Published online before print May 20, 2004, doi: 10.1161/01.RES.0000132745.76882.70
© 2004 American Heart Association, Inc.
Molecular Medicine |
Angiogenesis Inhibitor, TNP-470, Prevents Diet-Induced and Genetic Obesity in Mice
From the Microbiology and Tumor Biology Center (E.B., R.C., Y.C.), Karolinska Institutet, Stockholm, Sweden; The Wenner-Gren Institute (B.G., B.C.), The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden; and Metabolism Unit (B.A., P.P.), Center for Metabolism and Endocrinology, Department of Medicine and Molecular Nutrition, Center for Nutrition and Toxicology, Novum, Karolinska Institutet at Huddinge University Hospital, Stockholm, Sweden.
Correspondence to Yihai Cao, MD, PhD, Microbiology and Tumor Biology Center, Karolinska Institutet, 171 77 Stockholm, Sweden. E-mail yihai.cao{at}mtc.ki.se
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Abstract |
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Adipose tissue growth has been proposed to involve recruitment of new blood vessels. Here, we test the hypothesis that delivery of an angiogenesis inhibitor in mice may prevent diet-induced obesity, the most common type of obesity in humans. We show that systemic administration of a selective angiogenesis inhibitor, TNP-470 (AGM-1470), prevents obesity in high caloric diet-fed wt mice as well as in genetically leptin-deficient ob/ob mice. Inhibition of obesity in mice by TNP-470 involves a reduction of vascularity in the adipose tissue. This therapeutic strategy appears to selectively affect the growth of adipose tissue as measured by the ratio between total fat and lean body mass. Interestingly, the treatment with TNP-470 results in decreased serum levels of low-density lipoprotein cholesterol. Furthermore, insulin levels are reduced, which indicates increased insulin sensitivity, suggesting that angiogenesis inhibitors may prevent the development of type II diabetes. Our findings suggest that similarly to growth and organogenesis in other tissues, adipose tissue growth is dependent on angiogenesis. Our observations may have conceptual implications for the prevention of obesity and related disorders.
Key Words: neovascularization • adipogenesis • obesity • TNP-470 • leptin
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Introduction |
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Obesity has become a worldwide major public health problem. Approximately 30% of the population in the US is estimated to be obese.1 The obese population has an increased risk for diabetes, dyslipidemia, cardiovascular disease, cancer, and sleep-breathing disorders.2–5 The causes of increased human obesity are directly linked to a high dietary fat intake and to reduced physical exercise. In fact, obesity resulting from inappropriate food-intake is the most common cause of human obesity, although genetic factors may also play a role.4,6
The inappropriate growth of adipose tissue by increasing both the number and size of adipocytes leads to obesity. Several hormones and cytokines, such as leptin and neuropeptide Y, have been found to be critical components controlling adipogenesis in the body.7,8 Inactivating mutations of either leptin (ob/ob) or its functional receptors (db/db) result in genetic obesity in mice and humans.2,8 Leptin have been shown to stimulate angiogenesis.9–11 These findings suggest that the targets of adipogenesis regulatory hormones are located both in the central nervous system and in peripheral tissues. Tissue growth and organ regeneration are angiogenesis-dependent.12 Several studies show that adipogenesis and angiogenesis are tightly correlated during fat mass deposit.13–16 We hypothesized that adipogenesis is concomitantly accompanied by new blood vessel growth, and thus suppression of angiogenesis would prevent adipogenesis and obesity independent of the obesity cause. To test this hypothesis, we chose a well-characterized angiogenesis inhibitor, TNP-470 (AGM-1470), to treat high-fat diet-fed C57Bl/6 wt and ob/ob mice. TNP-470 is a synthetic analog of fumagillin, which selectively inhibits endothelial cell growth and angiogenesis.17 The angiostatic mechanism of TNP-470 involves suppression of methionine aminopeptidase (MetAP-2) in endothelial cells.18
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Methods |
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Animals
All animal studies were reviewed and approved by the animal care and use committee of the Stockholm Animal Ethics Board. An expanded Methods section can be found in the online data supplement available at http://circres.ahajournals.org.
