s-trans-trans-farnesylthiosalicylic-acid and Breast-Neoplasms

Aquaporin (AQP) water channels facilitate water transport across cellular membranes and are essential in regulation of body water balance. Moreover, several AQPs are overexpressed or ectopically expressed in breast cancer. Interestingly, several in vitro studies have suggested that AQPs can affect the response to conventional anticancer chemotherapies. Therefore, we took a systematic approach to test how AQP1, AQP3 and AQP5, which are often over-/ectopically expressed in breast cancer, affect total viability of 3-dimensional (3D) breast cancer cell spheroids when treated with the conventional anticancer chemotherapies Cisplatin, 5-Fluorouracil (5-FU) and Doxorubicin, a Combination of the three drugs as well as the Combination plus the Ras inhibitor Salirasib. Total viability of spheroids overexpressing AQP1 were decreased by all treatments except for 5-FU, which increased total viability by 20% compared to DMSO treated controls. All treatments reduced viability of spheroids overexpressing AQP3. In contrast, only Doxorubicin, Combination and Combination + Salirasib reduced total viability of spheroids overexpressing AQP5. Thus, this study supports a significant role of AQPs in the response to conventional chemotherapies. Evaluating the role of individual proteins that contribute to resistance to chemotherapies is essential in advancing personalized medicine in breast carcinomas.

Topics: Aquaporin 1; Aquaporin 2; Aquaporin 3; Aquaporin 4; Aquaporin 5; Aquaporins; Breast Neoplasms; Doxorubicin; Female; Fluorouracil; Humans

Ras has long been viewed as a promising target for cancer therapy. Farnesylthiosalicylic acid (FTS), as the only Ras inhibitor has ever entered phase II clinical trials, has yielded disappointing results due to its strong hydrophobicity, poor tumor-targeting capacity, and low therapeutic efficiency. Thus, enhancing hydrophilicity and tumor-targeting capacity of FTS for improving its therapeutic efficacy is of great significance. In this study we conjugated FTS with a cancer-targeting small molecule dye IR783 and characterized the anticancer properties of the conjugate FTS-IR783. We showed that IR783 conjugation greatly improved the hydrophilicity, tumor-targeting and therapeutic potential of FTS. After a single oral administration in Balb/c mice, the relative bioavailability of FTS-IR783 was increased by 90.7% compared with FTS. We demonstrated that organic anion transporting polypeptide (OATP) and endocytosis synergistically drove the uptake of the FTS-IR783 conjugate in breast cancer MDA-MB-231 cells, resulting in superior tumor-targeting ability of the conjugate both in vitro and in vivo. We further revealed that FTS-IR783 conjugate could bind with and directly activate AMPK rather than affecting Ras, and subsequently regulate the TSC2/mTOR signaling pathway, thus achieving 2-10-fold increased anti-cancer therapeutic efficacy against 6 human breast cancer cell lines compared to FTS both in vivo and in vitro. Overall, our data highlights a promising approach for the modification of the anti-tumor drug FTS using IR783 and makes it possible to return FTS back to the clinic with a better efficacy.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Farnesol; Female; Humans; Mice; ras Proteins; Salicylates

The RAS and mTOR inhibitor S-trans-trans-farnesylthiosalicylic acid (FTS) is a promising anticancer agent with moderate potency, currently undergoing clinical trials as a chemotherapeutic agent. FTS has displayed its potential against a variety of cancers including endocrine resistant breast cancer. However, the poor pharmacokinetics profile attributed to its high hydrophobicity is a major hindrance for its continued advancement in clinic. One of the ways to improve its therapeutic potential would be to enhance its bioavailability to cancer tissue by developing a method for targeted delivery. In the current study, FTS was conjugated with the cancer-targeting heptamethine cyanine dye 5 to form the FTS-dye conjugate 11. The efficiency of tumor targeting properties of conjugate 11 against cancer cell growth and mTOR inhibition was evaluated in vitro in comparison with parent FTS. Cancer targeting of 11 in a live mouse model of MCF7 xenografts was demonstrated with noninvasive, near-infrared fluorescence (NIRF) imaging. The results from our studies clearly suggest that the bioavailability of FTS is indeed improved as indicated by log P values and cancer cell uptake. The FTS-dye conjugate 11 displayed higher potency (IC

Topics: Animals; Antineoplastic Agents; Biological Availability; Breast Neoplasms; Carbocyanines; Cell Line, Tumor; Cell Proliferation; Drug Delivery Systems; Farnesol; Female; Humans; MCF-7 Cells; Mice; Mice, Nude; ras Proteins; Salicylates; Tissue Distribution; TOR Serine-Threonine Kinases

