Systematic Analysis of E2F Expression and Its Relation in Colorectal Cancer Prognosis

The E2 factor (E2F) family of transcription factors is dysregulated in numerous cancer types and may play a vital role in the development of various malignancies. However, to our knowledge, the specific function of each of the E2Fs and their relation to the disease prognosis of colorectal cancer (CRC) patients remain unknown.

We used different publicly available databases and tools, such as ONCOMINE, GEPIA2, UALCAN, cBioPortal, Kaplan-Meier plotter, Metascape, and TIMER analysis, to do an in silico exploration of the potential roles of E2Fs in CRC.

In our analyses, we found a downregulation of E2F2 expression and an upregulation of E2F1 and E2F3-8 expression in CRC tissues compared to normal controls. These findings were consistent with our subgroup analysis using the different clinicopathological features of CRC patients. Furthermore, overexpression of E2F3 and E2F4 were significantly correlated with worse overall survival (OS) in colon cancer patients. Meanwhile, low levels of E2F2 resulted in a shorter OS in rectal cancer patients. The E2F family members had varying degrees of genetic alterations with the highest alteration rate observed in E2F1 (23%). Interestingly, a moderate positive express correlation had been found in the following E2F family members: E2F1 with E2F4, E2F2 with E2F7, E2F2 with E2F8, and E2F7 with E2F8. In addition, spearman analysis revealed that E2Fs have a strong positive correlation with the critical oncogenes in CRC patients. Lastly, the expression of E2Fs was significantly associated with the infiltration of six immune cells.

In this study, we found that E2F2, E2F3, and E2F4 have the potential to be novel prognostic biomarkers in CRC. The role of these E2F family members in disease pathology may be related to their functions in cell cycle regulation, therapeutic resistance, immune cell infiltration, and epithelia-to-mesenchymal transition. Further studies are required to validate our results; however, our findings may help provide a foundation for broadening our understanding of CRC pathology.