Molecular genetic studies on Chronic Lymphocytic Leukemia and Acute Myeloid Leukemia - with focus on prognostic markers

摘要

The present thesis is focused on the prognostic value of genetic variations and alterations in the initiation and development of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) patients. Several prognostic markers based on genetic or chromosomal aberrations are today used in clinic in these heterogeneous diseases. Novel biomarkers have been identified through next generation sequencing techniques and some of them may be useful as prognostic markers in clinical diagnostic. In papers I-IV we have investigated some of this markers in CLL and AML tumor cells. In papers I and III we investigated the prognostic value of the MDM2 SNP309 in relation to the presence of TP53 mutations in tumor cells from CLL and AML patients. The SNP309 G-allele was associated with a shorter overall survival in TP53 wildtype CLL and non-normal karyotype AML patients. Mutations in the TP53 gene were found in 6.2% in CLL and 21.7% in AML and were always associated with adverse overall survival. This was most significant observed among the AML patients, where the three year survival was zero. In paper II we investigated mutations in NOTCH1 and NOTCH2 as prognostic biomarkers in CLL. Notch1 and Notch2 play critical roles in lineage differentiation of white blood cells. We found mutation only in NOTCH1 in a frequency of 6.7% and our analysis revealed a shorter overall survival for these. NOTCH1 mutations were almost mutually exclusive with TP53 mutations and represented together 12.9% in CLL patients, and they may both be strong prognostic biomarkers in CLL. In paper IV we studied mutations in the tricarboxylic acid cycle. Metabolic disturbances in cancer cells have been known for many years, but recently mechanistic explanations have been identified. Hot spot mutations in IDH1/2 genes, result in neomorphic enzyme activities that results in global hypermethylation of the cancer cell genome. We found mutations in 21% of the AML patients. Among the CN-AML patients there is a lack of prognostic markers and in this subgroup we found patients with IDH2 mutations to have a shorter overall survival (3 vs. 21 months (p=0.009) for mutated and wild-type patients, respectively). Additionally, we also studied a SNP in the IDH1 gene, and both the IDH2 mutations and the SNP showed to have a potential as a new prognostic markers in CN-AML. In summary, the results in papers I-IV have a potential to function as novel prognostic biomarkers in the clinic for therapeutic considerations and may also be targets for novel drugs for CLL and AML patients.