Selenium Deficiency Exacerbates Hyperoxia-Induced Lung Injury in Newborn C3H/HeN Mice

Extremely preterm infants are often treated with supraphysiological oxygen, which contributes to the development of bronchopulmonary dysplasia (BPD). These same infants exhibit compromised antioxidant capacities due in part to selenium (Se) deficiency. Se is essential for basal and inducible antioxidant responses. The present study utilized a perinatal Se deficiency (SeD) mouse model to identify the combined effects of newborn hyperoxia exposure and SeD on alveolarization and antioxidant responses, including the identification of affected developmental pathways. Se-sufficient (SeS) and SeD C3H/HeN breeding pairs were generated, and pups were exposed to room air or 85% O2 from birth to 14 d. Survival, antioxidant protein expression, and RNA seq analyses were performed. Greater than 40% mortality was observed in hyperoxia-exposed SeD pups. Surviving SeD pups had greater lung growth deficits than hyperoxia-exposed SeS pups. Gpx2 and 4 protein and Gpx activity were significantly decreased in SeD pups. Nrf2-regulated proteins, Nqo1 and Gclc were increased in SeD pups exposed to hyperoxia. RNA seq revealed significant decreases in the Wnt/β-catenin and Notch pathways. Se is a biologically relevant modulator of perinatal lung development and antioxidant responses, especially in the context of hyperoxia exposure. The RNA seq analyses suggest pathways essential for normal lung development are dysregulated by Se deficiency.

17α-estradiol acts through hypothalamic pro-opiomelanocortin expressing neurons to reduce feeding behavior

Weight loss is an effective intervention for diminishing disease burden in obese older adults. Pharmacological interventions that reduce food intake and thereby promote weight loss may offer effective strategies to reduce age‐related disease. We previously reported that 17α‐estradiol (17α‐E2) administration elicits beneficial effects on metabolism and inflammation in old male mice. These observations were associated with reduced calorie intake. Here, we demonstrate that 17α‐E2 acts through pro‐opiomelanocortin (Pomc) expression in the arcuate nucleus (ARC) to reduce food intake and body mass in mouse models of obesity. These results confirm that 17α‐E2 modulates appetite through selective interactions within hypothalamic anorexigenic pathways. Interestingly, some peripheral markers of metabolic homeostasis were also improved in animals with near complete loss of ARC Pomc transcription. This suggests that 17α‐E2 might have central and peripheral actions that can beneficially affect metabolism cooperatively or independently.

Abstract 3776: Mechanistic evaluation of AG311 - an OXPHOS inhibitor - as a potential treatment for breast cancer

About fifty percent of breast cancer patients receiving a combination of surgery, radiation and systemic therapy will not remain cancer-free. Most solid tumors, including breast tumors, have hypoxic regions that can contribute to chemoresistance, radioresistance, and poor differentiation in tumors resulting in a poor clinical outcome in patients with advanced disease. It has been reported that mitochondrial respiration remains active in these hypoxic microenvironments. Complex I of the mitochondrial electron transport chain (ETC) has been shown to switch to a de-active catalytic state under hypoxic conditions. The purpose of this study was to investigate the potential anticancer action of a novel compound with antimitochondrial activity under hypoxic conditions. AG311 (5-[(4-Methylphenyl)thio]-9H-pyrimido[4,5-b]indole-2,4-diamine) is a small molecular weight compound shown to inhibit complex I activity in vitro and to drastically reduce mitochondrial oxygen consumption rate by 62.9% at 7.5 μM in breast cancer cells (p<0.001). In two triple negative breast cancer mouse models (MDA-MB-435 and 4T1), AG311 significantly reduced tumor volume by 85% and 81%, respectively (p<0.001 for both). In this current study, the effect of the microenvironment on AG311 mitochondrial inhibition was examined. First, it was shown that AG311 inhibited complex I activity not only in vitro, but also in breast cancer cells (54% inhibition, p<0.001) and tumor homogenate (50% inhibition, p = 0.01). AG311 induced greater cytotoxicity in cells (MDA-MB-435) cultured in glucose-depleted media (IC50 15.5 μM vs 20.0 μM, p<0.01), a condition favoring mitochondrial ATP production, as compared to normal glucose concentrations. Further, co-treatment of AG311 with dichloroacetate, a pyruvate dehydrogenase kinase inhibitor and stimulator of oxidative phosphorylation, showed a synergistic effect on cell kill (CI = 0.7 at 20 μM). Importantly, hypoxic conditions (1% O2) significantly sensitized cancer cells to AG311-induced cell death (from 43.3% to 30.1%, p = 0.019). Further, the effect of AG311 on the deactive form of complex I, which is promoted under hypoxic conditions was assessed by measuring NADH oxidation rate. The switch to the de-active state was thermally-induced in mitochondrial homogenates and once in this state, complex I activity was sensitized to AG311 inhibition (from 45.4% to 65.0% inhibition, p = 0.04). Thus, a mitochondrial inhibitor that preferentially inhibits the de-active state of complex I in hypoxic tumor regions could potentially provide a therapeutic benefit.

