Usefulness of combined treatment with mild temperature hyperthermia and/or tirapazamine in the treatment of solid tumors: its independence of p53 status.
Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or with neo vector as a control (SAS/neo) were inoculated subcutaneously into both hind legs of Balb/cA nude mice. Mice bearing the tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all proliferating (P) cells in the tumors. The mice then received tirapazamine (TPZ) with or without mild temperature hyperthermia (40 degrees C, 60 min) (MTH), gamma-ray irradiation with or without MTH and/or TPZ, cisplatin (CDDP) with or without MTH and/or TPZ, or paclitaxel (TXL) with or without MTH and/or TPZ. After each treatment, the tumors were excised, minced and trypsinized. The tumor cell suspensions thus obtained were incubated with a cytokinesis blocker (cytochalasin-B), and the micronucleus (MN) frequency in cells without BrdU labeling (i.e., quiescent (Q) cells) was determined by using immunofluorescence staining for BrdU. Meanwhile, 6 h after gamma-ray irradiation or 24 h after other cytotoxic treatments, tumor cell suspensions obtained in the same manner were used for determining the frequency of apoptosis in Q cells. The MN frequency and apoptosis frequency in total (P+Q) tumor cells were determined from the tumors that were not pretreated with BrdU. On the whole, gamma-ray irradiation and CDDP injection induced a higher frequency of apoptosis and lower frequency of MN in SAS/neo cells than SAS/mp53 cells. There were no apparent differences in the induced frequency of apoptosis and MN between SAS/neo and SAS/mp53 cells after TPZ or TXL treatment. MTH sensitized cells to TPZ-inducing cytotoxicity more markedly in SAS/mp53 and Q cells than in SAS/neo cells and total cells, respectively. In gamma-ray irradiation and CDDP treatment, the enhancement in combination with MTH and/or TPZ was more remarkable in SAS/mp53 cells and Q cells than in SAS/neo and total tumor cells, respectively. Also in the case of TXL treatment, the combination with MTH and/or TPZ induced a slightly greater enhancement effect in SAS/mp53 cells and Q cells. In view of the difficulty in controlling mutated p53 status tumors and intratumor Q cells, combination treatment with MTH and/or TPZ as a cooperative modality in cancer therapy is considered to have potential for controlling solid tumors as a whole.
Masunaga
Shin-ichiro
S
Radiation Oncology Research Laboratory, Research Reactor Institute, Kyoto University, Noda, Kumatori-cho, Sennan-gun, Osaka 590-0494. smasuna@rri.kyoto-u.ac.jp
Ono
Koji
K
Takahashi
Akihisa
A
Ohnishi
Ken
K
Ohnishi
Takeo
T
Suzuki
Minoru
M
Nagata
Kenji
K
Kinashi
Yuko
Y
Nagasawa
Hideko
H
Uto
Yoshihiro
Y
Hori
Hitoshi
H
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D001973:Bromodeoxyuridine / Q000032:analysis; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics / Q000473:pathology* / Q000532:radiotherapy / Q000628:therapy; D015687:Cell Hypoxia; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D003131:Combined Modality Therapy; D004249:DNA Damage; D005720:Gamma Rays; D016158:Genes, p53; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000473:pathology*; D006801:Humans; D006979:Hyperthermia, Induced; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015162:Micronucleus Tests; D009363:Neoplasm Proteins / Q000172:deficiency / Q000502:physiology; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000077704:Tirapazamine; D014227:Triazines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured / Q000637:transplantation; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000502:physiology; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D009363:Neoplasm Proteins; D011838:Radiation-Sensitizing Agents; D014227:Triazines; D016159:Tumor Suppressor Protein p53; D000077704:Tirapazamine; D001973:Bromodeoxyuridine; D017239:Paclitaxel; D002945:Cisplatin