TY - JOUR
T1 - Low-dose dose-response for reduced cell viability after exposure of human keratinocyte (HEK001) cells to arsenite
AU - Bogen, Kenneth T.
AU - Arnold, Lora L.
AU - Chowdhury, Aparajita
AU - Pennington, Karen L.
AU - Cohen, Samuel M.
N1 - Funding Information:
The research was funded (without input to study design, data analysis, or conclusions) by Electric Power Research Institute (EPRI) contracts MA10003705 (Exponent) and MA10003723 (UNMC). Our sincere thanks to Dr. Mirek Styblo at the University of North Carolina for the analysis of the arsenic concentrations in Dulbecco's PBS and the cell culture medium and to Dr. Bhavana Dave and the Cytogenetics Laboratory at the University of Nebraska Medical Center for the karyotyping of the HEK001 cell line.
Publisher Copyright:
© 2016
PY - 2017
Y1 - 2017
N2 - The in vitro arsenite (AsIII) cytotoxicity dose-response (DR) of human keratinocytes (HEK001) was examined at greater statistical resolution than ever previously reported using the MTT assay to determine cell viability. Fifty-four 96-well plates were treated with AsIII concentrations of 0.25, 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 25, or 30 μM. Because of unexpected variation in viability response patterns, a two-stage DR analysis was used in which data on plate-specific viability (%), estimated as 100% times the ratio of measured viability in exposed to unexposed cells, were fit initially to a generalized lognormal response function positing that HEK001 cells studied consisted of: a proportion P of relatively highly sensitive (HS) cells, a proportion Po of relatively resistant cells, and a remaining (1–P–Po) fraction of typical-sensitivity (TS) cells exhibiting the intermediate level of AsIII sensitivity characteristic of most cells in each assay. The estimated fractions P and Po were used to adjust data from all 54 plates (and from the 28 plates yielding the best fits) to reflect the condition that P = Po = 0 to provide detailed DR analysis specifically for TS cells. Four DR models fit to the combined adjusted data were each very predictive (R2 > 0.97) overall but were inconsistent with at least one of the data set examined (p < 10−5). Adjusted mean responses at ≤3 μM were approximately equal (p > 0.30) and exceeded 100% significance (p ≤ 10−6). A low-dose hormetic model provided the best fit to the combined adjusted data for TS cells (R2 = 0.995). Marked variability in estimates of P (the proportion of apparent HS cells) was unexpected, not readily explained, and warrants further study using additional cell lines and assay methods, and in vivo.
AB - The in vitro arsenite (AsIII) cytotoxicity dose-response (DR) of human keratinocytes (HEK001) was examined at greater statistical resolution than ever previously reported using the MTT assay to determine cell viability. Fifty-four 96-well plates were treated with AsIII concentrations of 0.25, 0.5, 1, 2, 3, 4, 5, 7, 10, 15, 20, 25, or 30 μM. Because of unexpected variation in viability response patterns, a two-stage DR analysis was used in which data on plate-specific viability (%), estimated as 100% times the ratio of measured viability in exposed to unexposed cells, were fit initially to a generalized lognormal response function positing that HEK001 cells studied consisted of: a proportion P of relatively highly sensitive (HS) cells, a proportion Po of relatively resistant cells, and a remaining (1–P–Po) fraction of typical-sensitivity (TS) cells exhibiting the intermediate level of AsIII sensitivity characteristic of most cells in each assay. The estimated fractions P and Po were used to adjust data from all 54 plates (and from the 28 plates yielding the best fits) to reflect the condition that P = Po = 0 to provide detailed DR analysis specifically for TS cells. Four DR models fit to the combined adjusted data were each very predictive (R2 > 0.97) overall but were inconsistent with at least one of the data set examined (p < 10−5). Adjusted mean responses at ≤3 μM were approximately equal (p > 0.30) and exceeded 100% significance (p ≤ 10−6). A low-dose hormetic model provided the best fit to the combined adjusted data for TS cells (R2 = 0.995). Marked variability in estimates of P (the proportion of apparent HS cells) was unexpected, not readily explained, and warrants further study using additional cell lines and assay methods, and in vivo.
KW - Arsenate
KW - Arsenic
KW - Cell culture
KW - Cell death
KW - Cytotoxicity
KW - HEK001 cells
UR - http://www.scopus.com/inward/record.url?scp=85006964937&partnerID=8YFLogxK
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U2 - 10.1016/j.toxrep.2016.12.003
DO - 10.1016/j.toxrep.2016.12.003
M3 - Article
C2 - 28959622
AN - SCOPUS:85006964937
VL - 4
SP - 32
EP - 38
JO - Toxicology Reports
JF - Toxicology Reports
SN - 2214-7500
ER -