| Objective:①To evaluate the value of 99mTc- diethylenetriamine pentaacetic acid-deoxyglucose (99mTc-DTPA-DG) in monitoring the early response of malignant tumors to chemotherapy.②To observe the uptake of 99mTc-DTPA-DG by the nucleus of lung cancer cells Calu-3, in order to prove if 99mTc-DTPA-DG could cut down the false positive rates (FPR) of tumors diagnosis and the utility of 99mTc-DTPA-DG in tumors, furthermore. Methods:①In vitro cultured lung cancer cells A549 (adenocarcinoma), breast cancer cells MCF-7, and colon carcinoma cells HT-29 were added into 24-well culture plate and divided into chemotherapeutic and control groups (added normal saline, ns), respectively. The chemotherapeutic drugs used in this study included cisplatin (5, 10μg/ml), paclitaxel (7, 14, 28μg/ml) and 5-fluorouracil (5-Fu, 35, 70μg/ml). Morphologic changes and apoptotic bodies of the cells were observed under an inverted microscope after the cells were treated with the drugs for 6 hours. The cells were digested, collected and double-stained with Annexin V (AV) and propidium iodide (PI), and the rate of apoptosis in each group was assessed by flow cytometry. In another experiment, 4 hours after the chemotherapy, 99mTc-DTPA-DG (0.1 ml, 37MBq/L) was added to each well, the cells were incubated for another 2 hours, and they were digested and collected, then the rate of uptake of 99mTc-DTPA-DG was determined usingγcounter.②The lung cancer cells (adenocarcinoma) were assigned to five groups: group a, 99mTc-DTPA-DG; group b, 18F-FDG; group c, 99mTc-DTPA; group d, 99mTcO4-; group e, saline. One of the radioactive drugs (5, 10 or 20μCi/0.1ml) was added into each well, 0.1ml ns was added in control groups. Five duplicate wells in each group. Incubated the cells for another 2 hours, the cells were digested and collected, then the radiocounting was determined usingγcounter in each group. Adopted the method of permeating and swelling to isolate cell nucleus, the radiocounting was determined again. The isolated cell nuclei were smeared and dyed with hematoxyline eosin (HE), then observed under microscope. Results:①After the lung cancer cells A549, breast cancer cells MCF-7 and colon cancer cells HT-29 were respectively treated with cisplatin, paclitaxel and 5-Fu for 6 hours, in all the chemotherapeutic groups of the three tumor cells, inverted microscope showed visible morphous changes and apoptotic bodies, and flow cytometry found apoptotic peaks and higher apoptotic rates. In all the three tumor cells, the apoptotic rates of the chemotherapeutic groups were higher than the control groups'. The differences between the chemotherapeutic groups and the controls'were all significant (P<0.05). Furthermore, the apoptotic rates rise as the dose of chemotherapeutics increased. The uptake rates of 99mTc-DTPA-DG by the three tumor cells in the chemotherapeutic groups were all significantly lower than those in the controls'(P<0.05), and the uptake rates decreased as the dose of chemotherapeutics increased.②After the isolated cell nuclei of lung cancer cells Calu-3 were smeared and dyed with HE, the nuclei were amethyst dyed by hematoxylin and the fewer cytoplasm showed pink dyed by eosin under microscope. The count results showed the proportion of isolated nuclei was reached 95% under microscope. The uptake of 99mTc-DTPA-DG and 18F-FDG by lung cancer cells Calu-3 determined byγcounter were all more than the groups of 99mTc-DTPA, 99mTcO4- and ns, the differences were significant (P<0.05). Moreover, the uptake of 18F-FDG was more than 99mTc-DTPA-DG. As the activity of 99mTc-DTPA-DG increased, the uptake decreased. As the activity of 18F-FDG increased, the uptake rates first rise then decreased. The differences among the uptake of 99mTc-DTPA, 99mTcO4- and ns were not significant (P>0.05). The uptake rates of 99mTc-DTPA-DG by cell nuclei were much higher than 18F-FDG (P<0.05). Conclusions:①The changes of uptake of 99mTc-DTPA-DG could reflect the effect of chemotherapy in tumors. The less uptake rates of 99mTc-DTPA-DG, the better effect. Therefore, 99mTc-DTPA-DG is a imaging agent, promising in the evaluation of early response of tumors to chemotherapy.②99mTc-DTPA-DG could enter tumor cell nuclei, so it might have value in distinguish inflammation and tumors. Accordingly, the FPR in diagnosis of tumors could decrease. 99mTc-DTPA-DG is a targeted molecular imaging agent in tumors diagnosis.
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