Adiponectin receptor 2 is negatively associated with lymph node metastasis of colorectal cancer

Association of Adiponectin Receptors with Metabolic and Immune Homeostasis Parameters in Colorectal Cancer: In Silico Analysis and Observational Findings

Adiponectin (ADIPOQ) as both a regulator of metabolic homeostasis and a protein involved in immune response might be of particular interest to contemporary laboratory medicine, especially in terms of minimally invasive diagnostics. The diverse roles of ADIPOQ with regard to the immune and metabolic aspects of colorectal carcinogenesis have been proposed. However, the expression of its receptors ADIPOR1 and ADIPOR2 is scarcely explored in peripheral blood mononuclear cells (PBMCs). Moreover, ADIPORs' relationships with the immune response mediator TNF-α have not been previously investigated in the PBMCs of CRC patients. This study used both in silico and observational case-control analyses with the aim of exploring the association of ADIPOR gene expression and ADIPOQ single nucleotide polymorphisms (SNPs) with the inflammatory marker TNF-α and lipid status parameters in patients with CRC. Publicly available transcriptomic datasets (GSE47756, GSE44076) obtained from analyses of monocytes and CRC tissue samples were employed for the in silico evaluation of ADIPORs' specific genetic traits. GSE47756 and GSE44076 datasets were processed with GSEA software to provide a genetic fingertip of different signaling pathways associated with ADIPORs' mRNA levels. The case-control aspect of the study included the PBMC samples of 73 patients diagnosed with CRC and 80 healthy volunteers. The PCR method was carried out for the PBMC gene expression analysis (ADIPOR1, ADIPOR2, TNF-α mRNA levels) and for the subjects' genotyping (ADIPOQ rs266729, ADIPOR1 rs7539542). GSEA showed significant associations of ADIPOR mRNA expression with gene sets related to metabolic and immune homeostasis in both datasets. The case-control study revealed the association of ADIPOR1 rs7539542 with reduced lipid status parameters in CRC. In addition, PBMC ADIPOR1 mRNA levels decreased in CRC (p < 0.001), whereas ADIPOR2 mRNA did not differ between the groups (p = 0.442). A reduction in PBMC TNF-α mRNA levels was noted in CRC (p < 0.05). Our results indicate that ADIPOR1 and ADIPOR2 play a significant role in the alteration of both metabolic and immune homeostasis during the progression of CRC. For the first time, ADIPOR1 is shown to be a specific receptor for mediating ADIPOQ's effects in the PBMCs of CRC patients.

The Adipokine Component in the Molecular Regulation of Cancer Cell Survival, Proliferation and Metastasis

A hormonal imbalance may disrupt the rigorously monitored cellular microenvironment by hampering the natural homeostatic mechanisms. The most common example of such hormonal glitch could be seen in obesity where the uprise in adipokine levels is in virtue of the expanding bulk of adipose tissue. Such aberrant endocrine signaling disrupts the regulation of cellular fate, rendering the cells to live in a tumor supportive microenvironment. Previously, it was believed that the adipokines support cancer proliferation and metastasis with no direct involvement in neoplastic transformations and tumorigenesis. However, the recent studies have reported discrete mechanisms that establish the direct involvement of adipokine signaling in tumorigenesis. Moreover, the individual adipokine profile of the patients has never been considered in the prognosis and staging of the disease. Hence, the present manuscript has focused on the reported extensive mechanisms that culminate the basis of poor prognosis and diminished survival rate in obese cancer patients.

AdipoR2 inhibits human glioblastoma cell growth through the AMPK/mTOR pathway

Background

AdipoR2, which belongs to the seven-transmembrane-domain receptor family, has been shown to play an important role in the development of human tumours, but the underlying mechanisms are poorly understood. In this study, we found that AdipoR2 expression correlates with glioma grade. In addition, we also investigated the mechanisms behind the antiproliferative effects of AdipoR2 in U251 cells (a human glioma cell line) using colony formation and WST-8 growth assays.

