Comparative study of human breast carcinoma MCF-7 cells differing in their resistance to doxorubicin: effect of ionizing radiation on apoptosis and TGF-beta production.
OBJECTIVE
The aim of the study was to investigate the survival and growth of human breast carcinoma MCF-7 cells with different sensitivity to doxorubicin and production of transforming growth factor beta-(TGF-beta) in dependence on the dose- and duration of X-ray in order to check if the cross-resistance to doxorubicin and radiation effects exists.


METHODS
Determination of cell number and valiability using trypan blue (0.1% (w/v)) exclusion method, Western blot analysis of p53 protein expression, biological testing of TGF-beta activity, lectinocytochemical analysis for apoptosis quantitative estimation in unirradiated and irradiated cells of both sublines of MCF-7 cells--sensitive (MCF-7(wt)) and resistant (MCF-7(DOX/R)) to doxorubicin.


RESULTS
It was found that doxorubicin-resistant breast cancer cells were also more refractory to X-radiation-dependent growth inhibition. There were revealed different effects of distinct doses of X-ray on p53 protein expression by cells of both sublines. The level of production of TGF-beta was compared in non-irradiated MCF-7 cells and in these cells exposed to X-radiation. It was shown that X-radiation increased TGF-beta activity in the conditioned medium of the irradiated cells of both doxorubicin-sensitive and -resistant lines.


CONCLUSIONS
The results of our study suggest that the biological effects of X-radiation on human breast cancer MCF-7 cells can be at least partly mediated by TGF-beta. Taking into account that TGF-beta is a potent natural immunosupressor, one may consider that an increased activity of this cytokine can intensify negative effects of X-radiation.
Institute of Cell Biology, National Academy of Sciences of Ukraine, Lviv 79005, Ukraine.
Inna
I
Chorna
Rostyslav
R
Bilyy
Leonid
L
Datsyuk
Rostyslav
R
Stoika
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000528:radiation effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014965:X-Rays
D000903:Antibiotics, Antineoplastic; D016212:Transforming Growth Factor beta; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin