Comparison of deregulated expression of cyclin D1 and cyclin E with that of cyclin dependent kinase 4 (CDK4) and CDK2 in human oesophageal squamous cell carcinoma

The expressions of cyclin D1, cyclin E, cyclin-dependent kinase 4 (CDK4), and CDK2 were immunohistochemically examined in 90 patients with human oesophageal squamous cell carcinoma (SCC) to determine their relationship to the tumour behaviour and patient prognosis. Nuclear immunostaining of cyclin D1 and cyclin E was observed in 28 (31.1%) and 27 tumours (30.0%) respectively. Thirty-nine tumours (43.3%) and 31 tumours (34.4%) exhibited both cytoplasmic and nuclear positivity for CDK4 and CDK2 respectively. Of 28 cyclin D1-positive and 27 cyclin E-positive tumours, CDK4 was overexpressed in 12 (42.8%) tumours and CDK2 in seven (25.9%) tumours respectively. There was no significant relationship in immunopositivity between cyclin D1 and CDK4 or between cyclin E and CDK2. Simultaneous immunoreactivity for both cyclin D1 and CDK4 was significantly associated with venous invasion (P < 0.05). In a univariate analysis, the prognosis of patients with tumours that were both cyclin D1- and CDK4-positive was significantly poorer than that of patients with cyclin D1-negative tumours (P < 0.05). In a multivariate analysis, both cyclin D1 and CDK4 immunoreactivities (P < 0.01) and tumour stage (P < 0.001) were recognized as independent risk factors. In this analysis, the hazard ratio for cyclin D1-positive and CDK4-negative cases compared with cyclin D1-negative cases was significant (hazard ratio = 3.1281 95% confidence interval = 1.418-6.899, P = 0.0047), No significant prognostic relevance was detected in both cyclin E and CDK2 immunoreactivity. Our in vivo findings suggest that in human oesophageal SCC, cyclin D1 and cyclin E and their functional partners, CDK4 and CDK2, often exhibit dysregulated overexpression in many cases, and that tumours with simultaneous expression of cyclin D1 and CDK4 are frequently associated with venous invasion and have a worse prognosis, statistically. Moreover, overexpression of cyclin D1 alone may also contribute to tumour progression independent of CDK4 overexpression.