Evaluation of NOV/CCN3,a Transcriptional Target of FOXO1 in Type2 Diabetes Mellitus

Abstract

SUMMARY T ype 2 DM is a chronic metabolic disease characterized by insulin resistance and beta cell dysfunction. It is an extremely heterogeneous disease in which the insulin resistance and beta cell dysfunction resulted from environmental and genetic factor. Studies showed that mediators of insulin-IGF1 signaling including FOXO1 had an important role in beta cell growth and function. This study was performed at Medical Biochemistry Department, Ain Shams Faculty of Medicine during the period from 2014–2016 and included 60 diabetic patients and 20 healthy controls. The aim of the present study was to evaluate the expression of FOXO1 and its target CCN3 in patients with type 2 diabetes mellitus in a trial to explore the molecular mechanism underlying β cell failure in T2DM and to correlate the relationship between the two gene expressions to each other, to the different cilinicopathological factors and to complications of T2DM. The expression of FOXO1 and CCN3 was measured by quantitative real time polymerase chain reaction (qPCR) in mononuclear cells obtained from blood samples.

Study groups were stratified into:  Group A: Healthy Controls.  Group B: patients with type 2 DM. o Group B1: patients with uncomplicated type 2 DM. o Group B2: patients with type 2 DM and microvascular complications. o Group B3: patients with type 2 DM and macrovascular complications. All participants went through complete medical assessment including family history of chronic non-communicable diseases, symptoms covering various systems and general examination including blood pressure measurements. Furthermore, anthropometric measurements were performed. Also, laboratory investigation including fasting glucose level, insulin level and HOMA1-IR was performed. RNA extraction was done from mononuclear cells followed by quantitative real-time PCR (qPCR) for measuring FOXO1 and CCN3 expression levels. The data were normalized using the endogenous GAPDH as reference control. Then the results were calculated and statistically analyzed by the SPSS software version 20. A highly significant correlation was found between the whole studied groups regarding fold change of FOXO1 and CCN3 expression indicating their synergistic effect (P<0.001).

There was no significant difference in FOXO1 and CCN3 expression between the groups with complicated type 2 DM and the group with uncomplicated type 2 DM.

Using 2.82 cutoff value, FOXO1 showed 78.3 % sensitivity, 95% specificity, 97.9% PPV, 59.3% NPV, 82.5% Accuracy. Positivity rates showed high significant difference between the groups, it was 82.5% among the groups with complicated type 2 DM, 70% among the uncomplicated type 2 DM group and 5% among the healthy controls (p ≤ 0.001). Using 3.71 cutoff value, CCN3 showed 73.3 % sensitivity, 90% specificity, 95.6% PPV, 52.9% NPV, 77.5% Accuracy. Positivity rates showed high significant difference between the groups, it was 77.5% among the groups with complicated type 2 DM, 65% among the uncomplicated type 2 DM group and 10% among the healthy controls (p ≤ 0.001). The combination between the two genes showed 93.3% sensitivity, 85% specificity, PPV of 94.9%, NPV of 80.9% and accuracy 91.2%.