Preliminary studies of the effects of gadolinium texaphyrin on the growth and radiosensitivity of EMT6 cells in vitro.
OBJECTIVE
To investigate the effects of gadolinium texaphyrin (GdTx) on the growth and radiation response of cells in vitro, in a limited set of experiments designed to examine some areas of controversy concerning the effects of this compound.


METHODS
Exponentially growing cultures of EMT6 mouse mammary tumor cells, grown in Dulbecco's Modified Eagle's Medium with 10% dialyzed fetal bovine serum, were treated with GdTx either prepared from powder or obtained as a solution similar to that used clinically, in either the presence or absence of equimolar ascorbic acid. Cell viability was measured using a clonogenic assay.


RESULTS
Treatment with GdTx in the presence of ascorbic acid dramatically altered the growth, appearance, and behavior of the cells; treatment with GdTx in the absence of ascorbic acid had only minimal effects. The effects of the powdered drug and the solution were similar. GdTx used with equimolar ascorbic acid altered the radiation dose-response curves of cells irradiated under aerobic and hypoxic conditions; no significant changes were observed without ascorbic acid.


CONCLUSIONS
The details of the protocols used in experiments examining the effects of GdTx have major effects on the outcomes. Our results suggest that differences in the protocols used by different groups in past studies with GdTx probably were important in producing the disparate results reported previously.
Rockwell
Sara
S
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520-8040, USA. sara.rockwell@yale.edu
Donnelly
Erling T
ET
Liu
Yanfeng
Y
Tang
Li-Qun
LQ
D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D003470:Culture Media; D004307:Dose-Response Relationship, Radiation; D004354:Drug Screening Assays, Antitumor; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000532:radiotherapy*; D008665:Metalloporphyrins / Q000627:therapeutic use*; D051379:Mice; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use*; D011853:Radiobiology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000528:radiation effects
D000970:Antineoplastic Agents; D003470:Culture Media; D008665:Metalloporphyrins; D011838:Radiation-Sensitizing Agents; C437683:motexafin gadolinium