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Mol. Cell. Biol., Aug 1995, 4249-4259, Vol 15, No. 8
AM Yahanda, JM Bruner, LA Donehower and RS Morrison
Loss or mutation of p53 is thought to be an early event in the malignant
transformation of many human astrocytic tumors. To better understand the
role of p53 in their growth and transformation, we developed a model
employing cultured neonatal astrocytes derived from mice deficient in one
(p53 +/-) or both (p53 -/-) p53 alleles, comparing them with wild-type (p53
+/+) cells. Studies of in vitro and in vivo growth and transformation were
performed, and flow cytometry and karyotyping were used to correlate
changes in growth with genomic instability. Early-passage (EP) p53 -/-
astrocytes achieved higher saturation densities and had more rapid growth
than EP p53 +/- and +/+ cells. The EP p53 -/- cells were not transformed,
as they were unable to grow in serum-free medium or in nude mice. With
continued passaging, p53 -/- cells exhibited a multistep progression to a
transformed phenotype. Late-passage p53 -/- cells achieved saturation
densities 50 times higher than those of p53 +/+ cells and formed large,
well- vascularized tumors in nude mice. p53 +/- astrocytes exhibited early
loss of the remaining wild-type p53 allele and then evolved in a manner
phenotypically similar to p53 -/- astrocytes. In marked contrast,
astrocytes retaining both wild-type p53 alleles never exhibited a
transformed phenotype and usually senesced after 7 to 10 passages. Dramatic
alterations in ploidy and karyotype occurred and were restricted to cells
deficient in wild-type p53 following repeated passaging. The results of
these studies suggest that loss of wild-type p53 function promotes genomic
instability, accelerated growth, and malignant transformation in
astrocytes.
Copyright © 1995, American Society for Microbiology
Astrocytes derived from p53-deficient mice provide a multistep in vitro model for development of malignant gliomas
Department of Surgical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, USA.
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