N\u3csup\u3e2\u3c/sup\u3e-Trimethylacetyl substituted and unsubstituted-N \u3csup\u3e4\u3c/sup\u3e-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d] pyrimidine-2,4-diamines: Design, cellular receptor tyrosine kinase inhibitory activities and in vivo evaluation as antiangiogenic, antimetastatic and antitumor agents

Six novel N4-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H- pyrrolo[2,3-d]pyrimidine-2,4-diamines and their N2-trimethylacetyl substituted analogs were synthesized as receptor tyrosine kinase (RTK) inhibitors. A microwave-mediated Sonogashira reaction was used as a key step for the synthesis of these compounds. Biological evaluation, in whole cell assays, showed that some analogs had remarkable inhibitory activity against a variety of RTKs and in particular cytotoxic activity against A431 tumor cells in culture. The inhibitory data against RTKs in this study demonstrated that variation of the 4-anilino substituents of these analogs dictates both potency and specificity of inhibitory activity against various RTKs. The study also supported the hypothesis that interaction of substituents on the 2-amino group with hydrophobic site-II provides an increase in potency. Compound 8 of this series was selected for evaluation in vivo in a B16-F10 syngeneic mouse tumor model and exhibited significant reduction in tumor growth rate, in tumor vascular density and in metastases to the lung compared to the control. © 2012 Elsevier Ltd. All rights reserved

Novel tricyclic indeno[2,1-d]pyrimidines with dual antiangiogenic and cytotoxic activities as potent antitumor agents

We designed, synthesized and evaluated 13 novel tricyclic indeno[2,1-d]pyrimidines as RTK inhibitors. These analogues were synthesized via a Dieckmann condensation of 1,2-phenylenediacetonitrile followed by cyclocondensation with guanidine carbonate to afford the 2-amino-3,9-dihydro- indeno[2,1-d]pyrimidin-4-one. Sulfonation of the 4-position followed by displacement with appropriately substituted anilines afforded the target compounds. These compounds were potent inhibitors of platelet-derived growth factor receptor β (PDGFRβ) and inhibited angiogenesis in the chicken embryo chorioallantonic membrane (CAM) assay compared to standards. In addition, compound 7 had a two digit nanomolar GI 50 against nine tumor cell lines, a submicromolar GI 50 against 29 of other tumor cell lines in the preclinical NCI 60 tumor cell line panel. Compound 7 also demonstrated significant in vivo inhibition of tumor growth and angiogenesis in a B16-F10 syngeneic mouse melanoma model. © 2012 Elsevier Ltd. All rights reserved

Development and characterization of a preclinical model of breast cancer lung micrometastatic to macrometastatic progression.

Most cancer patients die with metastatic disease, thus, good models that recapitulate the natural process of metastasis including a dormancy period with micrometastatic cells would be beneficial in developing treatment strategies. Herein we report a model of natural metastasis that balances time to complete experiments with a reasonable dormancy period, which can be used to better study metastatic progression. The basis for the model is a 4T1 triple negative syngeneic breast cancer model without resection of the primary tumor. A cell titration from 500 to 15,000 GFP tagged 4T1 cells implanted into fat pad number four of immune proficient eight week female BALB/cJ mice optimized speed of the model while possessing metastatic processes including dormancy and beginning of reactivation. The frequency of primary tumors was less than 50% in animals implanted with 500-1500 cells. Although implantation with over 10,000 cells resulted in 100% primary tumor development, the tumors and macrometastases formed were highly aggressive, lacked dormancy, and offered no opportunity for treatment. Implantation of 7,500 cells resulted in >90% tumor take by 10 days; in 30-60 micrometastases in the lung (with many animals also having 2-30 brain micrometastases) two weeks post-implantation, with the first small macrometastases present at five weeks; many animals displaying macrometastases at five weeks and animals becoming moribund by six weeks post-implantation. Using the optimum of 7,500 cells the efficacy of a chemotherapeutic agent for breast cancer, doxorubicin, given at its maximal tolerated dose (MTD; 1 mg/kg weekly) was tested for an effect on metastasis. Doxorubicin treatment significantly reduced primary tumor growth and lung micrometastases but the number of macrometastases at experiment end was not significantly affected. This model should prove useful for development of drugs to target metastasis and to study the biology of metastasis

The design and discovery of water soluble 4-substituted-2,6-dimethylfuro[2, 3-d]pyrimidines as multitargeted receptor tyrosine kinase inhibitors and microtubule targeting antitumor agents

The design, synthesis and biological evaluations of fourteen 4-substituted 2,6-dimethylfuro[2,3-d]pyrimidines are reported. Four compounds (11-13, 15) inhibit vascular endothelial growth factor receptor-2 (VEGFR-2), platelet-derived growth factor receptor β (PDGFR-β), and target tubulin leading to cytotoxicity. Compound 11 has nanomolar potency, comparable to sunitinib and semaxinib, against tumor cell lines overexpressing VEGFR-2 and PDGFR-β. Further, 11 binds at the colchicine site on tubulin, depolymerizes cellular microtubules and inhibits purified tubulin assembly and overcomes both βIII-tubulin and P-glycoprotein-mediated drug resistance, and initiates mitotic arrest leading to apoptosis. In vivo, its HCl salt, 21, reduced tumor size and vascularity in xenograft and allograft murine models and was superior to docetaxel and sunitinib, without overt toxicity. Thus 21 affords potential combination chemotherapy in a single agent. © 2014 Elsevier Ltd. All rights reserved

