Overexpression of the cytokinesis regulator PRC1 activates the p53 pathway due to cytoplasmic microtubule-bundling resulting in senescence of A549 lung cancer cells

Protein regulator of cytokinesis 1 (PRC1) is a microtubule-bundling protein with essential roles in mitosis and cytokinesis. In this study we investigated the potential nuclear functions of PRC1 and the consequences of overexpression of PRC1 by using lung cancer cell lines stably expressing inducible expression constructs for PRC1. Ectopically expressed PRC1 resulted in proliferation defects, multi-nucleation and enlargement of cells which were directly linked to microtubule-bundling within the cytoplasm. Genome wide expression profiling by RNA sequencing revealed that the p53 pathway is activated upon overexpression of PRC1 resulting in cellular senescence. A mutant of PRC1 unable to enter into the nucleus induced the same gene sets as wildtype PRC1, suggesting that PRC1 has no nuclear-specific functions in lung cancer cells. The depletion of p53 switched the response to PRC1 overexpression or depletion from senescence to apoptosis. In addition, treatment with cisplatin, a commonly used chemotherapeutic drug, enhanced the proliferation defects due to deregulated PRC1, implicating PRC1 as a possible therapeutic target for cancer. Taken together, PRC1 needs to be tightly regulated to allow unperturbed proliferation of lung cancer cells. RNA-seq analysis of A549 lung cancer cells after overexpression of PRC1 or PRC1-NLS3A.