A study of the expression of Cyclin E and its isoforms in tumor and adjacent mucosa, correlated to patient outcome in early colon cancer

Abstract

Background. Cyclin E, a key regulator in the cell cycle, is often over-expressed in malignant disease. It can present as full length (FL) and low-molecular-weight (LMW) isoforms. The purpose of this study was to characterize the expression pattern of cyclin E in colon cancer, both in tumor and in macroscopically normal adjacent mucosa. A secondary aim was to study the possible correlation to clinical factors and patient outcome. Material and method. Tumor and mucosa tissue from 114 patients with radically operated, non-metastatic colon tumors were analyzed. The cyclin E expression was measured by Western Blot in the tumor and adjacent mucosa using the antibody targeting C-terminal. The cyclin E expression was correlated to both pathology factors as differentiation grade and to the patient outcome. Results. Cyclin E was detected in both tumor and adjacent mucosa and in both FL and LMW-forms. FL was present in 29 (25.4%) tumors and only in three (2.6%) mucosa samples, the corresponding figures for the LMW-isoforms were 80 (70.2%) and 67 (58.8%). There was no correlation between the cyclin E expression and gender, age, tumor location or tumor pathology. Patients with a high expression of LMW isoforms (p < 0.03) or a high total expression (FL+LMW) (p < 0.006) had higher risks of recurrence and thus a worse survival. Conclusion. Cyclin E is expressed in FL- and LMW-forms in both colon tumors and the macroscopically normal adjacent mucosa. A high expression of cyclin E in tumor was associated with an increased risk of tumor recurrence and a worse outcome. It could be a possible prognostic marker in non-metastatic colon cancer.