Antiangiogenic Therapy
Ob/ob mice and C57Bl/6 mice, fed a high-fat or a standard diet, were subcutaneously injected with TNP-470 at the dose of 20 mg/kg every other day. Control animals were injected with the same amount ethanol in phosphate-buffered saline. In the second ob/ob mice experiment, a dose of 15 mg/kg TNP-470 was used. Pair-feeding was performed as previously described (for further information see supplemental methods section).19
Histological Analysis
Immunohistochemical analysis was performed as previously described9 (see supplemental online Methods section). Adipocyte size and number were calculated as previously described.20
Mouse Corneal Assay
The corneal angiogenesis assay was performed as previously described (for further information see online Methods section).21 Ob/ob mice were 13-weeks-old and wt mice were 9-weeks-old at the time of implantation.
Analysis of Serum and Lipoprotein Lipids and Carbohydrates
Total cholesterol, triglycerides, glucose, free fatty acids, insulin, corticosterone levels in serum, and lipoprotein cholesterol and triglyceride contents were determined as previously described (see online Methods section).22
Calorimetry
Whole-animal oxygen consumption measurements were performed by indirect calorimetry and body composition was measured as previously described23,24 (see online Methods section).
Cell Culture
3T3-L1 mouse preadipocytes and bovine capillary endothelial cells were maintained and assayed as previously described (see online Methods section).25,26
Statistics
The significance of differences between groups was tested by 2-tailed Student t test, or by 1-way ANOVA, followed by post-hoc comparisons according to least significant difference test (see online Methods).27
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Results |
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Antiobesity Effect of TNP-470 in ob/ob Mice
Young (4- to 5-week-old) ob/ob mice that had not yet developed pronounced obesity (body weight 15 to 25 grams) were systemically treated with TNP-470. The drug was administered at a dose of 20 mg/kg every other day and was in a dose range previously proven effective in antiangiogenic treatment of cancer in mice.28 Body weight, body length, and food consumption were monitored. In the first set of experiments, the TNP-470-treated group (n=6) did not show any significant increase in body weight over the 12-week treatment period (Figure 1A and online Figure IA). These mice continued to grow in body length at a slightly slower rate than the nontreated control group (n=6), resulting in decreasing body mass index (BMI) scores over time (online Figure IB). After 1 week of treatment, both body weight and BMI of TNP-470-treated mice were lower than those of control animals (P<0.01). In contrast, mice in the nontreated control group continuously gained body weight from week 1 until the termination of the experiment. By week 8, mice in the nontreated group were severely obese, with an average body weight of >40 grams and a BMI of >0.55 g/cm2 (online Figure IA and IB). During the experiment, we observed a reduced food intake in TNP-470-treated ob/ob mice (Figure 1B).
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Encouraged by these initial results, we performed further studies by including, as an appropriate control, a group of mice pair-fed to the TNP-470-treated animals. In this second set of experiments, we were able to validate our initial finding that body weight and BMI were significantly reduced after 3-week treatment and 4-week treatment, respectively, by TNP-470 (n=6), as compared with both ad libitum-fed (n=6, P<0.01) and pair-fed (n=6, P<0.05) control groups (Figure 1C and online Figure IC). The growth in body length of TNP-470-treated ob/ob mice was slightly inhibited by week 5 as compared with both control groups (Figure 1D, P<0.01). Because the growth of body length also may require angiogenesis, the inhibitory effect of TNP-470 was not surprising.
Autopsy examination of TNP-470-treated ob/ob mice after 8-week treatment revealed that the depots of subcutaneous and omental fat were dramatically decreased compared with both ad libitum-fed and pair-fed control mice (Figure 1E). Dissection of total subcutaneous, perigonadal, and omental adipose tissues showed that the fat depots from the TNP-470-treated mice were significantly reduced compared with both control groups (P<0.01) (Figure 1F and 1G). Liver weights were also significantly reduced in the TNP-470-treated mice (Figure 1F). The percentage of total body fat (total body fat/total body weight) was significantly reduced (>10%) in TNP-470-treated mice as compared with both control groups (P<0.01) (Figure 1G). As a result, a relative increased ratio of lean body mass/body weight was detected in the TNP-470-treated group (P<0.01) (Figure 1H). Reduction of body weight by TNP-470 was thus well-correlated with reduction of adipose tissue mass (Figure 1I). These data demonstrate that the growth of adipose tissue was selectively inhibited by TNP-470. It should be emphasized that mice treated with TNP-470, at a dose of 20 mg/kg every other day, did not experience any toxic side effects as previously reported.28
Inhibition of Neovascularization in Adipose Tissue
To study whether the antiangiogenic effect might be involved in the antiobesity activity of TNP-470, we examined the degree of vascularization of adipose tissues of TNP-470-treated and nontreated ob/ob animals. We found that adipose tissue of nontreated animals was highly vascularized with an average vascular density of >300 microvessels/mm2 as revealed by an anti-CD31 antibody (Figure 2A and 2D). This vascular density is nearly 2-fold higher than that detected in tumor tissues,29 a finding in agreement with previous observations that adipose tissue is highly vascularized.30,31 However, a significant reduction of vascularization was detected in the adipose tissue of the TNP-470-treated mice as compared with the nontreated obese animals (Figure 2B, 2E, and 2F) (P<0.001). Notably, the average size of adipocytes in subcutaneous fat deposits of the TNP-470-treated group was smaller than that in the control group (Figure 2A, 2B, 2D, and 2E). Control adipose tissue from nonobese wt mice also contained a high density of microvessels (Figure 2C). However, the number of microvessels in adipose tissue of nonobese mice was significantly less than that of obese mice (Figure 2F), suggesting that active angiogenesis occurs in growing adipose tissues. Thus, the antiobesity effect of TNP-470 correlated with a reduction of neovascularization in the adipose tissue.
