The Effects Of ALA-PDT And DPC4 Gene Transfection Combination On The Cell Cycle Of Colon Carcinoma

Objective and background: Colorectal cancer is a common malignant tumor, its incidence rate and mortality rate both situated the second in the digestive tract tumor disease in China. With the living standard raising and the changes of dietary pattern, the incidence rate of colorectal cancer, especially the colon cancer, presented an ascending tendency in recent years. At present, the incidence rate of colon cancer has surpassed the rectal cancer, it obviously changes the primarily pattern that the incidence rate of rectal cancer ranked as the first among all colorectal cancer since long ago in China. This tendency is consistent with the situation of western developed country. At present, etiology and pathogenesis of colorectal cancer and the mechanism of the disease incidence are still not completely expounded; surgery is still the main and effective methods to treat the disease. However, the rate of 5 years survival has not been improved. With the development of molecular biology, distinct improvement has been made on gene therapy of tumor. It is become a developing direction that the complex therapy, such as surgery is combined with radiotherapy, chemotherapy, gene therapy and so on, on the treatment of colorectal cancer.Tumor is concerned with a disease of cell cycle, which abnormal proliferation of cells caused by the cell cycle out of control is a main origin of tumor. Therefore, it is an effective method to restrain the multiplication of tumor cell and delay the tumor development, by regulating the growth cycle of tumor cell. As the most important key point of cell cycle development, the G1/S check point which located between G1 and S phase is an ideal contacted point to interfere in tumor developing.Photodynamic therapy (PDT) is a treatment for abnormal cells and tissues, by exposed abnormal cells or tissues to photosensitizer followed by irradiation with visible light of the appropriate wavelength, Upon light absorption, the photosensitizer undergoes excitation that brings it in its excited triplet state and produce reactive oxygen species such as singlet state oxygen in cells and to kill them. The mechanism of photodynamic therapy is not well defined, but it is reported that PDT resulted in arrest the cell cycle in G0-G1 phase and apoptosis in tumor cell.