title: Differential oncogenic Ras signaling and senescence in tumor cells.
abstract: Several studies have shown that forced expression of oncogenic H-ras can induce a senescence-like permanent growth arrest in normal cells. Here we report that expression of oncogenic H-ras in human osteosarcoma U2OS cells also resulted in a senescence-like flat and enlarged cell morphology and permanent growth arrest. In contrast to normal human fibroblasts, U2OS cells were arrested independently of the p16 and ARF tumor suppressors. Treatment with a MEK inhibitor or a p38MAPK inhibitor interrupted oncogenic H-ras-induced growth arrest in U2OS cells, suggesting that activation of MAPK pathways is important. To further determine whether this process is unique to oncogenic H-ras signaling, we examined the effect of oncogenic K-ras on normal cells and human osteosarcoma cells. Similar to oncogenic H-ras, oncogenic K-ras also induced senescence in normal fibroblasts, while transforming immortalized mouse fibroblasts. However, in contrast to oncogenic H-ras, oncogenic K-ras failed to induce a permanent growth arrest in osteosarcoma U2OS cells. Additionally, cells transduced with oncogenic K-ras exhibited distinguishable cellular changes compared to those transduced with oncogenic H-ras. In summary, we report for the first time that oncogenic H-ras signaling can trigger a senescence-like growth arrest in tumor cells, independent of the p16 and ARF tumor suppressors. This result suggests that tumor cells may harbor a senescence-like program that can be activated by ras signaling. Moreover, our study uncovered a cell type-dependent differential response to oncogenic K-ras, as compared to oncogenic H-ras.
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
authors.forename: Teeru
authors.initials: T
authors.lastname: Bihani
authors.forename: Douglas X
authors.initials: DX
authors.lastname: Mason
authors.forename: Tonya J
authors.initials: TJ
authors.lastname: Jackson
authors.forename: Shang Chiung
authors.initials: SC
authors.lastname: Chen
authors.forename: Benjamin
authors.initials: B
authors.lastname: Boettner
authors.forename: Athena W
authors.initials: AW
authors.lastname: Lin
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D018816:Genes, cdc / Q000187:drug effects / Q000502:physiology*; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014161:Transduction, Genetic; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D018631:ras Proteins