Citation Format: Anja Bastian, Satoshi Matsuzaki, Kenneth M. Humphries, Lora C. Bailey-Downs, Aleem Gangjee, Michael A. Ihnat. Mechanistic evaluation of AG311 - an OXPHOS inhibitor - as a potential treatment for breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3776.

Abstract 4451: Novel small molecule AG311 induces tumor cell death through inhibition of mitochondrial electron transport

Mitochondria are emerging as an attractive target for new anticancer therapy. The inhibition of the mitochondrial electron transport chain (ETC) provides an alternate and selective mechanism for killing cancer cells, bypassing upstream apoptosis-inducing pathways. The mechanism is based on the fact that cancer cells have higher mitochondrial membrane potential rendering them inherently susceptible to increased reactive oxygen species (ROS) generation such as superoxide through the respiratory chain. In addition pharmacological inhibition of complex I and III at the ubiquinone-binding site could further increase superoxide production. Taken together, this mitochondrial sensitivity represents a promising approach to selectively kill cancer cells. The purpose of this study was to investigate the mitochondria-associated cell death of AG311, a novel anticancer compound. AG311 (5-[(4-Methylphenyl)thio]-9H-pyrimido[4,5-b]indole-2,4-diamine) is a small molecular weight compound designed by our group. AG311 has been shown to induce rapid mitochondrial depolarization resulting in necrotic cell death in a cancer cell-selective manner. In two mouse orthotopic breast cancer models (MDA-MB-435 and 4T1), AG311 significantly reduced tumor volume by 85% and 81%, respectively (n = 4 - 6), with no apparent systemic toxicity.

In this study, we aimed to identify the mitochondrial protein target(s) of AG311 in cancer cells. First, upregulation of the mitochondrial ETC by culturing MDA-MB-435 cells in galactose media sensitized cells to AG311-induced cell death. Mitochondrial oxygen consumption (XFe96 extracellular flux analyzer) drastically decreased by 62.9% (± 12.9, n = 8) in response to AG311 (7.5 μM). The effect of AG311 on mitochondrial ETC complexes was determined by spectrophotometrically measuring NADH oxidation in the presence of antimycin A (complex I), ubiquinol reduction (complex III-IV) or cytochrome c oxidation (complex IV). It was found that AG311 inhibited complex I and III activity, but not complex IV. Further kinetic assays suggested that AG311 competitively inhibited ubiquinone binding and significantly induced generation of mitochondrial superoxide (estimated with MitoSOX Red). Finally, treatment with antioxidants (e.g. lipoic acid) partially prevented AG311-induced cell death. In summary, the present results indicate mitochondrial ubiquinone as a likely target for AG311-induced selective cancer cell death through generation of mitochondrial superoxide. This together with the previously demonstrated efficacy further substantiates the use of AG311 as an anticancer agent.

Citation Format: Anja Bastian, Lora C. Bailey-Downs, Jessica E. Thorpe, Ravi Kumar Vyas Devambatla, Aleem Gangjee, Kenneth M. Humphries, Michael A. Ihnat. Novel small molecule AG311 induces tumor cell death through inhibition of mitochondrial electron transport. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4451. doi:10.1158/1538-7445.AM2015-4451

Identification of novel drugs to target dormant micrometastases

BACKGROUND

Cancer-specific survival has changed remarkably little over the past half century, mainly because metastases that are occult at diagnosis and generally resistant to chemotherapy subsequently develop months, years or even decades following definitive therapy. Targeting the dormant micrometastases responsible for these delayed or occult metastases would represent a major new tool in cancer patient management. Our hypothesis is that these metastases develop from micrometastatic cells that are suppressed by normal extracellular matrix (ECM).

