Olsalazine inhibits cell proliferation and DNA methylation in canine lymphoid tumor cell lines

Abnormal DNA methylation is involved in the initiation and progression of lymphoid tumors. Hence, DNA demethylating agents are promising candidate drugs for chemotherapy against these tumors. The salicylic acid derived anti-inflammatory agent, olsalazine, reportedly suppresses DNA methyltransferase in human cells and has the potential to be clinically applied as a DNA demethylating agent. In this study, we investigated the effects of olsalazine on cell proliferation and DNA methylation using canine lymphoid tumor cell lines (CLBL-1, GL-1, and UL-1). Treatment with olsalazine led to significant cell growth inhibition and increased the apoptotic rate in all three cell lines. Treatment with olsalazine reduced the total amount of 5-methylcytosine in genomic DNA, as assessed by enzyme-linked immunosorbent assay. Genome-wide analysis of DNA methylation revealed that 1,801 to 5,626 CpG sites showed decreased DNA methylation levels in three cell lines, including the promoter regions of ADAM23, FES, and CREB3L1 genes. The outcomes of the present study demonstrate that a DNA demethylating agent olsalazine, inhibits cell proliferation and DNA methylation in canine lymphoid tumor cells, suggesting that it can be a candidate drug for the treatment of lymphoid tumors in dogs.

Tumorigenicity depends on angiogenic potential of tumor cells: dominant role of vascular endothelial growth factor and/or fibroblast growth factors produced by tumor cells

The aim of this study was to determine the role of tumor-derived angiogenic factors in solid tumor formation. We compared the angiogenic potential of tumorigenic and non-tumorigenic human tumor cell lines. All tumorigenic cell lines induced angiogenesis in vivo and their angiogenesis-inducing abilities were higher than those of the other non-tumorigenic cell lines. This in vivo angiogenic potential was well correlated with the in vitro endothelial cell growth-stimulating activity contained in the cell extract or conditioned medium of each cell line. The endothelial cell growth-stimulating activities of these cell lines were completely inhibited by neutralizing antibodies to basic fibroblast growth factor (bFGF), acidic FGF (aFGF) or vascular endothelial growth factor (VEGF). Furthermore, the levels of tumor-derived endothelial cell growth-stimulating activities depended on the amounts of angiogenic factors such as VEGF and bFGF produced by tumor cells. Although VEGF transcripts were detected in all of the cell lines by RT-PCR assay, the non-tumorigenic cell lines showed poor productivity of VEGF as well as FGFs and had less or non-potency for endothelial cell growth stimulation. These findings suggest that the increase in production of angiogenic factors by tumor cells is necessary for their in vivo angiogenic and tumorigenic potentials, and that VEGF and FGFs are the major mediators of tumor-induced angiogenesis.

Orally active docetaxel analogue: synthesis of 10-deoxy-10-C-morpholinoethyl docetaxel analogues

To improve cytotoxicity of 10-deoxy-10-C-morpholinoethyl docetaxel analogues against various tumor cell lines including resistant cells expressing P-glycoprotein (P-gp), we modified the 7-hydroxyl group to hydrophobic groups (methoxy, deoxy, 6,7-olefin, alpha-F, 7-beta-8-beta-methano, fluoromethoxy). Among these analogues, the 7-methoxy analogue showed the strongest cytotoxicity. This analogue showed potent activity against B16 melanoma BL6 in vivo by oral administration.

Growth inhibitory effect of a new camptothecin analog, DX-8951f, on various drug-resistant sublines including BCRP-mediated camptothecin derivative-resistant variants derived from the human lung cancer cell line PC-6

DX-8951f, a new water-soluble camptothecin (CPT) derivative, has been reported to show potent antitumor effects against various tumors in vitro and in vivo. We further evaluated the cytotoxic effect of DX-8951f against eight drug-resistant sublines derived by stepwise exposure of human oat cell carcinoma PC-6 to various drugs. In paclitaxel-, adriamycin-, vincristine- and etoposide-resistant cells, overexpression of P-glycoprotein (P-gp) and a correlative reduction in drug accumulation and typical drug-sensitivity pattern were confirmed. The etoposide-resistant line with the highest P-gp level was cross-resistant also to SN-38, CPT-11 and topotecan (TPT), but not to 9-aminocamptothecin (9-AC), CPT and DX-8951f. SN-38- and CPT-11-resistant cells, of which topoisomerase I activities and levels were similar to those of the parent cells, showed cross-resistance clearly to TPT, 9-AC and mitoxantrone, but hardly to DX-8951f. In these two resistant sublines, the intracellular topotecan level was significantly lower than that in parental PC-6 and the reduced accumulation was found to be mediated by breast cancer resistant protein (BCRP). The cisplatin-resistant variant, which had a 2-fold increase in glutathione content, showed no cross-resistance and the 5-fluorouracil-resistant variant, which had a 50% decrease in glutathione content, exhibited collateral sensitivity to most of the other anticancer agents including DX-8951f. We concluded that DX-8951f showed a potent cytotoxic effect on various types of drug-resistant cells.

