Role of primary cilium in pancreatic ductal adenocarcinoma (Review)
INTERNATIONAL JOURNAL OF ONCOLOGY
Authors: Sabanovic, Berina; Giulietti, Matteo; Piva, Francesco
Abstract
The primary cilium is a non-motile cellular structure extending from the apical membrane of epithelial cells that is involved in several processes due to its ability to receive and elaborate different signals. Ciliogenesis and its obliteration are essential for proliferating cells, and several signalling pathways are responsible for their regulation. In fact, the primary cilium is a central hub for numerous signalling pathways implicated in a variety of biological processes, such as the Hedgehog, mammalian target of rapamycin and Wnt pathways. Loss of primary cilia has been recently correlated with different types of tumours, including pancreatic ductal adenocarcinoma (PDAC). K-Ras and HDAC2 were recently identified as possible ciliogenesis regulators in PDAC, likely acting through Aurora A kinase (AURKA) which, in turn, controls inositol polyphosphate-5-phosphatase E. However, the exact molecular mechanisms underlying this regulatory effect remain to be fully elucidated. In the present study, the regulation of the main genes involved in primary cilia assembly/resorption was reconstructed showing the links with the Hedgehog and phosphoinositide 3-kinase/AKT pathways. Finally, by analysing gene expression databases, the regulatory genes that have high probability to be associated with prognosis, histological grade and pathological stage in patients with PDAC have been highlighted. However, further experimental studies are required to reach definitive conclusions on the roles of these genes. Improving our understating of ciliogenesis and its regulators may help develop ciliotherapies using histone deacetylase and AURKA inhibitors, which may induce re-differentiation of tumour cells into normal cells by reducing tumour growth or inducing apoptosis of cancer cells.
Coming in the Air: Hypoxia Meets Epigenetics in Pancreatic Cancer
CELLS
Authors: Geismann, Claudia; Arlt, Alexander
Abstract
With a five-year survival rate under 9%, pancreatic ductal adenocarcinoma (PDAC) represents one of the deadliest tumors. Although the treatment options are slightly improving, PDAC is the second leading cause of cancer related death in 2020 in the US. In addition to a pronounced desmoplastic stroma reaction, pancreatic cancer is characterized by one of the lowest levels of oxygen availability within the tumor mass and these hypoxic conditions are known to contribute to tumor development and progression. In this context, the major hypoxia associated transcription factor family, HIF, regulates hundreds of genes involved in angiogenesis, metabolism, migration, invasion, immune escape and therapy resistance. Current research implications show, that hypoxia also modulates diverse areas of epigenetic mechanisms like non-coding RNAs, histone modifications or DNA methylation, which cooperate with the hypoxia-induced transcription factors as well as directly regulate the hypoxic response pathways. In this review, we will focus on hypoxia-mediated epigenetic alterations and their impact on pancreatic cancer.