Association of plasma adiponectin concentrations with chronic lymphocytic leukemia and myeloproliferative diseases

Tumor Cell Survival Factors and Angiogenesis in Chronic Lymphocytic Leukemia: How Hot Is the Link?

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of neoplastic CD5+/CD19+ B lymphocytes in the blood. These cells migrate to and proliferate in the bone marrow and lymphoid tissues. Despite the development of new therapies for CLL, drug resistance and disease relapse still occur; novel treatment approaches are therefore still needed. Inhibition of the angiogenesis involved in the progression of CLL might be a relevant therapeutic strategy. The literature data indicate that vascular endothelial growth factor, angiopoietin-2, and matrix metalloproteinase-9 are pro-angiogenic factors in CLL. A number of other CLL factors might have pro-angiogenic activity: fibroblast growth factor-2, certain chemokines (such as CXCL-12 and CXCL-2), tumor necrosis factor-α, insulin-like growth factor-1, neutrophil gelatinase-associated lipocalin, and progranulin. All these molecules contribute to the survival, proliferation, and migration of CLL cells. Here, we review the literature on these factors' respective expression profiles and roles in CLL. We also summarize the main results of preclinical and clinical trials of novel agents targeting most of these molecules in a CLL setting. Through the eradication of leukemic cells and the inhibition of angiogenesis, these therapeutic approaches might alter the course of CLL.

Obesity and Leukemia: Biological Mechanisms, Perspectives, and Challenges

PURPOSE OF REVIEW

To examine the epidemiological data on obesity and leukemia; evaluate the effect of obesity on leukemia outcomes in childhood acute lymphoblastic leukemia (ALL) survivors; assess the potential mechanisms through which obesity may increase the risk of leukemia; and provide the effects of obesity management on leukemia. Preventive (diet, physical exercise, obesity pharmacotherapy, bariatric surgery) measures, repurposing drugs, candidate therapeutic agents targeting oncogenic pathways of obesity and insulin resistance in leukemia as well as challenges of the COVID-19 pandemic are also discussed.

RECENT FINDINGS

Obesity has been implicated in the development of 13 cancers, such as breast, endometrial, colon, renal, esophageal cancers, and multiple myeloma. Leukemia is estimated to account for approximately 2.5% and 3.1% of all new cancer incidence and mortality, respectively, while it represents the most frequent cancer in children younger than 5 years. Current evidence indicates that obesity may have an impact on the risk of leukemia. Increased birthweight may be associated with the development of childhood leukemia. Obesity is also associated with worse outcomes and increased mortality in leukemic patients. However, there are several limitations and challenges in meta-analyses and epidemiological studies. In addition, weight gain may occur in a substantial number of childhood ALL survivors while the majority of studies have documented an increased risk of relapse and mortality among patients with childhood ALL and obesity. The main pathophysiological pathways linking obesity to leukemia include bone marrow adipose tissue; hormones such as insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. Obesity represents a risk factor for leukemia, being among the only known risk factors that could be prevented or modified through weight loss, healthy diet, and physical exercise. Pharmacological interventions, repurposing drugs used for cardiometabolic comorbidities, and bariatric surgery may be recommended for leukemia and obesity-related cancer prevention.

Obesity, bone marrow adiposity, and leukemia: Time to act

Obesity has taken the face of a pandemic with less direct concern among the general population and scientific community. However, obesity is considered a low-grade systemic inflammation that impacts multiple organs. Chronic inflammation is also associated with different solid and blood cancers. In addition, emerging evidence demonstrates that individuals with obesity are at higher risk of developing blood cancers and have poorer clinical outcomes than individuals in a normal weight range. The bone marrow is critical for hematopoiesis, lymphopoiesis, and myelopoiesis. Therefore, it is vital to understand the mechanisms by which obesity-associated changes in BM adiposity impact leukemia development. BM adipocytes are critical to maintain homeostasis via different means, including immune regulation. However, obesity increases BM adiposity and creates a pro-inflammatory environment to upregulate clonal hematopoiesis and a leukemia-supportive environment. Obesity further alters lymphopoiesis and myelopoiesis via different mechanisms, which dysregulate myeloid and lymphoid immune cell functions mentioned in the text under different sequentially discussed sections. The altered immune cell function during obesity alters hematological malignancies and leukemia susceptibility. Therefore, obesity-induced altered BM adiposity, immune cell generation, and function impact an individual's predisposition and severity of leukemia, which should be considered a critical factor in leukemia patients.

Expression of AdipoR1 and AdipoR2 and Serum Level of Adiponectin in Gastric Cancer

BACKGROUND

Cancer is one of the major causes of death worldwide and the third leading cause of death in Iran. One of the proteins that are considered having anticancer effects is the adiponectin hormone. Adiponectin leads to programmed cell death, prevents cell growth and proliferation, and increases the expression levels of BCL2.

