ROLE OF METHYLTRANSFERASE LIKE-3 (METTL3) IN PANCREATIC DUCTAL ADENOCARCINOMA (PDAC) PROGRESSION
Author ORCID Identifier
Date of Graduation
Masters of Science (MS)
Dr. Anirban Maitra
Dr. Xiaodong Cheng
Dr. Cullen Taniguchi
Dr. Sean Post
Dr. William Mattox
Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive cancer with about a 10% five-year survival rate. The grim prognostic situation of pancreatic cancer patients underlines the need to identify novel molecular targets. Recent studies have brought to attention, the need to therapeutically exploit epigenetic pathways, apart from only targeting genetic mutations to effectively combat PDAC. To that effect, METTL3-mediated post-transcriptional methylation of RNA transcripts have been shown to contribute to cancer progression in multiple cancer types.
METTL3 deposits methyl groups onto adenosine bases within specific consensus sequences in RNA, resulting in the formation of N-6 methyl adenosine (m6A). m6A is the most abundant internal modification in mRNA and affects gene expression while also playing crucial roles in early-stage development, organogenesis, and cell-fate determination.
To investigate the effect of METTL3 in PDAC, we analyzed TCGA RNA-Seq expression profile data for the PAAD patient cohort and found that METTL3 expression is positively correlated with patient survival. The difference in median survival between patients expressing METTL3 at a higher level than average compared to patients expressing low levels of METTL3 was 6 months. We generated METTL3 knockdown clones of human pancreatic cancer cell lines (Panc-1 and MiaPaca-2) using shRNA targeting and performed in vitro assays to determine differences in growth and migratory characteristics upon METTL3 knockdown. METTL3 loss decreased proliferation and migration rates in MiaPaca-2 cells and decreased proliferation rate in Panc-1 cells when compared to control cell lines. As METTL3 is physiologically important in inducing differentiation and repressing pluripotent identity, we investigated the effect METTL3 knockdown exerts on EMT-associated markers in these pancreatic cancer cell lines. We found that in the epithelial cell line, Panc-1 upon METTL3 knockdown there was a reduction in E-Cadherin expression, along with a concordant increase in N-Cadherin and Vimentin expression. Our results indicate that expression of METTL3 positively regulates patient survival in PDAC, reduces proliferation and migration rates of pancreatic cancer cell lines, and induces an EMT-like phenotype.
Pancreatic cancer, METTL3, RNA methylation, m6A, EMT