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. 2014 Nov 7;9(11):e110844. doi: 10.1371/journal.pone.0110844

Figure 4. Tetraploid clones show resistance to cisplatin (CP) and ionizing radiation (IR)-induced apoptosis.

Figure 4

A) Five diploid clones isolated from Nutlin treated D3 cells (D3 Diploid) and D8 cells (D8 Diploid), and five tetraploid clones isolated from Nutlin treated D3 cells (D3 Tetraploid) and D8 cells (D8 Tetraploid) were untreated (NT) or exposed to CP (20 µM) or IR (10 Gy) for 48 hrs. The percentage of cells with sub-G1 DNA was determined. Shown are the mean results from three separate experiments, bars, Standard error (SE). * significance value (P<0.05). B) Tetraploid clones (T3, TD6) and their diploid counterparts (D3, D81B) were untreated (NT) or exposed to CP (20 µM) or IR (10 Gy) for 72 hrs. The percentage of cells with sub-G1 DNA (propidium iodide staining) was determined. Shown are the mean results from three separate experiments, bars, Standard error (SE). * significance value (P<0.05). C) The indicated diploid and tetraploid clones were untreated (NT) or exposed to CP (20 µM) or IR (10 Gy) for 24 hrs. p53, p21, and MDM2 protein levels were determined by immunoblotting and quantified. Numbers indicate the relative level of each protein. Actin was used as a loading control. D) The indicated diploid and tetraploid clones untreated (NT) or exposed to CP (20 µM) or IR (10 Gy) for 48 hrs. Cleaved PARP and Caspase-3 protein levels were determined by immunoblotting and quantified relative to the untreated. E) qRT-PCR was used to determine mRNA levels for the indicated genes in diploid (D3, D81B) and tetraploid (T3, TD6) clones that were either untreated (NT) or exposed to CP (20 µM) or IR (10 Gy) for 24 hrs. The level of each mRNA transcript in untreated diploid clones (D3 NT, D81B NT) was considered “1.0”, and all other values are plotted relative to it.