AIM

The aim of this study was to assay the expression of adiponectin receptors (AdipoR1 and AdipoR2) genes in gastric cancer patients.

MATERIALS AND METHODS

In this case-control study, 42 gastric cancer patients and 52 volunteers as healthy controls were enrolled. Total RNA was extracted. cDNA was synthesized by the reverse transcription method, and expression analysis was performed by real-time PCR. The serum level of adiponectin was also measured by ELISA.

RESULTS

The expression of both AdipoR1 and AdipoR2 was significantly higher than the control group (p = 0.02). Serum adiponectin was significantly lower in gastric cancer cases when compared with normal controls (p = 0.03).

CONCLUSION

We found that expression level of AdipoR1 and AdipoR2 is strongly higher; however, the level of circulating adiponectin is lower in gastric cancer. Our study suggests that the expression of AdipoR1 and AdipoR2, besides the low level of adiponectin, may play an important role in the development and/or progression of gastric cancer.

Role of bone marrow adipocytes in leukemia and chemotherapy challenges

Adipose tissue (AT) is an extramedullary reservoir of normal hematopoietic stem cells (HSCs). Adipocytes prevent the production of normal HSCs via secretion of inflammatory factors, and adipocyte-derived free fatty acids may contribute to the development and progression of leukemia via providing energy for leukemic cells. In addition, adipocytes are able to metabolize and inactivate therapeutic agents, reducing the concentrations of active drugs in adipocyte-rich microenvironments. The aim of this study was to detect the role of adipocytes in the progression and treatment of leukemia. Relevant literature was identified through a PubMed search (2000-2018) of English-language papers using the following terms: leukemia, adipocyte, leukemic stem cell, chemotherapy, and bone marrow. Findings suggest the striking interplay between leukemic cells and adipocytes to create a unique microenvironment supporting the metabolic demands and survival of leukemic cells. Based on these findings, targeting lipid metabolism of leukemic cells and adipocytes in combination with standard therapeutic agents might present novel treatment options.

The prognostic value of serum and bronchoalveolar lavage levels of adiponectin in advanced non-small-cell lung cancer

Aim

We aimed to explore the prognostic implications of adiponectin (APN) levels in the serum and bronchoalveolar lavage (BAL) of patients with advanced NSCLC.

Materials & methods

29 newly diagnosed patients with stage IV NSCLC were prospectively enrolled. Baseline serum and BAL levels of APN were assayed by ELISA and correlated with various clinicopathological parameters, including overall survival.

Results

No statistically significant correlations were observed between the serum or BAL levels of APN and the clinicopathological parameters evaluated. The only prognostic factor identified, both by univariate and multivariate survival analyses, was performance status.

Conclusion

The results of our cohort failed to reveal any prognostic significance of serum and BAL levels of APN in stage IV NSCLC.

High Serum Adiponectin Level Is a Risk Factor for Anemia in Japanese Men: A Prospective Observational Study of 1,029 Japanese Subjects

Erythroid abnormalities including anemia and polycythemia are often observed in the general clinical setting. Because recent studies reported that adiponectin negatively affects hematopoiesis, we performed a prospective observational study to assess the relationship between anemia and adiponectin, as well as other parameters, in 1029 Japanese subjects (477 men and 552 women) 40 years of age and older. Body measurements, blood tests, and nutrition intake studies were performed at baseline, and 5 to 7 years later (follow-up). Hemoglobin (Hb) and hematocrit (Hct) levels in men with high serum adiponectin levels were lower at follow-up than at baseline. Multiple regression analysis showed that age, body mass index, adiponectin, and glutamic-pyruvic transaminase were significantly associated with erythroid-related variables (red blood cells, Hb, and Hct) in both men and women (P <0.05). In a logistic regression analysis, adiponectin, fasting blood glucose, and β-natriuretic peptide were significant risk factors for anemia in men, and blood urea nitrogen and amylase were significant risk factors in women. Physical features and nutrient intake were not risk factors for anemia. Our study demonstrates, both clinically and epidemiologically, that a high serum adiponectin level decreases the amounts of erythroid-related variables and is a risk factor for anemia in Japanese men.

Evolving role of adiponectin in cancer-controversies and update

Adiponectin (APN), an adipokine produced by adipocytes, has been shown to have a critical role in the pathogenesis of obesity-associated malignancies. Through its receptor interactions, APN may exert its anti-carcinogenic effects including regulating cell survival, apoptosis and metastasis via a plethora of signalling pathways. Despite the strong evidence supporting this notion, some work may indicate otherwise. Our review addresses all controversies critically. On the whole, hypoadiponectinaemia is associated with increased risk of several malignancies and poor prognosis. In addition, various genetic polymorphisms may predispose individuals to increased risk of obesity-associated malignancies. We also provide an updated summary on therapeutic interventions to increase APN levels that are of key interest in this field. To date efforts to manipulate APN levels have been promising, but much work remains to be done.

