The T197A Knock-in Model of Cdkn1b Gene to Study the Effects of p27 Restoration In Vivo

• Published in: Molecular cancer therapeutics Vol. 18; no. 2; pp. 482 - 493
• Main Authors: De Marco, Carmela, Rinaldo, Nicola, De Vita, Fernanda, Forzati, Floriana, Caira, Elvira, Iovane, Valentina, Paciello, Orlando, Montanaro, Donatella, D'Andrea, Sara, Baldassarre, Gustavo, Papparella, Serenella, Malanga, Donatella, Baldi, Alfonso, Viglietto, Giuseppe
• Format: Journal Article
• Language: English
• Published: United States 01-02-2019
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-18-0134

The CDK inhibitor, p27
, encoded by the
gene can negatively modulate cell proliferation. The control of p27 activity during the cell cycle is regulated at multiple levels, including transcription, translation, and protein stability. The last residue of p27 (threonine 198 in human, threonine 197 in mouse) is involved in the control of protein stability. We have generated a murine knock-in model (
) in which threonine 197 is replaced by alanine, which renders p27 protein highly unstable due to a high rate of proteasomal degradation. Expectedly,
mice present with increased body size and weight, organomegaly, and multiple organ hyperplasia, similar to what is observed in
mice. We investigated the effects exerted by the restoration of normal levels of p27 protein in the tissue of
mice. We found that proteasome inhibition with bortezomib rescues the hyperplasia induced by the lack of p27 expression in
but not in
mice. However, BAY 11-7082, a proteasome inhibitor that stabilizes IκB but not p27, fails to rescue hyperplasia in
mice. Bortezomib increases p27 half-life and reduces the proliferation in MEFs derived from
but not from
mice, whereas BAY 11-7082 had no effect on the protein levels of p27 and on the proliferation rate of
MEFs.The results presented here demonstrate that
mice represent an attractive
model to investigate whether the targeting of p27 degradation machinery might prove beneficial in the treatment of a variety of human proliferative disorders caused by increased turnover of p27 protein.