DNAJC25 is downregulated in hepatocellular carcinoma and is a novel tumor suppressor gene.

HSP40, also known as DnaJ, is one of the subfamilies of the heat shock protein family. DnaJ/Hsp40 proteins act as co-chaperones by binding to the chaperone Hsp70 through their J domain and stimulating ATP hydrolysis to aid protein translation, folding, unfolding, translocation and degradation. They are implicated in various human diseases, including neurodegenerative disorders and cancer. In the present study, we cloned and identified a new gene, DnaJ (HSP40) homolog, subfamily C, member 25 (DNAJC25), which is localized to the cytoplasm. Real-time PCR revealed that the expression of DNAJC25 is particularly high in the liver and is down-regulated in hepatocellular carcinoma (HCC) compared with adjacent normal tissues. The overexpression of DNAJC25 led to an inhibition of colony growth both in quantity and size. Flow cytometry analysis indicated that DNAJC25 also significantly increased cell apoptosis. Our data, therefore, indicate that DNAJC25 plays an important role in hepatocellular carcinogenesis, and should be further studied as a potential tumor suppressor candidate.