Photoradiation therapy with protoporphyrin disodium for human hepatocelluar carcinoma transplanted nude mice

In the present report, we studied about in vivo anti-tumour effect by photoradiation therapy (PRT) with proroporphyrin disoduim (PPNa) and hematoporphyrin derivative (HpD). To investigate anti-tumour effect by PRT, human hepatocellular carcinomas transplanted to the flanks of BALB/c/nu nu mice were injected intratumorrally 2 mg of HpD, PPNa or 0.9% NaC1 48hours before laser irradiation (514.5 nm, 0.1w, 30minutes.) The results revealed that laser irradiation alone had no anti-tumour effect, while PRT with PPNa had intense anti-tumour effect (p<0.05) more than PRT with HpD. These results showed that PRT with PPNa may have clinical use. INTRODUCTION Recently, considerable interest has been aroused by possibility of inducing the regression of tumours in experimental animals and humam by PRT. In order to extend PRT to wide clinical use, it will be worthwhile to find out the new photosensitizer which is less toxic and rather strong. This report describes the experiments in this field and demonstrates that human hepatocellular carcinomas in nude mice can be remarkably destoroyed by the combination of PPNa and an argon laser. MATERIALS AND METHODS Cell cultures and animals: Human hepatocellar carcinoma cells maintained in RPMI 1640 medium (GIBCO, Grand Island, N.Y.) containing 10% fetal calf serum (Microbiological Associates Inc.) Cells were rinsed and suspended in 0.9% NaC1 and lx107 cells were injected to flanks s.c. of BALB/c/nu nu mice. After tumour cell injections, the volume of the tumour was determined from caliper measurements of length, width and height of the tumour and the empirical fomula (Loney, et al., 1975) V=1/2LWH. Photosensitizer: Protoporphyrin disodium (TOKYO TANABE, Co., Ltd., Japan) was adjusted 10mg/m1 in distilled water. Hematoporphirin derivative (5mg/ml) was obtained from Roswell Park Memorial Institue (Buffalo, N.Y.) 第4巻 第1号 1984年3月 日本 レーザー医学会誌 93 Laser irradiation: An argon laser (COHERENT, Supergraphite CR-8) was transmitted by a flexible quarts fiber and irradiated through 23G needle intratumorrally with an energy of 0.1W and the irradiation time was 30 minutes. RESULTS Tumour regression curve: As shown in Fig. I, neither laser irradiation group (514.5 nm, 0.1W, 30 minutes) nor PPNa treatment group, 2 mg/animal, intratumoral injection were different from control group, while photoradiation groups had tumour regression after treatment. And PRT with PPNa group had marked anti-tumour effect more than PRT with HpD group (Fig. 2). Histological study: After experiments, all animals were sacrificed and histological studies were performed. Irradiations at 0.1W for 30 minutes produced no histological change in three tumours on mice which not injected PPNa, whereas injection of a total dose of 2mg PPNa or HpD resulted in tumour regression or complete disappearance of tumour. DISCUSSION We have already reported that PPNa might be effectiveas a photosensi-tizer.In vitro 51Cr release assayhad revealedthat PPNa alone had nocytocidaleffect,while laserirradiationin the presenceof PPNahad intense cytocidaleffect morethan HpD. Furthermore,this studyrevealedthat PRT with PPNa hadremarkableanti-tumoureffect in vivo.Therefore,PPNa may be used as a new photosensitizerfor photoradiationtherapy for cancer.REFERENCES1. Dougherty,T.J., et al. J. NatlCancer Inst., 55, 115, 1975.2. Dougherty,T.J., et al. CancerRes., 38, 2628, 1978.3. HAYATA, Y., et al. Chest, 81, 269,1982.4. H. KASHIMURA, H. FUKUTOMI, et al.,The Journal of Japan Society forlaser Medicine,3, 496, 1982.Fig. 1