[Proliferation and tumorigenity of the murine hepatoma cells irradiated with polychromatic visible and infrared light].

In experiments in vitro, the effect of the polychromatic visible (VIS) light combined with polychromatic infrared light (VIS-IR, 480-3400 nm) and the effect of the entire spectrum of VIS radiation (385-750 nm) on the viability and proliferative activity of the murine hepatoma cells MH22a. In experiments in vivo, changes of tumorigenic properties of cells MH22a have been studied after the same kinds of light exposure. It was shown that irradiation of the hepatoma cells with two kinds of polychromatic light at a wide range of doses (4.8-38.4 J/cm2) did not lead to an increase in the number of dead cells for 24-72 h of cultivation and did not cause retardation of the hepatoma cell proliferation. Moreover, VIS-IR light at a dose of 4.8 J/cm2 and VIS light at a dose 38.4 J/cm2 stimulated cell proliferation in 24 h. Proliferation index increased by 1.6 and 1.4 times, respective, and the time of the cell number doubling decreased as compared with control. Studying the tumorigenic properties of irradiated tumor cells showed that, for 30 days after transplantation, of hepatoma cells in 24 h after their irradiation with VIS-IR light at a dose of 4.8 J/cm2 to syngenic mice C3HA, the tumor volume reduced significantly (2.6-4 times) of all stages of observation. The incidence of tumor formation decreased, whereas the survival of the tumor-bearing mice did not change. Transplantation of cells irradiated with the same light at a dose of 9.6 J/cm2 did not lead to significant changes of the tumor volume, the tumor formation incidence, and animal survival. The main contribution to the antitumor effect of the VIS-IR light seems to be made by the VIS component, as transplantation of cells irradiated with VIS alone light at a dose of 38.4 J/cm2 also stimulating proliferation of hepatoma cells in vitro into mice resulted in a reduction of their tumorigenic properties. However, the IR component in the combined VIS-IR radiation enhanced the antitumor effect of the VIS light; as a result, this effect was manifested after use of doses 8 times lower (4.8 J/cm2) than in the case of the VIS light alone (38.4 J/cm2). Mechanisms of the decrease of tumorigenic properties of hepatoma cells after irradiation with polychromatic light ad doses stimulating their proliferation in vitro are studied.