Peptide derived from progranulin of the carcinogenic liver fluke, Opisthorchis viverrini stimulates cell hyperproliferation and proinflammatory cytokine production.

Purpose Progranulin (PGRN) is a secreted glycoprotein growth factor with roles in wound healing, inflammation, angiogenesis and malignancy. An orthologue of the gene encoding human PGRN was identified in the carcinogenic liver fluke Opisthorchis viverrini . Methods Sequence structure, general characteristics and possible function of O. viverrini PGRN was analyzed using bioinformatics. Expression profiles were investigated with quantitative RT-PCR, western blot and immunolocalization. A specific peptide of Ov -PGRN was used to investigate a role for this molecule in pathogenesis. Results The structure of the gene coding for O. viverrini PGRN was 36,463 bp in length, and comprised of 13 exons, 12 introns, and a promoter sequence. The Ov-pgrn mRNA is 2,768 bp in length and encodes an 846 amino acids with a predicted molecular mass of 91.61 kDa. Ov -PGRN exhibited one half and seven complete granulin domains. Phylogenetic analysis revealed that Ov -PGRN formed its closest relationship with PGRN of liver flukes in the Opisthorchiidae. Transcripts of Ov - pgrn were detected in several developmental stages, with highest expression in the metacercaria, indicating that Ov -PGRN may participate as a growth factor in the early development of O. viverrini . Western blot analysis revealed the presence of detected Ov -PGRN in both soluble somatic or excretory/secretory products, and immunolocalization indicated high levels of expression in the tegument and parenchyma of the adult fluke. Co-culture of a human cholangiocyte cell line and a peptide fragment of Ov -PGRN stimulated proliferation of cholangiocytes and upregulation of expression of the cytokines IL6 and IL8. Conclusion Ov-PGRN is expressed throughout the life cycle of liver fluke, and likely plays a key role in development and growth.