Adiponectin-induced antiangiogenesis and antitumor activity involve caspase-mediated endothelial cell apoptosis

Obesity and cancer: at the crossroads of cellular metabolism and proliferation

Obesity is associated with an increased risk of cancer. The mechanisms underlying this association include but are not limited to increased systemic inflammation, an anabolic hormonal milieu, and adipocyte-cancer crosstalk, aberrant stimuli that conspire to promote neoplastic transformation. Cellular proliferation is uncoupled from nutrient availability in malignant cells, promoting tumor progression. Elucidation of the mechanisms underlying the obesity-cancer connection will lead to the development of novel metabolism-based agents for cancer prevention and treatment.

Mechanisms behind the link between obesity and gastrointestinal cancers

Obesity and obesity-related disorders such as non-alcoholic fatty liver disease (NAFLD), metabolic syndrome and type 2 diabetes exhibit an increased risk of developing various gastrointestinal cancers. These malignancies include mainly esophageal, gastric, colorectal, pancreatic and hepatocellular carcinoma. Whereas underlying pathomechanisms remain unclear, chronic inflammation accompanying obesity has evolved in the last years as a crucial contributing factor. Obesity is also commonly characterized by inflammation in the organ where those cancers appear. Various pathways might participate involving rather diverse components such as innate immunity, (adipo)-cytokines such as adiponectin or leptin, insulin, insulin-like growth factors, the gut's microbiota and others. An imbalance in these systems could substantially contribute to chronic inflammation and subsequent cancer development. Future studies have to elucidate in more detail underlying mechanisms in the development of obesity-related carcinogensis and potential therapeutic strategies besides weight loss.

Metabolic syndrome and renal cell carcinoma

BACKGROUND

Metabolic syndrome (MS) is a cluster of metabolic abnormalities, which has been regarded as a pivotal risk factor for cardiovascular diseases. Recent studies focusing on the relationship between MS and cancer have recognized the significant role of MS on carcinogenesis. Likewise, growing evidence suggests that MS has a strong association with increased renal cell carcinoma (RCC) risk. This review outlines the link between MS and RCC, and some underlying mechanisms responsible for MS-associated RCC.

MATERIALS AND METHODS

A National Center for Biotechnology Information PubMed search (http://www.pubmed.gov) was conducted using medical subject headings 'metabolic syndrome', 'obesity', 'hypertension', 'diabetes', 'dyslipidemia', and 'renal cell carcinoma'.

RESULTS

This revealed that a variety of molecular mechanisms secondary to MS are involved in RCC formation, progression, and metastasis. A deeper understanding of these molecular mechanisms may provide some strategies for the prevention and treatment of RCC.

CONCLUSIONS

In summary, there is a large body of evidence regarding the link between MS and RCC, within which each component of MS is considered to have a close causal association with RCC.

Adiponectin inhibits neutrophil apoptosis via activation of AMP kinase, PKB and ERK 1/2 MAP kinase

Neutrophils are abundant, short-lived leukocytes that play a key role in the immune defense against microbial infections. These cells die by apoptosis following activation and uptake of microbes and will also enter apoptosis spontaneously at the end of their lifespan if they do not encounter a pathogen. Adiponectin exerts anti-inflammatory effects on neutrophil antimicrobial functions, but whether this abundant adipokine influences neutrophil apoptosis is unknown. Here we report that adiponectin in the physiological range (1–10 μg/ml) reduced apoptosis in resting neutrophils, decreasing caspase-3 cleavage and maintaining Mcl-1 expression by stabilizing this anti-apoptotic protein. We show that adiponectin induced phosphorylation of AMP-activated kinase (AMPK), protein kinase B (PKB), extracellular signal-regulated kinase (ERK 1/2) and p38 mitogen activated protein kinase (MAPK). Pharmacological inhibition of AMPK, PKB and ERK 1/2 ablated the pro-survival effects of adiponectin and treatment of neutrophils with an AMPK specific activator (AICAR) and AMPK inhibitor (compound C) respectively decreased and increased apoptosis. Finally, activation of AMPK by AICAR or adiponectin also decreased ceramide accumulation in the neutrophil cell membrane, a process involved in the early stages of spontaneous apoptosis, giving another possible mechanism downstream of AMPK activation for the inhibition of neutrophil apoptosis.

Association between chemotherapy and plasma adipokines in patients with colorectal cancer

BACKGROUND

A link between chemotherapy, the serum level of selected adipokines and clinical outcome in colorectal patients was investigated.

METHODS

Leptin, adiponectin, resistin, visfatin and insulin were measured by ELISA in colorectal cancer patients before and 3 months after the administration of cancer therapy. From August 2012 to August 2013, 34 patients with pathologically documented advanced colorectal cancer (T3/T4 with metastases or nodal status up to N3) and measurable metastatic disease, who required palliative chemotherapy based on the combination of 5-fluorouracil, oxaliplatin and irinotecan, were prospectively recruited in this study. Patients previously underwent curative surgical tumour resection, but the disease was disseminated (metastases in the liver and/or lungs) at the time of admission to the hospital.

RESULTS

Of the 34 patients in this study, 5 accomplished a chemotherapy course with partial response (PR), 23 with SD (stabilisation) and 6 with progression (PD). For further study, only patients with good prognostic outcomes (i.e., PR and SD patients) were included. The mean level of leptin before chemotherapy was 26.39 ± 9.53 ng/ml. After six courses of cancer treatment, the leptin level increased by 118-57.44 ± 27.72 ng/ml (p<0.001). Additionally, the adiponectin level increased considerably (47%) from 9.89 ± 3.96 ng/ml to 14.51 ± 7.79 ng/ml (p<0.001). In contrast to leptin and adiponectin, the resistin and visfatin levels decreased significantly from 7.24 ± 1.17 and 1.98 ± 0.44 to 6.36 ± 1.36 and 1.48 ± 0.34 ng/ml (p<0.001), respectively. Insulin also declined remarkably from 16.20 ± 1.96 to 12.87 ± 1.80 (p<0.001). There were no significant differences the between male and female patients regarding age, BMI, and leptin, adiponectin, resistin, visfatin and insulin serum levels.

CONCLUSIONS

The results of the present study are relevant because we found that chemotherapy in colorectal cancer patients, in addition to its beneficial clinical impact on the course of disease, positively affects cytokine production and release (increases the anti-inflammatory adiponectin and decreases visfatin and resistin, which are proangiogenic and promote cancer cell proliferation). The restoration of adequate adipose tissue function is essential for patients to achieve a good survival prognosis.

