Identification of E2F transcription factor 7 as a novel potential biomarker for oral squamous cell carcinoma

As a tumor-accelerating transcriptional factor, E2F transcription factor 7 (E2F7) was up-regulated in many forms of cancers. Nevertheless, little has been reported about the impacts of E2F7 on oral squamous cell carcinoma (OSCC). Here, we aimed to probe whether E2F7 had influences on OSCC and its potential mechanism.

The expression of E2F7 in OSCC tissues was analyzed using the data acquired from TCGA and ONCOMINE databases. E2F7 prognostic value in OSCC patients was analyzed utilizing TCGA database. The expression of E2F7 in OSCC cell lines was detected by qRT-PCR. Gain-and loss-function of E2F7 assays in TCA-83 and CAL27 cells were performed respectively to inquire the function of E2F7. Western blotting was applied to test the alternations of EMT-related markers.

In OSCC tissues, E2F7 was highly expressed. Besides, high expression of E2F7 predicted worse prognosis in OSCC patients. Moreover, E2F7 was over-expressed in TCA-83, HSC-4 and CAL27 (all OSCC cell lines) cells relative to that in HNOK (a normal cell line) cells. Gain-and loss-function assays displayed that deficiency of E2F7 suppresses CAL27 cell growth, migration, invasion and E2F7 high-expression resulted in inverse outcomes in TCA-83 cells. Finally, we found that silencing of E2F7 facilitated E-cadherin protein expression level and reduced N-cadherin, Vimentin and Snail protein levels in CAL27 cells, whilst E2F7 high-expression exhibited the opposite effects in TCA-83 cells.

These outcomes indicated that E2F7 performs a carcinogenic role in OSCC, which provides a theoretical basis for the therapeutic strategies of OSCC.