Visfatin, Obesity, and Cancer

A Physiological Approach to Inflammatory Markers in Obesity

Obesity is one of the most critical health problems all over the world; it is associated with metabolic dysfunction and overnutrition. Changes in the physiological function of adipose tissue, leading to altered secretion of adipocytokines, inflammatory mediators release, and chronic low-grade inflammation, are seen in obesity. Macrophages, neutrophils, CD4+ and CD8+ T cells, B cells, natural killer T (NKT) cells, eosinophils, mast cells, and adipocytes are involved in the inflammatory response that occurs during obesity. Various inflammatory markers are released from these cells. In this chapter, we will mention inflammatory mechanisms and markers of obesity.

Inhibition of PI3K/Akt and ERK signaling decreases visfatin-induced invasion in liver cancer cells

OBJECTIVES

Visfatin is found in adipose tissue and is referred to as nicotinamide phosphoribosyltransferase (Nampt). Visfatin has anti-apoptotic, proliferative, and metastatic properties and may mediate its effects via ERK and PI3K/Akt signaling. Studies have yet to determine whether inhibition of kinase signaling will suppress visfatin-induced liver cancer. The purpose of this study was to determine which signaling pathways visfatin may promote liver cancer progression.

METHODS

HepG2 and SNU-449 liver cancer cells were exposed to visfatin with or without ERK or PI3K/Akt inhibitor, or both inhibitors combined. These processes that were assessed: proliferation, reactive oxygen species (ROS), lipogenesis, invasion, and matrix metalloproteinase (MMP).

RESULTS

Inhibition of PI3K/Akt and combination of inhibitors suppressed visfatin-induced viability. ERK inhibition in HepG2 cells decreased visfatin-induced proliferation. ERK inhibitor alone or in combination with PI3K inhibitors effectively suppressed MMP-9 secretion and invasion in liver cancer cells. PI3K and ERK inhibition and PI3K inhibition alone blocked visfatin's ROS production in SNU-449 cells. These results corresponded with a decrease in phosphorylated Akt and ERK, β-catenin, and fatty acid synthase.

CONCLUSIONS

Akt and ERK inhibition differentially regulated physiological changes in liver cancer cells. Inhibition of Akt and ERK signaling pathways suppressed visfatin-induced invasion, viability, MMP-9 activation, and ROS production.

Melanoma Progression under Obesity: Focus on Adipokines

Simple Summary

Obesity is a rapidly growing public health problem and the reason for numerous diseases in the human body, including cancer. This article reviews the current knowledge of the effect of molecules secreted by adipose tissue-adipokines on melanoma progression. We also discuss the role of these factors as markers of incidence, metastasis, and melanoma patient survival. Understanding the functions of adipokines will lead to knowledge of whether and how obesity promotes melanoma growth.

Abstract

Obesity is a growing problem in the world and is one of the risk factors of various cancers. Among these cancers is melanoma, which accounts for the majority of skin tumor deaths. Current studies are looking for a correlation between obesity and melanoma. They suspect that a potential cause of its development is connected to the biology of adipokines, active molecules secreted by adipose tissue. Under physiological conditions, adipokines control many processes, including lipid and glucose homeostasis, insulin sensitivity, angiogenesis, and inflammations. However, when there is an increased amount of fat in the body, their secretion is dysregulated. This article reviews the current knowledge of the effect of adipokines on melanoma growth. This work focuses on the molecular pathways by which adipose tissue secreted molecules modify the angiogenesis, migration, invasion, proliferation, and death of melanoma cells. We also discuss the role of these factors as markers of incidence, metastasis, and melanoma patient survival. Understanding the functions of adipokines will lead to knowledge of whether and how obesity promotes melanoma growth. Further studies may contribute to the innovations of therapies and the use of adipokines as predictive and/or prognostic biomarkers.

Visfatin and Rheumatoid Arthritis: Pathogenetic Implications and Clinical Utility

Objective:

Analysis and generalization of data related to visfatin involvement in the pathogenesis of inflammation at various stages of rheumatoid arthritis.

Data Synthesis:

Visfatin is an adipocytokine which has also been identified in non-adipose tissues. It influences directly on the maturation of B cells, which are involved in autoantibody production and T cell activation. Visfatin can promote inflammation via regulation of pro-inflammatory cytokines including TNF, IL-1β and IL-6. The concentration of circulating visfatin in rheumatoid arthritis patients is higher compared to healthy individuals. Several studies suggest that visfatin level is associated with rheumatoid arthritis activity, and its elevation may precede clinical signs of the relapse. In murine collagen-induced arthritis, visfatin levels were also found to be elevated both in inflamed synovial cells and in joint vasculature. Visfatin blockers have been shown to confer fast and long-term attenuation of pathological processes; however, most of their effects are transient. Other factors responsible for hyperactivation of the immune system can participate in this process at a later stage. Treatment of rheumatoid arthritis with a combination of these blockers and inhibitors of other mediators of inflammation can potentially improve treatment outcomes compared to current therapeutic strategies. Recent advances in the treatment of experimental arthritis in mice as well as the application of emerging treatment strategies obtained from oncology for rheumatoid arthritis management could be a source of novel adipokine-mediated anti-rheumatic drugs.