We have recently designed and developed a dual-functional drug carrier that is based on poly(ethylene glycol) (PEG)-derivatized farnesylthiosalicylate (FTS, a nontoxic Ras antagonist). PEG5K-FTS2 readily form micelles (20-30 nm) and hydrophobic drugs such as paclitaxel (PTX) could be effectively loaded into these micelles. PTX formulated in PEG5K-FTS2 micelles showed an antitumor activity that was more efficacious than Taxol in a syngeneic mouse model of breast cancer (4T1.2). In order to further improve our PEG-FTS micellar system, four PEG-FTS conjugates were developed that vary in the molecular weight of PEG (PEG2K vs PEG5K) and the molar ratio of PEG/FTS (1/2 vs 1/4) in the conjugates. These conjugates were characterized including CMC, drug loading capacity, stability, and their efficacy in delivery of anticancer drug PTX to tumor cells in vitro and in vivo. Our data showed that the conjugates with four FTS molecules were more effective than the conjugates with two molecules of FTS and that FTS conjugates with PEG5K were more effective than the counterparts with PEG2K in forming stable mixed micelles. PTX formulated in PEG5K-FTS4 micelles was the most effective formulation in inhibiting the tumor growth in vivo.

Topics: Animals; Breast Neoplasms; Disease Models, Animal; Drug Carriers; Farnesol; Female; HCT116 Cells; Hemolysis; Humans; Inhibitory Concentration 50; Magnetic Resonance Spectroscopy; Mammary Neoplasms, Experimental; MCF-7 Cells; Mice; Mice, Inbred BALB C; Micelles; Paclitaxel; Polyethylene Glycols; Salicylates

S-trans, trans-farnesylthiosalicylic acid (FTS) is a synthetic small molecule that acts as a potent and especially nontoxic Ras antagonist. It inhibits both oncogenically activated Ras and growth factor receptor-mediated Ras activation, resulting in the inhibition of Ras-dependent tumor growth. In this work, an FTS conjugate with poly(ethylene glycol) (PEG) through a labile ester linkage, PEG5K-FTS2(L), was developed. PEG5K-FTS2 conjugate readily forms micelles in aqueous solutions with a critical micelle concentration of 0.68 μM, and hydrophobic drugs such as paclitaxel (PTX) could be effectively loaded into these particles. Both drug-free and PTX-loaded micelles were spherical in shape with a uniform size of 20-30 nm. The release of PTX from PTX-loaded PEG5K-FTS2 micelles was significantly slower than that from Taxol formulation. In vitro cytotoxicity studies with several tumor cell lines showed that PEG5K-FTS2(L) was comparable to FTS in antitumor activity. Western immunoblotting showed that total Ras levels were downregulated in several cancer cell lines treated with FTS or PEG5K-FTS2(L). The micellar formulation of PTX exhibited more in vitro cytotoxic activity against several tumor cell lines compared with free PTX, suggesting a possible synergistic effect between the carrier and the codelivered drug. The antitumor activity of the PTX loaded PEG5K-FTS2(L) micelles in a syngeneic murine breast cancer model was found to be significantly higher than that of Taxol, which may be attributed to their preferential tumor accumulation and a possible synergistic effect between PEG5K-FTS2 carrier and loaded PTX.

Topics: Animals; Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cell Line, Tumor; Drug Delivery Systems; Farnesol; Female; HCT116 Cells; Humans; Mice; Mice, Inbred BALB C; Micelles; Paclitaxel; Polyethylene Glycols; Random Allocation; Rats; Salicylates

Farnesyltransferase inhibitors (FTIs) are being developed to block Ras-mediated actions, but current data suggest that the FTIs act through other non-Ras pathways. A new agent, farnesylthiosalicylic acid (FTS), blocks the binding of Ras to membrane acceptor sites and causes a marked reduction in Ras levels. Accordingly, FTS could be a useful new agent for the treatment of hormone-dependent breast cancer. We examined the dose-response effects of FTS on the growth of MCF-7 breast cancer cells in vitro and in vivo. Further, we dissected out its specific effects on cell proliferation and apoptosis by measuring BrdU incorporation into DNA and by using an ELISA assay to quantitate the magnitude of apoptosis. FTS and its solubilized conjoiner FTS-cyclodextrin markedly inhibited cell growth in MCF-7 breast cancer cells in culture and in xenografts. This agent exerted dual effects to reduce cell proliferation as assessed by BrdU incorporation and to enhance apoptosis as quantitated by ELISA assay. These data suggest that FTS is a promising agent to be developed for treatment of hormone-dependent breast cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cyclodextrins; Dose-Response Relationship, Drug; Estradiol; Farnesol; Female; Humans; Injections, Intraperitoneal; Mammary Neoplasms, Experimental; Mice; Mice, Nude; Neoplasms, Hormone-Dependent; ras Proteins; Salicylates; Xenograft Model Antitumor Assays