Metabolic function of the CTRP family of hormones

Maintaining proper energy balance in mammals entails intimate crosstalk between various tissues and organs. These inter-organ communications are mediated, to a great extent, by secreted hormones that circulate in blood. Regulation of the complex metabolic networks by secreted hormones (e.g., insulin, glucagon, leptin, adiponectin, FGF21) constitutes an important mechanism governing the integrated control of whole-body metabolism. Disruption of hormone-mediated metabolic circuits frequently results in dysregulated energy metabolism and pathology. As part of an effort to identify novel metabolic hormones, we recently characterized a highly conserved family of 15 secreted proteins, the C1q/TNF-related proteins (CTRP1-15). While related to adiponectin in sequence and structural organization, each CTRP has its own unique tissue expression profile and non-redundant function in regulating sugar and/or fat metabolism. Here, we summarize the current understanding of the physiological functions of CTRPs, emphasizing their metabolic roles. Future studies using gain-of-function and loss-of-function mouse models will provide greater mechanistic insights into the critical role CTRPs play in regulating systemic energy homeostasis.

Obesity and colorectal cancer: role of adipokines in tumor initiation and progression

Obesity-associated diseases account for a large portion of public health challenges. Among obesity-related disorders, a direct and independent relationship has been ascertained for colorectal cancer (CRC). The evidence that adipocyte hypertrophy and excessive adipose tissue accumulation (mainly visceral) can promote pathogenic adipocyte and adipose tissue-related diseases, has led to formulate the concept of "adiposopathy", defined as adipocyte and adipose tissue dysfunction that contributes to metabolic syndrome. Adipose tissue can, indeed, be regarded as an important and highly active player of the innate immune response, in which cytokine/adipokine secretion is responsible for a paracrine loop between adipocytes and macrophages, thus contributing to the systemic chronic low-grade inflammation associated with visceral obesity, which represents a favorable niche for tumor development. The adipocyte itself participates as a central mediator of this inflammatory response in obese individuals by secreting hormones, growth factors and proinflammatory cytokines, which are of particular relevance for the pathogenesis of CRC. Among adipocyte-secreted hormones, the most relevant to colorectal tumorigenesis are adiponectin, leptin, resistin and ghrelin. All these molecules have been involved in cell growth and proliferation, as well as tumor angiogenesis and it has been demonstrated that their expression changes from normal colonic mucosa to adenoma and adenocarcinoma, suggesting their involvement in multistep colorectal carcinogenesis. These findings have led to the hypothesis that an unfavorable adipokine profile, with a reduction of those with an anti-inflammatory and anti-cancerous activity, might serve as a prognostic factor in CRC patients and that adipokines or their analogues/antagonists might become useful agents in the management or chemoprevention of CRC.

Insulin, estrogen, inflammatory markers, and risk of benign proliferative breast disease

Women with benign proliferative breast disease (BPBD) are at increased risk for developing breast cancer. Evidence suggests that accumulation of adipose tissue can influence breast cancer development via hyperinsulinemia, increased estrogen, and/or inflammation. However, there are limited data investigating these pathways with respect to risk of BPBD. We evaluated serologic markers from these pathways in a case-control study of postmenopausal women nested within the Women's Health Initiative Clinical Trial. Cases were the 667 women who developed BPBD during follow-up, and they were matched to 1,321 controls. Levels of insulin, estradiol, C-reactive protein (CRP), and adiponectin were measured in fasting serum collected at baseline. Conditional logistic regression models were used to estimate ORs for the association of each factor with BPBD risk. Among nonusers of hormone therapy, fasting serum insulin was associated with a statistically significant increase in risk of BPBD (OR for highest vs. lowest quartile = 1.80; 95% confidence interval, CI, 1.16-2.79; Ptrend = 0.003) as were levels of estradiol (OR for highest vs. lowest tertile = 1.89; 95% CI, 1.26-2.83; Ptrend = 0.02) and CRP (OR for highest vs. lowest quartile = 2.46; 95% CI, 1.59-3.80; Ptrend < 0.001). Baseline adiponectin level was inversely associated with BPBD risk (OR for highest vs. lowest quartile = 0.47; 95% CI, 0.31-0.71; Ptrend < 0.001). These associations persisted after mutual adjustment, but were not observed among users of either estrogen alone or of estrogen plus progestin hormone therapy. Our results indicate that serum levels of estrogen, insulin, CRP, and adiponectin are independent risk factors for BPBD and suggest that the estrogen, insulin, and inflammation pathways are associated with the early stages of breast cancer development.

Vascular rarefaction mediates whitening of brown fat in obesity

Brown adipose tissue (BAT) is a highly vascularized organ with abundant mitochondria that produce heat through uncoupled respiration. Obesity is associated with a reduction of BAT function; however, it is unknown how obesity promotes dysfunctional BAT. Here, using a murine model of diet-induced obesity, we determined that obesity causes capillary rarefaction and functional hypoxia in BAT, leading to a BAT "whitening" phenotype that is characterized by mitochondrial dysfunction, lipid droplet accumulation, and decreased expression of Vegfa. Targeted deletion of Vegfa in adipose tissue of nonobese mice resulted in BAT whitening, supporting a role for decreased vascularity in obesity-associated BAT. Conversely, introduction of VEGF-A specifically into BAT of obese mice restored vascularity, ameliorated brown adipocyte dysfunction, and improved insulin sensitivity. The capillary rarefaction in BAT that was brought about by obesity or Vegfa ablation diminished β-adrenergic signaling, increased mitochondrial ROS production, and promoted mitophagy. These data indicate that overnutrition leads to the development of a hypoxic state in BAT, causing it to whiten through mitochondrial dysfunction and loss. Furthermore, these results link obesity-associated BAT whitening to impaired systemic glucose metabolism.

Challenges of imaging for cancer in patients with diabetes and obesity

A growing body of evidence supports a connection among diabetes (predominantly type 2), obesity, and cancer. Multiple meta-analyses of epidemiological data show that people with diabetes are at increased risk of developing a variety of different cancers and suffer from an increased rate of perioperative complications and cancer mortality. Computed tomography (CT) has played an important role in diagnosis and staging of cancer. Positron emission tomography is complementary to CT in the diagnosis, staging, and evaluation of treatment response for many types of cancer. Because of generally poor clinical outcome of cancers when they are detected in late stages, more research is now focused on stratifying risk to allow personalized screening of at-risk patients and cancer detection at an earlier stage. In this review, we summarize basic noninvasive imaging techniques currently in use to detect cancer with emphasis on the challenges of imaging for early cancer detection in obese patients with diabetes.

