Study type: Medical/biological study (experimental study)

Inhibition of DNA synthesis and enhancement of the uptake and action of methotrexate by low-power-density microwave radiation in L1210 leukemia cells. med./bio.

Published in: Cancer Res 1980; 40 (4): 1002-1005

Aim of study (acc. to author)

To study the effects of low power density microwave radiation (continuous and pulsed wave) on the uptake and action of methotrexate (MTX), the inhibtion of DNA synthesis in murine leukemia cells in vitro, and the MTX treatment of mice bearing this leukemia.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1 GHz
Modulation type: pulsed, CW
Exposure duration: 20 min
Exposure 2: 1 GHz
Modulation type: CW
Exposure duration: 20 min

Exposure 1

Main characteristics
Frequency 1 GHz
Type
Waveform
Exposure duration 20 min
Modulation
Modulation type pulsed, CW
Exposure setup
Exposure source
Setup falcon tissue culture flask (1.2 cm x 3.7 cm x 8 cm), kept below the antenna.
Additional info The samples were located at 15 to 20 mm from the horn antenna.
Parameters
Measurand Value Type Method Mass Remarks
power density 100 W/m² mean measured - PW irradiation.
power density 50 W/m² peak value measured - 500 W/m²; CW irradiation.
power density 111 mW/cm² peak value measured - 1210 W/m²; PW irradiation.

Exposure 2

Main characteristics
Frequency 1 GHz
Type
Waveform
Exposure duration 20 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 50 W/m² peak value measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

MTX concentrations of 0.2 µM and irradiation times of 20 min, the authors found that continuous wave low power density microwave exposure enhances the uptake of [³H]MTX as compared to nonirradiated controls. The enhancement is observed in only a small range of power densities (5 to 25 mW/cm²). Microwave exposure alone has an inhibitory effect on the [³H]dUrd incorporation into DNA. Compared to cell suspensions treated with MTX alone, groups treated with microwave irradiation followed by MTX exhibit an augmentation of inhibition of DNA synthesis. Combined treatment of L1210-bearing mice with microwave irradiation and MTX in vivo prolonged the duration of survival over that mice treated with MTX alone. This indicates a greater killing of leukemia cells. The results suggest that the therapeutic index of MTX may be improved by the use of microwave irradiation at low power densities.

Study character:

Study funded by