Study On The Microenvironment Of Lung Adenocarcinoma A549 Cells Transplanted Subcutaneously

Objective: To evaluate the ability of 99 m Tc-3PRGD2 SPECT/CT to detect the angiogenesis of subcutaneous A549 cell grafts,to clarify the relationship between tumor blood vessels,tumor hypoxia and tumor proliferation,and to further understand the tumor microenvironment.Methods:Ten subcutaneous tumor models of lung adenocarcinoma A549 cells in nude mice were established.The body weight and tumor volume of the nude mice were monitored regularly,and the tumor growth was detected by bioluminescence with IVIS.99 m Tc-3PRGD2 SPECT/CT was performed to detect tumor neovascularization when the mean volume of subcutaneous graft grew to about 0.3-0.5cm3.After the mice were killed,the subcutaneous graft tumors were completely stripped and made into frozen sections.CD31,pinonidazole and EDU immunofluorescence staining were performed.Finally,the spatial correspondence of the three tumors was analyzed.Results:1.99 m Tc-3PRGD2 SPECT/CT revealed a tumor/muscle(T/NT)value of 4.20±1.33.In immunofluorescence staining,the microvessel density(CD31)was 41.20±18.60,the cell proliferation rate was0.10±0.32,and the semi-quantitative fluorescence intensity in hypoxia region was116.71±9.36.It was found that the T/NT value of 99 m Tc-3PRGD2(4.20±1.33)was positively correlated with the microvascular density(41.20±18.60)(r=0.88,P < 0.05),and had no correlation with the cell proliferation rate(0.10±0.32)(r=0.32,P=0.41),nor with the semi-quantitative fluorescence intensity(116.71±9.36)in the hypoxia region(r=-0.16,P=0.66).(2):(1)on the space within the whole A549 subcutaneous transplantation tumor cell proliferation activity,has a broad and abundant new blood vessels,and at the same time there are a number of cells lack of oxygen,the three exist within the tumor,but on a slightly different distribution,area,the high density of vascular tumor proliferation of tumor cells of the region and the lack of oxygen has certain boundaries.(2)Necrotic cavities are widely found in subcutaneous graft tumors.There are more cavities in the center of the tumor than in the edge of the tumor.The cells around the cavities are generally hypoxic,while dense microvessels and vigorous cell proliferation areas surround the outer zone of hypoxic regions(necrotic cavities--hypoxic--proliferative regions and vascular regions).3.In the necrotic area that is about to form a cavity,the number of cells is sparse,no clear blood vessels and proliferating cells are seen,and occasionally there are scattered hypoxic cells.Conclusion:1.The T/NT value of 1.99 m TC-3PRGD2 is positively correlated with the microvascular density of A549 subcutaneous graft tumor.RGD is a good target probe for tumor angiogenesis.2.99 m TC-3PRGD2 can develop subcutaneous graft tumor of A549 well 2 hours after administration,and can be used noninvasively for malignant tumor detection.3.There are extensive areas of neovascularization,tumor proliferation and hypoxia in the subcutaneous tumor graft of A549.4.The cells around the necrotic cavity are generally hypoxic,and the proliferating tumor cells and blood vessels surround the hypoxic area.