| IntroductionColorectal cancer is the forth most prevalent carcinoma and the second most frequent cause of death from cancer in the United States, with an estimated 129,400 new cases and 56,600 deaths in 1999. Histologic features of colorectal cancer that have been found to be of prognostic significance include depth of tumor invasion, tumor grade, extramural large vessel invasion and peritumoral lymphocytic response. The G1 - S transition of the cell cycle in mammalian cells is controlled by protein complexs composed of cyclins and cyclin - dependent kinases ( Cdks). The activity of cyclin - Cdk complexes is affected by cyclin - dependent kinase inhibitors including P27kip1. P27kIp1 protein binds to cyclin D - Cdk4, cyclin E - Cdk2 and cyclinA - Cdk2 complex inhibiting their activities during the cell cycle. The protein appears to play a role in both cell proliferation and differentiation. Recently, alterd expression of p27kip1 has been described in a variety of malignancies including esophageal, gastric, prostatic, breast, lung and thyroid cancers. An inverse correlation of p27kip1 expression to a p'atients outcome was found in the patients with colorectal cancer. Carcinoma of the right - sided colon occurs in approximately 30% of patients with colorectal cancer. Right - sided cancers have more frequent polypoid/exophytic growth, larger size, poor differentiation, ex-tracellular mucin production, and peritumoral Crohns -like lymphoid reaction. Biologically, cancers from the right colon are more likely to be associated with microsatellite instability and mutations in transforming growth factor - beta type II receptor. This study was designed to determine p27kip1 protein expression in primary colorectal cancers in relation to histologic parameters including TNM stage, depth of tumor invasion, regional lymph node status, histologic grade and recurrence status. In order to eliminate site - specific variables of p27 kip1 protein expression, we selectively investigated right - sided colon cancers.Materials and MethodsA total of 76 patients with right - sided colon adenocarcinoma from 1993 to 1996 were randomly selected by retrospective review of the pathologists at the Liaoning Cancer Hospital. These patients included 32 males and44 females with a mean age of 61 years old (ranging from 23 - 79 years old). All patients had undergone colonic resection as an initial curative treatment. Following period was over 5 years. The TNM stage was according to WHO grading system; I / II : 38, I/IV: 38; histologic grade: I :25, H: 26,1: 25. The expression of p27kip1 and ki67 protein was measured by immunohistologic staining. Colorectal cancer specimens had been fixed in formalin and embedded in paraffin wax, according to routine procedures. For this study, 4um sections were prepared.Monoclonal antibody of p27kip1 and ki67 were from Maxim Biotech Inc Fuzhou. Immunoreactivity to p27kip1 and ki67 occurring in nuclei was considered positive. Statistical analyses were performed using SPSS version 10. 0. To test the relationship between the expression of p27 kip1 and the clinico - pathological characterization, Pearson Chi -Square test was performed. The Kendall rank correlation analysis was used to test relation of p27kip1 and ki67.Results1. The expression of p27kip1l in the right - sided colon cancer. 40 out of 76 cases (52.6% ) stained ( + ) , including 27 cases (35.9% ) stained ( + + ) and 13 cases (17.1% ) stained ( + ).2. The correlation between the expression of p27kip1 and the clini-copathological factors. There were significant correlations between p27kip1 expression and the following clinicopathological factors: clinical stage (r= -0.316, p =0.004), invasive depth (r = -0.319, p = 0. 003) , regional lymph node status (r = -0. 239 ,p =0. 032) , histo-logic grade (r =0.368, p =0.000) and various modes of recurrence (r= -0. 369, p = 0. 001). There were an inverse correlation between p27 kip1 expression and clinical stage, invasive depth, lymph node status an...
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