Figure 1

Phenylbutyrate sensitizes cisplatin-resistant head and neck cancer cell lines. (A) The head and neck cancer cell lines UM-SCC-1, -6 and -25 were treated with 2 mM phenylbutyrate (PB) for 5 days, 5 μM cisplatin for 3 days or pretreated with phenylbutyrate for 48 hrs followed by the addition of 5 μM cisplatin for 3 days. After treatments, cell viability/proliferation from each cell sample was determined using the WST-1 assay and values are expressed as a percentage of control cells. Error bars represent the standard error of the mean of triplicate samples. (B) Cells treated as in (A) were collected (both floating and attached cells), fixed and stained with propidium iodide and cells with sub-G1 DNA content were counted as apoptotic cells. The values are expressed as percentage of sub-G1 cells of total cells analyzed and error bars represent the standard error of the mean of triplicate samples. (C) Adherent UM-SCC-1 cells treated as in (A) were trypsinized and seeded at low densities in fresh media and incubated for 14 days. Clonogenic survival (%) is expressed as the fraction of surviving cells compared to control cells and expressed as a percentage with error bars represent the standard error of the mean of triplicate samples.