45A ncRNA Expression Leads to Chromosomal Instability and Cytoskeletal Dynamics Impairment by Modulating GTSE1/p53/AurB Subcellular Localization.

45A non-coding RNA overexpression induces modifications to the neuroblastoma cell cytoskeleton, leading to a cascade of reactions that interfere with proliferation control, cell migration, and tumorigenic potential. Through real-time RT-PCR, Western blotting, and immunofluorescence analysis, we investigated the different expression and/or localization of GTSE1, MCAK, Aurora B, and p53 and the altered organization of tubulin in different NB cell models stably overexpressing or downregulating 45A ncRNA. The proper regulation of these proteins' expression and function is fundamental in cytoskeleton organization, as their impairment leads to chromosomal instability. We demonstrate that 45A ncRNA not only directly regulates the expression of the aforementioned proteins but can also affect GTSE1 subcellular localization: in 45A-overexpressing cells, the protein is accumulated in nuclei, while 45A downregulation leads to significant GTSE1 cytoplasm relocation and simultaneous p53 cytoplasmatic sequestration. This shuttling of the oncosuppressor reduces the apoptotic potential of 45A-downregulating cells, explaining the observed resistance to toxoids. Furthermore, 45A overexpression leads to an increased number of abnormal spindles, thus promoting chromosomal instability and possibly explaining the increased tumorigenic potential exhibited by 45A-overexpressing cells. These data highlight the role of 45A ncRNA in the functional regulation of several proteins involved in microtubule dynamics, supporting its possible relevance in prognosis.