Stable expression of the human dopamine transporter in N27 cells as an in vitro model for dopamine cell trafficking and metabolism.

Dopamine (DA) metabolism and cell trafficking are critical for the proper functioning of DA neurons. Disruption of these DA processes can yield toxic products and is implicated in neurological conditions including Parkinson's disease (PD). To investigate pathogenic mechanisms involving DA neurons, in vitro models that recapitulate DA metabolism and trafficking in vivo are crucial. N27 cells are a widely used model for PD; however, these cells exhibit little expression of the DA transporter (DAT) confounding studies of DA uptake and metabolism. This lack of adequate DAT expression calls into question the use of this cell line as a model to study DA cell trafficking and metabolism. To overcome this problem, we stably expressed the human DAT (hDAT) in N27 cells to develop cells that we named N27-BCD. This approach allows for characterization of toxicants that may alter DA metabolism, trafficking, and/or interactions with DAT. N27-BCD cells are more sensitive to the neurotoxins 1-methyl-4-phenylpyridinium (MPTP/MPP+) and 6-hydroxydopamine (6-OHDA). N27-BCD cells allowed for clear observation of DA metabolism, whereas N27 cells did not. Here, we propose that stable expression of hDAT in N27 cells yields a useful model of DA neurons to study the impact of altered DA cell trafficking and metabolism.

Combination chemotherapy against B16 melanoma: bleomycin/vinblastine, bleomycin/cis-diamminedichloroplatinum, 5-fluorouracil/BCNU and 5-fluorouracil/methyl-CCNU.

Four antitumor drug combinations which are currently in clinical use were evaluated experimentally using the murine B16 melanoma model. Bleomycin plus vinblastine produced an increase in life span over either of the two agents alone against both intraperitoneal and subcutaneous B16. This combination also resulted in a large number of long-term survivors. Bleomycin plus cis-platinum produced slight enhancement against subcutaneous B16, but showed no advantage against intraperitoneal B16. The combination of 5-fluorouracil plus methyl-CCNU significantly increased survival time against the intraperitoneal tumor, and produced long-term survivors as well. The combination of 5-fluorouracil plus BCNU was not more effective than BCNU or 5-fluorouracil alone. These data were compared with the degree of success reported from the clinics against a variety of solid human neoplasms.