Lsh-deficient murine embryonal fibroblasts show reduced proliferation with signs of abnormal mitosis.
Genomic hypomethylation and chromosomal instability are frequent characteristics of human cancer cells. Targeted deletion of Lsh leads to a global defect in genomic methylation, and Lsh-deficient mice die at birth with a reduced body weight. Here, we examine the growth pattern of embryonal fibroblasts derived from Lsh-/- mice. The absence of Lsh leads to a severe proliferative defect of fibroblasts with lower saturation density, early signs of senescence, and a lower frequency of immortalization. The impaired growth rate in vitro may be in part responsible for the small size of Lsh-deficient mice. In addition, Lsh-/- fibroblasts accumulated high centrosome numbers, formed multipolar spindles, displayed micronuclei formation, and elevated nuclear DNA content. A similar increase in centrosome abnormalities was observed when wild-type fibroblasts were treated with a DNA-demethylating agent, suggesting that genomic hypomethylation plays an important role in mitotic defects of Lsh-/- murine embryonal fibroblasts, possibly by altering chromatin structure. Because supernumerary centrosomes are a common feature in cancer cells, this Lsh-dependent pathway has the potential to contribute to genetic instability and chromosomal aberrations during tumor progression.
Fan
Tao
T
Laboratory of Molecular Immunoregulation, Basic Research Program, Science Applications International Corporation-Frederick, Inc., National Cancer Institute, Building 469, Frederick, MD 21702-1201, USA.
Yan
Qingsheng
Q
Huang
Jiaqiang
J
Austin
Sharon
S
Cho
Edward
E
Ferris
Doug
D
Muegge
Kathrin
K
D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002478:Cells, Cultured; D018385:Centrosome / Q000187:drug effects / Q000502:physiology; D004265:DNA Helicases / Q000172:deficiency* / Q000235:genetics; D000077209:Decitabine; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D051379:Mice; D008938:Mitosis / Q000235:genetics; D008941:Spindle Apparatus / Q000378:metabolism
D000077209:Decitabine; D004265:DNA Helicases; D001374:Azacitidine