| Radiotherapy is an important local treatment method of malignant tumor treatment process. However, there are many natural defects of the conventional rays in the process of irradiation. As the distribution of their depth dose presents exponential damping form, it will cause certain damages to healthy tissues around the tumor while arriving at the tumor zone to destroy the tumor cells. Clinically, in order to avoid irradiation damage to normal tissues, the total irradiation dose is usually reduced. Recent research indicates that it may enhance the malignant tumor’s ability to spread when the conventional rays receive inadequate irradiation dosage. Therefore, people actively seek out a superior ray for radiation therapy-the heavy ion beam. Heavy ion is a kind of ray with high linear energy transfer (LET), and it has a steep high dosage Bragg peak in the terminal of its radiation range, which can kill the tumor cells to the largest extent; it possesses high relative biological effectiveness. Compared with the conventional rays, the heavy ion beam can cause more serious damage to the tumor cells, and it is also praised as the most ideal radiotherapy ray of the21st century.The tumor’s invasion to the surrounding tissues is the earliest stage of tumor metastasis, which is also a complex process which multiple factors participate in. During this process, Matrix Metalloproteinases (MMPs) is the most important proteolytic enzyme in human body, playing a significant role in both adhesion and invasion of cancer cells. Matrix metalloproteinase has an enhancement both in expression and activity in many cancer tissues of human being, among which matrix metalloproteinase-2and matrix metalloproteinase-9(MMP-2, MMP-9) are the key factors in tumor invasion process. MMP-2and MMP-9can disintegrate the IV collagen and elastin component on the basement membrane of cells, making the tumor cells enhance the ability of breaking through the basement membrane and promoting the tumor cells’invasion towards the surrounding tissues.This experiment mainly researches human tongue squamous cancer cell line Tca8113with irradiation by X-ray in different dosages and13C6+heavy ion beam. The experiment focuses on observing the expression change of MMP-2and MMP-9in human tongue squamous cancer cells, so as to reflect the impact of two irradiations on the ability of preventing tumor invasion. Result as follow:Compared with the blank control group, the expression contents of MMP-2irradiated by1Gy X-ray all increase after12hours,24hours and48hours (p<0.05). The expression content peak appears at the point of24hours (p<0.01), and the expression content of MMP-2reduces at the point of48hours; the expression level of MMP-2in the cell decreases at different time-points after4Gy X-ray radiation but it bears no statistical differences (p>0.05). After conducting irradiation on1Gy and4Gy X-ray, the expression of MMP-9in cells doesn’t appear any obvious change (p>0.05).After the irradiation of1Gy heavy ion beam towards squamous cell carcinoma of the tongue, the MMP-2shows the increase of expression content (p<0.05) at the point of12hours while its expression level decreases obviously at the time points of24hours and48hours (p<0.05). Low-dose heavy ion beam doesn’t have obvious effects on the expression of MMP-9in tongue squamous carcinoma cells (p>0.05); after using4Gy heavy ion beam to irradiate the tumor cells, the expressions of MMP-2and MMP-9have obvious decreases (p<0.05).The result addicted that low dosage X-ray can enhance the tongue squamous cell carcinoma Tca8113cell’s extracorporeal invasion ability; while the high dosage X-ray has no obvious influence on the tongue squamous cell carcinoma Tca8113’s invasion ability. Low-dose heavy ion beam irradiation has no effect on the invasion ability of tongue squamous cell carcinoma Tca8113; while high-dose heavy ion beam irradiation can obviously restrain the invasion ability of tongue squamous cell carcinoma. Compared with X-rays, heavy ion beams have higher biology efficiency. |
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