TY - JOUR
T1 - Resistance to bleomycin in cancer cell lines is characterized by prolonged doubling time, reduced DNA damage and evasion of G2/M arrest and apoptosis
AU - Wang, Qi
AU - Cui, Kangping
AU - Espin-Garcia, Osvaldo
AU - Cheng, Dangxiao
AU - Qiu, Xiaoping
AU - Chen, Zhuo
AU - Moore, Malcolm
AU - Bristow, Robert G.
AU - Xu, Wei
AU - Der, Sandy
AU - Liu, Geoffrey
PY - 2013/12/4
Y1 - 2013/12/4
N2 - Background: To establish, characterize and elucidate potential mechanisms of acquired bleomycin (BLM) resistance using human cancer cell lines. Seven BLM-resistant cell lines were established by exposure to escalating BLM concentrations over a period of 16-24 months. IC50 values and cell doubling times were quantified using a real time cytotoxicity assay. COMET and γ-H2AX assays, cell cycle analysis, and apoptosis assessment further investigated the mechanisms of BLM resistance in these cell lines. Results: Compared with parental cell lines, real time cytotoxicity assays revealed 7 to 49 fold increases in IC50 and a mean doubling time increase of 147% (range 64%-352%) in BLM-resistant sub-clones (p<0.05 for both). Higher maintenance BLM concentrations were associated with higher IC50 and increased doubling times (p<0.05). Significantly reduced DNA damage (COMET and γ-H2AX assays), G2/M arrest, and apoptosis (p<0.05 for each set of comparison) following high-dose acute BLM exposure was observed in resistant sub-clones, compared with their BLM-sensitive parental counterparts. Three weeks of BLM-free culturing resulted in a partial return to BLM sensitivity in 3/7 BLM-resistant sub-clones (p<0.05). Conclusion: Bleomycin resistance may be associated with reduced DNA damage after bleomycin exposure, resulting in reduced G2/M arrest, and reduced apoptosis.
AB - Background: To establish, characterize and elucidate potential mechanisms of acquired bleomycin (BLM) resistance using human cancer cell lines. Seven BLM-resistant cell lines were established by exposure to escalating BLM concentrations over a period of 16-24 months. IC50 values and cell doubling times were quantified using a real time cytotoxicity assay. COMET and γ-H2AX assays, cell cycle analysis, and apoptosis assessment further investigated the mechanisms of BLM resistance in these cell lines. Results: Compared with parental cell lines, real time cytotoxicity assays revealed 7 to 49 fold increases in IC50 and a mean doubling time increase of 147% (range 64%-352%) in BLM-resistant sub-clones (p<0.05 for both). Higher maintenance BLM concentrations were associated with higher IC50 and increased doubling times (p<0.05). Significantly reduced DNA damage (COMET and γ-H2AX assays), G2/M arrest, and apoptosis (p<0.05 for each set of comparison) following high-dose acute BLM exposure was observed in resistant sub-clones, compared with their BLM-sensitive parental counterparts. Three weeks of BLM-free culturing resulted in a partial return to BLM sensitivity in 3/7 BLM-resistant sub-clones (p<0.05). Conclusion: Bleomycin resistance may be associated with reduced DNA damage after bleomycin exposure, resulting in reduced G2/M arrest, and reduced apoptosis.
UR - http://www.scopus.com/inward/record.url?scp=84891781779&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0082363
DO - 10.1371/journal.pone.0082363
M3 - Article
C2 - 24349265
AN - SCOPUS:84891781779
SN - 1932-6203
VL - 8
JO - PLoS ONE
JF - PLoS ONE
IS - 12
M1 - e82363
ER -