METHODS

A new screening method was developed that compared the effect of drugs on the proliferation of cells grown on a normal ECM gel (small intestine submucosa, SISgel) to cells grown on plastic cell culture plates. The desired endpoint was that cells on SISgel were more sensitive than the same cells grown as monolayers. Known cancer chemotherapeutic agents show the opposite pattern.

RESULTS

Screening 13,000 compounds identified two leads with low toxicity in mice and EC50 values in the range of 3-30 μM, depending on the cell line, and another two leads that were too toxic to mice to be useful. In a novel flank xenograft method of suppressed/dormant cells co-injected with SISgel into the flank, the lead compounds significantly eliminated the suppressed cells, whereas conventional chemotherapeutics were ineffective. Using a 4T1 triple negative breast cancer model, modified for physiological metastatic progression, as predicted, both lead compounds reduced the number of large micrometastases/macrometastases in the lung. One of the compounds also targeted cancer stem cells (CSC) isolated from the parental line. The CSC also retained their stemness on SISgel. Mechanistic studies showed a mild, late apoptotic response and depending on the compound, a mild arrest either at S or G2/M in the cell cycle.

CONCLUSIONS

In summary we describe a novel, first in class set of compounds that target micrometastatic cells and prevent their reactivation to form recurrent tumors/macrometastases.

A small molecule with anticancer and antimetastatic activities induces rapid mitochondrial-associated necrosis in breast cancer

Therapy for treatment-resistant breast cancer provides limited options and the response rates are low. Therefore, the development of therapies with alternative chemotherapeutic strategies is necessary. AG311 (5-[(4-methylphenyl)thio]-9H-pyrimido[4,5-b]indole-2,4-diamine), a small molecule, is being investigated in preclinical and mechanistic studies for treatment of resistant breast cancer through necrosis, an alternative cell death mechanism. In vitro, AG311 induces rapid necrosis in numerous cancer cell lines as evidenced by loss of membrane integrity, ATP depletion, HMGB1 (high-mobility group protein B1) translocation, nuclear swelling, and stable membrane blebbing in breast cancer cells. Within minutes, exposure to AG311 also results in mitochondrial depolarization, superoxide production, and increased intracellular calcium levels. Additionally, upregulation of mitochondrial oxidative phosphorylation results in sensitization to AG311. This AG311-induced cell death can be partially prevented by treatment with the mitochondrial calcium uniporter inhibitor, Ru360 [(μ)[(HCO2)(NH3)4Ru]2OCl3], or an antioxidant, lipoic acid. Additionally, AG311 does not increase apoptotic markers such as cleavage of poly (ADP-ribose) polymerase (PARP) or caspase-3 and -7 activity. Importantly, in vivo studies in two orthotopic breast cancer mouse models (xenograft and allograft) demonstrate that AG311 retards tumor growth and reduces lung metastases better than clinically used agents and has no gross or histopathological toxicity. Together, these data suggest that AG311 is a first-in-class antitumor and antimetastatic agent inducing necrosis in breast cancer tumors, likely through the mitochondria.

Abstract 4023: Identification of novel compounds to target dormant micrometastatic cells