Adiponectin and colorectal cancer

Colorectal cancer is an obesity-related malignancy. Adiponectin is an adipokine produced exclusively by adipose tissue, and its concentration in the serum is reduced in obesity. A low serum level of adiponectin is associated with an increased risk of various types of malignancies including colorectal cancer. These facts suggest that the epidemiological link between obesity and cancer may have a significant association with adiponectin. Although numerous studies of colorectal cancer have been reported, the results are conflicting about the anti-cancer effect of adiponectin, and how adiponectin affects carcinogenesis or cancer development remains controversial. Because adiponectin has multiple systemic effects and exists as a high serum concentration protein, the main role of adiponectin should be regulation of homeostasis, and it would not likely act as an anti-cancerous hormone. However, as epidemiological evidence shows, a low adiponectin level may be a basic risk factor for colorectal cancer. We speculate that when the colonic epithelium is stimulated or damaged by another carcinogen under the condition of a low adiponectin level, carcinogenesis is promoted and cancer development is facilitated. In this report, we summarize recent findings of the correlation between adiponectin and colorectal cancer and investigate the effect of adiponectin on colorectal cancer.

The diverse roles of adiponectin in non-small-cell lung cancer: current data and future perspectives

In recent years, there is growing research interest for the biological role of adipose tissue-derived bioactive factors, mainly including adipokines, in various forms of cancer. Adiponectin (APN) is the most abundant circulating adipokine, and a key mediator of several cancer-related processes, such as cell proliferation, apoptosis, regulation of tumor cell invasion and angiogenesis. In this review we summarize and critically discuss the published literature on the diverse roles of APN in non-small-cell lung cancer, including its implication in lung cancer development, its use as a diagnostic and prognostic biomarker, and its correlation with cancer-related cachexia. The main challenges and future perspectives, mainly with regard to the potential development of APN-targeted therapeutic agents in cancer therapeutics, are also briefly presented and discussed.

Adiponectin enhances Imatinib anti-tumour activity in human chronic myeloid leukaemia cells with serum levels associated with Imatinib efficacy in early chronic phase patients

OBJECTIVES

Adiponectin, a functional ligand of adiponectin receptor-1 (AdipoR1) and adiponectin receptor-2 (AdipoR2), has been found to be linked to risk of development of chronic myeloid leukaemia (CML). Imatinib, as its first-line therapy, exhibits striking activity in both chronic and accelerated phases of the condition. However, numerous clinical trials have shown that many patients become refractory or experience relapses. Thus, development of new, hopefully effective Imatinib-based treatment strategies, are still needed.

MATERIALS AND METHODS

Effects of recombinant adiponectin protein, in enhancing Imatinib anti-tumour activities, in K562 and MEG-01 CML cells, were examined in vitro and in vivo. Forty-eight consecutive newly diagnosed adult patients with Bcr-Abl-positive CML, in the early chronic phase (ECP), were enrolled in the study. Imatinib efficacy, plasma adiponectin levels and their correlations were analysed.

RESULTS

Data presented here indicate that adiponectin enhanced Imatinib efficacy in vitro and in vivo. Furthermore, this augmented effect was due to inhibition of Bcr-Abl tyrosine kinase activity in an AdipoR1-dependent way, while AdipoR2 was not involved. Most importantly, additional clinical data revealed that adiponectin plasma levels in CML ECP patients, correlated with Imatinib efficacy.

CONCLUSIONS

Adiponectin enhanced Imatinib anti-tumour activity in human chronic myeloid leukaemia cells and its serum levels were associated with Imatinib efficacy, in early chronic phase patients.

Adiponectin signals through Adiponectin Receptor 1 to reverse imatinib resistance in K562 human chronic myeloid leukemia cells

Adiponectin, a member of adipokines, is a functional ligand for Adiponectin Receptor-1 (AdipoR1) and Adiponectin Receptor-2 (AdipoR2), and has been found to be linked to the risk of CML. Imatinib has undoubtedly revolutionised the management and outcome of chronic myeloid leukemia (CML), however imatinib resistance has been recognized as a major problem in CML therapy. In this study, we first established imatinib-resistant K562 CML cells, and then evaluated the effect of Adiponectin in reversing imatinib resistance. The data presented here demonstrated that Adiponectin was able to reverse K562 resistance to imatinib in vitro and in vivo. Additional data with molecular approaches suggested that the reversion of Adiponectin in imatinib resistance signals through AdipoR1 but not AdipoR2 to downregulate Bcr-Abl expression and effect in imatinib-resistant K562 CML cells. Taken together, our data showed that Adiponectin can reverse imatinib resistance in CML, and to a certain extent elucidate the mechanism of Adiponectin reversing imatinib resistance that may provide a new and promising approach in imatinib resistance management in CML therapy.