Clinicopathological roles of adiponectin and leptin receptors in endometrial carcinoma

To clarify the roles of adiponectin receptor (AdipoR) and leptin receptor (ObR) in endometrial carcinoma, the expression of AdipoR-1 and -2 and ObR in endometrial cancer was examined immunohistochemically, and correlations with clinicopathological implications were also analysed. Paraffin-embedded tissues were obtained from 77 patients with endometrial carcinoma and were stained immunohistochemically using antibodies against AdipoR-1, AdipoR-2 and ObR. AdipoR-1, AdipoR-2 and ObR were localised predominantly in the cell membrane and cytoplasm of tumour cells and normal endometrial cells. In 77 cases of endometrial cancer, positive expression was observed in 46 cases (59.7%) for AdipoR-1, 47 cases (61.0%) for AdipoR-2 and 33 cases (42.9%) for ObR. Expression of AdipoR-1 was observed most in stage I cases, G1 tumours, tumours with shallow myometrial invasion, tumours negative for lymphovascular space involvement, cases negative for adnexal invasion and cases with no lymph node metastasis. However, the expression of AdipoR-2 and ObR showed no correlation with any clinicopathological factors. Kaplan-Meier analyses revealed that progression-free and overall survival times were longer in cases with positive AdipoR-1 expression compared with negative AdipoR-1 expression. Poor expression of AdipoR-1, thus, appears to be associated with tumour grade, myometrial invasion, adnexal invasion, lymph-vascular space involvement and lymph node metastasis, as well as poor prognosis, in endometrial cancer.

Tumour PDGF-BB expression levels determine dual effects of anti-PDGF drugs on vascular remodelling and metastasis

Anti-platelet-derived growth factor (PDGF) drugs are routinely used in front-line therapy for the treatment of various cancers, but the molecular mechanism underlying their dose-dependent impact on vascular remodelling remains poorly understood. Here we show that anti-PDGF drugs significantly inhibit tumour growth and metastasis in high PDGF-BB-producing tumours by preventing pericyte loss and vascular permeability, whereas they promote tumour cell dissemination and metastasis in PDGF-BB-low-producing or PDGF-BB-negative tumours by ablating pericytes from tumour vessels. We show that this opposing effect is due to PDGF-β signalling in pericytes. Persistent exposure of pericytes to PDGF-BB markedly downregulates PDGF-β and inactivation of the PDGF-β signalling decreases integrin α1β1 levels, which impairs pericyte adhesion to extracellular matrix components in blood vessels. Our data suggest that tumour PDGF-BB levels may serve as a biomarker for selection of tumour-bearing hosts for anti-PDGF therapy and unsupervised use of anti-PDGF drugs could potentially promote tumour invasion and metastasis.

Effects of weight loss and pharmacotherapy on inflammatory markers of cardiovascular disease

Obesity is currently an epidemic, and the prevalence of cardiovascular risk factors is increasing dramatically as a result. Visceral adiposity is correlated with a proinflammatory and prothrombotic state that is believed to promote atherosclerosis and acute coronary syndromes. This article will review clinical trials on the effects of weight loss and pharmacotherapy on obesity associated inflammatory and thrombotic markers linked with cardiovascular disease.

Adiponectin and leptin molecular actions and clinical significance in breast cancer

Obesity is an important public health problem and major risk factor for postmenopausal breast cancer. Adipose tissue is the major component involved in the control of the metabolism through energy homeostasis, adipocyte differentiation, insulin sensitivity and the activation of anti-inflammatory metabolic and immune pathways. Leptin and Adiponectin pathways are involved in proliferation process in breast cancer. Current review describes potential relationship between the molecular actions and clinical significance of leptin and adiponectin in breast cancer.

The role of adipose tissue and obesity in causing treatment resistance of acute lymphoblastic leukemia

Obesity is responsible for ~90,000 cancer deaths/year, increasing cancer incidence and impairing its treatment. Obesity has also been shown to impact hematological malignancies, through as yet unknown mechanisms. Adipocytes are present in bone marrow and the microenvironments of many types of cancer, and have been found to promote cancer cell survival. In this review, we explore several ways in which obesity might cause leukemia treatment resistance. Obese patients may be at a treatment disadvantage due to altered pharmacokinetics of chemotherapy and dosage "capping" based on ideal body weight. The adipose tissue provides fuel to cancer cells in the form of amino acids and free fatty acids. Adipocytes have been shown to cause cancer cells to resist chemotherapy-induced apoptosis. In addition, obese adipose tissue is phenotypically altered, producing a milieu of pro-inflammatory adipokines and cytokines, some of which have been linked to cancer progression. Given the prevalence of obesity, understanding its role and adipose tissue in acute lymphoblastic leukemia treatment is necessary for evaluating current treatment regimen and revealing new therapeutic targets.

The role of obesity in gastrointestinal cancer: evidence and opinion

There is increasing recognition of the impact of being overweight and obese on the development of cancers at diverse sites including the gastrointestinal tract. Large epidemiological studies indicate that up to 14% of tumours may be related to obesity. Pathophysiological mechanisms underpinning this association are not well understood and so are discussed in this review.

Waist-to-thigh ratio is a predictor of internal organ cancers in humans: findings from a cohort study

OBJECTIVE

Studies have shown that some specific body measures are associated with the occurrence of cancers. Few studies have demonstrated the relationship with more comprehensive approaches. This study aims to explore body measures and the combinations associated with internal organ cancers.

METHODS

Three-dimensional anthropometric body surface scanning data collected 10,215 participants from the health examination department in a medical center of Taiwan during 2000-2010. Follow-up was conducted for an average of 8 years, and 244 internal organ cancer cases were identified.

RESULTS

An increased risk of internal organ cancers was observed among the subjects with larger waist circumference/smaller thigh circumference, in which waist-to-thigh ratio (WTR) was constructed. Comparing the subjects in the fourth quartile for WTR to the subjects in the first quartile with multiple Cox regression analysis yielded a hazard ratio of 1.842 (95% confidence interval, 1.131~2.999). The association between WTR quartile and internal organ cancers was stronger among male participants, older participants, and participants with chronic conditions.

CONCLUSIONS

The study has revealed that WTR is the most significant predictor for the occurrence of cancer in Asian populations. Because it is easy to measure and open to modification, WTR may be more useful in clinical and preventive medicine in the future.