Methods

The U251 cell line was cultured in vitro. Western blotting was used to detect the expression of relevant proteins. Quantitative RT-PCR was used to detect AdipoR1 and AdipoR2 expression. Flow cytometry was used to detect cell cycle assay results. The gene expression profiles of glioma samples from the CGGA database were analysed by MATLAB and GSEA software.

Results

The AMPK/mTOR pathway plays a central role in the regulation of cell proliferation, differentiation and migration and may promote tumorigenesis. Therefore, we can control cancer progression by modulating the AMPK/mTOR pathway. However, there is no information on the relationship between AdipoR and AMPK/mTOR in central nervous system tumours such as GBM. In this study. We found 648 upregulated genes and 436 downregulated genes correlated with AdipoR2 expression in 158 glioma samples. GSEA suggested that AdipoR2 is a cell cycle-associated gene. The results of the flow cytometry analysis indicated that AdipoR2 induced G0/G1 cell cycle arrest in U251 cells. Furthermore, we identified the AMPK/mTOR signalling axis to be involved in AdipoR2-induced cell cycle arrest.

Conclusions

Our results suggest that AdipoR2 may represent a novel endogenous negative regulator of GBM cell proliferation. These findings also suggest that AdipoR2 may be a promising therapeutic target in GBM patients.

Overexpression of Adiponectin Receptors in Opium Users with and without Cancer

Aim

Opium addiction is a serious public health concern in the Middle East countries causing various illnesses. Opium use is associated with an increased risk of several cancers; however, the underlying mechanisms are not yet fully elucidated. Altered levels of adiponectin and its related main receptors, Adiponectin receptor 1 and 2 (AdipoR1 and AdipoR2) have been associated with several malignancies. Opium users are at risk of various cancers. All together let us to the hypothesis that probable overexpression of AdipoRs in opium users might be linked to the occurrence of cancer in this population.

Methods

One hundred opium users along with 100 healthy non-opium users were enrolled in the study. Opium users were followed up for 5 years (2014–2019) to evaluate the occurrence of malignancies. AdipoR1 and AdipoR2 expressions were measured using a flow cytometry method.

Results

Expression of AdipoR1 and AdipoR2 was significantly higher in opium users compared with the healthy control group (P=0.0001 and 0.0001, respectively). Eight opium users developed cancer during the follow-up period. Subjects abusing opium developed cancer by 8.6 folds comparing to non-opium users (P=0.034; OR=8.6; 95% CI (1.06–70.1)). Expression of these two receptors was significantly higher in opium users developing cancer compared with cancer-free opium (P=0.001).

Conclusion

Considering the significant overexpression of AdipoR1 and AdipoR2 in opium users and in opium users who developed malignancies and the association between upregulation of these receptors in most cancers affecting opium users and assessment of AdipoRs may serve as an early detection tool of cancer in this population.

The Role of Adipokines in the Establishment and Progression of Head and Neck Neoplasms

Adipokines constitute a family of protein factors secreted by white adipose tissue (WAT), that regulate the functions of WAT and other sites. Leptin, adiponectin and resistin, are the main adipokines present in serum and saliva, targeting several tissues and organs, including vessels, muscles, liver and pancreas. Besides body mass regulation, adipokines affect glucose homeostasis, inflammation, angiogenesis, cell proliferation and apoptosis, and other crucial cell procedures. Their involvement in tumor formation and growth is well established and deregulation of adipokine and adipokine receptors' expression is observed in several malignancies including those located in the head and neck region. Intracellular effects of adipokines are mediated by a plethora of receptors that activate several signaling cascades including Janus kinase/ Signal transducer and activator of transcription (JAK/ STAT pathway), Phospatidylinositol kinase (PI3/ Akt/ mTOR) and Peroxisome proliferator-activated receptor (PPAR). The present review summarizes the current knowledge on the role of adipokines family members in carcinogenesis of the head and neck region. The diagnostic and prognostic significance of adipokines and their potential role as serum and saliva biomarkers are also discussed.