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Inhibition of Corneal Neovascularization
To further investigate if ob/ob mice responded to the antiangiogenic effect of TNP-470, and to evaluate the systemic efficacy of TNP-470 treatment at a dose of 20 mg/kg every other day, we performed the mouse corneal angiogenesis assay in ob/ob mice and in wt C57Bl/6 mice. Vascular endothelial growth factor (VEGF) or fibroblast growth factor-2 (FGF-2) was implanted into corneas of mice as previously described.9,21 FGF-2 or VEGF induced robust angiogenic responses in corneas of both control groups (n=5 mice/group) (Figure 3A to 3D). TNP-470 treatment almost completely prevented corneal neovascularization induced by either FGF-2 or VEGF in ob/ob mice (n=4) (Figure 3G and 3H). Similarly, FGF-2-induced and VEGF-induced corneal angiogenesis were potently inhibited by systemic administration of TNP-470 in C57Bl/6 mice (Figure 3E and 3F). The inhibitory effect of TNP-470 on corneal neovascularization in ob/ob mice was comparable with that in wt C57Bl/6 mice (Figure 3I). The measured areas of corneal neovascularization in both TNP-470-treated groups were significantly smaller than those in control groups (P<0.0001) (Figure 3I). This demonstrated that systemic administration of TNP-470 produced potent antiangiogenic effects against both VEGF- and FGF-2-induced angiogenesis in ob/ob as well as in wt C57Bl/6 mice.
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Lipid and Carbohydrate Metabolism in ob/ob Mice
Analysis of triglycerides in serum showed no significant differences between the groups of ob/ob mice (Figure 4C). However, triglyceride content in very-low-density lipoprotein (VLDL) particles was higher in the TNP-470-treated mice as compared with ad libitum-fed and pair-fed animals (Figure 4A). Analysis of serum cholesterol showed a slight reduction in TNP-470-treated animals when compared with their pair-fed controls (Figure 4D). A further reduction (
35%) was observed when the TNP-470-treated ob/ob mice were compared with the ad libitum-fed animals (P<0.01). Analysis of lipoprotein cholesterol pattern demonstrated that the reduction in total serum cholesterol was caused by a decrease in cholesterol confined to the LDL particles (Figure 4B).
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A tendency for a reduction in serum glucose was observed in the TNP-470 group (Figure 4E). This was associated with reductions of insulin levels by 75% (P<0.05) and 84% (P<0.001), when the TNP-470-treated mice were compared with pair-fed and ad libitum-fed controls, respectively (Figure 4F). No differences were observed for free fatty acids (FFA) among the groups (Figure 4G), nor were corticosterone levels affected by TNP-470 (data not shown). However, the product of insulin times FFA, an indirect measurement of insulin resistance, was significantly lower in TNP-470-treated group as compared with both controls (Figure 4H), indicating an increased insulin sensitivity.
Antiobesity Effect in High-Fat Diet-Fed wt Mice
Because genetically related obesity represents only a small proportion of the cause of human obesity, most cases are probably caused by inappropriate intake of dietary fat.32 Thus, we investigated if TNP-470 treatment could prevent obesity in mice fed a high-fat diet (45 kcal% fat in food). Unlike in ob/ob mice, TNP-470 had little influence on food intake in these wt mice (Figure 5A). Systemic treatment of C57Bl/6 mice (n=6) with TNP-470 at the dose of 20 mg/kg significantly prevented body weight gain by 2 weeks of treatment as compared with controls (P<0.05) (Figure 5B). The antiobesity effect became pronounced after 4 weeks of treatment (P<0.01). This effect appeared to be continuously increased during extended treatments with TNP-470 as seen by week 10 (P<0.001). In contrast, body length was nearly identical in treated and control groups (Figure 5C).
