John, Bramis, Panayotis, Zacharatos, Ioannis, Papaconstantinou, Athanassios, Kotsinas, Frangisca, Sigala, Dimitrios P, Korkolis, Nikolaos, Nikiteas, Anastasia, Pazaiti, Christos, Kittas, Elias, Bastounis, and Vassilis G, Gorgoulis
E2F-1 is an intriguing transcription factor that accumulates the integrated signal of the G1-S transition regulators. Its role in cell fate, as depicted from in vivo models and a few studies on human tissues, is a matter of debate, since it confers a tissue-specific oncogenic or tumor suppressor behavior. In the present work, in an attempt to shed light on the role of E2F-1 in colon cancer, we examined E2F-1 expression in a series of 45 colon carcinomas and we further correlated it with tumor kinetics. E2F-1 expression and proliferation were evaluated by immunohistochemistry as the percentage of E2F-1 (E2F-1 index: EI) and Ki-67 (Proliferation index: PI)-positive cells, respectively; whereas apoptosis was estimated as the percentage of positive, by TUNEL assay, cells (Apoptotic index: AI). The relationship between E2F-1 expression and tumor kinetics was assessed by microscopical evaluation in semi-serial tissue sections and statistical analysis. Our results demonstrated that E2F-1 expression was inversely correlated with tumor growth (GI=PI/AI) (p=0.002). Specifically, the histological observations showed that E2F-1 was expressed in lesions with high apoptotic incidence and low proliferation. These results also supported the statistical findings showing that EI was inversely correlated with PI (p0.001) and positively associated with AI (p = 0.013). In conclusion, we suggest a tumor-suppressive behavior of E2F-1 in colon carcinomas.