Activation of S6 signaling is associated with cell survival and multinucleation in hyperplastic skin after epidermal loss of AURORA-A Kinase

Weston Kenneth Ryan, Josiah Fernandez, Mikayla Katherine Peterson, David William Sheneman, Brendan Keefe Podell, Subhajyoti De, Enrique Carlo Torchia

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Abstract

The role of mitosis in the progression of precancerous skin remains poorly understood. To address this question, we deleted the mitotic Kinase Aurora-A (Aur-A) in hyperplastic mutant p53 mouse skin as an experimental tool to study the G2/M transition in precancerous keratinocytes and AUR-A’s role in this process. Epidermal Aur-A deletion (Aur-A epiΔ ) led to marked keratinocyte enlargement, pleomorphism, multinucleation, and attenuated induction of cell death. This phenotype was characteristic of slippage after a stalled mitosis. We also observed altered or impaired epidermal differentiation, indicative of a partial skin barrier defect. The upregulation of mTOR/PI3K signaling was implicated as a mechanism by which keratinocytes may evade cell death after AUR-A deficiency. This was evidenced by the ectopic expression of the pathway readout, p-S6, in the basal layer of Aur-A epiΔ skin and its mitotic upregulation in isolated keratinocytes. We further tested whether our findings were extended to skin carcinoma cells. The chemical inhibition of AUR-A led to a similar mitotic delay, polyploidy/multinucleation, and attenuated cell death in skin cancer cell lines. Moreover, inhibition of mTOR/PI3K signaling ameliorated the effects caused by the deficiency of AUR-A activity but was also associated with the persistence of mitotic p-S6 detection in surviving cancer cells. These results show the induction of multinucleation/polyploidy may be a compensatory state in keratinocytes that allows for cellular survival and maintenance of partial barrier function in face of aberrant cell division or differentiation. Moreover, mTOR/PI3K signaling is active in the mitosis of hyperplastic keratinocytes expressing mutant p53 and is further enhanced by stalled mitosis, indicating a potential resistance mechanism to the use of anti-mitotic drugs in the treatment of skin cancers.

Original languageEnglish (US)
Pages (from-to)548-564
Number of pages17
JournalCell Death and Differentiation
Volume26
Issue number3
DOIs
StatePublished - Mar 1 2019

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All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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