ERV3 Human endogenous provirus mRNAs are expressed in normal and malignant tissues and cells, but not in choriocarcinoma tumor cells

Messenger RNA expression of a human endogenous provirus, ERV3, has been characterized in 170 specimens of normal and malignant human tissues and cells. In contrast to the high expression in first‐trimester and full‐term placental chorionic villi, most other human tissues expressed ERV3 mRNAs at a level of 2–30% of placenta. However, ERV3 mRNAs were not detected in choriocarcinoma tumor cell lines. These studies suggest that the ERV3 provirus may have been preempted for a biological function and disruption of its mRNA expression results in choriocarcinoma.