Management of erythropoiesis: cross-sectional study of the relationships between erythropoiesis and nutrition, physical features, and adiponectin in 3519 Japanese people

Although erythroid abnormalities (anemia and polycythemia) are commonly observed pathological conditions, not much information about borderline abnormalities is available. In this study, a cross-sectional study to analyze the relationships between erythropoiesis and nutrition, physical features, and laboratory test findings was conducted in middle-aged and older men and women. The study included 3519 Japanese people (1579 men and 1940 women), age 40 years and over. Analysis of variance showed that the group with a tendency to anemia was older, had a lower body mass index and diastolic blood pressure, and had higher serum adiponectin and creatinine. Multiple regression analysis showed that adiponectin, triglycerides, and total protein were common factors that affected erythropoiesis in both men and women. Hepatic, renal, and cardiac functions were also factors involved in erythropoiesis in men and in postmenopausal women. In addition, nutrient factors such as alcohol, vitamins, and carbohydrates were also significantly involved in erythropoiesis in men, but there were no significant nutrient factors involved in erythropoiesis in either premenopausal or postmenopausal women. This study showed that factors that influence erythropoiesis differ between men, premenopausal women, and postmenopausal women, and it suggested that appropriately modifying erythropoiesis management for each group of people is essential.

Adiponectin as a routine clinical biomarker

Adiponectin is a protein synthesized and secreted predominantly by adipocytes into the peripheral blood. However, circulating adiponectin level is inversely related with body weight, especially visceral fat accumulation. The mechanism of this paradoxical relation remains obscure. Low circulating adiponectin concentrations (hypoadiponectinemia; <4 μg/mL) are associated with a variety of diseases, including dysmetabolism (type 2 diabetes, insulin resistance, hypertension, dyslipidemia, metabolic syndrome, hyperuricemia), atherosclerosis (coronary artery disease, stroke, peripheral artery disease), sleep apnea, non-alcoholic fatty liver disease, gastritis and gastro-esophageal reflux disease, inflammatory bowel diseases, pancreatitis, osteoporosis, and cancer (endometrial cancer, postmenopausal breast cancer, leukemia, colon cancer, gastric cancer, prostate cancer). On the other hand, hyperadiponectinemia is associated with cardiac, renal and pulmonary diseases. This review article focuses on the significance of adiponectin as a clinical biomarker of obesity-related diseases. Routine measurement of adiponectin in patients with lifestyle-related diseases is highly recommended.

Role of adiponectin and its receptors in cancer

Adiponectin (APN), a novel hormone/cytokine derived from adipocyte tissue, is involved in various physiological functions. Genetics, nutrition, and adiposity are factors contributing to circulating plasma concentrations of APN. Clinical correlation studies have shown that lower levels of serum APN are associated with increased malignancy of various cancers, such as breast and colon cancers, suggesting that APN has a role in tumorigenesis. APN affects insulin resistance, thus further influencing cancer development. Tumor cells may express receptors for APN. Cellular signaling is the mechanism by which APN exerts its host-protective responses. These factors suggest that serum APN levels and downstream signaling targets of APN may serve as potential diagnostic markers for malignancies. Further research is necessary to clarify the exact role of APN in cancer diagnosis and therapy.

Adiponectin deficiency suppresses lymphoma growth in mice by modulating NK cells, CD8 T cells, and myeloid-derived suppressor cells

Previously, we found that adiponectin (APN) suppresses IL-2-induced NK cell activation by downregulating the expression of the IFN-γ-inducible TNF-related apoptosis-inducing ligand and Fas ligand. Although the antitumor function of APN has been reported in several types of solid tumors, with few controversial results, no lymphoma studies have been conducted. In this study, we assessed the role of APN in immune cell function, including NK cells, CTLs, and myeloid-derived suppressor cells, in EL4 and B16F10 tumor-bearing APN knockout (KO) mice. We observed attenuated EL4 growth in the APNKO mice. Increased numbers of splenic NK cells and splenic CTLs were identified under naive conditions and EL4-challenged conditions, respectively. In APNKO mice, splenic NK cells showed enhanced cytotoxicity with and without IL-2 stimulation. Additionally, there were decreased levels of myeloid-derived suppressor cell accumulation in the EL4-bearing APNKO mice. Enforced MHC class I expression on B16F10 cells led to attenuated growth of these tumors in APNKO mice. Thus, our results suggest that EL4 regression in APNKO mice is not only due to an enhanced antitumor immune response but also to a high level of MHC class I expression.