Conclusion:

The ongoing surge of interest in anticytokine therapy makes further study of visfatin highly relevant as it may serve as a base for innovational RA treatment.

Clinical significance of circulating omentin levels in various malignant tumors: Evidence from a systematic review and meta-analysis

Aberrant circulating level of omentin has been reported in various solid tumors. However, whether decreased or increased levels of omentin contribute in cancer risk is remained controversial in different epidemiological studies. This comprehensive meta-analysis of observational studies was conducted to investigate the association between circulating omentin level and human cancer risk. An electronic search of health-related databases, was performed to identify all eligible studies in English, up to July 2019. Combined standard mean difference (SMD) with 95%CI was computed to assess the correlation of omentin levels with human cancer risk in a random effect model. The risk of publication bias was also evaluated using Funnel plot and Egger regression tests. A total of 16 studies with 1106 cases and 3078 healthy controls were included. Pooled SMD analysis based on the cancer type, revealed a strong correlation of omentin level and cancer risk in patients with colorectal (SMD = 2.08, 95%CI: 1.67-2.50, P < 0.001), prostate (SMD = 1.38, 95%CI: 1.15-1.62, P < 0.001), and breast (SMD = -0.78, 95%CI: -1.1, -0.45, P < 0.001) cancers. Elevated circulating omentin levels was also found in cancer patients with BMI ≥ 25 (SMD = 1.33, 95%CI: 0.52-2.15, P = 0.001) indicating a potential role for omentin in development of some obesity-linked cancers. The findings of this meta-analysis indicated a significant association of omentin level with greater risk of colorectal, pancreas, and breast tumors. Circulating omentin level may represent a potential novel biomarker for early detection of colorectal, prostate, and breast cancers especially in overweight/obese subjects. Further prospective well-designed studies are warranted to confirm our findings.

Circulating visfatin levels and cancers risk: A systematic review and meta-analysis

Visfatin levels have been reported to be abnormal in many types of cancers. However, epidemiological studies yielded inconsistent results. Therefore, a meta-analysis was performed to assess the association between circulating visfatin levels and cancer risk. A systematic search was conducted for relevant studies in health-related electronic databases up to March 2018. Data related to standard mean difference (SMD) and overall odds ratio (ORS) were collected and analyzed. Summary SMD and pooled OR with 95% CIs were calculated using a random-effect model. Funnel plot and Egger's linear regression test were conducted to examine the risk of publication bias. A total of 27 studies with 2,693 cases and 3,040 healthy controls were included in meta-analysis for pooling SMD analysis. The results of the meta-analysis showed a significant higher visfatin levels in patients with various cancers than in controls, with a pooled SMD of 0.88, 95% CI = 0.56-1.20, p = 0.000. In subgroup, metaregression, Galbraith plot, and sensitivity analysis showed no substantial difference among all the analyzed factors. Data from 14 studies were also used for pooling ORs analysis. Metaresults revealed that high visfatin levels were associated with cancer risk (OR = 1.24, 95% CI: 1.14-1.34, p = 0.000). No evidence of publication bias was observed for pooling ORs and SMD analysis. This meta-analysis indicated a significant association between high circulating visfatin levels and increased risk of various cancers. Visfatin may represent a potential biomarker for early detection of cancers who may benefit from preventive treatment.Note.

The role of extracellular and intracellular Nicotinamide phosphoribosyl-transferase in cancer: Diagnostic and therapeutic perspectives and challenges

Nicotinamide phosphoribosyl-transferase (Nampt) or pre-B cell colony-enhancing factor or visfatin represents a pleiotropic molecule acting as an enzyme, a cytokine and a growth factor. Intracellular Nampt plays an important role in cellular bioenergetics and metabolism, particularly NAD biosynthesis. NAD biosynthesis is critical in DNA repair, oncogenic signal transduction, transcription, genomic integrity and apoptosis. Although its insulin-mimetic function remains a controversial issue, extracellular Nampt presents proliferative, anti-apoptotic, pro-inflammatory, pro-angiogenic and metastatic properties. Nampt is upregulated in many malignancies, including obesity-associated cancers, and is associated with worse prognosis. Serum Nampt may be a potential diagnostic and prognostic biomarker in cancer. Pharmacologic agents that neutralize Nampt or medications that decrease Nampt levels or downregulate signaling pathways downstream of Nampt may prove to be useful anti-cancer treatments. In particular, Nampt inhibitors as monotherapy or in combination therapy have displayed anti-cancer activity in vivo and in vitro. The aim of this review is to explore the role of Nampt in cancer pathophysiology as well as to synopsize the mechanisms underlying the association between extracellular and intracellular Nampt, and malignancy. Exploring the interplay of cellular bioenergetics, inflammation and adiposopathy is expected to be of importance in the development of preventive and therapeutic strategies against cancer.