Molecular Imaging Studies Of Photodynamic Diagnosis By Laser In The Diagnosis Of Early Stage Colon Cancer

This paper covers the following two aspects:1.A research about the effect of a new type of water-soluble photosensitizer galactose phthalocyaninet to the diagnosis of colon cancerObjective: malignant have caused serious harm to human health,including colon cancer which is a common malignant tumor of digestive system.The incidence and mortality of colon cancer in China are obviously rising,which thus caused wide attention in The field of medicine.Early stage colon cancer can hardly show any performance,advanced colon carcinoma may appear the symptom such as the change of the bowl evacuation habit.Methods for the diagnosis of colon cancer include: pneumobarium double contrast,endoscope?CT?MRI?etc,but all of them have limitations.The photodynamic diagnosis has become a hot research topic in recent years,because of its outstanding advantages which includes no radiation,causing small injury to normal tissue,a strong patient tolerance,making real-time diagnosis at the early stage of tumor.Photosensitizer is the key to the photodynamic diagnosis,so more and more scholars made a study of photosensitizer and its optimization.This topic utilized 4 kinds of phthalocyanine photosensitizer(T1~T4)modified by galactose,through detecting the spectroscopy characteristics,fat-water distribution coefficient,and cell absorption properties,the subcellular localization,and biological safety testing to determine the most suitable photosensitizer for diagnosis application,so as to provide some experimental data for clinical diagnosis.Methods: The ultraviolet spectrum and fluorescence spectrum of photosensitizer T1~T4 were detected;Reverse thin layer chromatography(TLC)was used to detect the T1~T4 fat-water distribution coefficient;The fluorescence spectrophotometer was used to detect the impact of concentration and incubation time of T1~T4 on the uptake mount of colon CT-26 cell;Laser confocal microscope was used to detect the subcellular localization of T1~T4,MTT method was used to detect the difference of cytotoxic effect between colon cancer cells(LOVO?CT-26)and normal cells under the action of T1,with or without the presence of laser,and the IC50 value was calculated;The spectrum analyzer was used to study the diagnosis effect of photosensitizer T1 on the orthotopic implantation of colon cancer model.All the data was described with(x ± s),SPSS16.0 statistical software was used to deal with data,mean compared by t test and analysis of variance(ANOVA S-N-K test),with P<0.05 for the difference was statistically significant.Results: The maximum wavelength of ultraviolet absorption T1~T4 is at around 680 nm,fluorescence emission wavelength is at around 690 nm,which fits the characteristics of photosensitizer that ultraviolet absorption spectrum and fluorescence spectrum are in near infrared region(600~800);this kind of photosensitizer has a strong water solubiliy and will not cause too much damage to normal tissue.According to the results of Fat-water distribution coefficient.The uptake mount and absorption rate of CT-26 colon cancer cells to T1 are highest and fastest,which is better than T2 and T3,T4 shows almost no absorption;Compound cell positioning results show that under the same concentration,the amount of T1 into cells is the highest,its fluorescent signal is the strongest,it has more distribution in lysosome,less distribution in mitochondria;With the presence of light,the cytotoxic effect of T1 on colon cancer cells is stronger than normal cells;Animal experiments show that the fluorescence spectrums of the normal tissue,tumor tissue and the tumor tissue after the application of photosensitizer are different.(P<0.05)Conclusion: T1 with its advantages such as the strongest fat-soluble ability,the fastest absorption rate,the strongest fluorescence intensity can be used for fluorescence imaging in the diagnosis of colon cancer.Animal experiments also confirm that T1 mediated photodynamic fluorescence imaging has a certain application value and prospect.2.A research about a new type of water-soluble galactose phthalocyanine photose nsitizer and its antitumor properties and related mechanism.Objective: At the same time of studying the photodynamic diagnosis effect of ga lactose phthalocyanine photosensitizer T1 on colon cancer.we found such photosensiti zer has certain inhibition on tumor,so this topic studied the impact of this new type o f galactose phthalocyanine photosensitizer on colon cancer cell proliferation and the related mechanism,providing certain experiment basis for the photodynamic treatment of colon cancer.Methods: At the concentration of IC50,the autophagy,apoptosis and necrosis of colon cancer cell under the action of TI-PDT were detected through MDC staining and flow cytometry;The cell membrane and intracellular ultrastructure of colon cancer cell under the action of TI-PDT were detected through scanning electron microscopy(SEM)and transmission electron microscope;The Bcl-2,Bax,Beclin1 gene expression in colon cancer cell under the action of TI-PDT were detected through RT-PCR.All the data was described with(x ± s),SPSS16.0 statistical software was used to deal with data,mean compared by t test and analysis of variance(ANOVA S-N-K test),with P<0.05 for the difference was statistically significant.Results: T1-PDT can induce the autophagy of colon cancer cells,but can hardly influence the apoptosis of cell.Scanning electron microscopy(sem)and transmission electron microscopy(sem)results showed that the T1-PDT can cause cell autophagy,and the autophagosome is produced.Its damage to mitochondrial is not apparent,it can cause the shrinkage of cell membrane,the disappearance of pseudopod and even cell burst.RT-PCR result shows that T1-PDT has small effect on Bcl-2?Bax gene expression,and can enhance the Beclin 1 gene expression.(P<0.05)Conclusion: The main mechanism of T1 mediated photodynamic therapy of colorectal cancer is causing cancer autophagy.