Antiproliferative activity and mechanism of action of DZ-3358, a novel pyrimidinyl pyrazole derivative

The novel pyrimidinyl pyrazole derivative, 1-[5-methyl-1-(2-pyrimidinyl) -4-pyrazolyl]-3-[4-(3-chlorophenyl)-1-piperazinyl]-1-trans-propene hydrochloride (DZ-3358), was found through random screening to exhibit anti-proliferative activity against human and murine cancer cell lines. DZ-3358 induced the mitotic arrest of P388 murine leukemia cells at 0.4 microgram/ml in a time-dependent manner, and inhibited porcine tubulin polymerization. Furthermore, using immunofluorescence techniques, we observed microtubule formation in NUGC-3 human gastric cancer cells treated with DZ-3358. Microtubule formation was disordered, similar to that which occurred when such cells were treated with colchicine. These findings suggest that the mechanism of the anti-proliferative effect of DZ-3358 is the inhibition of mitosis due to the blocking of tubulin polymerization. The differential pattern of growth inhibitory concentrations of DZ-3358 against a series of cancer cell lines was compared with that of colchicine and vincristine, and no correlation was found with the pattern of these two drugs. DZ-3358 may be useful as a new type of tubulin inhibitor and anti-cancer drug.

Synthesis and antitumor activity of novel pyrimidinyl pyrazole derivatives

Novel pyrimidinyl pyrazole derivatives were synthesized and examined for cytotoxic and antitumor activity. Mannich reaction was employed to construct this scaffold. Among the compounds synthesized, a series of propene derivatives exhibited a potent cytotoxic activity against some tumor cell lines including multidrug resistant cell lines due to the overexpression of P-glycoprotein. The vinyl bond moiety in the scaffold was believed to be required for the cytotoxic activity. Among them, compound 14 g, when administered intraperitoneally, showed potent antitumor activity against the malignant ascites caused by intraperitoneal inoculation of P388 cells in mice. This compound also showed high activity against a solid tumor Meth A mouse fibrosarcoma when administered both intraperitoneally and orally.

Drug resistance and P-glycoprotein expression in endothelial cells of newly formed capillaries induced by tumors

The inhibitory effects of vincristine (VCR) with or without verapamil (VER) on angiogenesis in mouse subcutaneous fascia induced by mouse sarcoma 180 cells were assessed using the dorsal air sac method. VCR combined with VER had inhibitory effects on tumor-induced angiogenesis, but VCR alone did not inhibit capillarization. The chemosensitivity of human umbilical vein endothelial cells (HUVEC) and tumor-derived endothelial cells from rat KMT-17 fibrosarcoma (TEC) was examined using the microculture tetrazolium assay. VCR and taxol had strong anti-proliferative activity against HUVEC, but only weakly inhibited the proliferation of TEC. In combination with VER, VCR and Taxol inhibited the proliferation of TEC. Cisplatin, mitomycin C, and 5-fluorouracil had weakly anti-proliferative activity against both HUVEC and TEC. Expression of P-glycoprotein (P-gp) was found in TEC, but not in HUVEC using western blot analysis. These findings indicate that drug resistance and P-gp expression appeared on newly formed capillaries induced by rodents tumors.

Further investigation of phenanthroindolizidine alkaloids from Tylophora tanakae

In addition to ten alkaloids previously described, we have isolated two alkaloid N-oxides from Tylophora tanakae MAXIM. (Asclepiadaceae). Further, the polar fraction of the leaves and caules of this plant cultivated in a farm afforded two new polar alkaloids. The structures of the four products were determined. The relation between the structure and cytotoxic activity of this group of alkaloids is discussed.

Minor daphnane-type diterpenoids from Wikstroemia retusa

In addition to huratoxin, pimelea factor P2, and wikstroelides A-G from the fresh bark, eight daphnane-type diterpenoids, wikstroelides H-O, were isolated from the bark and stem, and their structures established. Cytotoxicity was assayed on some wikstroelides.