Expression of plasma membrane receptor genes during megakaryocyte development

Megakaryocyte (MK) development is critically informed by plasma membrane-localized receptors that integrate a multiplicity of environmental cues. Given that the current understanding about receptors and ligands involved in megakaryocytopoiesis is based on single targets, we performed a genome-wide search to identify a plasma membrane receptome for developing MKs. We identified 40 transmembrane receptor genes as being upregulated during MK development. Seven of the 40 receptor-associated genes were selected to validate the dataset. These genes included: interleukin-9 receptor (IL9R), transforming growth factor, β receptor II (TGFBR2), interleukin-4 receptor (IL4R), colony stimulating factor-2 receptor-beta (CSFR2B), adiponectin receptor (ADIPOR2), thrombin receptor (F2R), and interleukin-21 receptor (IL21R). RNA and protein analyses confirmed their expression in primary human MKs. Matched ligands to IL9R, TGFBR2, IL4R, CSFR2B, and ADIPOR2 affected megakaryocytopoiesis. IL9 was unique in its ability to increase the number of MKs formed. In contrast, MK colony formation was inhibited by adiponectin, TGF-β, IL4, and GM-CSF. The thrombin-F2R axis affected platelet function, but not MK development, while IL21 had no apparent detectable effects. ADP-induced platelet aggregation was suppressed by IL9, TGF-β, IL4, and adiponectin. Overall, six of seven of the plasma membrane receptors were confirmed to have functional roles in MK and platelet biology. Also, results show for the first time that adiponectin plays a regulatory role in MK development. Together these data support a strong likelihood that the 40 transmembrane genes identified as being upregulated during MK development will be an important resource to the research community for deciphering the complex repertoire of environmental cues regulating megakaryocytopoiesis and/or platelet function.

Comparison of adiponectin concentration between pancreatic cancer and colorectal cancer

INTRODUCTION

Adiponectin (ADP) is an adipocytokine secreted by the adipose tissue which can be a useful marker in oncogenesis. Preliminary studies suggest that adiponectin rates differ according to the type of cancer.

AIM OF STUDY

Compare ADP plasma levels in pancreatic cancer (PC) and colorectal cancer (CRC) in a prospective monocentric study.

PATIENTS AND METHODS

The study included all the incident cases of PC gathered from a university hospital in France from January 2006 till September 2007. A control population of incident cases of colorectal cancer (CRC), matching on age, gender, and tumor staging was set in the same period. In addition to demographic data, the other parameters analyzed were: ADP rate, insulinoresistance (Homa-test), presence of a dysmetabolic syndrome, evolution of weight and data concerning the tumor (staging, tumor markers: ACE, CA19.9).

RESULTS

33 CRC and 53 PC were analyzed. Type 2 diabetes was found in 18.2% of the CRC cases and 39.6% of the PC (p = 0.037). The mean ADP level was significantly higher in PC versus CRC (20.9 microgram/l versus 15.9 microgram/l; p = 0.03). In multivariate analysis , after adjusting for gender, age, bilirubinemia and weigth loss, the variables independently associated with a high level of ADP (> 10 microG/L) were type 2 diabetes (OR = 0.05, p = 0.01), insulinoresistance (OR = 0.42, p = 0.05) and PC (OR = 12.03, p = 0.047).

CONCLUSION

ADP concentration is higher in PC patients than in CRC patients. ADP concentration > 10 microgram/l was independently associated with pancreatic cancer. Our data confirm that adiponectin rates differ strongly according to the type of cancer.

The role of adiponectin in cancer: a review of current evidence

Excess body weight is associated not only with an increased risk of type 2 diabetes and cardiovascular disease (CVD) but also with various types of malignancies. Adiponectin, the most abundant protein secreted by adipose tissue, exhibits insulin-sensitizing, antiinflammatory, antiatherogenic, proapoptotic, and antiproliferative properties. Circulating adiponectin levels, which are determined predominantly by genetic factors, diet, physical activity, and abdominal adiposity, are decreased in patients with diabetes, CVD, and several obesity-associated cancers. Also, adiponectin levels are inversely associated with the risk of developing diabetes, CVD, and several malignancies later in life. Many cancer cell lines express adiponectin receptors, and adiponectin in vitro limits cell proliferation and induces apoptosis. Recent in vitro studies demonstrate the antiangiogenic and tumor growth-limiting properties of adiponectin. Studies in both animals and humans have investigated adiponectin and adiponectin receptor regulation and expression in several cancers. Current evidence supports a role of adiponectin as a novel risk factor and potential diagnostic and prognostic biomarker in cancer. In addition, either adiponectin per se or medications that increase adiponectin levels or up-regulate signaling pathways downstream of adiponectin may prove to be useful anticancer agents. This review presents the role of adiponectin in carcinogenesis and cancer progression and examines the pathophysiological mechanisms that underlie the association between adiponectin and malignancy in the context of a dysfunctional adipose tissue in obesity. Understanding of these mechanisms may be important for the development of preventive and therapeutic strategies against obesity-associated malignancies.

