DNA synthesis in LLC cells

Therefore, we compared the tumor cytotoxicity between EPA ethylester and the accelerated test-formed by-products in in vitro models. The inhibitory effects of E-1 (EPA ethylester dimer) and E-2 (EPA hydroxyethylester) isolated from EPAD on DNA synthesis in LLC cells were stronger than those of EPA ethylester Fig. (9) . Furthermore, it was found that the effects of E-1 (EPA ethylester... 

The antitumor and antimetastatic activities of EPAD may be due to the combination of inhibition of DNA synthesis in LLC cells, increase of tumor apoptosis, inhibition of tumor-induced neovascularization, and activation of CD8 T cells however, the antitumor activity of EPA ethylester may be due to the combination of inhibition of DNA synthesis in LLC cells, an increase of tumor apoptosis, inhibition of tumor-induced neovascularization, and activation of NK cells. Thus, it is suggested that the mechanisms of the antitumor and/or antimetastatic actions of EPAD and EPA ethylester involve different immune functions, and the EPA ethylester dimer and EPA hydroxy ethylester may contribute to these actions. 

To characterize the antitumor and/or antimetastatic activities, the effects of carp oil and oleic acid on DNA synthesis in LLC cells, adherence of LLC cells to human adult dermal microvascular endothelial cells (HMVEC), and Matrigel-induced angiogenesis (in vitro and in vivo) were tested. Carp oil inhibited DNA synthesis in LLC cells at 100 and 1000 pg/mL, but not at 0.1 to 10 pg/mL Table (10) . Oleic acid inhibited DNA synthesis in LLC cells at 1000 pM Table (11) . Carp oil inhibited the Matrigel-induced tube-like network formation of HMVEC at 1000 pg/mL, but not at 0.1 to 100 pg/mL Table (10) . 

Table 11. Effects of oleic acid on DNA synthesis in LLC cells, Matrigel-induced capillary-like tube network Formation from HMVEC, and the adherence ofLLC cells to HMVEC (in vitro)1...

These findings suggest that the mechanisms of the antitumor and the antimetastatic actions of carp oil might involve the inhibition of DNA synthesis in LLC cells, and the inhibition of angiogenesis through the inhibition of LLC cell adherence to the microvascular endothelium. 

On the other hand, the inhibitory actions of oleic acid on metastasis in the liver and metastatic tumor growth in the liver, cannot be explained by the effects of DNA synthesis in LLC cells, and microvascular endothelial cells, or the adherence of LLC cells to the microvascular endothelium rather, these inhibitory actions by oleic acid are partly attributable to the inhibition of the angiogenesis induced by tumors. In conclusion, it seems likely that the antitumor and antimetastatic activities of carp oil may be partly ascribed to a fatty acid, oleic acid, as an active substance. However, the antitumor and antimetastatic effects of carp oil are insufficiently by themselves to explain the action of oleic acid. Further work is in progress to identify the active substance(s) in carp oil. 

Sphingosine and sphingosine 1-phosphate can induce DNA synthesis in growth-arrested Swiss 3T3 cells. FBj incubated with the cells elevated sphingosine and induced an increase in [ H] thymidine incorporation into DNA (59). Further studies showed that sphinganine was required for stimulation of DNA synthesis. Studies with LLC-PK renal cells showed a close correlation between fumonisin-induced cytotoxicity and inhibition of de novo sphingolipid biosyntheses (82). However, studies with primary rat hepatocytes have not shown any relationship between cytotoxicity and elevation of free sphingoid bases (38). 

In primary rahhit proximal tuhular (RPT) cells cisplatin exposure resulted in an inhihition of DNA synthesis, which is most likely related to the primary anti-tumorigenic mechanism of this compound i.e. DNA inter and intra strand cross linking [117]. RNA and protein synthesis were decreased in RPT cells and quiescent LLC-PK cells upon cisplatin exposure [117, 118]. Other effects of cisplatin on cultured RPT include a decrease in glucose uptake, an inhihition of Na -K ATPase and alterations in total glutathione content [117]. In the normal rat kidney (NRK) cell hne cisplatin (IpM for 48h) induced a marked increase in the level of lipid peroxides [119]. 

The nephrotoxicity of 16 continues to generate considerable interest. Orellanine was highly toxic to mice (LD50 = 12.5 mg/kg i.p.)[101] and caused interstitial nephritis and tubular necrosis in mouse kidney [102], A summary of 16-induced changes in renal function and morphology has been reported [103]. In LLC-PKi renal epithelial cell cultures, 16 decreased the activity of alkaline phosphatase and lactate dehydrogenase, and decreased the incorporation of H-leucine and H-thymidine [104]. Orellanine was a noncompetitive inhibitor of renal alkaline phosphatase, but a competitive inhibitor of the intestinal and placental enzymes [105]. In canine kidney MDCK cell cultures, 16, or a metabolite of 16, inhibited protein, RNA and DNA synthesis [106]. 

Further data concerning the mechanism of action of 2-g-D-ribofuran-osylthiazole- carboxamide 2 (tiazofurin), in comparison with ribavirin and pyrazofurin have appeared. Marked inhibition of DNA and RNA synthesis by 2 was noted. Synthesis of the selenium analog of 2 was also reported. This compound, 3, was <5 fold more potent than 2 in cell tissue culture (P388, L1210 cells) and showed good Lewis Lung Carcinoma (LLC)... 

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