Inhibition of tumor growth in mice by microwave hyperthermia, Streptolysin S and Colcemide

Abstract

Mice with transplanted Sarcoma 180 were irradiated 2 hours daily; 1st through 14th day after transplantation with 3‐GHz microwaves at a power density of 40 mW/cm2. The irradiation resulted in an increase of rectal temperature by 3 to 4 °C. Some animals that were exposed to radiation received daily an IP injection of 1 mg/kg of Colcemide (synthetic Colchicine) or of 0.5 mG/kg of purified Streptolysin S or of both compounds. On the 14th day after transplantation half of each group of mice received 1 μCi/g IP 3H‐thymidine; the other halves 3H‐uridine, 1 μCi/g IP. Three hours later all of the mice were killed; the tumors were dissected, then measured for mass and radioactivity. Mean tumor mass, number of regressed tumors and averaged counts of radioactivity were calculated for each group. Microwave hyperthermia resulted in reduction of tumor mass by about 40%; the reduction was enhanced when microwave hyperthermia was combined with Colcemide and/or Streptolysin S. In the combined treatment with all three factors the tumor mass was reduced by about 70%. Inhibition of the tumor's growth was accompanied by reduced uptake of 3H‐thymidine and 3H‐uridine into the tumorous tissues.

Heat treatment induces an increase in intracellular cyclic AMP content in human epidermoid A-431 cells

“…Heat exposure acts primarily at the plasma membrane, and causes changes in many intracellular parameters [1]. For example, heat induces an intracellular acidification, due partly to an inhibition of the Na+/H+ antiporter [2,3].…”

Retarded tumor growth and greater longevity in mice after fetal irradiation by 2450‐MHz microwaves

“…They compared data from two comparably heated groups of mice with tumors and concluded that remarkably high cure rates in vivo in the face of high rates of survival of the malignant cells in vitro imply a response by the host. That appropriately graded and timed hyperthermia can enhance immunological reactivity is a matter of record [Mondovi et al, 1972;Czerski, 1975;Huang, Engle, and Elder, 1977;Liburdy, 1977;Szmigielski et al, 1977;Wiktor-Jedrzejczak et al, 19771, but all such reports known by us have been based on hyperthermia that has been introduced after experimental induction of neoplasms or shortly before tests of immunological reactivity. We report here data on the effects of in utero and early postnatal hyperthermia that indirectly support the view that enhanced immunological competency is a long-term sequela of the early febrile experience.…”