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

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.

Tumor-specific hyperactive low-molecular-weight cyclin E isoforms detection and characterization in non-metastatic colorectal tumors.

PURPOSE: Several molecules involved in cancer biology have been studied as potential prognostic markers. Recently, overexpression of cyclin E and its low-molecular-weight (LMW) isoforms has been reported to be the most prominent prognostic marker in breast cancer, surpassing proliferation index, ploidy, and axillary nodal involvement. Furthermore, cyclin E and p53 are considered the main factors controlling the euploid equilibrium in human cells. We investigated the status of cyclin E and p53 in cell lines and tissue samples of colorectal cancer, one of the leading causes of death from a tumor in the Western world. EXPERIMENTAL DESIGN: We analyzed colorectal cancer cells, from established cell lines and patient specimens, to determine the protein levels of cyclin E and p53, and to detect p53 and APC mutations, microsatellite and chromosome instability. In addition, we assessed the presence of cyclin E LMW isoforms and their enzymatic activity. RESULTS: Colorectal cancer cells expressed hyperactive LMW forms both in vitro and in vivo. These tumor-specific isoforms are correlated to genomic instability even in p53-proficient cells, and represented a constant feature in the tumors analyzed. CONCLUSIONS: In colorectal cancer, the formation of cyclin E LMW forms is an early event leading to DNA-damage checkpoint-independent proliferation. Collectively, our results provide evidence that evaluation of LMW forms could represent a novel tool in the molecular characterization of colorectal tumors aimed at identifying sensitive prognostic factors and uncovering subsets of high-risk patients within the traditional categories.

Porous silicon surfaces: a candidate substrate for reverse protein arrays in cancer biomarker detection.

This paper introduces a new substrate for reverse-phase protein microarray applications based on macroporous silicon. A key feature of the microarray substrate is the vastly surface enlarging properties of the porous silicon, which simultaneously offers highly confined microarray spots. The proof of principle of the reverse array concept was demonstrated in the detection of different levels of cyclin E, a possible cancer biomarker candidate which regulates G1-S transition and correlates with poor prognosis in different types of human cancers. The substrate properties were studied performing analysis of total cyclin E expression in human colon cancer cell lines Hct116 and SW480. The absence of unspecific binding and good microarray quality was demonstrated. In order to verify the performance of the 3-D textured macroporous surface for complex biological samples, lysates of the human tissue spiked to different levels with cell extract overproducing cyclin E (Hct116) were arrayed on the chip surface. The samples were spotted in a noncontact mode in 100 pL droplets with spots sizes ranged between 50 and 70 mum and spot-to-spot center distances 100 mum, allowing microarray spot densities up to 14 000 spots per cm(2). The different sample types of increasing complexities did not have any impact on the spot intensities recorded and the protein spots showed good homogeneity and reproducibility over the recorded microarrays. The data demonstrate the potential use of macroporous silicon as a substrate for quantitative determination of a cancer biomarker cyclin E in tissue lysates.