title: Genetic interaction between Rb and K-ras in the control of differentiation and tumor suppression.
abstract: Although the retinoblastoma protein (pRb) has been implicated in the processes of cellular differentiation, there is no compelling genetic or in vivo evidence that such activities contribute to pRb-mediated tumor suppression. Motivated by cell culture studies suggesting that Ras is a downstream effector of pRb in the control of differentiation, we have examined the tumor and developmental phenotypes of Rb and K-ras double-knockout mice. We find that heterozygosity for K-ras (i) rescued a unique subset of developmental defects that characterize Rb-deficient embryos by affecting differentiation but not proliferation and (ii) significantly enhanced the degree of differentiation of pituitary adenocarcinomas arising in Rb heterozygotes, leading to their prolonged survival. These observations suggest that Rb and K-ras function together in vivo, in the contexts of both embryonic and tumor development, and that the ability to affect differentiation is a major facet of the tumor suppressor function of pRb.
authors.affiliation: Department of Medial Oncology, Dana-Farber Cancer Institute, 44 Binney St., Boston, MA 02115, USA.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Takahashi
authors.forename: Bernardo
authors.initials: B
authors.lastname: Contreras
authors.forename: Roderick T
authors.initials: RT
authors.lastname: Bronson
authors.forename: Massimo
authors.initials: M
authors.lastname: Loda
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ewen
mesh_terms: D000483:Alleles; D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002453:Cell Cycle; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D004396:Coloring Agents / Q000494:pharmacology; D003433:Crosses, Genetic; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras; D005838:Genotype; D006579:Heterozygote; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation; D017570:MyoD Protein / Q000378:metabolism; D009369:Neoplasms / Q000235:genetics*; D010902:Pituitary Gland / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D012260:Ribonucleases / Q000378:metabolism; D013997:Time Factors; D015533:Transcriptional Activation; D019076:Transgenes
chemical_list: D004396:Coloring Agents; D017570:MyoD Protein; D016160:Retinoblastoma Protein; D012260:Ribonucleases; D001973:Bromodeoxyuridine