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.

Clinical significance of AGE-RAGE axis in colorectal cancer: associations with glyoxalase-I, adiponectin receptor expression and prognosis

Background

Advanced glycation end products (AGEs) and their receptor RAGE emerge as important pathogenic contributors in colorectal carcinogenesis. However, their relationship to the detoxification enzyme Glyoxalase (GLO)-I and Adiponectin receptors (AdipoR1, AdipoR2) in colorectal carcinoma (CRC) is currently understudied. In the present study, we investigated the expression levels of the above molecules in CRC compared to adjacent non-tumoral tissue and their potential correlation with clinicopathological characteristics and patients’ survival.

Methods

We analyzed the immunohistochemical expression of AGE, RAGE, GLO-1, AdipoR1 and AdipoR2 in 133 primary CRC cases, focusing on GLO-I. The tumour MSI status was further assessed in mucinous carcinomas. Western immunoblotting was employed for validation of immunohistochemical data in normal and tumoral tissues as well in three CRC cell lines. An independent set of 55 patients was also used to validate the results of univariate survival analysis regarding GLO-I.

Results

CRC tissue showed higher intensity of both AGE and RAGE expression compared with normal colonic mucosa which was negative for GLO-I in most cases (78 %). Western immunoblotting confirmed AGE, RAGE and GLO-I overexpression in tumoral tissue. GLO-I expression was directly related to RAGE and inversely related to AGE immunolabeling. There was a trend towards higher expression of all markers (except for RAGE) in the subgroup of mucinous carcinomas which, although of borderline significance, seemed to be more prominent for AdipoR1 and AGE. Additionally, AGE, AdipoR1 and Adipo R2 expression was related to tumor grade, whereas GLO-1 and AdipoR1 to T-category. In survival analysis, AdipoR2 and GLO-I overexpression predicted shortened survival in the entire cohort and in early stage cases, an effect which for GLO-I was reproduced in the validation cohort. Moreover, GLO-I emerged as an independent prognosticator of adverse significance in the patients’ cohort.

Conclusions

We herein provide novel evidence regarding the possible interactions between the components of AGE-RAGE axis, GLO-I and adiponectin receptors in CRC. AGE and AdipoR1 are possibly involved in colorectal carcinogenesis, whereas AdipoR2 and GLO-I emerged as novel independent prognostic biomarkers of adverse significance for patients with early disease stage. Further studies are warranted to extend our observations and investigate their potential therapeutic significance.

Esophageal adenocarcinoma and obesity: peritumoral adipose tissue plays a role in lymph node invasion

Obesity is associated with cancer risk in esophageal adenocarcinoma (EAC). Adipose tissue directly stimulates tumor progression independently from body mass index (BMI), but the mechanisms are not fully understood. We studied the morphological, histological and molecular characteristics of peritumoral and distal adipose tissue of 60 patients with EAC, to investigate whether depot-specific differences affect tumor behavior. We observed that increased adipocyte size (a hallmark of obesity) was directly associated with leptin expression, angiogenesis (CD31) and lymphangiogenesis (podoplanin); however, these parameters were associated with nodal metastasis only in peritumoral but not distal adipose tissue of patients. We treated OE33 cells with conditioned media (CM) collected from cultured biopsies of adipose tissue and we observed increased mRNA levels of leptin and adiponectin receptors, as well as two key regulator genes of epithelial-to-mesenchymal transition (EMT): alpha-smooth muscle actin (α-SMA) and E-cadherin. This effect was greater in cells treated with CM from peritumoral adipose tissue of patients with nodal metastasis and was partially blunted by a leptin antagonist. Therefore, peritumoral adipose tissue may exert a direct effect on the progression of EAC by secreting depot-specific paracrine factors, and leptin is a key player in this crosstalk.

