Obesity and Breast Cancer: Association of Serum Adiponectin, Leptin, and Adiponectin–Leptin Ratio as Risk Biomarkers

Association of serum adiponectin levels and ADIPOQ SNP rs2241766 with breast cancer risk in Indian women

Context

Adiponectin, an adipokine, and its gene polymorphisms have been associated with breast cancer risk in various populations.

Subjects and Methods

In this study, we evaluated the association of the circulating levels of adiponectin and adiponectin gene polymorphism SNP rs2241766 with breast cancer and its clinicopathological characteristics in Indian women. A case-control study was carried out with 60 Ductal Infiltrating Breast Carcinoma patients and 60 age-matched healthy controls. Serum adiponectin levels were measured by ELISA. SNP genotyping was done by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism.

Statistical Analysis

Serum adiponectin levels were compared using the Mann Whitney U test. The frequency of genotypes was compared using the Chi-square test. The odds ratio was calculated using logistic regression.

Results

Lower serum adiponectin level was associated with increased risk of breast cancer in postmenopausal women (OR - 7.69; 95% CI - 2.16-27.43, P = 0.002) but not in the reproductive age group women. There was no association between adiponectin levels with the TNM stage of the tumor, histopathological grade, erbB2, and ER/PR status. The SNP rs2241766 polymorphism was not associated with breast cancer risk but the mutant genotypes TG/GG was found to be significantly associated with the lower histopathological grade of the tumor (X2 (2, N = 60) = 8.62, P = 0.01).

Conclusion

Our results suggest that low serum adiponectin levels are associated with an increased risk of breast cancer in postmenopausal women. The TG/GG genotypes of SNP rs2241766 polymorphism were associated with a lower histological grade of the tumor.

Globular Adiponectin Inhibits Breast Cancer Cell Growth through Modulation of Inflammasome Activation: Critical Role of Sestrin2 and AMPK Signaling

Adiponectin, an adipokine predominantly derived from adipose tissue, exhibits potent antitumor properties in breast cancer cells. However, its mechanisms of action remain elusive. Inflammasomes—intracellular multimeric protein complexes—modulate cancer cell growth in a complicated manner, as well as playing a role in the innate immune system. Herein, we examined the potential role of inflammasomes in the antitumor activity of adiponectin and found that globular adiponectin (gAcrp) significantly suppressed inflammasomes activation in breast cancer cells both in vitro and in vivo conditions, as determined by decreased expression of inflammasomes components, including NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and the apoptosis-associated speck-like protein containing a CARD (ASC), and inhibition of interleukin-1β and caspase-1 activation. Treatment with pharmacological inhibitors of inflammasomes caused decrease in cell viability, apoptosis induction, and G0/G1 cell cycle arrest, suggesting that inflammasomes activation is implicated in the growth of breast cancer cells. In addition, treatment with gAcrp generated essentially similar results to those of inflammasomes inhibitors, further indicating that suppression of breast cancer cell growth by gAcrp is mediated via modulation of inflammasomes. Mechanistically, gAcrp suppressed inflammasomes activation through sestrin2 (SESN2) induction, liver kinase B1 (LKB-1)-dependent AMP-activated protein kinase (AMPK) phosphorylation, and alleviation of endoplasmic reticulum (ER) stress. Taken together, these results demonstrate that gAcrp inhibits growth of breast cancer cells by suppressing inflammasomes activation, at least in part, via SESN2 induction and AMPK activation-dependent mechanisms.