The following cells were used: (1) Normal and cancerous standard permanent cell lines represented by primary normal human dermal fibroblasts (NHDFs, PromoCell, Heidelberg, Germany) isolated from the dermis of the juvenile foreskin or adult skin and highly radioresistant U-87 glioblastoma cells (ATCC HTB-14, LGC Standards, United Kingdom), respectively; and (2) Tumor and tumor-adjacent primary cell cultures isolated from patients with squamous cell cancer of head and neck (tumor and tumor-adjacent tissues). While the permanent cell lines represented biologically homogeneous and technically relatively easy samples, tumor cell primary cultures were considered highly heterogeneous and challenging samples.
The protocol for patient primary culture isolation was described in [78] (link). The primary culture was cultivated in RPMI-1640 medium with Pen/Strep antibiotic solution (PAA Laboratories GmbH, Austria) and 10% fetal bovine serum (FBS, Biochrom, USA), at 37 °C and 5.0% CO2 in a humidified atmosphere up to 50% confluence. NHDF and U-87 cells were grown in Dulbecco's modified essential medium (DMEM, Life Technologies) supplemented with 10% fetal calf serum (FCS) and a 1% gentamicin–glutamine solution (all reagents from Sigma-Aldrich).
The protocol for patient primary culture isolation was described in [78] (link). The primary culture was cultivated in RPMI-1640 medium with Pen/Strep antibiotic solution (PAA Laboratories GmbH, Austria) and 10% fetal bovine serum (FBS, Biochrom, USA), at 37 °C and 5.0% CO2 in a humidified atmosphere up to 50% confluence. NHDF and U-87 cells were grown in Dulbecco's modified essential medium (DMEM, Life Technologies) supplemented with 10% fetal calf serum (FCS) and a 1% gentamicin–glutamine solution (all reagents from Sigma-Aldrich).