Protein expression following γ-irradiation relevant to growth arrest and apoptosis in colon cancer cells
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To study expression of proteins previously connected to radiotherapy response in rectal cancer patients, namely, p53, TAp73, ΔNp73, survivin and PRL-3, after irradiation in colon cancer cells to gain standing ground for further studies of pathways and mechanisms.
Three colon cancer cell lines (KM12C, KM12SM and KM12L4a) with one origin were radiated with γ-radiation. Radiosensitivity was determined with cell cycle, survival fraction at 5 Gy (SF5) and apoptosis analysis and protein expression by Western blot.
Following irradiation, KM12C showed no cell cycle arrest, and low SF5 and apoptosis, whilst KM12L4a showed high SF5 and apoptosis. KM12SM had moderate radiosensitivity. After irradiation, the anti-apoptotic ΔNp73 and mitosis-factor PRL-3 increased in KM12C and the radioresistance factor survivin increased in KM12L4a.
The cell lines seem to have evolved different protein patterns regarding the studied proteins and partly therefore developed different resistance mechanisms, less apoptosis for KM12C and continued proliferation for KM12L4a, after γ-irradiation.
KeywordsColon cancer cells p73 Survivin PRL-3 γ-Irradiation Apoptosis
The authors are grateful to Dan Josefsson, Sara Olsson and Erik Angland (Department of Radiophysics, University Hospital, Linköping, Sweden) for helping us with the radiation of the cells. The authors are also thankful to Karin Roberg (Division of Otorhinolaryngology, University Hospital, Linköping, Sweden) for sharing all her knowledge on cell culture and apoptosis. The cell lines used in the study was kindly provided by Prof. I. J. Fidler (M. D. Anderson Cancer Center, Houston, TX). The study was supported by grants from the Swedish Cancer Foundation, and the Health Research Council in the South-East of Sweden.
Conflict of interest statement
We declare that we have no conflict of interest.
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