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Apoptosis-stimulating protein of p53 (ASPP2) heterozygous mice are tumor-prone and have attenuated cellular damage–response thresholds

By Kerstin M. Kampa, Jared D. Acoba, Dexi Chen, Joel Gay, Hunjoo Lee, Kelly Beemer, Emerson Padiernos, Nataya Boonmark, Zhiyi Zhu, Alice C. Fan, Alexis S. Bailey, William H. Fleming, Christopher Corless, Dean W. Felsher, Louie Naumovski and Charles D. Lopez

Abstract

The expression of ASPP2 (53BP2L), a proapoptotic member of a family of p53-binding proteins, is frequently suppressed in many human cancers. Accumulating evidence suggests that ASPP2 inhibits tumor growth; however, the mechanisms by which ASPP2 suppresses tumor formation remain to be clarified. To study this, we targeted the ASPP2 allele in a mouse by replacing exons 10–17 with a neoR gene. ASPP2−/− mice were not viable because of an early embryonic lethal event. Although ASPP2+/− mice appeared developmentally normal, they displayed an increased incidence of a variety of spontaneous tumors as they aged. Moreover, γ-irradiated 6-week-old ASPP2+/− mice developed an increased incidence of high-grade T cell lymphomas of thymic origin compared with ASPP2+/+ mice. Primary thymocytes derived from ASPP2+/− mice exhibited an attenuated apoptotic response to γ-irradiation compared with ASPP2+/+ thymocytes. Additionally, ASPP2+/− primary mouse embryonic fibroblasts demonstrated a defective G0/G1 cell cycle checkpoint after γ-irradiation. Our results demonstrate that ASPP2 is a haploinsufficient tumor suppressor and, importantly, open new avenues for investigation into the mechanisms by which disruption of ASPP2 pathways could play a role in tumorigenesis and response to therapy

Topics: Biological Sciences
Publisher: National Academy of Sciences
OAI identifier: oai:pubmedcentral.nih.gov:2657427
Provided by: PubMed Central
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