Pancreatic ductal adenocarcinoma and transcription factors: role of c-Myc.

Introduction: Deregulated expression/activation of transcription factors is a key event in the establishment and progression of human cancer. Furthermore, most oncogenic signaling pathways converge on sets of transcription factors that ultimately control gene expression patterns resulting in cancer development, progression, and metastasis.

Methods: Ductal pancreatic adenocarcinoma (PDA) is the main type of pancreatic cancer and the fourth leading cause of cancer mortality in the Western world. The early stage of the disease is characterized by pancreatic intraepithelial neoplasia lesions bearing mutations in the K-RAS proto-oncogene, which progress to malignant PDA by accumulating additional mutations in the tumor suppressor gene CDKN2A (p16) and in SMAD4 and TP53 transcription factors. The involvement of other signaling pathways in PDA development and progression is an active area of research which may help to clarify the critical steps of this devastating disease.

Results: In this regard, several in vitro and in vivo data have demonstrated the contribution of the transcription factor c-Myc to pancreatic carcinogenesis although the molecular mechanisms are poorly understood. c-Myc is a proto-oncogene which has a pivotal function in growth control, differentiation and apoptosis and is known to act as a downstream transcriptional effector of many signaling pathways involved in these processes. It is regulated at multiple levels and its abnormal expression contributes to the genesis of many human tumors.

Conclusions: This review focuses on the role of c-Myc in pancreatic embryonic development and homeostasis as well as its involvement on pancreatic tumorigenesis. Evidences showing that c-Myc function is highly dose and cell context dependent, together with its recently demonstrated ability to reprogram somatic cells towards a pluripotent stem cell-like state, indicate that the role of c-Myc in pancreas pathophysiology might have been previously underscored.