Adiponectin: an attractive marker for metabolic disorders in Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory lung disease which may be complicated by development of co-morbidities including metabolic disorders. Metabolic disorders commonly associated with this disease contribute to lung function impairment and mortality. Systemic inflammation appears to be a major factor linking COPD to metabolic alterations. Adipose tissue seems to interfere with systemic inflammation in COPD patients by producing a large number of proteins, known as “adipokines”, involved in various processes such as metabolism, immunity and inflammation. There is evidence that adiponectin is an important modulator of inflammatory processes implicated in airway pathophysiology. Increased serum levels of adiponectin and expression of its receptors on lung tissues of COPD patients have recently highlighted the importance of the adiponectin pathway in this disease. Further, in vitro studies have demonstrated an anti-inflammatory activity for this adipokine at the level of lung epithelium. This review focuses on mechanisms by which adiponectin is implicated in linking COPD with metabolic disorders.

Association between adiponectin gene polymorphisms and risk of colorectal cancer: A Meta-analysis

AIM: To investigate the association between adiponectin (ADIPOQ) gene polymorphisms and risk of colorectal cancer (CRC).

METHODS: All eligible case-control studies published up to March 2013 were identified by searching PubMed, Web of Science, CNKI, Wanfang and VIP. Effect sizes of odds ratio (OR) and 95% confidence interval (95%CI) were calculated by using a fixed- or random-effect model.

RESULTS: A total of 9 case-control studies were included. There were eight studies (2024 cases and 2777 controls) for rs1501299G/T polymorphism, five studies (1401 cases and 1691 controls) for rs2241766T/G polymorphism and five studies (2945 cases and 3361 controls) for rs266729C/G polymorphism. Overall, a significant association was observed for rs2241766T/G polymorphism under heterozygote comparison (TG vs TT: OR = 1.22, 95%CI: 1.05-1.43), while there was no significant association for rs2241766 polymorphism under other genetic models, and for other two polymorphisms under all genetic models.

CONCLUSION: Our meta-analysis indicates that adiponectin rs2241766T/G polymorphism, rather than rs1501299G/T and rs266729C/G polymorphisms, is associated with the risk of colorectal cancer.

Underactivation of the adiponectin-adiponectin receptor 1 axis in clear cell renal cell carcinoma: implications for progression

Energy-sensing pathways, normally coordinated by 5' AMP-activated protein kinase (AMPK), are dysregulated in renal cell carcinoma (RCC). Obesity can accentuate the pre-existing pro-tumorigenic metabolic machinery in RCC cells through its associated obesogenic hormonal milieu, characterized by lower circulating levels of adiponectin. In RCC patients, low adiponectin levels associate clinically with more aggressive disease. We investigated the adiponectin signaling pathway in RCC, focusing on adiponectin receptor 1 (AdipoR1) and associated activation of AMPK. AdipoR1 protein in RCC and normal surrounding renal tissues was determined by Western blot analysis and immunohistochemistry. Anti-tumorigenic effects of adiponectin in RCC cells in vitro were investigated via VEGF and MMP ELISA and invasion assays. Using in vivo models of RCC, the effect of AdipoR1-knockdown (shRNA) on tumor latency, growth and dissemination were determined. AdipoR1 protein was significantly reduced in clear cell RCC specimens. Adiponectin treatment inhibited VEGF, MMP-2 and MMP-9 secretion and activity and invasive and migratory capacities of RCC cells. AMPKα1-knockdown (shRNA) attenuated adiponectin's effects. In cells stably expressing AdipoR1-specific shRNA, AMPK activation by adiponectin was significantly reduced compared to cells expressing control shRNA. In vivo, AdipoR1 knockdown increased the growth, dissemination and angiogenesis of RCC. These findings suggest that deficiencies in the entire adiponectin hormonal axis (the hormone and its receptor) result in underactivation of AMPK leading to increased angiogenic and invasive capacities of RCC. The established link between obesity and RCC can therefore be further explained by the adiponectin deficiency in obese individuals together with reduced AdipoR1 protein in RCC.

Adipose tissue immunity and cancer

Inflammation and altered immune response are important components of obesity and contribute greatly to the promotion of obesity-related metabolic complications, especially cancer development. Adipose tissue expansion is associated with increased infiltration of various types of immune cells from both the innate and adaptive immune systems. Thus, adipocytes and infiltrating immune cells secrete pro-inflammatory adipokines and cytokines providing a microenvironment favorable for tumor growth. Accumulation of B and T cells in adipose tissue precedes macrophage infiltration causing a chronic low-grade inflammation. Phenotypic switching toward M1 macrophages and Th1 T cells constitutes an important mechanism described in the obese state correlating with increased tumor growth risk. Other possible synergic mechanisms causing a dysfunctional adipose tissue include fatty acid-induced inflammation, oxidative stress, endoplasmic reticulum stress, and hypoxia. Recent investigations have started to unravel the intricacy of the cross-talk between tumor cell/immune cell/adipocyte. In this sense, future therapies should take into account the combination of anti-inflammatory approaches that target the tumor microenvironment with more sophisticated and selective anti-tumoral drugs.

Angiogenesis and vascular functions in modulation of obesity, adipose metabolism, and insulin sensitivity

White and brown adipose tissues are hypervascularized and the adipose vasculature displays phenotypic and functional plasticity to coordinate with metabolic demands of adipocytes. Blood vessels not only supply nutrients and oxygen to nourish adipocytes, they also serve as a cellular reservoir to provide adipose precursor and stem cells that control adipose tissue mass and function. Multiple signaling molecules modulate the complex interplay between the vascular system and the adipocytes. Understanding fundamental mechanisms by which angiogenesis and vasculatures modulate adipocyte functions may provide new therapeutic options for treatment of obesity and metabolic disorders by targeting the adipose vasculature.

Mucus and adiponectin deficiency: role in chronic inflammation-induced colon cancer

PURPOSE

This study aims to define the role of adiponectin (APN) in preventing goblet cell apoptosis and in differentiation of epithelial cells to goblet cell lineage resulting in greater mucus production and hence greater protection from chronic inflammation-induced colon cancer (CICC).

METHODS

Six- to eight-week-old male APNKO and C57BL/6 (WT) mice were randomly distributed to three treatment groups: DSS, DMH, DSS + DMH and control. Chronic inflammation was induced in DSS and DSS + DMH group by administrating 2 % DSS in drinking water for 5 days followed by 5 days of normal drinking water and this constitutes one DSS cycle. Three cycles of DSS were administered to induce chronic inflammation. Cancer was induced in both APNKO and WT mice in DMH and DSS + DMH groups by intraperitoneal injections of DMH (20 mg/kg body weight) once for DSS + DMH group and once per week for 12 weeks for DMH group. On day 129, the colon tissue was dissected for mucus thickness measurements and for genomic studies. HT29-C1.16E and Ls174T cells were used for several genomic and siRNA studies.

