Optimizing the antitumor selectivity of PVP-Hypericin re A549 cancer cells and HLF normal cells through pulsed blue light.

Photodynamic therapy (PDT) is based on the preferential accumulation of photosensitizer in cancer cells with subsequent cytotoxicity mediated by singlet oxygen production after light excitation. As photosensitizers accumulate also in the surrounding non-cancer cells, the risk of damaging them by photosensitization is a limitation of PDT. Thus, minimizing the side-effects of PDT on normal cells is one of the challenging problems in medical practice. This paper studies the PDT side-effects of PVP-Hypericin (PVP: polyvinylpyrrolidone) photosensitizer excited with continuous or pulsed irradiation, on combined cell lines of human lung carcinoma epithelial cells (A549) and normal primary human lung fibroblast cells (HLF). In vitro PDTs are performed using pulsed or continuous irradiation with irradiance intensities I(*)=1.59, 6.34 and 14.27 mW/cm(2). The LED pulse lengths L are 0.127, 1.29, 13, 54.5 and 131 ms. Then fluorescence and phototoxicity of PVP-Hypericin in the A549 cancer cells are compared with those of HLF normal cells. Although, PVP-Hypericin accumulates more in A549 cancer cells, the results show that HLF cells produce dose-dependent photoreactions in the presence of photosensitizer. PVP-Hypericin induces the most optimized anticancer efficacy with moderate side-effects for I(*)=14.27 mW/cm(2) and L=131 ms.

Induction of DNA synthesis in primary mouse hepatocytes is associated with nuclear pro-transforming growth factor alpha and erbb-1 and is independent of c-jun.

For growth stimulation of liver cells by hepatocyte growth factor (HGF) or transforming growth factor alpha (TGFalpha) via receptor tyrosine kinases, c-fos/c-jun has been considered a point of intersection for cross-talk between the different signal transduction pathways. Recent evidence strongly implicates translocation of pro-TGFalpha into the nucleus as an important step preceding the initiation of hepatic DNA synthesis. We asked whether an active c-jun is required for the nuclear translocation of pro-TGFalpha and its stimulatory effect on DNA synthesis. For this purpose we used mice with c-jun inactivated post partum in hepatocytes by the Cre-loxP recombination system (c-jun(Deltaliver)). Nuclear fractions from control and c-jun(Deltaliver) mouse livers contained TGFalpha as pro-form of 17 kDa and the epidermal growth factor receptor (erbb-1) with molecular weights of 170 and 150 kDa (truncated form). Hepatocytes were isolated by collagenase perfusion and cultivated. A lack of c-jun did not alter the apoptotic activity but significantly suppressed DNA synthesis in the cultured hepatocytes. In control and c-jun(Deltaliver) cells DNA synthesis was almost always associated with nuclear presence of pro-TGFalpha. 76.5 +/- 6.8% of hepatocytes with pro-TGFalpha positive nuclei and only 4.52 +/- 1.31% of hepatocytes with negative nuclei exhibited DNA replication. About 85% of the pro-TGFalpha positive nuclei also contained erbb-1. Treatment of cultures with mature TGFalpha or HGF elevated the frequency of pro-TGFalpha positive nuclei replicating DNA; HGF and TGFalpha-induced nuclear pro-TGFalpha and DNA synthesis significantly more in c-jun(Deltaliver) than in control hepatocytes. These results suggest that (i) a lack of c-jun suppresses basal rates of DNA replication in hepatocytes; (ii) c-jun deficient hepatocytes show a pronounced growth response towards HGF or TGFalpha; (iii) nuclear translocation of pro-TGFalpha together with erbb-1 and its association with DNA synthesis are independent of c-jun.