Quantification of tumour-induced angiogenesis by image analysis

Quantitative techniques for in vivo and in vitro angiogenesis were developed using an image analyser. In the in vivo study, a Millipore chamber filled with mouse sarcoma 180 (S180) cells was transplanted subcutaneously to the dorsal side of a mouse, and the area of neovascularization induced by the tumour cells was quantified by image analysis. Images of vascular networks with poor contrast had their contrast improved by Laplacean transformation. The area of vascular network was 16.9 mm2 in the control group without tumour cells and 44.2 mm2 in the group with tumour cells, demonstrating a significant increase in neovascularized area by tumour cells. In the in vitro study, migration of vascular endothelial cells was induced with conditioned media of S180 cells. Image analysis was used to count automatically the nuclei of migrated endothelial cells, which were stained violet with Giemsa's solution. This automated measurement by image analyser is expected to save labour and time. Checkerboard analysis revealed that the endothelial cell migration induced by S180-conditioned medium was due to chemotaxis. The quantitation method using an automated image analyser is valuable in evaluating the induction of neovascularization by tumours and the effect of pharmacological agents on tumour angiogenesis in vivo and in vitro.

Inhibitory effects of a bacteria-derived sulfated polysaccharide against basic fibroblast growth factor-induced endothelial cell growth and chemotaxis

The effects of sulfated polysaccharides on the growth and chemotaxis of endothelial cells promoted by basic fibroblast growth factor (bFGF), a heparin-binding growth factor, and epidermal growth factor (EGF), a non-heparin-binding growth factor, were examined. The binding abilities of these two growth factors to D-gluco-D-galactan sulfate (DS-4152) were the same as to heparin. DS-4152 inhibited the growth and chemotaxis of the cells stimulated by bFGF, and prevented the binding of bFGF to the cells at both its low and high affinity binding sites: the former and the latter are heparin-like molecules and receptor proteins for bFGF, respectively. However, DS-4152 affected neither the binding of EGF to endothelial cells nor the proliferation and chemotaxis of the cells stimulated by the factor. Heparin also inhibited the binding of bFGF to low affinity binding sites to the same degree as DS-4152, but had little effect on the binding of bFGF to high affinity sites and no effects on bFGF-induced endothelial cell growth. Chondroitin sulfate A prevented neither the binding of bFGF to both sites of the cells nor bFGF-induced cell proliferation. We thus concluded that the inhibitory effects of DS-4152 against the growth and chemotaxis of endothelial cells induced by bFGF might be due to the prevention of bFGF binding to its receptor proteins resulting from the binding of DS-4152 to bFGF.

Quantification of experimental pulmonary metastases by image analyzer

Image analysis techniques for quantifying experimental pulmonary metastases were developed using Lewis lung carcinoma (3LL) and B16 melanoma. Binary images of the metastatic colonies were differentiated by staining the lung parenchyma. Thus, it became possible for the image analyzer to determine automatically the size and number of the metastatic foci. Image analysis was used successfully to evaluate the inhibitory effect of adriamycin on spontaneous metastases of 3LL. Although the inhibitory effect was not detected by the usual counting method, a significant reduction of the area of metastatic foci was detected by image analysis.

Inhibition of angiogenesis and tumor growth by a synthetic laminin peptide, CDPGYIGSR-NH2

A laminin-derived synthetic peptide, Cys-Asp-Pro-Gly-Tyr-Ile-Gly-Ser-Arg-NH2 (CDPGYIGSR-H2), containing an active site for cell binding inhibited both angiogenesis and solid tumor growth. It potently suppressed both embryonic angiogenesis of the chick chorioallantoic membrane and migration of vascular endothelial cells induced by a tumor-conditioned medium but neither the in vitro proliferation of endothelial cells nor that of tumor cells. Additionally, in in vivo tests, CDPGYIGSR-NH2 markedly inhibited both the growth of s.c. solid tumor of Sarcoma 180 and that of Lewis lung carcinoma (3LL) in the lungs. On the contrary, ascitic tumor growth of Sarcoma 180 was not affected by this peptide, even though the same cell source was used. It was concluded that solid tumor growth inhibition by CDPGYIGSR-NH2 was due not a direct effect on cell growth but to antiangiogenic effect mediated by the inhibition of endothelial cell migration.