Effect of beta-carotene-rich tomato lycopene beta-cyclase ( tlcy-b) on cell growth inhibition in HT-29 colon adenocarcinoma cells.

Lycopene beta-cyclase (tlcy-b) tomatoes, obtained by modulating carotenogenesis via genetic engineering, contain a large amount of beta-carotene, as clearly visible by their intense orange colour. In the present study we have subjected tlcy-b tomatoes to an in vitro simulated digestion and analysed the effects of digestate on cell proliferation. To this aim we used HT-29 human colon adenocarcinoma cells, grown in monolayers, as a model. Digested tomatoes were diluted (20 ml, 50 ml and 100 ml/l) in culture medium and added to the cells for different incubation times (24 h, 48 h and 72 h). Inhibition of cell growth by tomato digestate was dose-dependent and resulted from an arrest of cell cycle progression at the G0/G1 and G2/M phase and by apoptosis induction. A down-regulation of cyclin D1, Bcl-2 and Bcl-xl expression was observed. We also found that heat treatment of samples before digestion enhanced beta-carotene release and therefore cell growth inhibition. To induce with purified beta-carotene solubilised in tetrahydrofuran the same cell growth inhibition obtained with the tomato digestate, a higher amount of the carotenoid was necessary, suggesting that beta-carotene micellarised during digestion is utilised more efficiently by the cells, but also that other tomato molecules, reasonably made available during digestion, may be present and cooperate with beta-carotene in promoting cell growth arres

Expression of Liver-specific Genes-coding For Plasma-proteins In Protein-deficiency

AbstractProtein deficiency leads to a decreased concentration of plasma proteins, although it is not clear whether this response is caused by alterations in gene transcription or in post-transcriptional events. The aim of this study was to investigate the expression of some liver-specific genes coding for plasma proteins in rats kept on a protein-free diet for 30 days. Cloned cDNA probes for the albumin, transthyretin, retinol-binding protein and prothrombin genes were used in Northern hybridizations to total liver RNA to compare their transcript levels in protein-deficient and control animals. Liver polysomes were also isolated and fractionated from the two groups of animals to examine the possible effects of protein deficiency on translation of the mRNAs. The results indicate that the albumin and transthyretin mRNAs are present in lower amounts in protein deficiency. The distribution profile along sucrose gradients shows that all mRNAs are undergoing translation, but in protein-deficient animals a small but consistent fraction of each mRNA is also present in the non-polysomal, low molecular weight fractions