Abstract B094: The role of paraspeckles and splicing regulation in driving basal-like pancreatic cancer

Abstract

Abstract The basal-like pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive type of mesenchymal PDAC that resists treatment and has a poor prognosis. Understanding the mechanisms driving basal-like PDAC biology will be essential for development of treatment strategies for this aggressive tumor. We have previously shown that loss of the tumor-suppressive non-coding RNA Neat1 recapitulate the phenotype of Arid1a-deficient mice (a component of the SWI/SNF chromatin remodeling complex) in a mouse model for PDAC, with loss of exocrine pancreatic identity and development of acinar- and ductal-derived lesions (Mello et al., 2017), suggesting that Neat1 and Arid1a may share a common molecular mechanism. We now demonstrate that the loss of these two divergent genes induce the emergence of basal-like PDAC. This provides an opportunity to probe for shared features specific to Neat1- and Arid1a-deficient PDAC, as compared to PDAC in which both genes are functional. Notably, our data indicate that both Neat1- and Arid1a-deficient pancreatic cells fail to form nuclear paraspeckles, i.e. structures implicated in the retention of RNA splicing factors. Consistent with this idea, we also find significantly increased exon-skipping, including a sub-set of such events shared between Neat1- and Arid1a-deficient PDAC. In addition, nucleotide sequence motifs associated with exon-skipping locations suggest involvement of RNA splicing factors known to accumulate in paraspeckles, such as Srsf1, Srsf2, Srsf10, Rbm38, Dazap1 and others. We also show that, upon genetic or pharmacological attenuation of splicing regulator function, basal-like PDAC develop epithelial features, reminiscent of mesenchymal-epithelial transition, reduce both their proliferation and migration potential and undergo cell death. Our findings provide an important opportunity to elucidate the molecular pathways that link aberrant RNA splicing and paraspeckle deficiency to basal-like PDAC, providing new insight for the development of mechanism-based novel PDAC treatment strategies to improve patient outcome. Citation Format: Zamira G. Soares, Emily Berry, Dakarai Esgdaille, Jennifer Twardowski, Stephano S. Mello. The role of paraspeckles and splicing regulation in driving basal-like pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B094.