Effects of sequence and temperature of hyperthermia and peplomycin on human pharyngeal carcinoma KB cells in vitro.
To maximize the interactive effect, we examined the time sequence of high (above 43 degrees C) or low (below 43 degrees C)-hyperthermia and peplomycin (PEP)(0.5 microgram/ml). Simultaneous or post-hyperthermic PEP treatment at 44 degrees C resulted in a slight synergistic effect with thermoenhancement ratios (TER) of 1.30 or 1.34, respectively. However, at 42 degrees C, maximal interaction was obtained (TER = 10.19) when KB cells were simultaneously heated with PEP. Furthermore, pre-treatment at 44 degrees C for 25 min or 42 degrees C for 4 h enhanced PEP cytotoxicity more than that of post-treatment at 44 degrees C for 25 min or 42 degrees C for 4 h, respectively. However, chemoenhancement ratios (CER) of pre-treatment at 44 degrees C for 25 min and at 42 degrees C for 4 h were 19.1 and 3.5, respectively, although the isothermic dose decreased the cell count to 60% in both cases. These results indicated that simultaneous or post-hyperthermic PEP treatment with high-hyperthermia, and simultaneous PEP treatment with low-hyperthermia, are the most effective means of PEP thermochemotherapy with hyperthermia.
Ohtsubo
T
T
Department of Otolaryngology Fukui Medical School, Japan.
Saito
H
H
Noda
I
I
Sugimoto
C
C
Saito
T
T
Kano
E
E
D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D007624:KB Cells / Q000187:drug effects*; D017663:Peplomycin / Q000494:pharmacology*; D013696:Temperature; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects
D017663:Peplomycin