Low doses of gamma-rays can induce the expression of mdr gene.
We reported earlier that human cervical carcinoma HeLa cells exposed to 30 fractions of 0.5 Gy gamma-rays became resistant to cisplatin, methotrexate and vincristine, but retained the same sensitivity to gamma-rays and ultraviolet light. The aim of this study was to examine whether a small number of gamma-ray fractions, with a lower daily dose, may also change the sensitivity of preirradiated cells to different cytotoxic drugs. Using the modified MTT staining procedure, we found that cells preirradiated with 5 or 10 daily fractions of only 0.17 Gy gamma-rays did not alter their sensitivity to mitomycin, cisplatin, methotrexate, 5-fluorouracil, etoposide and doxorubicin. However, 10 fractions of gamma-rays induced resistance to vincristine and vinblastine. Our immunocytochemical experiments using monoclonal antibody JSB-1 show that the plasma membrane P-glycoprotein is involved in the induced resistance to Vinca alkaloids.
Osmak
M
M
Department of Molecular Medicine, Ruder Bosković Institute, Zagreb, Croatia.
Miljanić
S
S
Kapitanović
S
S
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance / Q000235:genetics* / Q000528:radiation effects*; D004354:Drug Screening Assays, Antitumor; D005720:Gamma Rays; D015870:Gene Expression; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D014748:Vinca Alkaloids / Q000494:pharmacology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D014748:Vinca Alkaloids