RESULTS

APNKO mice have more tumors and tumor area in DSS + DMH group than WT mice. APN deficiency downregulated goblet to epithelial cell ratio and enhanced the colonic mucosal erosion with reduced mucus thickness. APN increases Muc2 production with no affect on Muc1 production. APN abated goblet cell apoptosis, while APN deficiency reduced epithelial to goblet cell differentiation.

CONCLUSION

APN may be involved in reducing the severity of CICC by preventing goblet cell apoptosis and increasing epithelial to goblet cell differentiation.

Trans-3,4,5,4'-tetramethoxystilbene, a resveratrol analog, potently inhibits angiogenesis in vitro and in vivo

Aim:

Trans-3,4,5,4′-tetramethoxystilbene (DMU-212) has shown strong antiproliferative activities against a variety of cancer cells. The aim of this study was to investigate the anti-angiogenic effects of DMU-212 in vitro and in vivo.

Methods:

Human umbilical vein endothelial cells (HUVECs) were used in this study. Cell viability was studied with MTT assay, and cell apoptosis was evaluated using TUNEL assay and morphological observation. The expression of the related genes and proteins was analyzed with qRT-PCR and Western blot, respectively. Angiogenesis of HUVECs were studied using cell migration and capillary-like tube formation assays in vitro, and mouse Matrigel plug assay and chick chorioallantoic membrane (CAM) assay in vivo. The tyrosine kinase activities of VEGFR1 and VEGFR2 were measured using commercial kits.

Results:

DMU-212 (5–80 μmol/L) significantly inhibited VEGF-stimulated proliferation of HUVECs (IC₅₀ value was approximately 20 μmol/L), and induced apoptosis. Furthermore, DMU-212 concentration-dependently inhibited VEGF-induced migration of HUVECs and capillary-like structure formation in vitro. DMU-212 also inhibited VEGF-induced generation of new vasculature in Matrigel plugs in vivo with significantly decreased area of infiltrating CD31-positive endothelial cells, and inhibited newly formed microvessels in chick CAMs. Moreover, DMU-212 concentration-dependently suppressed VEGF-induced phosphorylation of VEGFR2, and inhibited phosphorylation of multiple downstream signaling components in the VEGFR2 pathway, including c-Src, FAK, Erk1/2, Akt, mTOR, and p70S6K in HUVECs. DMU-212 had no effect on VEGF-induced phosphorylation of VEGFR1.

Conclusion:

DMU-212 is a potent inhibitor of angiogenesis that exerts anti-angiogenic activity at least in part through the VEGFR2 signaling pathway.

A lower serum level of middle-molecular-weight adiponectin is a risk factor for endometrial cancer

BACKGROUND

The present study was undertaken to examine the correlation between serum levels of adiponectin isoforms and the risk for endometrial cancer.

METHODS

This retrospective case-control study included 43 Japanese women with endometrial cancer and 62 Japanese women with no history of cancer. Serum levels of total adiponectin and the respective isoforms were determined by enzyme-linked immunosorbent assay. Multivariate logistic regression analysis was performed on the serum levels of total adiponectin and its isoforms, high molecular weight, middle molecular weight, and low molecular weight adiponectins, after adjustment for confounders (age, body mass index, hypertension, and diabetes mellitus).

RESULTS

The distribution of body mass index revealed a statistically significant difference between patients and controls (P = 0.001). A statistically significant difference (P < 0.01) was also found in the incidence of diabetes mellitus between the two groups, although there was no significant difference in the incidence of hypertension. In controls, an inverse correlation was observed between body mass index and serum adiponectin levels. However, in patients, an inverse correlation was found only between body mass index and serum middle molecular weight adiponectin level. After adjustment for confounding variables, the factor found to be most closely associated with endometrial cancer was a lower serum level of middle molecular weight adiponectin (adjusted odds ratio 4.89, 95 % confidence interval value 1.25-19.11, P = 0.022).

CONCLUSION

Low serum level of middle molecular weight adiponectin was the only independent risk factor for endometrial cancer suggesting that the application of adiponectin might prevent or decrease the risk for endometrial cancer.

Non-B, non-C hepatocellular carcinoma (Review)

Although most hepatocellular carcinoma (HCC) is related to viral infection, there is a substantial population of HCC patients (5-20%) who are negative for both markers of hepatitis B virus and hepatitis C virus infection [non-B, non-C (NBNC) hepatitis] in Japan and the incidence of NBNC-HCC has recently tended to increase. The most common cause of liver disease in developed countries is non‑alcoholic fatty liver disease (NAFLD), which includes non‑alcoholic steatohepatitis (NASH) and its related complications. Increased body mass index and diabetes mellitus are associated with developing NAFLD and NASH, which is a severe form of NAFLD. Furthermore, increasing clinical evidence supports the fact that NAFLD and NASH can progress to liver cirrhosis and even HCC. A detailed understanding of the epidemiology, etiology, molecular mechanism, clinical features and prognosis of NBNC-HCC could improve our screening and therapy of this disease. In this review, we primarily focus on clinical aspects of NBNC-HCC and refer to our current knowledge of this cancer.

Plasma adiponectin and soluble leptin receptor and risk of colorectal cancer: a prospective study

Adipokines are adipocyte-secreted hormones that may mediate the etiologic link between obesity and colorectal cancer; however, the evidence from large prospective studies is limited. We prospectively evaluated the association of plasma adiponectin and soluble leptin receptor (sOB-R) with colorectal cancer risk within the Nurses' Health Study (1990-2008) and the Health Professionals Follow-up Study (1994-2008) among 616 incident colorectal cancer cases and 1,205 controls selected using risk-set sampling and matched on age and date of blood draw. In unconditional logistic regression with adjustment for matching factors and multiple risk factors, plasma adiponectin was significantly associated with reduced risk of colorectal cancer among men, but not among women. Compared with men in the lowest quartile of adiponectin, men in the highest quartile had a relative risk (RR) for colorectal cancer of 0.55 [95% confidence interval (CI), 0.35-0.86; Ptrend = 0.02]. The corresponding RR in women was 0.96 (95% CI, 0.67-1.39; Ptrend = 0.74). Plasma sOB-R was not associated with overall colorectal cancer risk in either men or women. A significant heterogeneity was noted in the association between sOB-R and colorectal cancer by subsite in women (Pheterogeneity = 0.004); sOB-R was significantly associated with increased risk of rectal cancer but not colon cancer. These findings support a role for adiponectin in colorectal carcinogenesis in men. Further studies are warranted to confirm these associations and elucidate potential underlying mechanisms.

