of non-cancerous nasopharyngeal control specimen from independent patients by IHC. The percentage of positive cells was divided into five grades (percentage scores):<10% (0), 11–25% (1), 26–50% (2), 51–75%(3), and >75% (4). The intensity of staining was divided into four grades (intensity scores): no staining (0), light brown (1), brown (2),and dark brown (3). Staining positivity was determined by the formula: overall scores = percentage score × intensity score. The total score ranged from 0 to 12, with negative staining (0–1) and positive expression (2–12). At last, 0 presented negative staining and 1 presented positive staining in the data file. (XLS 42 kb)13000_2016_589_MOESM1_ESM.xls
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- Increased expression of Cks1 protein is associated with lymph node metastasis and poor prognosis in nasopharyngeal carcinoma
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