Ns of both PAX9 (HR 3.14, 95 CI 1.589?.205, p <0.001) as well as CR…

Ns of both PAX9 (HR 3.14, 95 CI 1.589?.205, p < 0.001) as well as CRY1 (HR 3.53, 95 CI 1.789?.987, p < 0.001) were significantly associated with shorter TTFT (Fig. 5). However, high expression of only PAX9 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/21046519 gene (HR 3.29, 95 CI 1.172?.272, p = 0.016) was significantly associated with shorter OS (Fig. 6).Discussion Extremely variable clinical course of early stage CLL patients highlights the importance of well-described prognostic markers for clinical management of these patients. Various prognostic markers that are currently in use include IGHV mutational status [2], genomic abnormalities [3], expression of ZAP-70 [4], and CD38 [2]. Recent studies have associated specific DNA methylation signatures with specific prognostic subgroups in CLL [14?6, 19]. The present study has dealt with themethylation profiling of early stage CLL patients on the basis of their IGHV mutational status. The study has identified differential methylation of several genes such as NCOR2, SIX3, CHRM1, NRF1, CRY1, KCNJ2, and SOX5 that have been reported earlier to be differentially methylated in the IGHV-gene based subgroups [16, 28]. Besides, an association of promoter hypomethylation of MYLK with the IGHV unmutated cases was also observed in the current study. Since, higher expression of MYLK is known to be significantly correlated with poor clinical outcome [40], it is plausible that promoter hypomethylation of MYLK in the IGHV unmutated cases might be associated with poor prognosis. Furthermore, differential CpG promoter hypomethylation of two important hematopoietic transcription factors MEIS1 and TAL1 which are known methylation targets in B-cell ALL was also observed [41]. An analysis of signalling pathway network for genes with perturbed methylation profiles observed among IGHV unmutated patients indicated the involvement of calcium signalling pathway. Previous studies have suggested that altered Ca2+ signalling contributes to major tumor progression events including proliferation, migration, invasion, and metastasis [42, 43]. Recently, Muggen et al. [44] demonstrated an association of the IGHV mutational status with the level of basal Ca2+ signalling in CLL. The present study provides evidence that aberrant methylation of genes involved in the calcium signalling pathway might be one of the mechanisms responsible for net differences in the basal Ca2+ signalling events. In the present analysis, an inverse correlation between methylation and gene expression was observed for 209 genes in CLL including transcription factors (ID4, NFATC1, TBX2, TAL1, MEIS1), SPRY family members (SPRY1, SPRY2) and SOX family members (SOX4, SOX7). Correlation of promoter methylation of ID4 gene with shortened patient survival has been alreadyTable 3 Association of relative risk of treatment initiation, time to first treatment and overall survival with the mRNA expression of 17 genes selected for validation in early Vitamin D2 stage CLL patients (n = 93)RR of treatment initiation RR 1.91 0.01 19 <0.001 NR 1.04 NR 1.06 NR 0.86 NR 1.45 1.05 1.6 1.77 3.14 1.34 21 47 0.84 1.33 1.02 0.93 0.67-1.55 0.61-1.41 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/18218841 0.87-2.04 0.25 0.92 0.92 0.556-1.268 0.52 47 48 43 47 48 48 29 22 20 21 16 24 19 21 21 0.86 0.459-1.614 0.64 1.23 0.652-2.330 0.52 0.94 0.510-1.740 0.85 0.96 0.523-1.792 0.92 0.857-2.997 0.949-3.335 1.589-6.205 0.723-2.518 0.570-1.945 0.87 0.14 0.07 <0.001 0.34 0.775-2.712 0.25 NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR 0.465-1.596 0.63 NR 7 7 11 7 11 10 8 11 7 5 13 5 13 8 10.