| Objective:To observe the effect of Photodynamic therapy(PDT)mediated by hematoporphrphyrin derivative(HpD)on tumors from implanted breast cancer cells in mice and investigates mechanisms of actions of PDT which might offer basement for clinical therapy of breast cancer.Methods:1.The mice were divided into four groups:group of normal control,three groups of treatment marked A,B and C(with treatment of the same concentration of Photosensitizer and different dosages of laser are as follow: HpD 1.0mg/ml,75J/cm2;HpD 1.0mg/ml,150J/cm2;HpD 1.0mg/ml,300J/cm2). These transplantation tumors in mice were treated with HpD-PDT.2.The volumes of transplantation tumors were measured,and then the change of morphology was observed under light microscope and electron microscope. 3.VEGF,PCNA,Bax and Bcl-2 Proteinum were detected by technology of immunohistochemistry at the points of 1d,3d,7d and 14d after treatments of HpD-PDT.Results:1.The growth of transplantation tumors in all groups was inhibited in different degrees after treatments of HpD-PDT,especially in group C.2.The strongest action on tumor vessel was observed at the 1stday after treatment of HpD-PDT.The most typical apoptosis occurred at 3rdday after treatment.The extent of cellular necrosis enlarged day after day.3.There was significant difference in the positive VEGF expression among all groups(P＜0.05).The positive expression in group C(HPD 1.0mg/ml,300J/cm2)was observed most obviously decreasing along with time going.There was significant difference in the positive PCNA expression among all groups(P＜0.05).The positive expression in group C(HpD 1.0mg/ml,300J/cm2)was observed most obviously decreasing along with time going.There was little differece in the positive Bax expression at points of 1d and 3d after treatment(P＞0.05).At 7d and 14d there were significant differences among all groups(P＜0.05).The positive expression in group C(HpD 1.0mg/ml,300J/cm2)was observed most obviously decreasing along with time going.There was significant difference in the positive Bcl-2 expression among all groups(P＜0.05).The positive expression in group C(HpD 1.0mg/ml,300J/cm2)was observed most obviously decreasing along with time going.The ratio of Bax/Bcl-2 was significantly different among groups at 1st day and 3rdday after treatment(P＜0.05),especially in group C.At points of 7d and 14d there were no significant difference(P＞0.05).Conclusions:1.HpD-PDT can inhibit the growth of breast cancer by the way of cutting blood supplying.The mechanisms may be to promote thrombogenesis by primary destroying on microcirculation system.In the other hand,HpD-PDT perhaps can inhibit neovascularization in tumor through down-regulating the expression of VEGF.2.HpD-PDT may inhibit the expression of PCNA in breast cancer cells so as to block the proliferation of tumor cells and promote the process of cellular necrosis.3.HpD-PDT may induce apoptotic by decreasing the Bcl-2 expression in breast cancer cells and up-regulating the ratio of Bax/Bcl-2.4.HpD-PDT was utilized to cure breast cancer transplantation tumors in mice which showed dose-effect associativity. The most effective light intensity was 300J/cm2.
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