C-Jun Transcription Factor Oncogenic Activation in Oral Carcinoma.

Introduction: Oral carcinogenetic is based on a variety of genomic imbalances (gross chromosome or specific gene alterations) that drive the normal oral mucosa to its neoplastic/dysplastic epithelial form and finally to a totally malignant tissue transformation. In this multi-step procedure, down-regulation of suppressor genes combined with overactivation of oncogenes are two crucial and partially early genetic events involved in the onset and progression of neoplastic/malignant epithelia transformation. More specifically, deregulation of strong transcription factors negatively affects the normal expression of a broad spectrum of genes that are involved in cell proliferation and signalling transduction to the nucleus.

Objective: The purpose of the current molecular review was to explore the c-Jun (chromosome location: 1p32-p31) transcription factor transformation mechanisms to oncogene in oral squamous cell carcinoma (OSCC).

Material and method: A systematic review of the literature was carried out by searching in PubMed international database. The year 2010 was set as a prominent time limit for the publication date of the articles in the majority of them, whereas specific references of great importance and historical value in the field of the c-Jun gene discovery and analysis were also included. The following keywords were used: c-Jun, oncogene, signaling pathway, oral, carcinoma, transcription. A pool of 45 important articles were selected for the present study at the basis of combining molecular knowledge with new targeted therapeutic strategies.

Results: C-Jun - as a part of the c-Jun/c-Fos transcription factors' complex -critically regulates the expression levels in a variety of genes inside the cellular microenvironment. A broad spectrum of malignancies, including OSCC, demonstrate c-Jun alterations driving the gene to its oncogenic phenotype. Interestingly, c-Jun oncogenic activation is mediated by high-risk human papilloma virus (HR-HPV) persistent infection in significant subsets of these malignancies.

Conclusions: C-Jun was the first oncogene - acting as a strong transcription factor - that was discovered and cloned 35 years ago. C-Jun is the living history of oncogenes and its discovery marks a significant step in the evolution of molecular biology.