Hormones of adipose tissue and their biologic role in lung cancer

INTRODUCTION

Adipose tissue secretes numerous bioactive peptides, collectively termed "adipocytokines" or "adipokines". Adipokines act in a paracrine, autocrine, or endocrine manner and regulate several physiological and pathological processes. Increasing evidence indicates that adipokines are implicated also in several malignancies, including lung cancer as well.

AIM

The aim of this study is to summarize data concerning adipokines in lung cancer pathogenesis, prognosis and survival; the role of adipokines in lung cancer cachexia is also examined.

MATERIALS AND METHODS

A systematic literature search was performed in the electronic database of Medline. Several studies and review articles met the inclusion criteria.

RESULTS

Leptin and adiponectin are the best studied adipokines. The majority of the relevant studies has investigated the potential correlations mainly between leptin, adiponectin, and sometimes also resistin, and nutritional status, systemic inflammation of lung cancer or lung cancer cachexia and have also assessed their prognostic significance. Few other studies have studied genetic variations in leptin, leptin receptor and adiponectin genes and their association with lung cancer susceptibility and prognosis. The ongoing list of adipokines associated with lung cancer also includes resistin, chemerin, and visfatin.

CONCLUSIONS

Increasing evidence points to the involvement of certain adipocytokines in lung cancer development, progression and prognosis. No conclusive evidence exists so far with regards to the role of adipocytokines in lung cancer cachexia. Future, longitudinal studies are warranted in order to clarify the role of adipocytokines in lung cancer and also uncover adipocytokines as novel therapeutic targets.

Scientific evidence for traditional claim of anti-obesity activity of Tecomella undulata bark

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Tecomella undulata is traditionally claimed in the treatment of various disease ailments including obesity and cancer. Till now there are no studies about anti-obesity activity of Tecomella undulata bark.

AIM OF THE STUDY

The present study was aimed to establish a scientific evidence for anti-obesity efficiency of ethyl acetate extract of Tecomella undulata bark (EATUB). Further to standardize the active fractions of EATUB using different biomarkers.

MATERIALS AND METHODS

We investigated activity of EATUB fractions (F1-F7) using 3T3-L1 fibroblasts. Further, F1-mediated effects were characterized by determining mRNA and protein levels of SIRT1, one of the key targets for the treatment of obesity, using semi-quantitative RT-PCR (sqRT-PCR) and western blot analysis. The consequences of modulation of SIRT1 on mRNA and protein levels of various adipogenesis mediators like PPARγ, C/EBPα, E2F1, leptin, adiponectin and LPL were also studied. In vivo studies were performed using High Fat Diet (HFD) obese mice.

RESULTS

Our data showed that compared to controls, preadipocytes and adipocytes incubated with F1 exhibited a significant decrease in adipogenesis and lipogenesis. In addition, sqRT-PCR and western blot analysis showed significant increase in SIRT1 and adiponectin levels and decrease in PPARγ, C/EBPα, E2F1, leptin and LPL levels in preadipocytes and adipocytes. In vivo studies of F1 in HFD induced obese mice showed significant improvement in lipid profile and glucose levels. The bioactive fraction (F1) was determined to possess 4.95% of ferulic acid.

CONCLUSION

Thus, our findings signified the beneficial effects of Tecomella undulata bark in pharmacologic interventions related to obesity and metabolic disorders. Ferulic acid and rutin are being reported and quantified for the first time from the bark of Tecomella undulata.

Obesity, an independent risk factor for hepatocellular carcinoma (HCC) in NAFLD non-cirrhotic patients

Hepatocellular carcinoma (HCC) is one of the most common malignancies with increasing incidence in developed countries. Epidemiological studies show that the cause of new discovered HCC cases remains unclear in 15%-50% of cases. Obesity and the subsequent/ underlying nonalcoholic fatty liver disease (NAFLD) can be responsible for most of these cases. The aim of our study was to estimate the risk of HCC in obese patients diagnosed with NAFLD, without clinical or imagistic features of liver cirrhosis, in order to see if HCC can develop in fatty liver in the absence of cirrhosis. Patients with regular/daily alcohol consumption or diagnosed with liver viral infections were excluded. We studied 214 obese patients with NAFLD over a period of 5 years. We evaluated all patients using abdominal ultrasound and serum alpha-fetoprotein every 6 month, in order to detect the HCC occurrence. Kaplan-Meier analysis estimated the cumulative incidence of HCC. Univariate and multivariate Cox regression analysis were used to assess associations between HCC and obesity. The median follow-up was 4.3 years. During the study period, 16 from 118 cirrhotic NFLAD patients (13.5%) and 12 from 96 non-cirrhotic NAFLD patients (12.5 %) developed HCC (p = 0.07, ns). The cumulative incidence of HCC was found to be 2.9% in obese patients with NAFLD-cirrhosis, compared with 2.2% in obese patients without cirrhosis (p = 0.09, ns). Multivariate regression analysis revealed that older age (p = 0.04) was independent variable associated with development of HCC in patients with/without NAFLDcirrhosis. Obesity seems to be an independent risk factor for HCC occurrence, regardless the presence of mild or advanced liver fibrosis in NAFLD patients.

Signaling pathways in the molecular pathogenesis of adenocarcinomas of the esophagus and gastroesophageal junction

Esophageal adenocarcinoma develops in response to severe gastroesophageal reflux disease through the precursor lesion Barrett esophagus, in which the normal squamous epithelium is replaced by a columnar lining. The incidence of esophageal adenocarcinoma in the United States has increased by over 600% in the past 40 years and the overall survival rate remains less than 20% in the community. This review highlights some of the signaling pathways for which there is some evidence of a role in the development of esophageal adenocarcinoma. An increasingly detailed understanding of the biology of this cancer has emerged recently, revealing that in addition to the well-recognized alterations in single genes such as p53, p16, APC, and telomerase, there are interactions between the components of the reflux fluid, the homeobox gene Cdx2, and the Wnt, Notch, and Hedgehog signaling pathways.

The relationship between inflammatory markers, angiogenesis, and obesity

Obesity is recognized as a chronic low grade and systemic inflammatory disease. Angiogenesis is critical for adipose tissue expansion. Several evidences have demonstrated that angiogenesis sustains inflammation by preparing oxygen and nutrients for inflammatory cells and inflammation in turn can cause insulin resistance, type 2 diabetes, and cardiovascular disease. The understanding of mechanisms of obesity especially main roles of inflammation and angiogenesis in fat mass expansion can lead to therapeutic approaches in growing field of obesity and its related disorders. In this review, we studied the relationship between obesity, angiogenesis, and inflammation.