Adaptive induction of NF-E2-related factor-2-driven antioxidant genes in endothelial cells in response to hyperglycemia

Hyperglycemia in diabetes mellitus promotes oxidative stress in endothelial cells, which contributes to development of cardiovascular diseases. Nuclear factor erythroid 2-related factor-2 (Nrf2) is a transcription factor activated by oxidative stress that regulates expression of numerous reactive oxygen species (ROS) detoxifying and antioxidant genes. This study was designed to elucidate the homeostatic role of adaptive induction of Nrf2-driven free radical detoxification mechanisms in endothelial protection under diabetic conditions. Using a Nrf2/antioxidant response element (ARE)-driven luciferase reporter gene assay we found that in a cultured coronary arterial endothelial cell model hyperglycemia (10–30 mmol/l glucose) significantly increases transcriptional activity of Nrf2 and upregulates the expression of the Nrf2 target genes NQO1, GCLC, and HMOX1. These effects of high glucose were significantly attenuated by small interfering RNA (siRNA) downregulation of Nrf2 or overexpression of Keap-1, which inactivates Nrf2. High-glucose-induced upregulation of NQO1, GCLC, and HMOX1 was also prevented by pretreatment with polyethylene glycol (PEG)-catalase or N-acetylcysteine, whereas administration of H2O2 mimicked the effect of high glucose. To test the effects of metabolic stress in vivo, Nrf2+/+ and Nrf2−/− mice were fed a high-fat diet (HFD). HFD elicited significant increases in mRNA expression of Gclc and Hmox1 in aortas of Nrf2+/+ mice, but not Nrf2−/− mice, compared with respective standard diet-fed control mice. Additionally, HFD-induced increases in vascular ROS levels were significantly greater in Nrf2−/− than Nrf2+/+ mice. HFD-induced endothelial dysfunction was more severe in Nrf2−/− mice, as shown by the significantly diminished acetylcholine-induced relaxation of aorta of these animals compared with HFD-fed Nrf2+/+ mice. Our results suggest that adaptive activation of the Nrf2/ARE pathway confers endothelial protection under diabetic conditions

Discovery of Antitubulin Agents with Antiangiogenic Activity as Single Entities with Multitarget Chemotherapy Potential

Antiangiogenic agents (AA) are cytostatic, and their utility in cancer chemotherapy lies in their combination with cytotoxic chemotherapeutic agents. Clinical combinations of vascular endothelial growth factor receptor-2 (VEGFR2) inhibitors with antitubulin agents have been particularly successful. We have discovered a novel, potentially important analogue, that combines potent VEGFR2 inhibitory activity (comparable to that of sunitinib) with potent antitubulin activity (comparable to that of combretastatin A-4 (CA)) in a single molecule, with GI₅₀ values of 10^–7 M across the entire NCI 60 tumor cell panel. It potently inhibited tubulin assembly and circumvented the most clinically relevant tumor resistance mechanisms (P-glycoprotein and β-III tubulin expression) to antimicrotubule agents. The compound is freely water-soluble as its HCl salt and afforded excellent antitumor activity <i>in vivo</i>, superior to docetaxel, sunitinib, or Temozolomide, without any toxicity

Growth of 4T1-Luc2GFP primary tumors: Timecourse.

<p>Primary tumor growth was recorded over a five week period from BALB/cJ mice implanted with 7,500 4T1-Luc2GFP cells into the mammary fat pad. (<b>A</b>) Tumor volume (mm³). (<b>B</b>) Tumor weight (mg). (<b>C</b>) Animal weights (g). Tumor volumes were calculated using the ellipsoidal method, volume (mm³) = 0.52×length × width². All data are mean ± <i>SEM</i> from two independent experiments with 5–8 mice for experiment one and 7–11 mice for experiment two and are fitted to a Gomperzian growth curve by Prism 6.0 software.</p

Summary of optimal cell number determination in the development of the metastatic mouse model.

<p>(<b>A</b>) Chart indicating the benefits of optimizing cell number for primary tumor take and metastatic progression in the 4T1 breast cancer model. (<b>B</b>) Percent tumor take in immune-proficient BALB/cJ mice implanted with 4T1-Luc2GFP cells into the number four mammary fat pad. Data are actual percent tumor take based on number of animals indicated above each bar from no fewer than nine independent experiments. Micrometastasis (<b>C</b>) and macrometastasis (<b>D</b>) in lung six weeks after implantation. Data are mean ± <i>SEM</i> from two independent experiments with <i>n</i> = 5 for experiment one, <i>n</i> = 10 for experiment two.</p