How platelet aggregation affects B16BL6 melanoma cell trafficking

Quantitation and visualization of tumor-specific T cells in the secondary lymphoid organs during and after tumor elimination by PET

Increased understanding in the area of trafficking behavior of adoptively transferred tumor-specific T cells could help develop better therapeutic protocols. We utilized the DUC18/CMS5 tumor model system in conjunction with a microPET scanner to study the DUC18 T cell distribution pattern in spleens and lymph nodes in live mice. Anti-Thy1.2 antibodies conjugated to 1,4,7,10-tetraazacyclododecane-N,N',N'',N''-tetraacetic acid (DOTA) and radiolabeled with (64)Cu were administered to three groups of BALB-Thy1.1 mice on days 4, 7, or 14 post-DUC18 T cell transfer. We were able to detect the transferred cells in all the major lymph nodes, spleens, and in tumors. Our findings suggest that tumor-specific T cells do not all preferentially localize to the tumors but they also home to all the major lymphoid organs; additionally the number of DUC18 T cells remains relatively constant during and after tumor elimination within each lymphoid organ.

Effect of PKC412, a selective inhibitor of protein kinase C, on lung metastasis in mice injected with B16 melanoma cells

PKC412, a selective inhibitor of protein kinase C (PKC), is currently in clinical trials as an anti-tumor drug. In the present study, we investigated the anti-metastatic effect of PKC412 using an experimental metastatic mouse model intravenously injected with melanoma cells. One-hour exposure to various concentrations of PKC412 (0.5, 5 and 50 microM) dose-dependently reduced the lung-metastatic potential of highly metastatic B16-F10 and -BL6 mouse melanoma cells in syngeneic mice. Following the exposure, PKC activities in B16-F10 and -BL6 cells were significantly decreased, but growth curves were not influenced. To elucidate the mechanism of the anti-metastatic effect of PKC412, we examined the activity to invade the extracellular matrix and the platelet-aggregating activity of the melanoma cells incubated with PKC412 (0.5, 5 and 50 microM) for 1 hour. PKC412 significantly reduced both the invasive and platelet-aggregating activities. These results suggest that PKC412 shows an anti-metastatic function through the inhibition of the invasive and/or platelet-aggregating activities of melanoma cells. PKC412 is potentially a promising candidate for an anti-metastatic agent.

Use of insulin to improve [18 F]fluorodeoxyglucose labelling and retention for in vivo positron emission tomography imaging of monocyte trafficking

While 18F-FDG labelling of monocytes would allow in vivo trafficking with positron emission tomography (PET), present methods suffer from poor retention of radioactivity. We investigated the feasibility of utilizing insulin for improved [18F]fluorodeoxyglucose (18F-FDG) labelling. Separated human monocytes and lymphocytes were labelled with 18F-FDG with or without 3 h insulin pre-incubation. Insulin had no effect on lymphocyte labelling (21.4+/-0.8% vs 20.8+/-1.1% efficiency, P=NS). However, for monocytes, insulin pre-incubation led to a 169+/-9% increase in labelling efficiency (19.3+/-4.1 vs 32.5+/-1.8, P<0.05), without significant effects on cell activation or viability. Moreover, while only 57.7+/-4.8% and 40.4+/-5.6% of the 18F-FDG was retained at 1 and 3 h for controls, the retention rate increased to 91.6+/-2.1% (P=0.01) and 86.5+/-1.9% (P<0.01) after insulin pre-incubation. Improved 18F-FDG retention was accompanied by a 70.3+/-7.4% decrease in glucose-6-phosphatase activity (P=0.02). PET imaging of rats showing hepatic ischaemia-reperfusion injury demonstrated higher liver uptake for monocytes labelled after insulin treatment. Thus, insulin improves monocytic 18F-FDG uptake and retention, and may provide a feasible labelling method for PET imaging.