Multigene analysis of Rb pathway and apoptosis control in esophageal squamous cell carcinoma identifies patients with good prognosis.

Deregulation of cell-cycle G(1)-restriction point control by disruption of Rb-pathway components is a frequent event in cancer. In concert with the inactivation of cell death pathways, such events not only contribute to tumor development but also determine the intrinsic and acquired resistance to cancer therapy and, ultimately, disease prognosis. We previously observed that the cyclin-dependent kinase inhibitor p16(INK4a) and the proapoptotic Bcl-2 homolog Bax are positive prognostic factors and identify patients with good prognosis in esophageal squamous cell carcinoma (SCC). In the present study, we therefore extend our analysis to additional genes controlling the G(1) restriction point and apoptosis, respectively. This retrospective analysis was performed in a cohort of 53 patients undergoing surgery for esophageal SCC with curative intent, i.e., R0 resection. Protein expression profiles of cyclin D1, p16(INK4a), Rb, p21(CIP/WAF-1), p53, Bax and Bcl-2 were analyzed by immunohistochemistry and compared to p53 mutational status, as determined by SSCP-PCR of exons 5-8. Loss of p16(INK4a), Rb, p21(CIP/WAF-1) or Bax and overexpression of cyclin D1 were associated individually with shorter overall survival, while Bcl-2 expression and p53 mutation were not of prognostic relevance. The longest survival was observed in a subgroup of patients whose tumors bore a combination of favorite genotypes, i.e., low cyclin D1 and high Rb, p21(CIP/WAF-1), p16(INK4a) and Bax protein expression. These results show that multigene analyses based on limited sets of functionally linked genes reliably identify patients with good vs. poor prognosis.