The Influence of Very Low Doses of Cisplatin on Tumor Cell Proliferation In Vitro and on Some Hematological and Enzymatic Parameters of Healthy Rats

Healthy rats had been treated for 2 or 6 weeks with 1.0 mL of 10-8 and 10-16 mg/mL of cisplatin. After 2 weeks of treatment, a significant increase in leukocyte and erythrocyte count and also in hematocrit was observed. Among leukocytes the number of neutrophils and eosinophils significantly increased. Biochemical analyses indicated a decrease in the glycogen content in the liver and kidneys after 2 weeks of treatment with low doses of cisplatin but at the end of the experiment (8th week of experiment) the stores of glycogen increased significantly. Biochemical analyses concerning the activity of some enzymes in the liver revealed a significant increase of peroxidase and acid phosphatase as well as catalase activities after 2 weeks of treatment. However, catalase was induced by a very low concentration of cisplatin, 10-16 mg/mL. After the cessation of cisplatin treatment the activity of enzymes returned to normal values. Human lung carcinoma cell line A549 (ECACC No 86012804) was also studied after treatment with the same doses of cisplatin and inhibition of its growth was observed. The results of these experiments strongly indicated that low doses of cisplatin could be stimulating for healthy cells but cytostatic for tumor cells. Possible mechanisms involved in the biological activity of very low cisplatin concentrations are discussed

Antiproliferative Activity of Melanoidins Isolated from Heated Potato Fiber (Potex) in Glioma Cell Culture Model

Potex constitutes a potato fiber preparation widely used as an ingredient to meat and bakery products which thermal treatment results in creation of new compounds. Melanoidins are high molecular weight brown end products of Maillard reaction, and few data presenting tumor cell growth inhibiting activity of melanoidins have been reported. Thus, in present study we utilized water extract of Potex roasted (180 degrees C for 2 h), whose chemical characterization revealed the presence of melanoidin complexes. Heated Potex extract inhibited C6 glioma cell proliferation in a dose-dependent manner measured by MTT method. High molecular weight components present in initial extract were responsible for stronger antiproliferative effect compared with low molecular weight fraction. Impaired MAPK (mitogen-activated protein kinase) and Akt signaling was found in cells treated with the extract. Moreover, flow cytometry analyses revealed the extract to induce G(1)/S arrest in glioma cells. Simultaneously, Western blot analysis showed elevated levels of p21 protein with concomitant decrease of cyclin D1. In conclusion, observed antiproliferative activity of melanoidins present in heated Potex was linked to disregulated MAPK and Akt signaling pathways, as well as to cell cycle cessation. These results suggest potential application of Potex preparation as a functional food ingredient and chemopreventive agent

Melanoidins isolated from heated potato fiber (Potex) affect human colon cancer cells growth via modulation of cell cycle and proliferation regulatory proteins

Melanoidins are brown, nitrogen containing, high molecular weight end products of Maillard reaction with poorly established activity towards tumor cells. The goal of present study was to verify whether both heated potato fiber Potex extract (180 degrees C for 2 h) and melanoidins isolated from the extract exerts growth-inhibiting activity in human colon cancer cells in vitro. The cells of LS180 colon cancer cell line were tested upon treatment with roasted potato fiber extract (AM4) as well as with high (HMW) and low (LMW) molecular weight fractions isolated from the extract, since both may be regarded as/or contain melanoidins. The tested compounds at concentration of 1000 mu g/ml reduced cell growth down to 45%, 69% and 54%, respectively. Furthermore, deregulated ERK1/2 signaling was revealed upon treatment. Moreover, multiple alternations in cell cycle regulators activity were found (i.e. cyclinD1, cyclin-dependent kinase 4 and 6, p21, p27, p53, pRb) leading to cell cycle cessation in GO phase. Importantly, LMW compounds revealed markedly stronger potential to alter specific molecular targets comparing to HMW compounds. Summarizing, the results emphasize that both high and low molecular weight melanoidins contribute to antiproliferative activity of heated potato fiber in LS180 colon cancer cells in vitro. (C) 2013 Elsevier Ltd. All rights reserved

Alpha-ketoglutarate (AKG) inhibits proliferation of colon adenocarcinoma cells in normoxic conditions

Background and objective. Alpha-ketoglutarate (AKG), a key intermediate in Krebs cycle, is an important biological compound involved in the formation of amino acids, nitrogen transport, and oxidation reactions. AKG is already commercially available as a dietary supplement and its supplementation with glutamine, arginine, or ornithine alpha-ketoglutarate has been recently considered to improve anticancer immune functions. It is well documented that AKG treatment of Hep3B hepatoma cells in hypoxia induced HIF-alpha (hypoxia-inducible factor) degradation and reduced vascular endothelial growth factor (VEGF) synthesis. Moreover, AKG showed potent antitumor effects in murine tumor xenograft model, inhibiting tumor growth, angiogenesis, and VEGF gene expression. However, the mechanisms of its anticancer activity in normoxia have not been examined so far. Results. Here, we report that in normoxia, AKG inhibited proliferation of colon adenocarcinoma cell lines: Caco-2, HT-29, and LS-180, representing different stages of colon carcinogenesis. Furthermore, AKG influenced the cell cycle, enhancing the expression of the inhibitors of cyclin-dependent kinases p21 Waf1/Cip1 and p27 Kip1. Moreover, expression of cyclin D1, required in G1/S transmission, was decreased, which accompanied with the significant increase in cell number in G1 phase. AKG affected also one the key cell cycle regulator, Rb, and reduced its activation status. Conclusion. In this study for the first time, the antiproliferative activity of AKG on colon adenocarcinoma Caco-2, HT-29, and LS-180 cells in normoxic conditions was revealed. Taking into consideration an anticancer activity both in hypoxic and normoxic conditions, AKG may be considered as a new potent chemopreventive agent