Background/Aims: Deregulation of cell cycle control is a hallmark of cancer. The primary cyclins (A, B1, D1, D3, and E) are crucial for cell cycle progression. Secondary cyclins (C and H) have putative indirect effects on cell cycle progression and have not previously been evaluated in colon cancer. This study examined cyclin protein expression and gene amplification in colon adenocarcinoma and the correlation with patient outcome. Methods: Immunohistochemistry and real time quantitative polymerase chain reaction were used to determine cyclin expression and gene amplification in 219 tumours. The results were compared with clinical variables and patient outcomes. Results: Cyclin H was overexpressed in all tumours, cyclin C in 88%, cyclin B1 in 58%, cyclin A in 83%, cyclin D3 in 36%, cyclin E in 25%, and cyclin D1 in 11% of the tumours. Extra gene copies of cyclin A were seen in 6.2% of the tumours, cyclin B1 in 9%, cyclin C in 26.9%, cyclin D1 in 55%, cyclin D3 in 20.5%, cyclin E in 19.1%, and cyclin H in 5.1%. A significant correlation between protein overexpression and gene amplification was seen for cyclin C only. High expression of cyclin A was independently associated with improved survival. Amplification of cyclin C was independently associated with an unfavourable prognosis. Conclusions: Amplification of the cyclin C gene was related to an unfavourable prognosis and high protein expression of cyclin A was associated with a better outcome in colon adenocarcinoma.

Deregulation of cell cycle control is a hallmark of cancer. The primary cyclins (A, B1, D1, D3 and E) are crucial for cell cycle progression. Secondary cyclins (C and H) have putative indirect effects on cell cycle propulsion and are not previously evaluated in breast cancer. We have examined protein expression and gene amplification of cyclins in breast carcinomas and correlated the findings with clinical follow-up data. We have previously demonstrated that over-expression of cyclin A is associated with poor prognosis in breast cancer patients. In this study we wanted to evaluate the mechanisms behinde overexpression of cyclin A, as well as the impact of other cyclins, both at the gene level and at the protein level, on prognosis of breast cancer patients. The impact of TP53 gene mutations on gene amplification of cyclins was also evaluated. Methods: Real-Time Quantitative PCR was used to detect gene amplification of cyclins in tumour tissue from 86 patients operated for invasive breast carcinomas, while immunohistochemistry was applied to detect protein expression of the same cyclins. Result: Of the 80-breast tumour samples available for cyclin A gene amplification analyses, 26.7% (23/80) was defined to have cyclin A gene amplification. 37.2% (32/79) had cyclin B1 gene amplification, 82.6% (71/82) of the samples harboured amplification of cyclin C gene, 74.4% (64/82) had cyclin D1 gene amplification, 41.9% (36/86) had cyclin D3 gene amplification, 29.1% (25/81) of the patients had cyclin E gene amplification and 9.3% (8/86) of the samples showed amplification of the cyclin H gene. When correlation between gene amplification and protein expression was evaluated, we observed a statistical significant correlation between gene amplification and protein expression of cyclin A (p = 0.009) and cyclin D3 (p < 0.001). However, the correlation between gene amplification and protein expression of cyclin A, as well as the prognostic value of cyclin A overexpression, was affected by gene amplification of cyclin E. Gene amplification of none of the other cyclins was associated with patient prognosis. There was a statistical significant correlation between TP53 gene mutations and gene amplification of cyclins A, D3 and B1. No correlation was observed between gene amplification of secondary cyclins (H and C) and TP53 gene mutations. Conclusions: The overexpression of cyclin A is correlated to gene amplification of both cyclin A and cyclin E. Over-expression of cyclin A is associated with poor prognosis in breast cancer patients. When analysed in a multivariate analyses model, gene amplification as well as protein expression of none of the other cyclins than cyclin A are associated with patient prognosis in breast carcinomas. TP53 gene mutation seems to correlate with gene amplification of primary, but not secondary cyclins.

The tumour suppressor gene p53 and its protein controls critical cellular functions in cell cycle regulation as well as in apoptosis. Recently, in an in vitro study on breast cancer cell line MCF-7, the apoptotic function of p53 has been shown to be altered by overexpression of cyclin A. In this study we have demonstrated a similar association in a consecutive series of 166 breast cancer patients operated for invasive breast carcinomas. We detected mutations (exon 5-8) in the tumour tissue from 28 (16.0%) of the patients, and positive immunoreactivity of p53 protein was detected in tumour tissue samples from 32 (18.8%) patients. A statistically significant correlation between TP53 gene mutations and positive immunohistochemistry of p53 protein was observed (p = 0.0038). Mutations of the TP53 gene, as well as positive immunoreactivity to p53, were associated with poor prognosis (mutations p = 0.053, HR = 1.8, 95% CI 0.99-3.4; positive immunoreactivity p = 0.029, HR 1.33, 95% CI 1.0-1.7; mutation and/or positive immunoreactivity p = 0.015, HR 2.1, 95% CI 1.2-3.7) when cyclin A was not included in the survival analysis. However, when cyclin A overexpression was included, alteration of the p53 protein (mutations and/or positive immunoreactivity) lost its statistical power (p = 0.088). In a stratified survival analysis the OR fell from 3.0 (95% CI 1.2-8.3, p = 0.03) in the low-expression cyclin A stratum to 1.3 (95% CI 0.42-4.1, p = 0.77) in the overexpression cyclin A stratum.

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