The association of adiponectin gene promoter variations with non-small cell lung cancer in a Han Chinese population

ADIPOQ rs2241766 SNP as protective marker against DIBC development in Mexican population

BACKGROUND

Adiponectin protein and some variations in its gene, ADIPOQ have recently been associated with cancer because they regulate glucose and lipid metabolism as well as anti-apoptotic and anti-inflammatory proteins.

AIM

The aim of this study was to analyse the relationship between selected biochemical markers, anthropometric indices and ADIPOQ rs2241766 and rs1501299 SNPs in ductal infiltrating breast cancer (DIBC) in a Mexican population.

METHODS

This cross-sectional study included 64 DIBC patients and 167 healthy women. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was performed to identify the genotypes of the rs2241766 (exon 2) and rs1501299 (intron 2) ADIPOQ polymorphisms. Corporal composition and biochemical markers included body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-hip ratio (WHR), glucose, cholesterol, triglycerides and high- and low-density lipoprotein cholesterol.

RESULTS

Patients with DIBC had higher serum glucose, WC and WHR than controls. Intergroup differences in allele and genotype frequencies were found for both polymorphisms (P < 0.05). Patients carrying the rs2241766 TT and TG genotypes had higher values of WC, HC and WHR, but only TG carriers had higher levels of glucose. For the SNP rs1501299, carriers of the GG genotype in the DIBC group had higher values of glucose, WC, HC and WHR than the respective control group.

CONCLUSIONS

These results suggest that WC, HC and WHR are better predictors of DIBC than BMI. The ADIPOQ SNP rs2241766 emerges as a protective factor, whereas rs1501299 is a risk factor for DIBC development in a Mexican population.

Adiponectin down-regulates CREB and inhibits proliferation of A549 lung cancer cells

INTRODUCTION

Adipokines are known to play a relevant role in a number of cancer related molecular pathways. Adiponectin is a major adipokine with anti-inflammatory and beneficial metabolic actions. Furthermore, it has been shown to exert anti-carcinogenic effects in various tumor models and some clinical studies suggested an inverse relationship between circulating levels of adiponectin and an increased risk for development of malignancies. On the other hand, the cyclic AMP response element binding (CREB) transcription factor has been clearly linked to lung cancer.

METHODS

we analyzed cell proliferation, cell cycle of A549 cells treated with adiponectin as well as CREB activation status in human lung adenocarcinoma A549 cells and in non-small cell lung cancer (NSCLC) samples.

RESULTS

adiponectin treatment, at concentrations ranging between 5 and 50 μg/ml mimicking human serum levels, has a significant effect on reducing tumor cell proliferation of A549 cells, mainly by altering cell cycle progression. Importantly, we provide evidence that adiponectin clearly inhibits in a dose- and time-dependent manner CREB phosphorylation (activation) and, at least in part, also the level of CREB protein itself, preceding and accompanying the anti-proliferative effects in response to adiponectin. Moreover, in agreement with previous studies demonstrating that CREB over-expression occurs in many tumors, we also show by western-blotting from lung specimen that CREB is significantly up-regulated in NSCLC samples compared to adjacent normal tissues from six patients.

CONCLUSIONS

Overall, our results represent the first evidence of CREB inhibition by adiponectin and may provide new insight into therapeutic strategies for lung cancer.

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.