Aberrant expressions of leptin and adiponectin receptor isoforms in chronic myeloid leukemia patients

BACKGROUND

Leptin and adiponectin receptors mediate the role of leptin in stimulating the growth of leukemic cells and the protective function of adiponectin undertaken in several malignancies such as leukemia. In this study, we investigated the involvement of the expression of leptin and adiponectin receptors in chronic myeloid leukemia (CML) pathogenesis.

METHODS

The expression of leptin receptor isoforms, OB-Rt, OB-Ra, and OB-Rb, and the expression of adiponectin receptors, AdipoR1 and AdipoR2, were measured as mRNA levels in two CML cell lines (K562 and Meg-01) and 20 CML patients and 24 healthy controls by using RT-PCR.

RESULTS

OB-Rt and OB-Ra isoforms expression of the leptin receptors were found to be significantly lower in Meg-01 cell lines than K562 cells. All leptin receptors were downregulated in CML patients and more particularly OB-Rb level was found to be undetectably low in normal PBMC as well as in CML patients. AdipoR1 expression level was higher in Meg-01 than in K562, whereas AdipoR2 level was found to be unchanged in both cell lines. Interestingly, while AdipoR1 expression increased in CML patients, AdipoR2 decreased. Moreover, imatinib therapy did not affect both leptin and adiponectin isoform expressions.

CONCLUSION

While the decrease in leptin receptor levels in CML patients was confirmed, the increase in AdipoR1 levels and relevant decrease in AdipoR2 levels depicted their possible involvement in CML pathogenesis. This suggests different functions of adiponectin receptors in CML development.

The role of adiponectin (ADIPOQ) gene polymorphisms in the susceptibility and prognosis of non-small cell lung cancer

To study the role of the adiponectin (ADIPOQ) gene single-nucleotide polymorphism (SNP) in the susceptibility and prognosis for non-small cell lung cancer (NSCLC), we recruited 344 patients with NSCLC, of which 141 had undergone surgical resection and post-surgery follow up. For controls, there were 264 healthy volunteers for the control group, matched in age and sex with the NSCLC patients. Genotyping of SNPs in the ADIPOQ gene, namely, rs266729 (11365C>G); rs822395 (4034A>C); rs822396 (3964A>G); rs2241766 (+45T>G) were performed. Of all SNPs in the ADIPOQ gene, only the TT genotype and T allele frequency of the rs2241766 were more prevalent in NSCLC subjects than in controls. The TT genotype of rs2241766 was significantly associated with susceptibility to NSCLC before and after adjustment for age, sex, body mass index, and smoking status. In the survival analyses of subjects receiving surgical resection, only the SNPs of rs2241766 were significantly related to overall survival of NSCLC. Our results suggest that the SNP rs2241766 of the ADIPOQ gene may determine both susceptibility to NSCLC, and the prognosis for those who underwent surgical treatment.

Adiponectin receptors are downregulated in human gastric cancer

BACKGROUND

Adiponectin has been shown to have suppressive effects on tumor development, but the expression of adiponectin receptors in tumor tissue has not been fully elucidated. The purpose of this study was to quantitatively evaluate the expression of two adiponectin receptors, AdipoR1 and AdipoR2, in gastric cancer tissue.

METHODS

The mRNA levels of AdipoR1 and AdipoR2 were evaluated by quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining in 67 gastric cancer tissues and their normal counterparts. In addition, the effects of cytokines on AdipoR1 and AdipoR2 expression in cultured gastric cancer cells were examined.

RESULTS

As compared to findings in the normal counterparts, AdipoR1 mRNA expression, standardized by β-actin mRNA, tended to be lower (cancer 0.488 ± 0.039, normal 0.955 ± 0.281, p = 0.0726) and AdipoR2 expression was significantly lower (0.818 ± 0.081, 1.500 ± 0.222, p = 0.0035) in gastric cancer tissue. Immunohistochemical examination showed the same tendency for AdipoR1 and AdipoR2 expression in epithelial cells. Moreover, AdipoR2 was strongly expressed in interstitial cells. However, the expression levels of these receptors did not show a strong correlation with various pathological factors. An in vitro experiment using two gastric cancer cell lines, MKN-74 and NUGC-3, showed that the expression levels of AdipoR1 and AdipoR2 were significantly decreased by transforming growth factor (TGF)-β in a dose-dependent manner.

CONCLUSIONS

Two major adiponectin receptors were decreased in gastric cancer as compared to findings in normal gastric epithelium. TGF-β may be involved in this receptor downregulation. This downregulation may be an ideal strategy for cancer cells to escape the antiproliferative effects of adiponectin in the initial phase of tumor development.

