[Expression and clinical significance of Ser10 phosphorylated p27(kip1) protein in human breast carcinoma]

Objective: To explore the expression and clinicopathological significance of Ser10 phosphorylated p27(kip1)(P-p27Ser10) protein in human breast carcinoma tissue. Methods: Tissue specimens were obtained from 111 cases with breast carcinoma from January 2004 to December 2005. And the expression of P-p27Ser10 protein for each specimen was detected by immunohistochemical (EnVision) analysis. Six representative paired samples of cancerous and paired adjacent normal tissues were collected and detected by Western blot. The relationships between the expression levels of P-p27Ser10 protein and its clinicopathological characteristics in primary breast carcinoma were retrospectively analyzed.The association of P-p27Ser10 and Jab1 protein was detected by co-immunoprecipitation method. Results: A high-level expression of P-p27Ser10 was present in cancerous tissues but not in paired adjacent normal tissues. The positive expression rate of P-p27Ser10 protein was as high as 88.3% (98/111) and 7.2% (8/111) in cancerous and paired adjacent normal tissues respectively (P<0.05). P-p27Ser10 expression was correlated with tumor size, lymph node metastasis and TNM stage (all P<0.05). P-p27Ser10 expression was significantly correlated with Ki-67 (r=0.582, P<0.05), and inversely correlated with p27 (r=-0.426, P<0.05). Co-immunoprecipitation revealed that the association of P-p27Ser10 and Jab1 protein was increased in breast carcinoma. Conclusion: Over-expression of P-p27Ser10 protein might play an important role in the pathogenesis of breast carcinoma. P-p27Ser10 protein therefore represents a novel diagnostic marker and therapeutic target in patients with breast carcinoma.