In spite of decades of research and billions of dollars, cancer-specific death rates have changed little, mainly because 90% of cancer patients who die succumb to metastatic disease. Our hypothesis is that the most vulnerable target for cancer therapy is the micrometastatic cell that leaves the primary tumor early in the disease history, lies dormant or suppressed by the normal extracellular matrix (ECM) and then emerges even decades later. We here describe a novel approach to identifying compounds that target micrometastatic cells suppressed by normal ECM. We first developed an in vitro 96-well format screen based on an earlier observation in our lab that the normal ECM suppresses the malignant phenotype. Using paired wells, one of which contains a normal ECM gel (small intestine submucosa, SISgel) and the other is just bare plastic, known cancer therapeutics show lower activity (more resistance) in cells grown on SISgel than on plastic. Our endpoint was the opposite pattern, namely more resistant on plastic. We screened 3,000 compounds in an NCI diversity set and identified 3 with the requisite activity. All had low toxicity in mice (<45 mg/kg). EC50 values were in the range of 3-30 µM, depending on the cell line. Screening of an additional 10K compounds identified 2 additional compounds, but they were too toxic to mice to be useful. We evaluated the activities of these compounds in vivo using a novel flank xenograft method we developed in which GFP-labeled cancer cells are co-injected with SISgel into the flank. The SISgel reprograms the cells and substantially normalizes them, even after the SISgel is resorbed such that a flat, glowing green spot marks the suppressed cells. Histopathology confirmed a substantial normalization. Cancer cells co-injected with Matrigel show rapid tumor growth. The lead compounds significantly eliminated the suppressed cells, whereas conventional chemotherapeutics were ineffective. Using a 4T1 triple negative breast cancer model modified for physiological metastatic progression; surprisingly, 2 of the 3 lead compounds given intraperitoneally or in osmotic pumps decreased primary tumor growth more effectively than did docetaxel and resulted in small decreases in small lung micrometastases. However, as predicted, the main effect was to significantly (P<0.01, one-way ANOVA/Tukey post test) reduce the formation of lung macrometastases almost to zero. Given this result, we tested the activity of these compounds against ALDH+ CD44v3+ stem cells (SC) isolated from the parental line and found that one of the compounds specifically targeted the SC (EC50 = 50 µM vs 630 µM for doxorubicin). The SC also retained their stemness on SISgel. Mechanistic studies showed a weak, late apoptotic response but depending on the compound, blocking either at G1/S or G2/M in the cell cycle. In summary we describe a novel, first in class set of compounds that target micrometastatic cells and prevent their differentiation into cancer cells that form tumors.

Citation Format: Robert E. Hurst, Michael A. Ihnat, Paul J. Hauser, Lora C. Bailey-Downs, Lilly Y. Bourgignon. Identification of novel compounds to target dormant micrometastatic cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4023. doi:10.1158/1538-7445.AM2014-4023

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.

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.

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 in vivo, superior to docetaxel, sunitinib, or Temozolomide, without any toxicity.

Solid phase synthesis and biological evaluation of probestin as an angiogenesis inhibitor

Probestin is a potent aminopeptidase N (APN) inhibitor originally isolated from the bacterial culture broth. Here, we report probestin synthesis by solid phase peptide synthesis (SPPS) method and evaluated its activity to inhibit angiogenesis using a chicken embryo chorioallantoic membrane (CAM) assay and a CAM tumor xenograft model. Results from these studies demonstrate that probestin inhibits the angiogenic activity and tumor growth.

Abstract 1389: Development and characterization of a natural model of triple negative breast micrometastasis

Physiologically relevant animal models of micrometastasis are lacking; yet micrometastasis activation leading to macrometastasis and/or recurrent tumors is a major cause of cancer mortality and treatment resistance. Tumor cell implantation metastasis models typically use large numbers of tumor cells and immune compromised rodents together with removal of primary tumors to maximize the number, size and speed of macrometastases. Genetic and chemical/physical tumorigenesis models are often inconveniently slow and do not provide consistent metastasis. In order to develop a platform for investigating the biology of micrometastasis and for drug development to target micrometastases, we developed a model to study this phenomenon in vivo. The 4T1 triple negative syngeneic breast cancer model was chosen without resection of the primary tumor. A cell titration from 100,000 to 500 4T1-GFP tagged cells was first completed, with cells implanted into fat pad 3 of immune proficient 8 wk female BALB/c mice. Implantation of 15,000-100,000 cells resulted in 90-100% primary tumor take by 7 days; a small number (less than 15) micrometastases into the lungs by 2 wk; 70-90% of the animals having macrometastases (as evidenced by a distinct blood supply using tetrarhodamine labeled dextran) by 4 wk; and with most animals becoming moribund by 5 wk. Implantation of 7,500 cells resulted in >90% tumor take by 10 days; in 30-250 micrometastases in the lung (with many animals having 5-10 brain micrometastases) 2 wk post-implantation; with the first small macrometastases present at 4 wk; with most (80%) animals having macrometastases at 5 wk and animals becoming moribund by 6 wk post-implantation. With animals seeded with 500-1500 cells, the time of micrometastasis to macrometastasis conversion and animal survival could be prolonged, though primary tumor take was less (40-60%) than with 7,500 cells. Finally, this model using 7,500 cells was used to test the efficacy of a first-line chemotherapeutic agent for breast cancer, docetaxel, given at its maximal tolerated dose (MTD; 30 mg/kg weekly). Although primary tumor growth could be significantly reduced by docetaxel (P<0.01; two way ANOVA/repeated measures post-test), the number of micro and macrometastases at the experiment end was not significantly affected by docetaxel treatment and animal weight, a measure of systemic toxicity, was significantly reduced in the docetaxel group (P<0.01, unpaired two-tailed students’ t-test).

