Analysis of the chemokine receptor CCR1 mutations in patients with chronic lymphocytic leukemia

Earlier, applying multiparameter flow cytometry analysis of peripheral blood (PB) CLL cells, we determined a correlation between the cell-surface expression of chemokine receptor CCR1 and negative prognostic marker CD38. The aim of this study was to identify mutations within the ccr1 gene in CLL patients with low, moderate, and high CD38 expression on leukemic cells. A ccr1 exon 2 genomic region, covering CDS, was amplified by PCR using PB mononuclear cell DNA of CLL patients. PCR products were cloned in the CloneJET plasmid vector. Ten clones for each sample were sequenced using Sanger method and analyzed in FinchTV software. Sequences were compared to the ccr1 Reference sequence (RefSeq: NM_001295.2) and analyzed in the NCBI dbSNP database. Thirty-one patient samples have been analyzed: 10 with low, 11 with moderate, and 10 with high CD38 expression. In 11 patients (35%), 10 single nucleotide variants (SNVs) within CCR1 CDS were detected: four were determined in patients with moderate CD38 expression (6-30% of CD38+ CLL cells), four – in patients with high CD38 expression (>30% of CD38+ CLL cells), and two - in CD38-negative patients. Notably, an identical frameshift variant was found in two patients from the CD38-moderate group. Three variants were identified in two to four patients. Variants that were not previously reported in the NCBI dbSNP database, were detected in 81% (25/31) of samples. Eight SNVs were detected in patients with the prognostic marker CD38 expressing leukemic cells, which suggests that the identified SNVs within the ccr1 exon 2 might correlate with the more aggressive type of the disease. Further analyses of the ccr1 exon 1 and 5’UTR, as well as an extended cohort of patients, are needed for unfailing conclusions. The study was conducted in the frame of the Latvian Council of Science research project No lzp-2018/1-0156.