Adiponectin is produced by lymphocytes and is a negative regulator of granulopoiesis

Lymphocytes have long been established to play an important role in the regulation of hematopoiesis and produce many cytokines that act on hematopoietic progenitor cells. Previous studies by our group have shown that normal, unstimulated lymphocytes produce a protein that inhibits normal bone marrow GM colony formation. Adiponectin is an adipokine that has been demonstrated to act as a negative regulator of hematopoiesis and immune function. This study aimed to determine if the inhibitory molecule that we described previously was adiponectin. Here, we show transcription, translation, and secretion of adiponectin from lymphocytes and demonstrate that its receptors, AdipoR1 and AdipoR2, are expressed by bone marrow MNCs. We show that although the adiponectin expression is low in lymphocytes, it is sufficient to induce a significant inhibitory effect on GM precursors (CFU-GM) and activate the AMPK pathway in these cells. The regulation of adiponectin production by lymphocytes and its detailed function in suppressing GM colony formation need to be elucidated now. Our findings suggest a functional role for adiponectin as a negative regulator of granulopoiesis.

B-cell chronic lymphocytic leukemia risk in association with serum leptin and adiponectin: a case-control study in Greece

AIM

Leptin and adiponectin are two well-studied adipokines in relation to malignancies. In this study, we examined the association between leptin/adiponectin and risk of B-cell chronic lymphocytic leukemia (B-CLL), as well as the relationships between adipokines and several established prognostic factors of B-CLL.

METHODS

Ninety-five patients with incident B-CLL and 95 hospital controls matched on age and gender were studied between 2001 and 2007, and blood samples were collected. Leptin, total and high molecular weight adiponectin, and prognostic markers of B-CLL were determined.

RESULTS

Cases had a higher body mass index (BMI) than controls (p = 0.01) and lower levels of leptin (p < 0.01). Significantly more cases than controls presented a family history of lymphohematopoietic cancer (LHC) (p = 0.01). Higher serum leptin levels were associated with lower risk of B-CLL adjusting for age, gender, family history of LHC, BMI and serum adiponectin; the multivariate odds ratio comparing highest to lowest tertile was 0.05 (95% CI 0.01-0.29, p trend < 0.001); Adiponectin was not significantly different between cases and controls.

CONCLUSION

Leptin was found to be inversely associated with risk of CLL but in contrast to prior studies of CLL and hematologic malignancies, this study found no significant association between CLL and adiponectin.

Adipocytokines in relation to Hodgkin lymphoma in children

This case-control study aims to explore the association of serum adiponectin/leptin with childhood Hodgkin lymphoma (HL). Study participants were 75 children with histologically confirmed HL, registered in the Nationwide Registry for Childhood Haematological Malignancies and 75 age- and gender-matched controls. Multiple conditional logistic regression analyses were performed, adjusting for sociodemographic and lifestyle parameters. Adiponectin levels were consistently higher among cases in all models with ORs >1.25; 95% CIs ranging from 0.9 to 1.8 and P-values from 0.09 to 0.20. By contrast, there was no association of serum leptin with HL. In conclusion, elevated serum adiponectin might be a risk factor for childhood HL.

Physical activity and hematologic cancer prevention

This chapter presents the epidemiologic evidence on the association between physical activity and hematologic cancers and related hypothesized biologic mechanisms. Some preliminary indications of a protective role for physical activity for non-Hodgkin's lymphoma, leukemia, multiple myeloma, and Hodgkin's lymphoma exist, but the level of epidemiologic evidence is still insufficient to make any definitive conclusions regarding the nature of these associations. Several plausible biologic mechanisms underlying the possible associations between physical activity and hematologic cancers have been proposed, including enhancement of immune function, reduction in obesity, improvement of antioxidant defense systems, impact on metabolic hormones, and anti-inflammatory effects. Future studies should improve the estimation of physical activity by using more reliable, valid, and comprehensive measurement tools, assessing all components of physical activity (type, intensity, and time period), and conducting intervention studies to evaluate the effect of physical activity on various biomarkers of cancer in order to provide further insight into plausible biologic mechanisms underlying the possible association between physical activity and hematologic cancers.

Metabolic syndrome and cancer

Since its first description by Reavan in 1988, accepted criteria for clinical identification of the components of metabolic syndrome have been promulgated by the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) and the World Health Organization (WHO) as well as the International Diabetes Federation (IDF), and the American Association of Clinical Endocrinologists (AACE). Insulin resistance is a common metabolic abnormality underlying type 2 diabetes mellitus and is also an independent risk factor for cardiovascular disease. Although ATP III identified cardiovascular disease (CVD) as the primary clinical outcome of the metabolic syndrome, we now have evidence that metabolic syndrome is associated with type 2 diabetes mellitus, polycystic ovarian disease, nonalcoholic fatty liver disease, and possibly some cancers. This review summarizes evidence in support of the relationship between metabolic syndrome and various cancers and possible underlying mechanisms and therapeutic interventions.

