Cancer-associated nucleolar morphological changes coincide with altered subcompartment organization and accelerated nascent rRNA trafficking in breast cancer cells

Cancer cells often display distinct nucleolar morphologies, but the relationship between these changes and the internal organization of nucleolar subcompartments and ribosomal RNA (rRNA) trafficking is not well understood. This study examines the nucleolar organization of non-cancerous MCF-10A mammary epithelial cells and cancerous MDA-MB-231 breast cancer cells.

The MDA-MB-231 cells show differences in nucleolar shape, along with altered spatial arrangements of two key components and faster movement of nascent rRNA within the nucleus. Using a drug called SU056, researchers can modify several structural and dynamic aspects of the nucleolus to resemble the MCF-10A cells. Conversely, a chemical treatment called 1,6-hexanediol can induce several cancer-like nucleolar features in the non-cancerous cells, which then revert back to their original state once the treatment is stopped.

These findings suggest that the cancer-associated nucleolar alterations are a combined reorganization across morphological, spatial, and dynamic dimensions. This reversibility indicates that the cancer-linked nucleolar organization can be modified in response to various factors. By connecting the morphology, subcompartment organization, and nascent rRNA dynamics within a single framework, this research offers a foundation for studying the development, maintenance, and alteration of different nucleolar profiles in cancer.