Molecular imaging of epidermal growth factor receptor in glioma-bearing rats / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the value of 11C-PD153035 as an EGFR imaging agent in C6 tumor-bearing rat.</p><p><b>METHODS</b>The tumor-bearing rats were generated by subcutaneous injection of glioma C6 cells. Positron emission tomography/computer tomography (PET/CT) scans started as soon as intravenous injection of 11C-PD153035 (15-20 MBq/0.3 ml) was completed, images were collected continuously. The region of interest (ROI) was used to study the percentage of radioactivity in major organs and implanted tumors in the rats. The accumulation and blocking study in vitro was completed.</p><p><b>RESULTS</b>There were significant differences in 11C-PD153035 uptake among major organs. The maximum uptake in the organs ranked in the following order: liver > gastrointestinal tract > kidney > lung > brain > muscle. Radioactivity could be also observed in the tumors. The radioactivity ratio (T/NT, target/non-target) peaked (4.15) at 40 - 50 min post injection. The in vitro blocking study showed that 11C-PD153035 uptaken by C6 cells could be blocked by PD153035.</p><p><b>CONCLUSION</b>The results of this study show that 11C-PD153035 can be uptaken by EGFR-expressing tumors. 11C-PD153035 has a potential as a bioprobe to yield useful information for both diagnosis and therapy of tumors. However, the high concentration of 11C-PD153035 in the gastrointestinal tract is unfavorably affecting the tumor detection in these organs.</p>

Down-regulation of TopI by RNA interference reduces the drug-sensitivity of small cell lung cancer cell lines to topotecan / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the expressions of TopI gene in small cell lung cancer cell line H446, and explore the influence of TopI on the chemosensitivity of the cell line to topotecan (TPT).</p><p><b>METHODS</b>Western blot was performed to detect the TopI expression in H446 cells. Lipofectamine 2000 was used for the transient transfection of H446 cells by siRNA, and the transfection efficacy was detected. TopI mRNA was analyzed by quantitative RT-PCR and TopI protein was detected by Western blot to selected effective siRNA. The drug-sensitivity to topotecan (TPT) was evaluated by MTT assay.</p><p><b>RESULTS</b>TopI gene was expressed in H446 cells. Lipofectamine 2000 mediated the siRNA effectively (88.67%). Compared with its parental cells, RT-PCR results showed that TopI mRNAs in transfected cells were reduced by (95.7 +/- 1.6)%, (90.8 +/- 1.6)%, (96.1 +/- 2.7)% and (96.3 +/- 1.8)%, respectively, and decreased significantly at protein level. By MTT assay, the inhibition rate of TPT to H446 cells transfected by siRNA was lower than that of control group at same concentrations (P < 0.01).</p><p><b>CONCLUSION</b>siRNAs can silence the expression of TopI and decrease the drug-sensitivity of H446 cells to TPT.</p>