Adiponectin suppresses tumorigenesis in Apc(Min)(/+) mice

Recent reports have shown that adiponectin has a suppressive effect on various types of malignancy. In order to clarify the role of adiponectin in colorectal carcinogenesis, we examined the effect of exogenous administration of adiponectin on intestinal polyp formation in C57BL/6J-Apc(Min)(/+) mice, which possess a point mutation in the Apc gene. And we found that adiponectin treatment significantly decreased the number of adenomatous polyps, especially polyps larger than 2mm in diameter, in the small intestine. Two major receptors for adiponectin, AdipoR1 and AdipoR2, were expressed in adenomatous polyps, and their expression levels were not altered by adiponectin injection. In conclusion, adiponectin suppresses the growth of intestinal adenomas in the Apc(Min)(/+) mice. Increasing the adiponectin level may be a new strategy for the prevention of colorectal cancer at an early step of carcinogenesis.

Prognostic relevance of serum levels and cellular expression of adiponectin in B-cell chronic lymphocytic leukemia

The correlation between well-established biological parameters of prognostic relevance in B-cell chronic lymphocytic leukaemia (CLL) [i.e., mutational status of the immunoglobulin heavy chain variable region (IgV(H)), ZAP-70- and CD38-expression] and adiponectin serum concentration was evaluated in a cohort of 69 previously untreated Binet stage A CLL patients. Adiponectin levels inversely correlated with absolute peripheral blood lymphocyte count (r = -0.254; P = 0.03), CD38-positive CLL cells (r = -0.294; P = 0.04) and ZAP-70 (r = -0.285; P = 0.03). The univariate Cox proportional hazard model demonstrated that, in addition with lower serum levels of adiponectin (P = 0.01), the unmutated IgV(H) condition (P = 0.002) and ZAP-70-positivity (P = 0.02) were associated with a shorter time to first treatment (TFT). However, in multivariate analysis only ZAP-70 positivity emerged as predictor of the TFT (P = 0.008). The levels of adiponectin in CLL were evaluated in 60 patients from an independent cohort investigated by gene expression profiling. Adiponectin gene expression was invariably low suggesting a limited (if any) role of leukemic cells in the production of circulating adiponectin levels. In contrast, both adiponectin receptor 1 (AdipoR1) and AdipoR2 mRNA were highly expressed by CLL cells with a degree of inter-patient variability. Our results, although preliminary, lend support to the idea that adiponectin secretion by bone marrow adipocytes might represent a possible promising drug target in the field of hematology.

Adiponectin in relation to malignancies: a review of existing basic research and clinical evidence

Adiponectin, an adipocyte-secreted hormone that plays an important role in diabetes and cardiovascular disease, may also be of importance in the development and progression of several malignancies. Circulating adiponectin concentrations, which are determined mainly by genetic factors, nutrition, and adiposity, are lower in patients with breast, endometrial, prostate, and colon cancer. It has thus been proposed that adiponectin may be a biological link between obesity (especially central obesity) and increased cancer risk. Adiponectin may influence cancer risk through its well-recognized effects on insulin resistance, but it is also plausible that adiponectin acts on tumor cells directly. Several cancer cell types express adiponectin receptors that may mediate the effects of adiponectin on cellular proliferation. Herein, we review recent evidence supporting a role of serum adiponectin concentrations as a novel risk factor and possible diagnostic marker for obesity-related malignancies, including cancers of the breast, endometrium, colon, and prostate. Further studies are needed to fully elucidate the potential role of adiponectin in cancer diagnostics and therapeutics.

Gender dimorphism in the myeloid differentiation of bone marrow precursor cells in a murine host bearing a T cell lymphoma

Little information is available regarding the existence of gender dimorphism of tumor growth for most types of tumors. In a previous report we have demonstrated the existence of gender dimorphism in the growth of a murine T cell lymphoma, designated as Dalton's lymphoma (DL); moreover, tumor-associated macrophages (TAM) were found to play a central role in the manifestation of gender dimorphism observed in the growth of this T cell lymphoma. In view of these observations, the present investigation was undertaken to study if gender dimorphism in the growth of a T cell tumor also could be associated with a gender-dependent differential myelopoiesis of bone marrow cells. We have demonstrated the existence of a gender dimorphism in the proliferation, apoptosis and myeloid differentiation of bone marrow cells obtained from male and female tumor-bearing hosts. Androgen and estrogen were found to alter directly the growth properties of bone marrow cells, as also determined by the use of receptor antagonists of these hormones, flutamide and tamoxifen. Bone marrow cells of male and female tumor-bearing hosts also showed a differential expression of the cell cycle and apoptosis regulatory protein p53 and macrophage-colony stimulating factor (M-CSF) genes. Bone marrow cells of male tumor-bearing hosts showed a predominant differentiation in the macrophage lineage whereas those of female tumor-bearing mice were in the granulocyte lineage. Bone marrow-derived macrophages (BMDM) from male and female tumor-bearing mice also showed the existence of gender dimorphism with respect to their differentiation and activation. These observations are of clinical significance with respect to understanding of the host-tumor relationship at the level of gender dimorphism of myelopoiesis.