Assistant professor Department of Pathology, Division of Tumor Pathology Asahikawa, Hokkaido, Japan
Background: We have previously reported that platelets are activated in microvessels within liver tumors, leading to the progression of hepatocellular carcinoma (HCC). Recently, it has been reported that the properties of platelets are altered by various factors released by tumor cells and tumor-associated cells. These platelets are termed “tumor educated platelets: TEPs”. However, it is unclear what functions TEPs acquire and how they promote carcinogenesis compared to normal platelets.
Aims: In this study, we focused and analyzed the biological properties of TEPs in a rat HCC model.
Methods: A chemically-induced rat HCC model was prepared in F344 rats by the Solt & Farber protocol. Platelets were isolated from peripheral blood of normal and rat HCC models (normal-PLTs and HCC-PLTs). These platelets were co-cultured with a rat HCC cell line (FAAHTC1) using cell culture inserts with a pore size of 0.4 µm. The proliferative activity of FAAHTC1 was then analyzed by the Alamar blue assay after 24 and 48 hours. Comprehensive transcripts analysis by RNA-sequencing was performed in RNA extracted from normal-PLTs and HCC-PLTs. An O-Propargyl-Puromycin (OPP)-based protein synthesis capacity assay was performed in each platelet by flowcytometry.
Results: Analysis in a co-culture model of platelets and HCC cell lines showed that HCC-PLTs more strongly promoted the proliferation of HCC cell lines. RNA sequencing analysis showed that HCC-PLTs contained more abundant transcripts encoding ribosome-associated and translation-associated proteins than normal-PLTs. Furthermore, flow cytometry showed that HCC-PLTs have a more robust protein de novo synthesis capacity than normal PLTs.
Conclusion(s): The results suggest that TEP has a more potent protein synthesis capacity than normal platelets and may promote hepatocarcinogenesis through the synthesis of tumor growth-associated proteins.
