Nitric oxide (NO), a free radical, has been implicated in the biology of human cancers, including breast cancer, yet it is still unclear how NO affects tumor development and propagation. We herein gradually adapted four human breast adenocarcinoma cell lines (BT-20, Hs578T, T-47D, and MCF-7) to increasing concentrations of the NO donor DETA-NONOate up to 600 muM. The resulting model system consisted of a set of fully adapted high nitric oxide ("HNO") cell lines that are biologically different from the "parent" cell lines from which they originated. Although each of the four parent and HNO cell lines had identical morphologic appearance, the HNO cells grew faster than their corresponding parent cells and were resistant to both nitrogen- and oxygen-based free radicals. These cell lines serve as a novel tool to study the role of NO in breast cancer progression and potentially can be used to predict the therapeutic response leading to more efficient therapeutic regimens.

The free radical nitric oxide (NO) is known to play an important role in the biology of human cancers, including lung cancer. However, it is still not clear how elevated amounts of nitric oxide affect tumor development and propagation. Herein we develop an in vitro model system to study these effects in lung tumor cells. Two cell lines-one human lung adenocarcinoma (A549) and one mouse adenocarcinoma (LP07) cell line-were adaptively grown in increasing concentrations of the NO donor DETA-NONOate over several months. Both cell lines were successfully adapted to high levels of NO (HNO). Experiments validated the adaptation occurred as a result of the exogenous NO produced by the DETA-NONOate, and was not merely a response to the chemical composition of DETA-NONOate. No morphological differences were observed between cells that were adapted to the HNO and cells which did not undergo the adaptation process (i.e., "parent cells"). Parent cells were unable to survive when placed directly in media containing high levels of DETA-NONOate, suggesting that the adapted cells underwent a biological change enabling them to survive and grow in a HNO environment. The adapted cells were found to grow faster than the parent cells under both normal growth conditions and stressful growth conditions (serum-less media, growth on soft agar) even when the DETA-NONOate was removed from the HNO culture media. These adapted cell lines can serve as a novel tool for use in future experiments designed to better understand the role nitric oxide plays in lung cancer.

Porphyrazines (pzs), or tetraazaporphyrins, can be viewed as porphyrinic macrocycles in which the porphyrin meso (CH) groups are replaced by nitrogen atoms; as such, it can be anticipated that pzs would show similar biocompatibility and biodistribution to those of porphyrins. However, distinctive chemical and physical features of the pzs differentiate them from either the porphyrins or phthalocyanines, in particular making them excellent candidates as optical imaging/therapeutic agents. The novelty of the pzs requires that we first determine how specific structures selectively alter biological function, leading to the development of "rules" that will be used to predict future biologically functional pzs. In the first of these studies, we present here a correlation of pz charge with biocompatibility for a suite of three pzs-neutral, negative, and positive. Confocal fluorescence microscopy and proliferation/viability measurements disclose that the three pzs differ in their toxicity, uptake, and localization in A549 human lung adenocarcinoma cells and WI-38 VA13 normal cells. Interestingly, the negatively charged pz exhibits selective dark toxicity in pulmonary adenocarcinoma cells.

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