AdipoRon: a possible drug for colorectal cancer prevention?

Colorectal cancer (CRC) is in the third place of the most common cancers. Certain risk factors can increase the development of CRC, including diet and inheritance. Several studies have shown that there is a potential link between obesity and CRC. Adipose tissue is known to be a largest endocrine organ in the body, with the ability to produce various cytokines including adiponectin. Two types of adiponectin receptor, AdipoR1 and AdipoR2, have been detected in various cancer tissues such as CRC. There is mounting evidence that AdipoR1 signaling occurs mainly through 5' AMP-activated protein kinase (AMPK) and adiponectin inhibits colorectal cancer cell growth via activation of AMPK, thereby suppression of the mammalian target of rapamycin (mTOR) pathway. Thus, adiponectin replacement-based therapies may represent a novel approach in CRC cell growth inhibition in early stages. AdipoRon is an adiponectin-like synthetic small molecule that activated both adiponectin receptors 1 and 2. We hypothesize that AdipoRon has antiproliferative effects of adiponectin and may suppress the CRC cell growth. With clarification of this drug's role in CRC, it can be used as chemoprevention in patients at risk of developing the disease.

Tumor expression of adiponectin receptor 2 and lethal prostate cancer

To investigate the role of adiponectin receptor 2 (AdipoR2) in aggressive prostate cancer we used immunohistochemistry to characterize AdipoR2 protein expression in tumor tissue for 866 men with prostate cancer from the Physicians' Health Study and the Health Professionals Follow-up Study. AdipoR2 tumor expression was not associated with measures of obesity, pathological tumor stage or prostate-specific antigen (PSA) at diagnosis. However, AdipoR2 expression was positively associated with proliferation as measured by Ki-67 expression quartiles (P-trend < 0.0001), with expression of fatty acid synthase (P-trend = 0.001), and with two measures of angiogenesis (P-trend < 0.1). An inverse association was observed with apoptosis as assessed by the TUNEL assay (P-trend = 0.006). Using Cox proportional hazards regression and controlling for age at diagnosis, Gleason score, year of diagnosis category, cohort and baseline BMI, we identified a statistically significant trend for the association between quartile of AdipoR2 expression and lethal prostate cancer (P-trend = 0.02). The hazard ratio for lethal prostate cancer for the two highest quartiles, as compared to the two lowest quartiles, of AdipoR2 expression was 1.9 (95% confidence interval [CI]: 1.2-3.0). Results were similar when additionally controlling for categories of PSA at diagnosis and Ki-67 expression quartiles. These results strengthen the evidence for the role of AdipoR2 in prostate cancer progression.

microRNA-423-3p promotes tumor progression via modulation of AdipoR2 in laryngeal carcinoma

Despite of the variety of combined modality treatments for laryngeal carcinoma have been introduced, the distance recurrence rate and 5-year overall survival rate over the past decades are still the major issues, underlining the importance to better understand the biological bases that contribute to disease progression. Here, we reported that miR-423-3p overexpressed in primary laryngeal carcinoma cell line where it plays a critical role in tumor progression. Suppression of miR-423-3p expression resulted in decreasing cell proliferation, clonogenicity, cell migration and invasion. By using in silico prediction algorithms for target identification, AdipoR2 (adiponectin receptor 2) and DUSP4 (MAP kinase phosphatase 2) were identified to be potential targets of miR-423-3p. Overexpression of miR-423-3p was associated with epigenetic silencing of AdipoR2 in human laryngeal carcinoma samples, which have been previously implicated in suppression of tumor proliferation and angiogenesis. Luciferase reporter assays and western blot further confirmed the direct interaction of miR-423-3p with AdipoR2. Our findings have demonstrated that miR-423-3p plays an important oncogenic role in laryngeal carcinoma progression, and further suggest that suppression of miR-423-3p expression might be useful for its clinical management.