Research Paper|Volume 1, Issue 12|pp 1008—1016

Quantifying pharmacologic suppression of cellular senescence: prevention of cellular hypertrophy versus preservation of proliferative potential

Zoya N. Demidenko^1,², Mikhail V. Blagosklonny^1,²

¹Oncotarget, Buffalo, NY 14263, USA
²Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263

Received: May 25, 2009Accepted: December 30, 2009Published: December 31, 2009

Copyright: © 2009 Demidenko et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Development of agents that suppress aging (aging suppressants) requires quantification of cellular senescence. Cellular senescence in vitro is characterized by a large cell morphology and permanent loss of proliferative potential. When HT-1080 cells were arrested by p21, they continued to grow exponentially in size and became hypertrophic with a 15-fold increase in the protein content per cell. These changes were mirrored by accumulation of GFP (driven by CMV promoter) per cell, which also served as a marker of cellular hypertrophy. Preservation of proliferative potential (competence) was measured by an increase in live cell number, when p21 was switched off. While modestly decreasing hypertrophy in p21-arresrted cells, rapamycin considerably preserved competence, converting senescence into quiescence. Preservation of proliferative potential (competence) correlated with inhibition of S6 phosphorylation by rapamycin. When p21 was switched off, competent cells, by resuming proliferation, became progressively less hypertrophic. Preservation of proliferative potential is a sensitive and quantitative measure of suppression of mTOR-driven senescence.