Hepatocellular Carcinoma, Down Regulated 1 (HEPN1)

HEPN1 encodes a predicted 10-kD peptide with 88 amino acids. RT-PCR revealed that HEPN1 was ubiquitously expressed in 23 nontumorous liver samples and that expression was either downregulated or lost in 22 of 23 HCC samples. HEPN1 expression was also significantly suppressed in several HCC cell lines and lost in HCC HepG2 cells. Immunofluorescence microscopy showed that HEPN1 localizes predominantly to the cytoplasm.

In colony formation assays, expression of HEPN1 reduced both the number of colonies and the number of cells. Fluorescence microscopy of transfected HepG2 cells revealed typical apoptotic morphology after about 16 hours. Results of an annexin V assay further indicated a role for HEPN1 in apoptosis.