afimoxifene and Neoplasms

To generate the first series of prodigiosene conjugates, the tripyrrolic skeleton was appended to estrone, tamoxifen and porphyrin frameworks by way of ester linkers and various hydrocarbon chain lengths. The ability of the conjugates to inhibit various types of cancer cells was evaluated in vitro. The porphyrin conjugates did not exhibit significant activity. The estrone conjugates exhibited modest activity, for the most part. However, significantly greater growth inhibition activity against certain breast, colon, lung, leukemia, melanoma and prostate cell lines was noted. This unusual effect for this first generation model class of compound warrants further investigation and comparison to cases where estrogens are linked to prodigiosenes via connection points that do not feature in estrogen receptor binding. The 4-hydroxytamoxifen conjugates exhibit nanomolar range activity against the MCF-7 breast cancer cell line, paving the way to expand the scope and connectivity of prodigiosene-tamoxifen conjugates.

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Estrone; Humans; MCF-7 Cells; Molecular Structure; Neoplasms; Porphyrins; Prodigiosin; Tamoxifen

Tamoxifen (TMX) is the most common clinical choice for the treatment of advanced or metastatic estrogen-dependent breast cancer. However, research on new challenging therapies is necessary due to its undesirable side effects and the limitation of the treatment only to the oral route. In this study, the antitumor activity of TMX-loaded nanoparticles based on different mixtures of alginate-cysteine and disulfide bond reduced bovine serum albumin was tested in vivo in MCF-7 nude mice xenograft model. These systems showed an enhancement of the TMX antitumor activity, since lower tumor evolutions and lower tumor growth rates were observed in mice treated with them. Moreover, histological and immunohistochemical studies revealed that treatments with TMX-loaded nanoparticles showed the most regressive and less proliferative tumor tissues. TMX biodistribution studies determined that TMX-loaded nanoparticles caused more accumulation of the drug into the tumor site with undetectable levels of TMX in plasma, reducing the possibility of delivering TMX to other not-targeted organs and, consequently, developing possible side effects. Thus, these TMX nanoparticulate systems are expected to provide a novel approach to the treatment of breast cancer in the future.

Topics: Alginates; Animals; Antineoplastic Agents, Hormonal; Cell Line, Tumor; Cysteine; Disulfides; Female; Glucuronic Acid; Hexuronic Acids; Humans; Mice; Mice, Nude; Nanoparticles; Neoplasms; Ovary; Serum Albumin, Bovine; Tamoxifen; Tumor Burden; Uterus; Xenograft Model Antitumor Assays

The high glucose consumption of tumor cells even in an oxygen-rich environment, referred to as the Warburg effect, has been noted as a nearly universal biochemical characteristic of cancer cells. Targeting the glycolysis pathway has been explored as an anti-cancer therapeutic strategy to eradicate cancer based on this fundamental biochemical property of cancer cells. Oncoproteins such as Akt and c-Myc regulate cell metabolism. Accumulating studies have uncovered various molecular mechanisms by which oncoproteins affect cellular metabolism, raising a concern as to whether targeting glycolysis will be equally effective in treating cancers arising from different oncogenic activities. Here, we established a dual-regulatable FL5.12 pre-B cell line in which myristoylated Akt is expressed under the control of doxycycline, and c-Myc, fused to the hormone-binding domain of the human estrogen receptor, is activated by 4-hydroxytamoxifen. Using this system, we directly compared the effect of these oncoproteins on cell metabolism in an isogenic background. Activation of either Akt or c-Myc leads to the Warburg effect as indicated by increased cellular glucose uptake, glycolysis, and lactate generation. When cells are treated with glycolysis inhibitors, Akt sensitizes cells to apoptosis, whereas c-Myc does not. In contrast, c-Myc but not Akt sensitizes cells to the inhibition of mitochondrial function. This is correlated with enhanced mitochondrial activities in c-Myc cells. Hence, although both Akt and c-Myc promote aerobic glycolysis, they differentially affect mitochondrial functions and render cells susceptible to the perturbation of cellular metabolic programs.

