merocyanine-dye and Carcinoma

The mechanism of resistance of cancer cells to the anticancer drug cisplatin is not fully understood. Using cisplatin-sensitive KB-3-1 and -resistant KCP-20 cells, we found that the resistant cells have higher membrane potential, as determined by membrane potential sensing oxonol dye. Electron spin resonance and fluorescence polarization studies revealed that the resistant cells have more "fluid" plasma membranes than the sensitive cells. Because of this observed difference in membrane "fluidity," we attempted modification of the plasma membrane fluidity by the incorporation of heptadecanoic acid into KB-3-1 and KCP-20 cell membranes. We found that such treatment resulted in increased heptadecanoic acid content and increased fluidity in the plasma membranes of both cell types, and also resulted in increased cisplatin resistance in the KCP-20 cells. This finding is in accord with our results, which showed that the cisplatin-resistant KCP-20 cells have more fluid membranes than the cisplatin-sensitive KB-3-1 cells. It remains to be determined whether the observed differences in biophysical status and/or fatty acid composition alone, or the secondary effect of these differences on the structure or function of some transmembrane protein(s), is the reason for increased cisplatin resistance.

Topics: Carcinoma; Cell Division; Cell Line, Tumor; Cell Membrane; Cisplatin; Clone Cells; Cyclic N-Oxides; Drug Resistance, Neoplasm; Fatty Acids; HeLa Cells; Humans; Isoxazoles; Membrane Fluidity; Membrane Lipids; Membrane Potentials; Membrane Proteins; Neoplasms; Potassium Channels; Pyrimidinones

The relationship between tumor cell differentiation and photosensitizer accumulation used in PDT is poorly defined. In the present work, specific cell differentiation of colon carcinoma CT26 cells induced by sodium butyrate was manifested by morphological changes, proliferation and protein expression and was correlated with the accumulation of endogenous and exogenous photosensitizes. Reduced accumulation of the endogenous protoporphyrin IX and the exogenous hypericin and MC540 was detected in differentiated cells. In contrast, a differentiation-dependent increase was measured with TPPS4, TMPyP, the pheophorbides (C5, C6, C12), HypS4 and helianthrone. In conclusion, PpIX, Hypericin and MC540 show specific binding and accumulation in poorly differentiated tumors, giving these tumors tissue-specific advantage in photo-diagnostic PDT applications.

Topics: Animals; Anthracenes; Butyrates; Carcinoma; Cell Cycle; Cell Differentiation; Colonic Neoplasms; Mice; Perylene; Photosensitizing Agents; Protoporphyrins; Pyrimidinones; Tumor Cells, Cultured