The anticancer drugs doxorubicin and bleomycin are well-known for their oxidative stress-mediated side effects in heart and lung, respectively. It is frequently suggested that iron is involved in doxorubicin and bleomycin toxicity. We set out to elucidate whether iron chelation prevents the oxidative stress-mediated toxicity of doxorubicin and bleomycin and whether it affects their antiproliferative/proapoptotic effects. Cell culture experiments were performed in A549 cells. Formation of hydroxyl radicals was measured in vitro by electron paramagnetic resonance (EPR). We investigated interactions between five iron chelators and the oxidative stress-inducing agents (doxorubicin, bleomycin and H(2)O(2)) by quantifying oxidative stress and cellular damage as TBARS formation, glutathione (GSH) consumption and lactic dehydrogenase (LDH) leakage. The antitumour/proapoptotic effects of doxorubicin and bleomycin were assessed by cell proliferation and caspase-3 activity assay. All the tested chelators, except for monohydroxyethylrutoside (monoHER), prevented hydroxyl radical formation induced by H(2)O(2)/Fe(2+) in EPR studies. However, only salicylaldehyde isonicotinoyl hydrazone and deferoxamine protected intact A549 cells against H(2)O(2)/Fe(2+). Conversely, the chelators that decreased doxorubicin and bleomycin-induced oxidative stress and cellular damage (dexrazoxane, monoHER) were not able to protect against H(2)O(2)/Fe(2+). We have shown that the ability to chelate iron as such is not the sole determinant of a compound protecting against doxorubicin or bleomycin-induced cytotoxicity. Our data challenge the putative role of iron and hydroxyl radicals in the oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin and have implications for the development of new compounds to protects against this toxicity.

Purpose: Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO₂ P25), are among the most produced nanomaterials worldwide. The broad use of TiO₂ P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO₂ P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO₂ P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO₂ P25 for biological testing in A549 cells and to evaluate their biological effects. Methods: We determined the size and crystallinity of TiO₂ P25. We used four techniques for TiO₂ P25 dispersion. We estimated the colloid stability of TiO₂ P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO₂ P25 (0– 100 μg.mL^{− 1}) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy. Results: We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO₂ P25. Under these conditions, TiO₂ P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO₂ P25 in A549 cells were met, similar results on the biological effects of TiO₂ P25 were obtained in two independent cell laboratories. Conclusion: We optimized the experimental conditions of TiO₂ P25 preparation for toxicity testing in A549 cells. The results presented here on TiO₂ P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO₂ P25 as a reference material.

We characterized the effect of phytic acid (inositol hexaphosphate, IP6) as a potential adjuvant in treatment of colorectal carcinoma and evaluated the optimal concentration and treatment time to produe the maximal therapeutic effect. There is some evidence that myoinositol (Ins) can potentiate anti-cancer effects of IP6. Therefore, we tested both IP6 and Ins individually and in combination on human cell lines HT-29, SW-480 and SW-620 derived from colorectal carcinoma in different stages of malignancy. The effect of tested chemicals on the cells was measured using metabolic activity assay (WST-1), DNA synthesis assay (BrdU), protein synthesis assay (Brilliant Blue) and apoptosis (caspase-3 activity). We tested IP6 and Ins at three concentrations: 0.2, 1 and 5 mM for 24, 48 and 72 h. The concentrations and incubation periods were chosen according to low toxicity of the tested substance that was observed in a long-term clinical study. We found that all employed concentrations of IP6 or IP6/Ins decreased proliferation of the cell lines, with the maximum decrease being observed in HT-29 cells. Metabolic activity of treated cells differed in response to IP6 and IP6/Ins treatment; in HT-29 and SW-620 significant decrease was observed only at the highest concentration, whereas in SW-480 cells metabolic activity was lower at each concentration except 0.2 and 1 mM IP6 or IP6/Ins in 24-h incubation. The results from protein content assay corresponded to the results obtained from WST assay. In addition, we found maximum increase in caspase-3 activity at concentration 5 mM IP6 or IP6/Ins in HT-29 cells and with IP6 at concentration of 0.2 mM or IP6/Ins in SW-480 cells with clear indication of Ins enhancing the proapoptotic effect of IP6 in all the cell lines studied.