The Genomic Copy Number Variation In Adult Acute Lymphoblastic Leukemia

Objective:To investigate the copy number variation (CNV) and loss of heterozygosity (LOH) inadult acute lymphoblastic leukemia(ALL).Methods:The copy number variation and loss of heterozygosity were detected with Affymetrix SNP6.0array. Java and software R were used to construct the Signal-Net based on KEGG, and to enrich the ALL related genes with significant CNV. The copy number variation of IKZF1gene was checked by FISH.Results:In Ph+B-ALL, the most frequent CNVs are gain at chrl3q, loss at chr6and recurrent LOH at chrl7p. In Ph+B-ALL, the most frequent CNVs are gain at chr7, loss at chr9p and recurrent LOH at chrl5q. In T-ALL, the most frequent CNVs are gain at chr20, loss at chrX and recurrent LOH at chr9p. These CNV regions included several candidate genes such asIKZF1, JAK2, CDKN2A/2B, ETV6etc. EGFR and IKBKG were in the center position of the Signal-Net, which may play anessential role in ALL. The copy number amplification of IKZF1gene is confirmed by FISH.Conclusion:SNP Array is a powerful tool to detect the CNV and LOH in ALL with high sensitivity and good repeatability. The identification of CNV and LOH in adult ALL assist to discover susceptibility genes, guide the classification of diagnosis and help the selection of treatment. Objective:This study was aimed to detect the expression of IKZF1gene isoforms in adult acute lymphoblastic leukemia (ALL) and investigate the clinical variants and prognosis of patients with IK6isoform, and to elucidate the inpacts on the JAK-STAT signaling pathway after overexoression IK6gene in ALL cell line Nalm-6cells.Methods:The expression of IKZF1gene isoforms were measured by nested RT-PCR in79newly diagnosed ALL patients. The clinical characteristics of IK6positive patients and overall survival (OS), disease-free survival (DFS) of the IK6positive group and IK6negative group were compared. Nalm-6cells were transfected with the expression plasmid pcDNA3.1-IK6by liposomes. PCR-Array and Western blot was used to analyze the effects of IK6on JAK-STAT pathway.Results:The results showed that IK1and IK2/3were the functional isoforms while the IK4,IK6,IK8and IK.9were the dominant negative isoforms in adult ALL. The dominant negative isoform IK6featured in34.4%B-ALL patients and22.2%T-ALL patients. Out of B-ALL patients, the BCR/ABL1positive rate and the percentage of high risk group patients in IK6positive group was higher than that in IK6negative group in B-ALL patients (P=0.027, P=0.048). The expression of IK6isoform did not correlate with gender, age and WBC counts in B-ALL and T-ALL patients. The overall survival and disease-free survival of IK6positive group were both lower than that of IK6negative group in Ph negative B-ALL patients (P=0.009, P=0.002). PCR-Array showed that after overexpression of IK6in Nalm-6cells, the expression level of11genes associated with JAK-STAT pathway was higher (IFNR, IL4, MCL1etc.) and the expression level of these2genes was lower (FAS and A2M). The overexpression of IK6induce the phosphorylation of STAT3and Erkl/2which may activate JAK-STAT pathway.Conclusion:IK6is a significant isoform of the expression of IKZF1gene in adult ALL patients, and can be used as a prognostic factor that could help to decide the treatment strategy of ALL patients. The activation of JAK-STAT pathway may perform an important mechanism in the poor prognosis of ALL patients.