Citation Format: Michael A. Ihnat, Lora C. Bailey-Downs, Jessica E. Thorpe, Bryan C. Disch, Anja Bastian, Taleah C. Farasyn, Paul J. Hauser, Robert E. Hurst. Development and characterization of a natural model of triple negative breast micrometastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1389. doi:10.1158/1538-7445.AM2013-1389

N2-Trimethylacetyl substituted and unsubstituted-N4-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 N(4)-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines and their N(2)-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.

Aging exacerbates obesity-induced oxidative stress and inflammation in perivascular adipose tissue in mice: a paracrine mechanism contributing to vascular redox dysregulation and inflammation

Obesity in the elderly individuals is increasing at alarming rates and there is evidence suggesting that elderly individuals are more vulnerable to the deleterious cardiovascular effects of obesity than younger individuals. However, the specific mechanisms through which aging and obesity interact to promote the development of cardiovascular disease remain unclear. The present study was designed to test the hypothesis that aging exacerbates obesity-induced inflammation in perivascular adipose tissue, which contributes to increased vascular oxidative stress and inflammation in a paracrine manner. To test this hypothesis, we assessed changes in the secretome, reactive oxygen species production, and macrophage infiltration in periaortic adipose tissue of young (7 month old) and aged (24 month old) high-fat diet-fed obese C57BL/6 mice. High-fat diet-induced vascular reactive oxygen species generation significantly increased in aged mice, which was associated with exacerbation of endothelial dysfunction and vascular inflammation. In young animals, high-fat diet-induced obesity promoted oxidative stress in the perivascular adipose tissue, which was associated with a marked proinflammatory shift in the profile of secreted cytokines and chemokines. Aging exacerbated obesity-induced oxidative stress and inflammation and significantly increased macrophage infiltration in periaortic adipose tissue. Using cultured arteries isolated from young control mice, we found that inflammatory factors secreted from the perivascular fat tissue of obese aged mice promote significant prooxidative and proinflammatory phenotypic alterations in the vascular wall, mimicking the aging phenotype. Overall, our findings support an important role for localized perivascular adipose tissue inflammation in exacerbation of vascular oxidative stress and inflammation in aging, an effect that likely enhances the risk for development of cardiovascular diseases from obesity in the elderly individuals.

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.

Growth hormone and IGF-1 deficiency exacerbate high-fat diet-induced endothelial impairment in obese Lewis dwarf rats: implications for vascular aging

Previous studies suggest that the age-related decline in circulating growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels significantly contribute to vascular dysfunction in aging by impairing cellular oxidative stress resistance pathways. Obesity in elderly individuals is increasing at alarming rates, and there is evidence suggesting that elderly individuals are more vulnerable to the deleterious cardiovascular effects of obesity than younger individuals. However, the specific mechanisms through which aging, GH/IGF-1 deficiency, and obesity interact to promote the development of cardiovascular disease remain unclear. To test the hypothesis that low circulating GH/IGF-1 levels exacerbate the pro-oxidant and proinflammatory vascular effects of obesity, GH/IGF-1-deficient Lewis dwarf rats and heterozygous control rats were fed either a standard diet or a high-fat diet (HFD) for 7 months. Feeding an HFD resulted in similar relative weight gains and increases in body fat content in Lewis dwarf rats and control rats. HFD-fed Lewis dwarf rats exhibited a relative increase in blood glucose levels, lower insulin, and impaired glucose tolerance as compared with HFD-fed control rats. Analysis of serum cytokine expression signatures indicated that chronic GH/IGF-1 deficiency exacerbates HFD-induced inflammation. GH/IGF-1 deficiency also exacerbated HFD-induced endothelial dysfunction, oxidative stress, and expression of inflammatory markers (tumor necrosis factor-α, ICAM-1) in aortas of Lewis dwarf rats. Overall, our results are consistent with the available clinical and experimental evidence suggesting that GH/IGF-1 deficiency renders the cardiovascular system more vulnerable to the deleterious effects of obesity.