Topics: Animals; Anti-Bacterial Agents; Cell Line; Cell Respiration; Doxycycline; Energy Metabolism; Enzyme Activation; Enzyme Inhibitors; Estrogen Antagonists; Fatty Acids; Glucose; Glycolysis; Humans; Mice; Mitochondria; Neoplasms; Oxidation-Reduction; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-myc; Recombinant Fusion Proteins; Tamoxifen

Folate-conjugate poly[(p-nitrophenyl acrylate)-co-(N-isopropylacrylamide)] sub-microgel (F-SubMG) was loaded with tamoxifen (TMX) to obtain low (9.0 ± 0.4 μg TMX/mg F-SubMG) and high (112.0 ± 15.0 μg TMX/mg F-SubMG) load TMX-loaded F-SubMGs. Maximum in vitro drug release (77 ± 2% to 90 ± 2% of loaded TMX) took place between 47 and 168 h. The cytotoxicity of unloaded F-SubMGs in MCF-7 and HeLa cells was low; although it increased for high F-SubMG concentration. The administration of 10 μM TMX by TMX-loaded F-SubMGs was effective on both cellular types. Cell uptake of F-SubMGs took place in both cell types, but it was larger in HeLa cells because they are folate receptor positive. After subcutaneous administration (2.8 mg TMX/kg b.w.) in Wistar rats, F-SubMGs were detected at the site of injection under the skin, and a significant amount of them were included inside adipocytes. Signs of rejection were not observed after 60 days of injection. Pharmacokinetic study showed an increase in mean residence time of TMX and 4-hydroxytamoxifen (4-OHTMX), as well as a metabolite ratio (MR = AUC(4OHTMX) /AUC(TMX) ) nine times larger, when TMX was administered by drug-loaded F-SubMGs. Since 4-OHTMX is a more potent (at least 100-fold higher) antiestrogen than TMX, administration of TMX-loaded F-SubMGs can be considered an advantage.

Topics: Acrylic Resins; Animals; Cell Line, Tumor; Drug Delivery Systems; Female; Folic Acid; Freeze Drying; Gels; Humans; Injections, Subcutaneous; Materials Testing; Microscopy, Electron, Scanning; Neoplasms; Rats; Rats, Wistar; Tamoxifen

Protein farnesyltransferase (FTase) is an enzyme responsible for posttranslational modification of proteins carrying a carboxy-terminal CaaX motif. Farnesylation allows substrates to interact with membranes and protein targets. Using gene-targeted mice, we report that FTase is essential for embryonic development, but dispensable for adult homeostasis. Six-month-old FTase-deficient mice display delayed wound healing and maturation defects in erythroid cells. Embryonic fibroblasts lacking FTase have a flat morphology and reduced motility and proliferation rates. Ablation of FTase in two ras oncogene-dependent tumor models has no significant consequences for tumor initiation. However, elimination of FTase during tumor progression had a limited but significant inhibitory effect. These results should help to better understand the role of protein farnesylation in normal tissues and in tumor development.

Topics: Alkyl and Aryl Transferases; Animals; Cell Proliferation; Embryo Loss; Embryo, Mammalian; Embryonic Development; Erythroid Cells; Estrogen Antagonists; Fibroblasts; Gene Expression; Homeostasis; Integrases; Liver; Lung; Mice; Mice, Knockout; Mutation; Neoplasms; ras Proteins; Skin Neoplasms; Spleen; Tamoxifen; Wound Healing

To investigate the functions of the p53 tumor suppressor, we created a new knock-in gene replacement mouse model in which the endogenous Trp53 gene is substituted by one encoding p53ER(TAM), a p53 fusion protein whose function is completely dependent on ectopic provision of 4-hydroxytamoxifen. We show here that both tissues in vivo and cells in vitro derived from such mice can be rapidly toggled between wild-type and p53 knockout states. Using this rapid perturbation model, we define the kinetics, dependence, persistence and reversibility of p53-mediated responses to DNA damage in tissues in vivo and to activation of the Ras oncoprotein and stress in vitro. This is the first example to our knowledge of a new class of genetic model that allows the specific, rapid and reversible perturbation of the function of a single endogenous gene in vivo.

