Effect of curcuma on radiation-induced apoptosis in human cancer cells.

There have been considerable efforts to search for naturally occurring substances for the intervention of carcinogenesis. Many components from dietary or medicinal plants have been identified that possess substantial chemopreventive properties. Curcuma, a yellow pigment from Curcuma longa, exhibits anti-inflammatory, antitumor, and antioxidative properties. Although its precise mode of action has not been elucidated so far, studies have shown that chemopreventive action of curcuma might be due to its ability to induce apoptosis (programmed cell death) in cancer cells. This original study was conducted in order to estimate whether curcuma enhances the radiation sensitivity of cancer cells. For this purpose, curcuma (concentrations ranging from 0 to 200 microM) was applied to human cancer cell cultures (HeLa, K-562 and IM-9) with or without X-irradiation (doses comprised between 0 and 8 Gy). Cell proliferation was monitored by trypan blue exclusion. For the estimation of apoptosis, changes in cell morphology and flow cytometry analysis (DNA content and presence of the sub-G1 peak) were performed. Microscopic examination of the curcuma-treated cells (with concentrations above 100 microM) showed a characteristic morphology of apoptosis. Furthermore, cells treated with curcuma exhibited a sub-G1 peak from which the magnitude was proportional to the concentration of curcuma. X-irradiation alone induced polyploidisation and apoptosis of the three cell lines, proportional to the doses of irradiation with a marked difference in radiation sensitivity between the cell lines (IM-9 < K-562 < HELA). However, when radiation and curcuma were applied together, our results showed that in HELA, K-562 and IM-9, curcuma showed a radiation sensitising effect only at the dose of 200 micro M. This result may open a perspective of synergical therapy at the condition to also address the intrinsic toxicity of curcuma on normal cells.

Polysulphone inhibits final differentiation steps of osteogenesis in vitro.

Biocompatibility is an important factor in the development of orthopedic implants as well as in the development of new tissue culture devices. Polysulphone has been used for orthopedic implants because of its mechanical properties, ease of sterilization, molding capacity, and biocompatibility. Therefore, polysulphone has been chosen as the prime material for the construction of tissue culture devices to be used for the cultivation of osteogenic cells (preosteoblast-like MN7 cells and primary bone marrow fragments), as well as complete fetal long bone explants under space flight conditions. Whereas polysulphone did not interfere with the proliferation in early stages of bone-forming cells, we show that leachable factors within the polysulphone polymer prevented the final steps of matrix formation as measured by collagen synthesis and matrix mineralization. These data argue against polysulphone as a material for orthopedic implants.

Use of the fluorescence-activated cell sorter (FACS) for in vitro assays of developmental toxicity.

Our objective is to predict embryotoxicity with reliable in vitro techniques. In several experimental systems, differentiation is accompanied by changes in the glycosylation pattern of cell-surface glycoconjugates. This is also the case with embryonal carcinoma cells. We have monitored the expression of receptors for wheat germ agglutinin (WGA). Murine embryonal carcinoma cells (P19 and F9) were exposed in vitro to xenobiotics for 1-3 days, then incubated successively with WGA-biotin (15 mug/ml) and streptavidin-phycoerythrin (SA-PE) (20 mug/ml), each for 30 min at room temperature. Cell-surface fluorescence was then analysed using a fluorescence-activated cell sorter (FACS). Exposure to 1 mum retinoic acid, a known inducer of differentiation, altered glycosylation as indicated by changes in WGA binding. Clear-cut effects were also observed after exposure to salts of arsenic (20 muM), or nickel (50 mum), and to methotrexate (1 mug/ml), fluorouracil (1.3 mug/ml) or actinomycin D (0.04 mug/ml). These compounds affected the percentage of positive cells the intensity of labelling, or both. Two non-teratogenic compounds (metronidazole and sulfonilamide) have also been tested and had no effect. Lectin histochemistry of embryonal carcinoma cells exposed to potentially toxic agents holds promise as a method for predicting embryotoxicity. FACS analysis allows rapid quantification.