Estradiol (E2) stimulates proliferation of hormone-dependent breast cancer and exerts downstream effects on growth factors and their receptors. Key among the pathways' mediating growth factor action is the MAP kinase signaling cascade and the PI-3 kinase pathway with its downstream effector mTOR. We postulated that farnesylthiosalicylic acid (FTS), a novel anti-Ras drug, could effectively inhibit hormone-dependent breast cancer because Ras activates both the MAP kinase and the PI3 kinase pathways. Wild-type MCF-7 cells and a long-term estrogen-deprived subline (LTED) were used to examine the effect of FTS on cell growth and on several biochemical parameters. FTS inhibited growth of both cell lines by reducing proliferation and inducing apoptosis. These effects correlated best with blockade of phosphorylation of PHAS-I and p70 S6 kinase, 2 downstream effectors of mTOR. We observed only minimal inhibition of Akt, an effector upstream of mTOR. Taken together, these findings demonstrate a novel effect of FTS to inhibit mTOR signaling and also suggest that mTOR has a key role in breast cancer cell proliferation. Unexpectedly, only minimal inhibition of MAP kinase occurred in response to FTS at concentrations that markedly reduced cell growth. These later data provide support for the concept that FTS exerts its effects predominantly by blocking mTOR and to a lesser effect by inhibition of MAP kinase in breast cancer cells.

Topics: Apoptosis; Blood; Breast Neoplasms; Cell Division; Cell Line, Tumor; DNA Replication; Enzyme Activation; Epidermal Growth Factor; Estradiol; Farnesol; Humans; Insulin-Like Growth Factor I; Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Kinases; Ribosomal Protein S6 Kinases; Salicylates; Signal Transduction; TOR Serine-Threonine Kinases

Tamoxifen (TAM) provides an effective agent for treatment of hormone-dependent breast cancer but resistance uniformly ensues upon continued use. Additional studies are required to define more precisely the mechanisms involved in development of resistance. We conducted systematic experimental and clinical studies based on the hypothesis that tumors exposed to TAM long-term may develop resistance by becoming hypersensitive to its estrogenic effects. These investigations uncovered new features of the TAM resistance (TR) phenomenon and identified possible means for its prevention and/or elimination. Initially we confirmed that TR may be divided into two subtypes, primary and acquired resistance, and that these differ by certain important characteristics including the level of the possible involvement of adaptive and genetic components. Then we distinguished at least three consequent stages of this phenomenon: stage I when TAM behaves as an antiestrogen, stage II with development of increased sensitivity to the agonistic (pro-estrogenic) properties of TAM and stage III with an adaptive increase in sensitivity to estradiol (E(2)). During this evolutionary process, as shown in vitro, MAP kinase (MAPK) and aromatase activities increase. The time frame of the increase in MAPK activity as a rule outpaces the increase in aromatase activity during the course of the development of TR. This may occur as a response to estrogen deprivation or interruption of the process of estrogen signaling and can be one of the promoting factors of increased aromatase activation. On the other hand, the chronology of these events indicates that changes in the MAPK cascade can be more important for the early steps of the development and maintenance of the TR state. Changes in local estrogen production/sensitivity to E(2) are perhaps essential for the later steps of this phenomenon. We have explored the use of a growth factor-blocking agent to abrogate the adaptive changes in sensitivity. Farnesylthiosalicylic acid (FTS), an inhibitor of GTP-Ras binding to its membrane acceptor site, reduces the increase in the number of MCF-7 cells induced by long-term TAM treatment. It also decreases MAPK activity in TAM-treated MCF-7 cells and in established TR cell lines. Alone or in combination with letrozole (presumably, through the influence on MAPK pathway) FTS exerts moderate inhibitory effects on aromatase activity in estrogen-deprived or estrogen-exposed MCF-7 cells. Taken together, our observa

Topics: Animals; Antineoplastic Agents, Hormonal; Aromatase; Aromatase Inhibitors; Breast Neoplasms; Drug Resistance, Neoplasm; Estradiol; Farnesol; Female; Humans; Immunoenzyme Techniques; Letrozole; Mice; Mice, Nude; Mitogen-Activated Protein Kinases; Neoplasm Transplantation; Nitriles; Receptors, Estrogen; Salicylates; Tamoxifen; Triazoles; Tumor Cells, Cultured