Background
Acute myeloid leukemia (AML) is a bone marrow malignancy having multiple molecular pathways driving its progress. In recent years, the main causes of AML considered all over the world are genetic variations in cancerous cells. The RUNX1 and FLT3 genes are necessary for the normal hematopoiesis and differentiation process of hematopoietic stem cells into mature blood cells, therefore they are the most common targets for point mutations resulting in AML.
Methods
We screened 32 CN-AML patients for FLT3-ITD (by Allele-specific PCR) and RUNX1 mutations (by Sanger sequencing). The FLT3 mRNA expression was assessed in all AML patients and its subgroups.
Results
Eight patients (25%) carried RUNX1 mutation (K83E) while three patients (9.37%) were found to have internal tandem duplications in FLT3 gene. The RUNX1 mutation data were correlated with clinical parameters and FLT3 gene expression profile. The RUNX1 mutations were observed to be significantly prevalent in older males. Moreover, RUNX1 and FLT3-mutated patients had lower complete remission rate, event-free survival rate, and lower overall survival rate than patients with wild-type RUNX1 and FLT3 gene. The RUNX1 and FLT3 mutant patients with up-regulated FLT3 gene expression showed even worse prognosis. Bradford Assay showed that protein concentration was down-regulated in RUNX1 and FLT3 mutants in comparison to RUNX1 and FLT3 wild-type groups.
Conclusion
This study constitutes the first report from Pakistan reporting significant molecular mutation analysis of RUNX1 and FLT3 genes including FLT3 expression evaluation with follow-up. This provides an insight that aforementioned mutations are markers of poor prognosis but the study with a large AML cohort will be useful to further investigate their role in disease biology of AML.
A number of studies have reported frequent incidence of c-kit gene mutations in association with core binding factor acute myeloid leukemia (CBF-AML). These genetic changes have become important prognostic predictors in patients with abnormal karyotype. Aim of this study was the detection of nucleotide alterations in newly diagnosed acute myeloid leukemia patients for three exons of c-kit gene, including cytogenetically normal patients. Thirty-one de novo AML patients were screened for any possible variations in exon 8, 11 and 17 sequences of c-kit proto-oncogene leading to amino acid substitutions or frame shift. Sanger sequencing method was employed followed by sequence analysis. Mutation data was then correlated with clinical and hematological parameters of patients and prognostic significance of genetic changes was assessed as well. The computational tools were then used to further understand the extent of damage caused by these mutations to c-kit protein. Fifteen (48.4%) mutant patients were observed with single, double or multiple mutations in one, two or all three exons studied. The analysis revealed eight new alterations which were not reported previously. Significant variation among mutant and non-mutant group of patients was observed with respect to FAB subtypes (x2 = 12.524, p = 0.029), Spleen size (x2 = 4.288, p = 0.038) and Red blood cell count (x2 = 8.447, p = 0.007). The survival analysis indicates poor overall and event free survival outcomes in mutant individuals. Furthermore, the in silico analysis suggests that changes in nucleotide sequences can possibly damage the protein structure and effect it’s function. This study emphasizes the need to consider screening of c-kit gene alterations not only in CBF-AML but in cytogenetically normal AML patients as well. In current investigation the effect of mutation Arg420Gly on structure and function of c-kit protein was investigated, as this was the most observed substitution in present cohort. Various bioinformatics tools and techniques were employed, which determined that Arg420Gly is possibly non-pathogenic mutation.
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