The Role of post-transcriptional regulation and EMT related genes expression in pancreatic cancer tissues

Pancreatic cancer is the fourth highest cause of cancer fatalities, with a 5-year survival rate of less than 10% [1]. The ability of tumor cells to resist treatment and invade surrounding tissues is influenced by a reversible developmental process known as epithelial-mesenchymal transition (EMT). EMT is triggered by transcription factors including SNAIL, SLUG, ZEB1/2 and TWIST [2]. ZEB1 is regarded as the most important EMT-TF, as it promotes pancreatic cancer stemness, invasion, and metastasis [3]. HuR, an RNA-binding protein, is a member of the ELAV family and is found in nearly all carcinomas, including pancreatic cancer. This protein is considered to be a key factor in cancer-related gene expression and EMT regulation, although its specific mechanisms in EMT are not yet fully understood [4]. To develop a new treatment method for pancreatic cancer it is necessary to determine the expression changes of EMT-TFs and HuR in pancreatic cancer pathogenesis. The aim of this study was to evaluate the expression of mRNA molecules responsible for post- transcriptional regulation and EMT in pancreatic cancer tissues. Postoperative pancreatic cancerous and precancerous tissues (n=30) were frozen at -80oC and used for this research. The RNA from the tissues was isolated using TRIzol as instructed by “Abexa” manufacturer. cDNAs were synthesized using a Reverse Transcription Kit and converted to 1 µg. The gene expressions of the tissues were measured using TaqMan® Fast Universal PCR Master Mix and TaqMan probes. The data was standardized using GAPDH and the relative change in expression was computed using the 2-ΔΔCq (Livak) method. The statistical analysis was conducted using GraphPad Prism and the Wilcoxon test with a p-value of <0.05 considered significant. All data was presented as median +/- interquartile range. Our results showed that all genes were down-regulated in comparison between the patient's cancerous and precancerous tissue. ZEB1 was found to have a median expression level of 0.2 with a p-valueof <0.001. ZEB2 had a median of 0.3 with a p-value of 0.00. SNAIL1 had a median of 0.1 with a p-value of <0.005, while TWIST had a median expression level of 0.4 with a p-value of <0.008. The post-transcriptional markerHuR and another marker that plays a role in EMT, known as SLUG, did not show any significant statistical difference as their p-value was greater than 0.05. Although the median was lower, 7 out of 30 patients showed higher ZEB1 expression and 5 of same patients has higher HuR expression. This enables us to categorize patients based on their ZEB1 and HuR expression and analyze clinical features within each group separately. In conclusion, our results suggest that the expression of EMT-TFs has been decreased, indicating EMT has already occurred in cancerous tissues. However, expression of ZEB1 along with HuR were increased in 5 pancreatic cancer patients. This would allow us to conclude that ZEB1 could be regulated by HuR. Grouping patients according to ZEB1 and HuR expression will let us evaluate clinical aspects in one or the other study group for future analysis.