Identification of a novel RNA giant nuclear body in cancer cells

Constitutive synthesis of oncogenic mRNAs is essential for maintaining the uncontrolled growth of cancer cells. However, little is known about how these mRNAs are exported from the nucleus to the cytoplasm. Here, we report the identification of a RNA giant nuclear body (RNA-GNB) that is abundant in cancer cells but rare in normal cells. The RNA-GNB contains a RNA core surrounded by a protein shell. We identify 782 proteins from cancer-associated RNA-GNBs, 40% of which are involved in the nuclear mRNA trafficking. RNA-GNB is required for cell proliferation, and its abundance is positively associated with tumor burden and outcome of therapies. Our findings suggest that the RNA-GNB is a novel nuclear RNA trafficking organelle that may contribute to the nuclear mRNA exporting and proliferation of cancer cells.