Kategorie: Maligní lymfomy a leukémie
Téma: Chronic lymphocytic leukemia and related disorders - Biology (Poster)
Číslo abstraktu: P846
Autoři: Prof. RNDr. Mgr. Marie Jarošová, CSc.; Mgr. Martina Hrubá; RNDr. Alexandra Oltová; Mgr. Helena Urbánková, Ph.D.; Mgr. Lenka Krůzová; Dr., Ing. Eva Kriegová; RNDr. Milena Holzerová, Ph.D.; MUDr. Vít Procházka, Ph.D.; MUDr. Renata Urbanová; doc. MUDr. Tomáš Papajík, CSc.; prof. MUDr. Michael Doubek, Ph.D.; MUDr. Věra Vozobulová; prof. MUDr. Karel Indrák, DrSc.
Background: Cytogenetic abnormalities such as del(13q), del(11q), trisomy 12, del(17p), 14q32 translocations or a complex karyotype and the mutational status of TP53, SF3B1, NOTCH1, and BIRC3 have improved present-day risk stratification in chronic lymphocytic leukemia (CLL). Recurrent cytogenetic abnormalities also include chromosome 6q deletion. It occurs at a relatively low frequency (3-6%) and its prognostic significance remains controversial; the same holds true for the extent of deletion and the candidate genes in the deleted region.
The objectives were to analyze a group of CLL patients with chromosome 6q deletion using arrayCGH, to determine the minimally deleted region (MDR) and the candidate genes located within the region, and to try to determine their relative gene expression, and evaluate some clinical characteristics.
Methods: The peripheral blood/bone marrow samples from a group of 1055 CLL patients in three hematology centers in the Czech Republic (Olomouc, Plzen and Brno) were analysed using conventional cytogenetics and FISH, and 6q deletion was found in 70 (6.6%) of the patients. ArrayCGH with chromosome 6 specific and oligonucleotide microarrays was performed in 52 patients (36 M/16 F; median age 61 years, Binet stage A (n=19), stage B (n=18), stage C (n=15), 25 pts at diagnosis, 27 pts in the course of the disease; 29 untreated and 23 treated; unmutated IGVH 41 pts). FOXO3, NF-kB, TBX21, IL-2 and BCL10 gene expression was assessed by quantititative RT-PCR in peripheral blood mononuclear cells obtained from CLL patients with/without 6q deletion (n=17/n=30) and in healthy controls (n=19); PGK1 as a normaliser.
Results: 6q deletion, as a single aberration, was observed in 9 (17%) patients and in 20 (38.4%) patients as part of complex karyotype. In one patient, chromothripsis of chromosome 6 was observed. arrayCGH confirmed high heterogeneity of the range of 6q deletion and MDR of 1.4 Mb was determined in the q21 region spanning eight genes (FOXO3, SOBP, SCML4, SEC63, OSTM1, NR2E1, LACE1, and ARMC2). Expression profiling of FOXO3, a regulator of cell cycle and/or apoptosis, revealed a lower number of FOXO3 transcripts in CLL patients with 6q deletion than in those without 6q deletion (p=0.03) and healthy subjects (p<0.0001). Of the genes (NF-kB, TBX21,IL-2 and BCL10) possibly influenced by FOXO3 levels, increased mRNA expression of NF-kB was detected in CLL patients with 6q deletion compared to patients without 6q deletion (p=0.03) and healthy controls (p<0.0001). Cytokine IL-2 expression was lower in patients with 6q deletion, but reached significance only between CLL patients with 6q deletion and controls (p=0.0003). The clinical evaluation of the deletion showed that 6q deletion was more prevalent in males; the patients had unmutated IGVH and were in more advanced clinical stages (Binet B and C).
Summary/Conclusion: In our CLL patients with 6q deletion, we determined MDR of 1.4Mb involving eight genes including FOXO3. Deletion of 6q was more frequently observed in males, patients with unmutated IGVH and in more advanced stages of the disease. The observed low mRNA expression of FOXO3 and high expression ofNF-kB in CLL patients with 6q deletion demands further investigation.
This work was supported by the grants: IGA MZ ČR NT 13576 and IGA-LF-2014-001.
Keywords: Array based comparative genomic hybridization, Chromosome 6, Chronic lymphocytic leukemia
Datum přednesení příspěvku: 16. 6. 2014