The Molecular Mechanism Of Alternative Splicing Of Integrin β1 Regulated Fyn Through HnRNP E1 In Pancreatic Cancer

BackgroundPancreatic cancer is a deadly disease with early invasion and metastasis of tumor cells.It is characterized by a dense desmoplastic reaction in which extracellular matrix proteins accumulate and surround tumor cells.By interaction with ECM,integrins and their related signaling molecules play important roles in regulating the invasion and metastasis of pancreatic cancer.To clarify the interaction between integrins and its intracellular signaling molecules can provide a new theoretical basis for understanding the metastasis of pancreatic cancer.Alternative splicing plays an important role in gene post-transcription modification.Aberrant pre-m RNA splicing in cancer is emerging as an important determinant of oncogenesis,thus a better understanding of tumor specific alternative splicing will p rovide the potential theoretical targets for the clinical diagnosis and treatment of cancer.Previous studies showed that Fyn,members of nonreceptor tyrosine kinases,and integrin β1 play important roles in regulating the metastasis of pancreatic cancer.Inhibition of Fyn activity induce the upregulation of hn RNP E1 and integrin β1C variant in pancreatic cancer cells.Consideration of hnRNP E1 plays inportant role in alternative splicing regulation,we speculate that the activity of Fyn can regulate the alternative splicing of integrin β1 by affecting the expression and function of hn RNP E1,thus resulting in influence the metastasis of pancreatic cancer.We investigated the mechanism underlying integrin β1 splicing regulated by the hn RNP E1 spliceosome.MethodsWe evaluated the relationship between the metastasis of pancreatic cancer and the expression of hn RNP E1 and integrin β1 variants in pancreatic cancer tissues;We analysized the expression of hn RNP E1 and integrin β1 variants affected by Fyn activity in Bx PC3 and Panc-1 pancreatic cancer cells;We evaluated the alternative splicing of integrin β1 modulated by hnRNP E1 expression in pancreatic cancer cells;We investigated the mechanism underlying integrin β1 alternative splicing regulated by hn RNP E1 spliceosome complex and we showed that Fyn-hnRNP E1-integrin β1 affected the mobility and metastasis of pancreatic cancer cells.ResultsCytoplasmic distribution of hn RNP E1 and expression of integrin β1A was correlated with the lymph node metastasis,hepatic metastases and tumor stage of pancreatic cancer and cytoplasmic distribution of hn RNP E1 and expression of integrin β1A had a correlated relationship with each other;Inhibition of Fyn activity upregulated Pak1 and hn RNP E1 and promoted the phosphorylation and nuclear localization of hnRNP E1,thus resulting in forming of the hnRNP E1 spliceosome complex which regulated the alterative splicing of integrin β1;In the hnRNP E1 spliceosome complex,hnRNP A1 and SF2/ASF were responsible for binding to the pre-mRNA of integrin β1 to achieve posttranscriptional modification;In vivo and in vitro studies showed that suppression of Fyn activity or overexpression of hnRNP E1 significantly decreased the mobility and metastasis of pancreatic cancer cells.ConclusionsInhibition of Fyn activity induce the nuclear localization of hn RNP E1 by upregulating PAK1 that resulting in forming of the hn RNP E1 spliceosome complex which regulate the alterative splicing of integrin β1 through the hn RNP A1 and SF2/ASF componets in pancreatic cancer;Thus Fyn-hnRNP E1-integrin β1 regulate the metastasis of pancreatic cancer.