The relationship between visceral obesity and colorectal cancer

SUMMARY The prevalence of obesity continues to rise globally and physicians and healthcare systems have to prepare for rising rates of obesity-associated disease. Aside from cardiovascular disease and diabetes, recent evidence suggests a strong association between obesity and the development of cancer, including colorectal cancer. Using BMI as a marker for obesity, excess body fat is associated with an increased risk of colorectal cancer; however, this relationship appears to be stronger among males and more consistent for colon rather than rectal cancer. Epidemiologic literature evaluating the risk of obesity on colorectal cancer survival using BMI is less consistent. Recent evidence suggests that visceral fat plays a greater role in the development of disease. Current research on the effect of visceral obesity on colorectal cancer outcomes is in its infancy, but may drive a new wave of practice for this ever-growing population of colorectal cancer patients.

The role of chronic inflammation in obesity-associated cancers

There is a strong relationship between metabolism and immunity, which can become deleterious under conditions of metabolic stress. Obesity, considered a chronic inflammatory disease, is one example of this link. Chronic inflammation is increasingly being recognized as an etiology in several cancers, particularly those of epithelial origin, and therefore a potential link between obesity and cancer. In this review, the connection between the different factors that can lead to the chronic inflammatory state in the obese individual, as well as their effect in tumorigenesis, is addressed. Furthermore, the association between obesity, inflammation, and esophageal, liver, colon, postmenopausal breast, and endometrial cancers is discussed.

Serum adiponectin and resistin levels in de novo and relapsed acute lymphoblastic leukemia children patients

BACKGROUND

Adipose tissue secretes a large number of adipocytokines such as leptin, resistin, and adiponectin. Many of these hormones and cytokines are altered in obese individuals and may lead to disruption of the normal balance between cell proliferation, differentiation, and apoptosis. The aim of our work was to investigate the disturbance of secretion of adiponectin and resistin in de novo and relapsed acute lymphoblastic leukemia (ALL) in Egyptian children and determine whether adiponectin and resistin are implicated in increased risk relapse compared to healthy individuals.

METHODS

Measurements of adiponectin and resistin were performed at diagnosis, in 32 patients with de novo ALL aged 3 to 18 years (mean 9.8 y) and 19 children with relapsed ALL aged 5 to 17 (mean 9.9 yr). 10 apparently healthy children with matched age and sex were used as controls.

RESULTS

Mean adiponectin levels were low (P < 0.05), whereas mean resistin levels were high (P<0.05) at diagnosis and relapsed ALL (compared to healthy controls). A significant decrease of adiponectin levels was observed in relapsed ALL compared to de novo ALL. In contrast resistin was significantly increased in relapsed ALL compared to de novo patients. Adiponectin in ALL subjects inversely correlated with resistin level (r = -0.51, P < 0.001).

CONCLUSION

Low adiponectin and high resistin level at diagnosis suggest their implication in ALL pathogenesis and may serve as potential clinically significant diagnostic markers to detect leukemic relapse.

Abdominal adiposity through adipocyte secretion products, a risk factor for endometrial cancer

BACKGROUND AND AIM

The adipose cell has been considered an inert cell from a secretory point of view. Studies over the past years have confirmed the capacity of the adipocyte to synthesize many substances including: adiponectin, leptin, which integrate multiple metabolic and endocrine signals. In the context of endometrial cancer, abdominal obesity as a risk factor is associated with a chronic inflammatory process, confirmed by the increase of inflammatory markers. The study aimed to identify a correlation between abdominal obesity, plasma adipokine levels and endometrial cancer.

MATERIAL AND METHOD

Two groups of patients were included in the study: group I - 44 patients diagnosed with endometrial cancer, group II - 44 patients without gynecological pathology or inflammatory disorders. After the performance of clinical examination and anthropometric measurements, abdominal fat was determined by dual X-ray absorptiometry and plasma adiponectin and leptin levels were measured.

RESULTS

A significantly higher abdominal fat and leptin value was found in the group of patients in with endometrial cancer (p < 0.0001), while the plasma adiponectin level was significantly lower, compared to the control group (p < 0.0001). Abdominal fat was in a negative linear correlation with the plasma adiponectin level and in a positive linear correlation with the plasma leptin level.

CONCLUSIONS

The measurement of adiponectin and leptin levels associated with the determination of abdominal adipose tissue can be a useful predictor factor for endometrial cancer.

Expression of adiponectin, leptin, and their receptors in ovarian endometrioma

OBJECTIVE

To evaluate the expression of leptin, leptin receptor (ObR), adiponectin, and adiponectin receptor (AdipoR) in ovarian endometriomas compared with normal endometrium, and to analyze relationships among adipokines and their receptors.

DESIGN

Experimental study.

SETTING

A clinic for the treatment of endometriosis and basic research laboratories.

PATIENT(S)

Forty-four women with endometriosis and 42 age-matched women with no laparoscopic evidence of endometriosis as control subjects.

INTERVENTION(S)

Endometrial tissue samples were obtained during laparoscopic surgery.

MAIN OUTCOME MEASURE(S)

Immunohistochemical staining for leptin, ObR, adiponectin, and AdipoR was performed with the use of tissue microarray. Clinical characteristics were reviewed from the patient's medical records. The effect of leptin on the expression of adiponectin was evaluated in endometriotic cell line using real-time reverse-transcription polymerase chain reaction.

RESULT(S)

Positive expression rates of leptin and ObR were significantly higher in ovarian endometrioma compared with normal endometrium, but those of adiponectin and AdipoR were similar (ovarian endometrioma vs. normal endometrium, respectively: leptin 100% vs. 59.5%; ObR 72.7% vs. 33.3%; adiponectin 31.8% vs. 42.9%; AdipoR 88.6% vs. 73.8%). Expression of adipokines and their receptors did not show any correlation with disease stage. A positive correlation was found between expression of ObR and adiponectin (correlation coefficient 0.488; P=.001). Leptin treatment in endometriotic cells induced mRNA expression of adiponectin.

CONCLUSION(S)

These data suggest that leptin and its receptor are induced in ovarian endometriomas, and that the leptin/ObR system regulates adiponectin gene expression in endometriotic cells.

Breast cancer and obesity: in vitro interferences between adipokines and proangiogenic features and/or antitumor therapies?

