ABSTRACT
SIRT1, a NAD dependent histone and protein deacetylase, is a member of the histone deacetylase class III family. We previously showed that SIRT1 mRNA expression is significantly lower in peripheral blood mononuclear cells (PBMCs) of multiple sclerosis (MS) patients during relapses than in stable patients. We have now investigated SIRT1 as a possible biomarker to predict relapse as well as responsiveness to glatiramer acetate (GA) treatment in relapsing-remitting MS (RRMS) patients. Over the course of 2years, a cohort of 15 GA-treated RRMS patients were clinically monitored using the Expanded Disability Status Scale and assessed for MS relapses. Blood samples collected from MS patients were analyzed for levels of SIRT1 and histone H3 lysine 9 (H3K9) acetylation and dimethylation. During relapses, MS patients had a lower expression of SIRT1 mRNA than did stable MS patients. In addition, there was a significant decrease in H3K9 dimethylation (H3K9me2) during relapses in MS patients when compared to stable patients (p=0.01). Responders to GA treatment had significantly higher SIRT1 mRNA (p=0.01) and H3K9me2 levels than did non-responders (p=0.018). Receiver operating characteristic analysis was used to assess the predictive power of SIRT1 and H3K9me2 as putative biomarkers: for SIRT1 mRNA, the predictive value for responsiveness to GA treatment was 70% (p=0.04) and for H3K9me2 was 71% (p=0.03). Our data suggest that SIRT1 and H3K9me2 could serve as potential biomarkers for evaluating patients' responsiveness to GA therapy in order to help guide treatment decisions in MS.
Subject(s)
Glatiramer Acetate/therapeutic use , Histones/metabolism , Multiple Sclerosis, Relapsing-Remitting/drug therapy , Multiple Sclerosis, Relapsing-Remitting/genetics , Sirtuin 1/metabolism , Acetylation , Adult , Biomarkers/metabolism , Female , Gene Expression Regulation , Humans , Male , Middle Aged , RNA, Messenger/genetics , RNA, Messenger/metabolism , Recurrence , Sirtuin 1/genetics , Young AdultABSTRACT
Currently there is critical need for the identification of reliable biomarkers to help guide clinical management of multiple sclerosis (MS) patients. We investigated the combined roles of Response Gene to Complement 32 (RGC-32), FasL, CDC2, AKT, and IL-21 as possible biomarkers of relapse and response to glatiramer acetate (GA) treatment in relapsing-remitting MS (RRMS) patients. Over the course of 2 years, a cohort of 15 GA-treated RRMS patients was clinically monitored and peripheral blood mononuclear cells (PBMCs) were collected at 0, 3, 6, and 12 months. Target gene mRNA expression was measured in patients' isolated PBMCs by real-time qRT-PCR. Compared to stable MS patients, those with acute relapses exhibited decreased expression of RGC-32 (p<0.0001) and FasL (p<0.0001), increased expression of IL-21 (p=0.04), but no change in CDC2 or AKT. Compared to non-responders, responders to GA treatment showed increased expression of RGC-32 (p<0.0001) and FasL (p<0.0001), and decreased expression of IL-21 (p=0.02). Receiver operating characteristic (ROC) analysis was used to assess the predictive accuracy of each putative biomarker. The probability of accurately detecting relapse was 90% for RGC-32, 88% for FasL, and 75% for IL-21. The probability of accurately detecting response to GA was 85% for RGC-32, 90% for FasL, and 85% for IL-21. Our data suggest that RGC-32, FasL, and IL-21 could serve as potential biomarkers for the detection of MS relapse and response to GA therapy.
Subject(s)
Cell Cycle Proteins/genetics , Glatiramer Acetate/therapeutic use , Leukocytes, Mononuclear/metabolism , Multiple Sclerosis/drug therapy , Multiple Sclerosis/genetics , Muscle Proteins/genetics , Nerve Tissue Proteins/genetics , Adult , Biomarkers/analysis , Biomarkers/metabolism , Cell Cycle Proteins/metabolism , Female , Humans , Interleukins/metabolism , Male , Middle Aged , Muscle Proteins/metabolism , Nerve Tissue Proteins/metabolism , RecurrenceABSTRACT
First described as a cell cycle activator, RGC-32 is both an activator and a substrate for CDC2. Deregulation of RGC-32 expression has been detected in a wide variety of human cancers. We have now shown that RGC-32 is expressed in precancerous states, and its expression is significantly higher in adenomas than in normal colon tissue. The expression of RGC-32 was higher in advanced stages of colon cancer than in precancerous states or the initial stages of colon cancer. In order to identify the genes that are regulated by RGC-32, we used gene array analysis to investigate the effect of RGC-32 knockdown on gene expression in the SW480 colon cancer cell line. Of the 230 genes that were differentially regulated after RGC-32 knockdown, a group of genes involved in chromatin assembly were the most significantly regulated in these cells: RGC-32 knockdown induced an increase in acetylation of histones H2B lysine 5 (H2BK5), H2BK15, H3K9, H3K18, and H4K8. RGC-32 silencing was also associated with decreased expression of SIRT1 and decreased trimethylation of histone H3K27 (H3K27me3). In addition, RGC-32 knockdown caused a significantly higher percentage of SW480 cells to enter S phase and subsequently G2/M. These data suggest that RGC-32 may contribute to the development of colon cancer by regulating chromatin assembly.