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Autopsy examination of high-fat diet-fed wt mice after 16-week treatment with TNP-470 revealed that the depots of subcutaneous, perigonadal, and omental fat were dramatically decreased as compared with control mice (P<0.001) (Figure 5D and 5E). Among these depots, the omental adipose tissue showed the most remarkable reduction (>5-fold decrease). Liver weights were slightly but significantly reduced in the TNP-470-treated mice (Figure 5D). The percentage of total body fat was significantly reduced (63%) in TNP-470-treated wt mice as compared with the control group (P<0.001) (Figure 5E). As a consequence of shifting this ratio, a relative increased percentage of lean body mass was detected in the TNP-470-treated group (P<0.001) (Figure 5F).
Measurement of Energy Expenditure in High-Fat Diet-Fed Mice
To investigate if the lower fat accumulation was caused by increased energy expenditure in TNP-470-treated high-fat diet-fed mice, we measured metabolic rates after 14-week treatment. Indirect calorimetric analysis (O2 consumption) showed no significant differences in basal resting metabolic rate at 30°C in TNP-470-treated mice as compared with controls (0.52±0.04 versus 0.61±0.06 mL O2/min per mouse, respectively) (online Table I). Further, the metabolic activity at rest during daytime at the habituated temperature (23°C) was also not increased by TNP-470 treatment as compared with controls (0.83±0.06 versus 0.99±0.07 mL O2/min per mouse, respectively), nor was the 1-hour total metabolism at 23°C increased (online Table I). Thus there were no detectable increases in energy expenditure in the TNP-470-treated mice that might have contributed to the reduction of body weight gain. Analyses of brown adipose tissue capacity, such as noradrenaline-induced increase in oxygen consumption and protein levels of uncoupling protein (UCP)-1 in brown adipose tissue, also showed that no increase in thermogenic capacity had been induced by TNP-470 treatment (online Table I).
Lipid and Carbohydrate Metabolism in High-Fat Diet-Fed wt Mice
Blood samples were analyzed after 12- and 16-week treatment and showed that serum levels of triglycerides were slightly reduced in the TNP-470-treated mice as compared with controls (Figure 6C). This reduction was mainly caused by a decrease in VLDL triglyceride content (Figure 6A). Further, a remarkable reduction (45%) in serum cholesterol was found at both time points (Figure 6C) and was related mainly to a decrease in LDL cholesterol (Figure 6B). Similar to ob/ob mice, serum levels of FFA seemed to be unaffected by TNP-470 treatment in high-fat diet-fed mice (Figure 6C). Interestingly, serum glucose levels were lower in TNP-470-treated mice as compared with controls (Figure 6D). Measurement of serum insulin revealed a remarkable reduction (80% to 90%) in TNP-470-treated mice at both time points (Figure 6E). The product of insulin times FFA was reduced by 90% in TNP-470-treated mice as compared with control mice (Figure 6F). Although these control wt mice, unlike the ob/ob animals, did not display high levels of insulin, the observed reduction of the insulin-times-FFA product during TNP-470 treatment is suggestive of increased insulin sensitivity. In addition to reduction of serum levels of lipids, cholesterol and triglyceride contents in livers of TNP-470-treated mice were significantly decreased (Figure 6G and 6H). There seemed to be a tendency (P=0.055) of decreased triglyceride content in skeletal muscles of TNP-470-treated animals, but no difference of cholesterol was found between the 2 groups (Figure 6G and 6H).
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Reduction of Adipose Tissue Neovascularization
To correlate the decrease in adipose tissue with reduced vascularization, we performed histological analysis of subcutaneous adipose depots. We found a 10-fold decrease in adipocyte size in TNP-470-treated high-fat diet-fed mice as compared with controls (online Figure IIA). As a result of the decreased in adipocyte size, the average number/mm2 of adipocytes was slightly increased (online Figure IIB). The vascular density in the TNP-470-treated samples was significantly reduced (online Figure IIC). However, this reduction was underestimated by the occurrence of significantly smaller adipocytes in this group. Thus, we compared the ratio between microvessel number and adipocyte number in both groups. A highly significant difference of vascularity was found between the 2 groups (online Figure IID). These data thus demonstrate that inhibition of neovascularization in the adipose tissue by TNP-470 contributed to the antiobesity effect.