Liver-specific knockdown of IGF-1 decreases vascular oxidative stress resistance by impairing the Nrf2-dependent antioxidant response: a novel model of vascular aging

Recent studies demonstrate that age-related dysfunction of NF-E2-related factor-2 (Nrf2)-driven pathways impairs cellular redox homeostasis, exacerbating age-related cellular oxidative stress and increasing sensitivity of aged vessels to oxidative stress-induced cellular damage. Circulating levels of insulin-like growth factor (IGF)-1 decline during aging, which significantly increases the risk for cardiovascular diseases in humans. To test the hypothesis that adult-onset IGF-1 deficiency impairs Nrf2-driven pathways in the vasculature, we utilized a novel mouse model with a liver-specific adeno-associated viral knockdown of the Igf1 gene using Cre-lox technology (Igf1(f/f) + MUP-iCre-AAV8), which exhibits a significant decrease in circulating IGF-1 levels (~50%). In the aortas of IGF-1-deficient mice, there was a trend for decreased expression of Nrf2 and the Nrf2 target genes GCLC, NQO1 and HMOX1. In cultured aorta segments of IGF-1-deficient mice treated with oxidative stressors (high glucose, oxidized low-density lipoprotein, and H(2)O(2)), induction of Nrf2-driven genes was significantly attenuated as compared with control vessels, which was associated with an exacerbation of endothelial dysfunction, increased oxidative stress, and apoptosis, mimicking the aging phenotype. In conclusion, endocrine IGF-1 deficiency is associated with dysregulation of Nrf2-dependent antioxidant responses in the vasculature, which likely promotes an adverse vascular phenotype under pathophysiological conditions associated with oxidative stress (eg, diabetes mellitus, hypertension) and results in accelerated vascular impairments in aging.

Long-term deficiency of circulating and hippocampal insulin-like growth factor I induces depressive behavior in adult mice: a potential model of geriatric depression

Numerous studies support the hypothesis that deficiency of insulin-like growth factor I (IGF-1) in adults contributes to depression, but direct evidence is limited. Many psychological and pro-cognitive effects have been attributed to IGF-1, but appropriate animal models of adult-onset IGF-1 deficiency are lacking. In this study, we use a viral-mediated Cre-loxP system to knockout the Igf1 gene in either the liver, neurons of the CA1 region of the hippocampus, or both. Knockout of liver Igf1 reduced serum IGF-1 levels by 40% and hippocampal IGF-1 levels by 26%. Knockout of Igf1 in CA1 reduced hippocampal IGF-1 levels by 13%. The most severe reduction in hippocampal IGF-1 occurred in the group with knockouts in both liver and CA1 (36% reduction), and was associated with a 3.5-fold increase in immobility in the forced swim test. Reduction of either circulating or hippocampal IGF-1 levels did not alter anxiety measured in an open field and elevated plus maze, nor locomotion in the open field. Furthermore, local compensation for deficiencies in circulating IGF-1 did not occur in the hippocampus, nor were serum levels of IGF-1 upregulated in response to the moderate decline of hippocampal IGF-1 caused by the knockouts in CA1. We conclude that adult-onset IGF-1 deficiency alone is sufficient to induce a depressive phenotype in mice. Furthermore, our results suggest that individuals with low brain levels of IGF-1 are at increased risk for depression and these behavioral effects are not ameliorated by increased local IGF-1 production or transport. Our study supports the hypothesis that the natural IGF-1 decline in aging humans may contribute to geriatric depression.