Topics: Animals; Apoptosis; Cells, Cultured; DNA Damage; Embryo, Mammalian; Fibroblasts; Gamma Rays; Gene Expression Regulation, Neoplastic; Genes, p53; Genes, ras; Intestine, Small; Mice; Mice, Transgenic; Models, Animal; Neoplasms; Spleen; Tamoxifen; Thymus Gland; Time Factors; Tumor Suppressor Protein p53; Whole-Body Irradiation

Apoptosis is a genetically encoded programme of cell death that can be activated under physiological conditions and may be an important safeguard against tumour development. Regions of low oxygen (hypoxia) and necrosis are common features of solid tumours. Here we report that hypoxia induces apoptosis in oncogenically transformed cells and that further genetic alterations, such as loss of the p53 tumour-suppressor gene or overexpression of the apoptosis-inhibitor protein Bcl-2, substantially reduce hypoxia-induced cell death. Hypoxia also selects for cells with defects in apoptosis, because small numbers of transformed cells lacking p53 overtake similar cells expressing wild-type p53 when treated with hypoxia. Furthermore, highly apoptotic regions strongly correlate with hypoxic regions in transplanted tumours expressing wild-type p53, whereas little apoptosis occurs in hypoxic regions of p53-deficient tumours. We propose that hypoxia provides a physiological selective pressure in tumours for the expansion of variants that have lost their apoptotic potential, and in particular for cells acquiring p53 mutations.

Topics: Animals; Apoptosis; Cell Hypoxia; Cell Line, Transformed; Cell Transformation, Neoplastic; Genes, p53; Mice; Neoplasm Transplantation; Neoplasms; Oxygen; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-myc; Rats; Receptors, Estrogen; Tamoxifen

In this study we provide evidence that tamoxifen, the widely used breast cancer drug, is a potent antagonist of glycolipid metabolism. When added to the medium of cultured multidrug resistant (MDR) KB-V-1 carcinoma cells, tamoxifen, at 5.0 microM, drastically lowered the levels of glucosylceramide (glc-cer), as evidenced by a reduction in glc-cer mass. In a similar fashion, in cultured human melanoma cells grown with [3H]galactose, tamoxifen inhibited formation of glc-cer by 44%, and retarded lactosylceramide and ganglioside formation by 50 and 35%, respectively. When glc-cer synthase of melanoma was assayed in cell-free incubations, the inclusion of tamoxifen, at a 1:10 molar ratio with ceramide, inhibited glc-cer synthesis by 50%. These results clearly reveal a new action of tamoxifen and thereby pose intriguing questions regarding mechanisms of action in the realm of estrogen receptor-independent modalities, including effects on MDR.

Topics: Antineoplastic Agents, Hormonal; Chromatography, Thin Layer; Drug Resistance, Multiple; Glucosylceramides; Glucosyltransferases; Glycosphingolipids; Glycosylation; Humans; KB Cells; Melanoma; Molecular Structure; Neoplasms; Tamoxifen; Tumor Cells, Cultured

Tamoxifen and 4-hydroxytamoxifen were both good inhibitors of iron-dependent lipid peroxidation in rat cardiac microsomes. Tamoxifen was also a good inhibitor of lipid peroxidation in liposomes prepared from the phospholipid obtained from rat liver microsomes. In a modified rat liver microsomal system containing a sufficiently low amount of peroxidizable phospholipid to make it comparable with the rat cardiac microsomal system, tamoxifen and 4-hydroxytamoxifen were of similar effectiveness as in the cardiac system. Tamoxifen is known to lower serum cholesterol levels, and the findings reported here indicate that the drug might also protect heart cell membranes against peroxidative damage. Potential cardioprotective and antiatherosclerotic benefits of tamoxifen are discussed in relation to the drug's use in cancer prevention and treatment.

Topics: Animals; Cardiovascular System; Dose-Response Relationship, Drug; Heart; Iron; Lipid Peroxidation; Liposomes; Male; Microsomes; Microsomes, Liver; Neoplasms; Phospholipids; Rats; Tamoxifen; Thiobarbituric Acid Reactive Substances