Hepatitis B virus X protein represses miRNA-148a to enhance tumorigenesis

Viruses prompt oncogenic transformation by genetically altering infected cells. Several recent studies have demonstrated that viruses alter the expression of microRNAs, non-coding RNA molecules that can block the expression of target genes. In this issue of the Journal of Clinical Investigation, Xiaoje Xu and colleagues at the Beijing Institute of Biotechnology report that miR-148a is repressed by hepatitis B virus (HBV) X protein (HBx) to promote growth and metastasis of liver cancer.

In normal liver cells, miR-148a represses the expression of the oncogenic protein HPIP, but the hepatitis B virus prevents expression of miR-148a, leading to increased levels of HPIP and subsequent oncogenic transformation. This study demonstrates that a cancer-associated virus promotes carcinogenesis through direct manipulation of a microRNA.