The biology of regulatory pathways of miRNAs, mRNAs and proteins unravels a specific -omics network in tumor-educated platelets from pancreatic cancer patients

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers, with a 5-year survival below 10%. Remarkably, PDAC patients with higher platelet levels have worse prognosis (Wang Y. et al. 2014), and tumor-educated platelets recently emerged as biomarkers for different tumors (Best M. et al., 2020). Thus, -omics data to understand the potential diagnostic and prognostic role of tumor-educated platelets (TEPs) in patients with pancreatic cancer are warranted and this study focuses on the identification of regulatory pathways of miRNA, mRNA and proteins, in order to build an -omics network of PDAC-TEPs compared to patients with benign disease. Materials and methods: Blood samples from 22 PDAC patients and patients with benign pancreatic diseases were collected. Leucocyte depleted-platelets were isolated to profile small RNAs, mRNAs, and proteins. Differential analyses of miRNAs, genes and proteins profiles were carried out separately. Ontology mining, miRNA-gene correlation analyses and integration of several available miRNA-gene targets databases, were used to build an interaction network of regulatory pathways. Results: Differential analyses revealed 473, 154 and 102 differentially expressed miRNAs, intron-spanning transcripts and proteins, respectively. Further in-depth exploration of platelets profiles at miRNA, gene and protein level showed most significant changes at miRNA levels suggesting a clear miRNome response of TEPs to external stimuli. In particular, integrative gene ontology analyses revealed spliceosome and ribosomal proteins enrichments in PDAC platelets suggesting a clear de novo protein machinery in response to tumor microenvironment. Conclusions: Our study demonstrates that platelets transcriptome and proteome have significant remodeling when comparing benign patients to PDAC. Integration of biology mining of the three –omics layers revealed a significant enrichment in RNA processing, splicing signal events and translation initiation, suggesting that PDAC-TEPs undergo specific splicing signals events to modulate their proteome and phenotype. Together, these analyses provide novel insights in the regulatory mechanisms within blood platelets and should prompt future studies for exploration of key pathways in disease development. Further research for the integration of additional -omic levels is warranted and we reckon that epigenetic regulation might have a leading position in driving TEPs’ phenotype.