Effects of HsRad51 overexpression on cell proliferation, cell cycle progression, and apoptosis.
Expression of the DNA repair and recombination protein human Rad51 (HsRad51) is increased in transformed cells and in cancer cell lines. In order to study the effects of acute HsRad51 ectopic overexpression on cell proliferation, cell cycle progression, and apoptosis, we generated clones of the human fibrosarcoma cell line HT1080 carrying a HsRad51 transgene under a repressible promoter. The HsRad51-overexpressing cells showed decreased plating efficiency and growth rate in a dose-dependent manner with regard to the degree of overexpression. An accumulation of HsRad51-overexpressing cells in G(2) was observed following release of cells after synchronization with double thymidine block. Moreover, the fraction of apoptotic cells measured by annexin V-FACS increased with the time of HsRad51 overexpression. In the light of these observations, sustained increased levels of HsRad51 may contribute to tumor progression by causing a selection for cells tolerant to the growth-suppressive and apoptosis-inducing effects of acute HsRad51 overexpression.
Flygare
J
J
Department of Biosciences, CNT, Novum, Karolinska Institute, SE-14157 Huddinge, Sweden. jenny.flygare@cnt.ki.se
Fält
S
S
Ottervald
J
J
Castro
J
J
Dackland AL
Hellgren
D
D
Wennborg
A
A
D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002999:Clone Cells / Q000166:cytology / Q000378:metabolism; D020552:Comet Assay; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000494:pharmacology; D005354:Fibrosarcoma / Q000378:metabolism; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D011401:Promoter Regions, Genetic; D051135:Rad51 Recombinase; D019076:Transgenes; D014410:Tumor Stem Cell Assay
D017304:Annexin A5; D004268:DNA-Binding Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004318:Doxycycline