Abstract 5692: Posttranscriptional molecular network facilitates KRAS-linked tumorigenesis via XRN1-miR-21 signaling in pancreatic cancers

Abstract

Abstract Aberrant expression of mutant KRAS and miRNA-21 (miR-21) are commonly attribute to malignancy and tumorigenic progression of pancreatic cancers. However, few studies have explored the molecular mechanism linking these two prognostic factors. In this study, we explored the underlying molecular bridge between KRAS and miR-21 regulation in pancreatic cancer. Functional integrative analysis of KRAS, an essential oncogenic driver in pancreatic cancer progression, and together with miR-21 revealed XRN1, a 5′-3′ exoribonuclease, as RNA-linked top-scored molecule with a strong survival correlation and malignancy in pancreatic cancer patients. Depletion of XRN1 led to severe reduction in mature miR-21 expression, while unaltered precursor miR-21 levels; indicating that the XRN1 is critical in miR-21 maturation at post-Drosha step in conjunction with Dicer. Moreover, miR-21 sensor-based experiment also confirmed the critical role of XRN1 on miR-21 biogenesis. Depletion experiments showed that XRN1 positively regulates proliferation and self-renewal capacity of pancreatic cancer cells via its 5′-3′ exoribonuclease activity and concomitantly elevated the expression of PTEN and PDCD4 which are the key miR-21 cellular downstream targets. shRNA-mediated XRN1 depletion also yielded smaller tumor volume and longer survival in pancreatic cancer xenografts and syngeneic model demonstrating the therapeutic potential of targeting XRN1. Subsequent silencing of KRAS reduced XRN1 expression in pancreatic cancer cells, suggesting that KRAS plays a key role in this XRN1-miR-21 axis. Furthermore, drug-resistant pancreatic cells showed elevated expression of both KRAS and XRN1-miR-21 indicating that this axis is also associated with drug sensitivity. In sum, these results suggest that a novel KRAS-XRN1 posttranscriptional regulatory axis plays a pivotal role in tumor progression by mediating miR-21-directed signaling, and thus may suggest a novel targeting strategy for pancreatic cancer therapeutics. Significance: This study identifies molecular regulatory interplay between KRAS and XRN1-miR-21 signaling in pancreatic cancers, elucidates how KRAS-XRN1 modulates tumorigenesis via miR-21, and demonstrates that targeting this signaling can contribute to therapeutic strategies for pancreatic cancers. [Y. Seo and S. E. Oh contributed equally to this work.] Citation Format: Yoona Seo, Seung Eon Oh, Jong Heon Kim. Posttranscriptional molecular network facilitates KRAS-linked tumorigenesis via XRN1-miR-21 signaling in pancreatic cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5692.