Transient inhibition of L929 cell mitosis and locomotion by argon ion laser irradiation.

Argon ion laser irradiation of L929 cells transiently inhibits both entry into and passage through mitosis without affecting clonogenic survival. Anaphase mitotic figures virtually disappear from irradiated cell monolayers although prophase + metaphase mitotic figures can still be identified. The total number of mitotic figures does not change significantly and time-lapse video recording shows that cells do not enter mitosis following irradiation.

Mechanism of action and spectrum of cell lines sensitive to a doxorubicin-transferrin conjugate.

A transferrin-doxorubicin conjugate exhibited greatly increased cytotoxicity relative to unconjugated doxorubicin toward a variety of cultured tumor cell lines. An L929 cell line selected for doxorubicin resistance was as sensitive to the transferrin-doxorubicin conjugate as was the parental unselected line. Quantitative measurements of doxorubicin fluorescence in single L929 cells showed that uptake was similar in amount when cells were exposed to equivalent concentrations of doxorubicin presented either free or as the transferrin-doxorubicin conjugate.

Mechanism of action and spectrum of cell types susceptible to doxorubicin photochemotherapy.

We have shown that, whereas argon ion laser irradiation alone is not cytocidal for L929 cells, it greatly increases the cytotoxicity of intracellular doxorubicin. The present study showed that light enhancement of doxorubicin cytotoxicity was not restricted to stock L929 cells, but could also be demonstrated using L929 cells selected for doxorubicin resistance and several standard cell lines that are relatively resistant to doxorubicin prior to selection. Light-enhanced cytotoxicity resulted in extensive nuclear DNA loss and was strongly inhibited by anoxia.

Photodynamic enhancement of doxorubicin cytotoxicity.

Argon ion laser irradiation at 514.1 nm and 488 nm dramatically increased doxorubicin cytotoxicity in an L929 cell clonogenic survival assay. The cytotoxicity was dependent on both the drug concentration and the total light energy delivered such that at 5 micrograms doxorubicin/ml and 800 J/cm2, cytotoxicity was enhanced by a factor of > 10(4) relative to that achieved with drug alone.

The role of reduced nicotinamide adenine dinucleotide phosphate in glucose- and temperature-dependent doxorubicin cytotoxicity.

The mechanism of doxorubicin resistance induced by glucose deprivation was examined using an L929 cell system. Resistance developed even when the synthesis of glucose-regulated proteins was suppressed by supplementing glucose-deprived cultures with uridine. Resistance was also not correlated with pyruvate availability, with DNA strand breaks, or with intracellular drug or nucleotide levels.