Effects of TNP-470 on Body Weight and Lipid Metabolism in wt Lean Mice
To investigate the effect of TNP-470 treatment in lean mice, we studied wt C57Bl/6 mice fed a standard animal diet. After 2-week treatment, food intake in the TNP-470-treated mice was slightly reduced (10%) as compared with ad libitum-fed mice. However, this reduction disappeared after 4 weeks, suggesting only transient effects of TNP-470 on suppression of food intake in wt mice (Figure 7A). Nevertheless, we included pair-fed controls in this experiment. After 7-week treatment, the body weight in TNP-470-treated mice was slightly, but not significantly, reduced as compared with pair-fed animals (n=6/group) (Figure 7B). The control ad libitum-fed mice weighed significantly more than the TNP-470-treated group already after 3 weeks (Figure 7B). It is possible that the decrease in body weight in the TNP-470-treated group was caused by the aforementioned transient decrease in food intake. However, we cannot completely exclude the possibility that TNP-470 treatment may also directly reduce body weight gain in wt mice fed a normal diet. In contrast, body length was only slightly, and not significantly, decreased in TNP-470-treated mice as compared with control groups (Figure 7C).
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). Control mice fed ad libitum (
) or pair-fed (
) received vehicle alone. Food intake was determined daily (A). Mouse body weight was measured 3 times per week (B). Body length was measured every week (C). Autopsy examination of adipose tissue distribution was performed after 7-week treatment. Subcutaneous, perigonadal, and omental fat depots and liver weights were measured (D). Total fat/total body weight (E) and lean mass/ total body weight (F) was calculated. A=ad libitum-fed group, P=pair-fed group, T=treated group. For comparisons with pair-fed group: *P<0.05, **P<0.01, ***P<0.001; or with ad libitum-fed controls: #P<0.05, ##P<0.01.Autopsy analyses revealed that subcutaneous and omental fat depots in TNP-470-treated mice were not reduced as compared with the ad libitum-fed group, despite the slight but significantly increased fat depots found in the pair-fed group (Figure 7D and 7E). Liver weights were similar between the groups. Lean mass was slightly reduced in the pair-fed group as compared with ad libitum-fed controls and TNP-470-treated mice, respectively (Figure 7F). Interestingly, serum lipid profiles including levels of triglycerides, cholesterol, and FFA did not differ between the TNP-470-treated group and control animals (online Figure IIIA). However, we found that serum insulin levels seemed to be decreased in the TNP-470-treated group (online Figure IIIB).
In conclusion, our data indicate that systemic treatment with TNP-470 prevents both genetically-related and high-fat diet-induced obesity in mice but does not affect lean mice beyond slight effects on food intake reduction. Interestingly, the inhibition of food intake by TNP-470 seemed to be most pronounced in the hyperphagic ob/ob mice, because food intake levels in wt C57Bl/6 lean mice and in high-caloric diet-fed mice were only slightly affected by this drug (Figures 1B, 5A, 7
A, and online Figure IV).
No Direct Effects on Preadipocytes by TNP-470
To investigate the potential direct inhibitory effects of TNP-470 on preadipocytes, we performed in vitro analyses of cell proliferation and differentiation. We found that TNP-470 did not arrest 3T3-L1 preadipocyte proliferation, even at concentrations up to 1 µmol/L (Figure 8A). This finding is in agreement with a previous report.15 In contrast, TNP-470, as expected, exhibited a potent inhibitory effect on bovine endothelial cell growth with an IC50 near 100 pM (Figure 8B). Thus, it is unlikely that TNP-470 would directly act on preadipocytes in vivo, especially as the concentration of TNP-470 in the blood after systemic delivery is estimated to be considerably lower (nM range).33 Further, we found that exposure of 3T3-L1 cells to TNP-470 did not prevent preadipocyte differentiation, because the treated cells accumulated intracellular lipid droplets to similar degrees as controls, even in the presence of TNP-470 concentrations up to 10 µmol/L (Figure 8C). Thus we conclude that inhibition of angiogenesis could play a critical and indirect role in suppression of adipogenesis.
