px-478 and Breast-Neoplasms

Despite an improvement of prognosis in breast and colon cancer, the outcome of the metastatic disease is still severe. Microevolution of cancer cells often leads to drug resistance and tumor-recurrence. To target the driving forces of the tumor microevolution, we focused on synergistic drug combinations of selected compounds. The aim is to prevent the tumor from evolving in order to stabilize disease remission. To identify synergisms in a high number of compounds, we propose here a three-step concept that is cost efficient, independent of high-throughput machines and reliable in its predictions.. We created dose response curves using MTT- and SRB-assays with 14 different compounds in MCF-7, HT-29 and MDA-MB-231 cells. In order to efficiently screen for synergies, we developed a screening tool in which 14 drugs were combined (91 combinations) in MCF-7 and HT-29 using EC. All 14 compounds exhibit antitumor effects on each of the three cell lines. The screening tool resulted in 19 potential synergisms detected in HT-29 (20.9%) and 27 in MCF-7 (29.7%). Seven of the top combinations were further verified over the whole dose response curve, and for five combinations a significant synergy could be confirmed. The combination Nutlin-3 (inhibition of MDM2) and PX-478 (inhibition of HIF-1α) could be confirmed for all three cell lines. The same accounts for the combination of Dichloroacetate (PDH activation) and NHI-2 (LDH-A inhibition). Our screening method proved to be an efficient tool that is reliable in its projections.. The presented three-step concept proved to be cost- and time-efficient with respect to the resulting data. The newly found combinations show promising results in MCF-7, HT-29 and MDA-MB231 cancer cells.

Topics: Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Cell Line, Tumor; Colonic Neoplasms; Dichloroacetic Acid; Drug Screening Assays, Antitumor; Drug Synergism; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Imidazoles; L-Lactate Dehydrogenase; Mustard Compounds; Phenylpropionates; Piperazines; Proto-Oncogene Proteins c-mdm2; Pyruvate Dehydrogenase Complex; Reproducibility of Results

Signal transducer and activator of transcription 3 (STAT3) interacts with many gene promoters and transcription factors such as hypoxia-induced factor 1α (HIF-1α). Recent evidences proposed that STAT3 and HIF-1α together are responsible for angiogenesis and immune response suppression. The main aim of this study was to inhibit STAT3 and HIF-1α and assess their effects on the expression of immunosuppressive cytokines. S31-201 and PX-478 were used to inhibit STAT3 and HIF-1α, respectively. In both hypoxic and normoxic conditions, intracellular levels of HIF-1α were evaluated by western blotting and flow cytometry. Supernatant levels were also measured for VEGF, IL-10, and TGF-β concentration. S31-201 suppressed proliferation of MCF-7 cells and led to reduced HIF-1α expression in both hypoxic and normoxic conditions. It also decreased production of the immunosuppressive cytokines. STAT3 inhibition suppressed tumor cell growth and cytokine production in a HIF-1α-dependent manner, and can be used as a promising target in cancer therapies.

Topics: Breast Neoplasms; Cell Proliferation; Cytokines; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Inhibitory Concentration 50; MCF-7 Cells; Mustard Compounds; Phenylpropionates; Small Molecule Libraries; STAT3 Transcription Factor

Considerable evidence shows that the tumor microenvironment is an active participant in preventing immunosurveillance and limiting the efficacy of anticancer therapies. Hypoxia is a prominent characteristic of the solid tumor microenvironment. The transcription factor hypoxia-inducible factor-1α (HIF-1α) is an important mediator of hypoxic response of tumor cells that modulates the expression of specific genes involved in tumor immunosuppression. Using a 4T1 breast cancer model, we show that in vivo administration of PX-478, an inhibitor of oxygen-sensitive HIF-1α, led to reduced expression of Foxp3 and VEGF transcript and/or protein, molecules that are directly controlled by HIF-1. When combined with dendritic cell (DC)-based vaccination, HIF-1α inhibition resulted in an augmented cytotoxic T lymphocyte effector function, improved proliferation status of T cells, increased production of inflammatory cytokine IFN-γ, as well as reduced regulatory function of T cells in association with slower tumor growth. Taken together, our findings indicate that the use of HIF-1α inhibition provides an immune adjuvant activity, thereby improves the efficacy of tumor antigen-based DC vaccine.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cancer Vaccines; Cell Proliferation; Cells, Cultured; Combined Modality Therapy; Dendritic Cells; Female; Forkhead Transcription Factors; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Immunotherapy, Adoptive; Interferon-gamma; Mammary Neoplasms, Animal; Mice; Mice, Inbred BALB C; Mustard Compounds; Phenylpropionates; T-Lymphocytes, Cytotoxic; Tumor Burden; Vascular Endothelial Growth Factor A