Flow Cytometric Analysis of the Influence of Myosmine on the Cell Cycle

Myosmine (3-(1-pyrrolin-2-yl)pyridine) is an alkaloid found in tobacco as well as various staple foods, fruits and vegetables. Myosmine has recently been suspected to be a tobacco-independent carcinogenic source. Using cell flow cytometry, we have examined the influence of myosmine on the cell cycle of murine erythroleukemia (MEL) cells in vitro and have compared this with its effects on murine bone marrow cells in vivo. Myosmine at low concentrations inhibited cell proliferation dose dependently; while at concentrations close to 300 μmol dm−3 it acted in a cytostatic fashion, that is, it increased the percentage of cells in the S and G2/M phases. At doses of 350–400 μmol dm−3 myosmine induced apoptosis and the hypoploid fraction. In vivo intraperitoneal injection of mice with 100 mg/kg of myosmine resulted in a statistically significant increase in the percentage of cells in S phase; i.e. from 13.75 to 18.22 %. The percentage of bone marrow cells in the G2/M phase increased from 6.79 to 8.93 % in treated mice compared to controls. All of these results are in agreement with the hypothesis that myosmine possesses genotoxic potential. (doi: 10.5562/cca1767

The study of the apoptogenic effect of pyrimidine derivatives on murine leukemia cells

BACKGROUND: In the light of the recent findings concerning the role of apoptosis and of tumor cell enzymes in cancer chemotherapy, the interest in pyrimidine derivatives has greatly increased. Thio- and hydrazine- pyrimidines were synthesized as potential antimetabolites inhibiting the biosynthesis of nucleic acids. Some of them demonstrated biological activity, including antibacterial and antitumor action. The aim of this study was to analyze the cytotoxic activity and the ability of some derivatives to induce apoptosis in murine leukemia cells. METHODS: Exponentially growing cells were incubated with compounds and after 24, 48, and 72 hours were stained with trypan blue and counted hemocytometrically. For detection of the cell fraction undergoing apoptosis, a morphological analysis was made using fluorescent dye propidium iodide. RESULTS: Eight thio- and hydrazine- pyrimidine derivatives were investigated. 2-Thiouracil and 6- hydrazinouracil did not influence the cell growth. 2,4-dithiouracil, 2-thio-4-hydrazinouracil, 2-hydrazinouracil, and 2-thio-5-fluorouracil decreased cell proliferation, but even at the highest studied concentration (1000 µM) had no cytostatic action. Only high concentrations of 2,4-dihydrazinouracil and 2- chloro-4-hydrazinouracil showed a strong cytotoxic activity. The treatment with 2,4-dihydrazinouracil as well as with 5-fluorouracil caused the appearance of apoptotic cells with typical fragmented condensed nuclei, ghosts and apoptotic bodies. In contrast, dead cells treated with 2-chloro-4-hydrazinouracil did not show apoptotic morphology. CONCLUSION: Among studied eight thio- and hydrazine- pyrimidine derivatives only 2,4-dihydrazinouracil demonstrated strong apoptogenic activity. Its active concentrations were about 100 times higher than apoptogenic concentrations of 5-fluorouracil which points to different mechanisms of cytotoxic action

Antiproliferative and apoptogenic effects of myosmine on erythroleukemia and hepatocellular carcinoma cells

Myosmine, 3-(1-pyrroline-2-yl) pyridine is a minor tobacco alkaloid that has also been found in various widely used foods. Recently, this phytochemical has been gaining an increasing interest as a potential risk factor for the development of oesophageal adenocarcinoma. This study aimed to examine the effects of myosmine on the cell viability and proliferative activity of erythroleukemia and hepatocellular carcinoma cells and to obtain additional information about the mechanisms underlying its cytotoxic activity. The in vitro cytotoxic effect of myosmine on the HepG2 and MEL tumour cell lines was assessed by MTT dye reduction and trypan blue dye exclusion assays. The alterations in the tumour cell morphology induced by myosmine were analysed by fluorescent microscopy after staining with acridine orange (AO)/ethidium bromide (EtBr) and 4′,6-diamidine-2′-phenylindole dihydrochloride (DAPI). Annexin V-FITC/propidium iodide (PI) staining was used to assess the apoptosis-inducing ability of myosmine. The modulating action of antioxidant treatment on myosmine-induced cytotoxicity against the HepG2 tumour cell line was also examined. The cell viability tests indicated that myosmine induced a significant dose-dependent reduction of the viability and proliferative activity of both tumour cell lines. Fluorescent microscopy studies revealed marked alterations in the morphology of myosmine-treated tumour cells with signs of cell cycle arrest and apoptosis. The results of the simultaneous treatment with myosmine and vitamin C showed modulating activity of vitamin C on the cytotoxic effect of myosmine with concentration- and time-dependent variations. The presented results could contribute to the assessment of the potential health risks associated with the dietary myosmine exposure. Abbreviations AO: acridine orange; DAPI: 4‘,6-diamidine-2‘-phenylindole dihydrochloride; DMEM: Dulbecco's modified Eagle medium; DMSO: dimethyl sulfoxide; EtBr: ethidium bromide; FITC: fluorescein isothiocyanate; GERD: gastroesophageal reflux disease; MEL: murine erythroleukemia; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NNN: N'-nitrosonornicotine; PBS: phosphate buffered saline; PI: propidium iodid

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The study of the apoptogenic effect of pyrimidine derivatives on murine leukemia cell