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Discussion |
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Current antiobesity approaches include restriction of food intake, increasing physical exercise, medication, and surgical intervention.34 These approaches aim to affect lipid metabolism, endocrine balance, energy expenditure rates, or degree of adipocyte maturation.34 However, some of these strategies may be valid only in certain types of obesity. For example, leptin is only effective in the treatment of monogenic obesity caused by functionally deficient leptin because of genetic mutations.35 Like other tissues in the body, the expansion of adipose tissue represents an imbalanced angiogenic phenotype. Several angiogenic factors including VEGF and leptin are expressed at high levels in expanding adipose tissues.10,11,36 A recently identified angiogenesis inhibitor, adiponectin, specifically produced by adipose tissues, is secreted at reduced levels in growing adipose tissues.26 Our present work showing that an angiogenesis inhibitor prevents obesity, both in ob/ob and wt mice, establishes a novel concept in the prevention of obesity irrespective of cause. Consistent with our findings, another group recently reported that several angiogenesis inhibitors, including angiostatin and endostatin could prevent genetically related obesity in mice.15 Our present data demonstrate that the angiogenesis inhibitor TNP-470 also prevents diet-induced obesity, the most common type of obesity in humans.
Although TNP-470 is a selective angiogenesis inhibitor in clinical trials for the treatment of cancer, high dosages of this agent may affect other systems in the body. Thus, we cannot exclude the possibility that TNP-470 may prevent obesity through mechanisms other than antiangiogenesis. For example, TNP-470 affects food intake, even though this reduction seems to mostly affect ob/ob mice, with only a slight or very slight effect in wt mice, depending on their dietary regimen. It is not clear why TNP-470 differentially influences food intake in different strains of mice. Nevertheless, the influence on food intake by TNP-470 can only partially explain its antiobesity effect because pair-fed control animals were significantly more obese than the TNP-470-treated ob/ob mice. It should be emphasized that food intake is regulated according to body size.
TNP-470 selectively inhibits endothelial cell proliferation but not preadipocyte proliferation or differentiation in vitro, supporting the hypothesis that the antiangiogenic activity may play an important role in the prevention of obesity. In agreement, we observed a decreased vascularization in adipose tissue of TNP-470-treated mice. In general, the adipose tissue is more remarkably plastic than any other tissue in that it can rapidly expand or regress throughout life. Because angiogenesis occurs only in actively growing tissues, it is not surprising that an angiogenesis inhibitor selectively suppresses the growth of adipose tissues without affecting quiescent vasculatures in adult mice. TNP-470 does not affect the quiescent nonproliferation vascular beds in other tissues.
Ob/ob mice are known to have a particular dyslipidemia characterized by decreased triglyceride levels in VLDL particles and an increased content of cholesterol in LDL and high-density lipoprotein.37 Interestingly, TNP-470 normalized this altered lipoprotein profile, without affecting high-density lipoprotein cholesterol levels. As observed for adipose tissue, only a minor part of the effects on lipoproteins could be explained by a reduction of food intake induced by TNP-470 in ob/ob mice. Comparing the ad libitum-fed, the pair-fed, and the TNP-470-treated mice, it seems that the effect of TNP-470 on VLDL triglycerides is independent of serum FFA levels. Furthermore, the degree of hypercholesterolemia seems to be related to the severity of obesity and diabetic phenotype in ob/ob mice.38 Thus, normalization of fat mass and increased insulin sensitivity by TNP-470 could ameliorate the lipoprotein profile. In nondiabetic high-fat diet-fed wt mice, TNP-470 also decreased insulin levels and improved lipoprotein profiles. However, we cannot exclude a possible direct effect of TNP-470 on hepatic triglyceride and cholesterol metabolism. This very interesting question remains to be further explored.
In conclusion, because development of obesity, cancer, and diabetic complications are all dependent on angiogenesis and the cause of these pathological conditions can be related, antiangiogenic therapy may prove to be multibeneficial in these disorders. Thus, angiogenesis inhibitors used alone or in combination with other therapies may become an important new strategy in the prevention of obesity.
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Acknowledgments |
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We thank Meit Björndahl and Maya H. Nisancioglu for critical reading of the manuscript, and Camilla Pramfalk and Lilian Larsson for valuable technical assistance. We thank Takeda Chemical Inc for kindly providing TNP-470 used in this study, and Dr. Claes Carneheim at Biovitrum AB (Stockholm, Sweden) for access to and help with the DEXA equipment. This work was supported by the Swedish Cancer Society, the Swedish Research Council, the Wallenberg Consortium North, the Åke Wiberg, the Lars Hiertas Minne, and the Swedish Heart-Lung Foundations.
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Footnotes |
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Received March 3, 2004; revision received May 7, 2004; accepted May 7, 2004.
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