Obesity is now considered as a risk factor for breast cancer in postmenopausal women. Adipokine levels are modulated in obesity, and may play a role in carcinogenesis. Moreover, obesity increases risk of cancer mortality. Here, we hypothesized that this increase could be due to a modification in angiogenesis, capital event in the development of metastases, and/or in effectiveness of cancer treatments. To test these assumptions, following a same experimental design and simultaneously the effects of leptin and adiponectin on angiogenesis were investigated, and the impact of hyperleptinemia on anticancer drug effectiveness was measured in physiological and obesity situations. Focusing on angiogenesis, the proliferation of endothelial cells (HUVEC), which expressed leptin and adiponectin receptors, was stimulated by leptin and inhibited by adiponectin. Both adipokines globally reduced apoptosis and caspase activity. Leptin increased migration whereas adiponectin decreased migration, and leptin enhanced the area of the tubes formed by HUVEC cells while adiponectin inhibited their formation. MCF7 and MDA-MB-231 cells treated with leptin secreted more VEGF than untreated cells, whereas adiponectin treatment inhibited VEGF secretion. Finally, MCF7 cells pre-treated with leptin were more invasive than untreated cells. This effect was not reproduced in MDA-MB-231 cells. In the MCF7 breast cancer cell line, leptin could induce cell proliferation and reduced the efficacy of all breast cancer therapies (tamoxifen, 5-fluorouracil, taxol and vinblastin). These results suggest that, in obesity situation, leptin– in contrast to adiponectin – may promote tumor invasion and angiogenesis, leading to metastases ‘apparition, and reduce treatment efficacy, which could explain the increased risk of cancer mortality in cases of overweight. The evidence suggests adipokines influence breast cancer issue and could play a significant role, especially in obese patients for which hyperleptinemia, hypoadiponectinemia and increased metastatic potential are described.

Hypoxia and adipose tissue function and dysfunction in obesity

The rise in the incidence of obesity has led to a major interest in the biology of white adipose tissue. The tissue is a major endocrine and signaling organ, with adipocytes, the characteristic cell type, secreting a multiplicity of protein factors, the adipokines. Increases in the secretion of a number of adipokines occur in obesity, underpinning inflammation in white adipose tissue and the development of obesity-associated diseases. There is substantial evidence, particularly from animal studies, that hypoxia develops in adipose tissue as the tissue mass expands, and the reduction in Po(2) is considered to underlie the inflammatory response. Exposure of white adipocytes to hypoxic conditions in culture induces changes in the expression of >1,000 genes. The secretion of a number of inflammation-related adipokines is upregulated by hypoxia, and there is a switch from oxidative metabolism to anaerobic glycolysis. Glucose utilization is increased in hypoxic adipocytes with corresponding increases in lactate production. Importantly, hypoxia induces insulin resistance in fat cells and leads to the development of adipose tissue fibrosis. Many of the responses of adipocytes to hypoxia are initiated at Po(2) levels above the normal physiological range for adipose tissue. The other cell types within the tissue also respond to hypoxia, with the differentiation of preadipocytes to adipocytes being inhibited and preadipocytes being transformed into leptin-secreting cells. Overall, hypoxia has pervasive effects on the function of adipocytes and appears to be a key factor in adipose tissue dysfunction in obesity.

Clinical significance of serum adipokines levels in lung cancer

Adipokines have a significant effect on metabolism, immunoinflammatory responses as well as on carcinogenesis; therefore, we aimed at evaluating their potential predictive and prognostic significance in lung cancer. Eighty patients--mean age 62.9 ± 9.2 years--with previously untreated lung cancer (61 NSCLC and 19 SCLC) of all stages and 40 healthy individuals were enrolled in this study. Serum levels of leptin, adiponectin and ghrelin were measured using human Radioimmunoassay kits. Serum leptin levels in lung cancer patients were lower compared to control (p < 0.0001), while adiponectin and ghrelin levels were significantly increased in patients (p = 0.0003 and p = 0.0043, respectively). Additionally, the leptin/adiponectin ratio was significantly lower in the patients group compared to controls (p < 0.0001]. There was no association between serum levels of adipokines and any of the patient clinicopathological characteristics or response to therapy. Nevertheless, patients with lower values of serum leptin had shorter overall survival (p = 0.014), whereas multivariate analysis revealed leptin levels as an independent prognostic factor for survival (p = 0.024, HR 0.452, CI 95 % 0.232-0.899). These results suggest that adipokines may play a role in the pathogenesis of lung cancer, while leptin serum levels might provide useful prognostic information.

Adiponectin regulates vascular endothelial growth factor-C expression in macrophages via Syk-ERK pathway

Adiponectin is exclusively expressed in adipose tissues and exhibits protective effects against cardiovascular and metabolic diseases. It enhances AMP-activated kinase (AMPK) and peroxisome proliferator-activated receptor α (PPARα) signaling in the liver and skeletal muscles, however, its signaling pathways in macrophages remain to be elucidated. Here, we show that adiponectin upregulated the expression of vascular endothelial growth factor (VEGF)-C, and induced phosphorylation of extracellular signal-regulated kinase (ERK) in macrophages. Inhibition of Syk abrogated adiponectin-induced VEGF-C expression and ERK phosphorylation. Furthermore, inhibition of ERK blocked the induction of VEGF-C gene. Inhibition of Syk, but not that of ERK, abrogated adiponectin-induced expression of cyclooxygenase (COX)-2, tissue inhibitor of metalloproteinase (TIMP)-1, and interleukin (IL)-6. These results indicate that adiponectin regulates VEGF-C expression via Syk-ERK pathway in macrophages.

Diabetes and risk of cancer

Diabetes and cancer represent two complex, diverse, chronic, and potentially fatal diseases. Cancer is the second leading cause of death, while diabetes is the seventh leading cause of death with the latter still likely underreported. There is a growing body of evidence published in recent years that suggest substantial increase in cancer incidence in diabetic patients. The worldwide prevalence of diabetes was estimated to rise from 171 million in 2000 to 366 million in 2030. About 26.9% of all people over 65 have diabetes and 60% have cancer. Overall, 8–18% of cancer patients have diabetes. In the context of epidemiology, the burden of both diseases, small association between diabetes and cancer will be clinically relevant and should translate into significant consequences for future health care solutions. This paper summarizes most of the epidemiological association studies between diabetes and cancer including studies relating to the general all-site increase of malignancies in diabetes and elevated organ-specific cancer rate in diabetes as comorbidity. Additionally, we have discussed the possible pathophysiological mechanisms that likely may be involved in promoting carcinogenesis in diabetes and the potential of different antidiabetic therapies to influence cancer incidence.