Hematology and Hemotherapy Center
Contributions
Type: Publication Only
Background
ABCF2 was previously identified by our group as genes differentially expressed in CML patients which are resistant to imatinib, in samples collected before and after dasatinib treatment (responsive and resistant) in a microarrays analysis study (SILVEIRA, RA et al. Hematology;19(1):31-41,2014). ABCF2 gene is a member of the ATP binding cassette (ABC) transporter family and although its function is not clear, studies with colorectal and breast cancer showed an association of low expression of ABCF2 and poor prognosis and non-response to palliative chemotherapy. The role of ABCF2 in CML pathogenesis is unknown.
Aims
The aim of this study was to analyse the expression profile of ABCF2 in CML patients without previous treatment, in CML patients treated with dasatinib (after imatinib failure) and in healthy donors.
Methods
Total RNA extraction of mononuclear cells from peripheral blood, transcription to cDNA, and qPCR were performed to analyze differential gene expression. ACTB and GAPDH were used as endogenous control. geNorm program was used to estimate the gene expression in arbitrary units (A.U.). Results were expressed as median and compared using non-parametric tests (Mann Whitney or Kruskal-Wallis). We evaluated 13 healthy donors (control group) and 39 CML patients treated with dasatinib in second line after imatinib failure: 25 responsive to dasatinib, all with complete cytogenetic response (CCyR), 15 of them with major molecular response (MMR) and 14 patients resistant to dasatinib. We also analyzed 9 samples collected at CML diagnosis from the group that was responsive to dasatinib. Only one patient of this group had no sample available after dasatinib treatment.
Results
ABCF2 expression was down-regulated in the newly diagnosed CML samples and in patients treated with dasatinib compared to control group (0.15 [0.05 – 0.91] versus (vs.) 0.35 [0.04 – 3.07] versus (vs.) 2.5 [0.61 – 4.84] P< 0.0001). There was no difference of expression between patients at diagnosis and patients treated with dasatinib (all patients) (P=0.09). However, ABCF2 expression was significantly lower in CML dasatinib-resistant patients when compared to dasatinib-responsive patients with MMR (0.35 [0.05 – 2.21] versus (vs.) 1.19 [0.14 – 3.07] P= 0.02). The expression of ABCF2 was down-regulated in 8 CML patients at diagnosis and its expression increased after treatment with dasatinib in patients that achieved MMR (0.22 [0.06 – 0.91] versus (vs.) 1.20 (0.14 – 2.73] P=0.049).
Summary
ABCF2 is down-regulated in newly diagnosed CML when compared to the healthy donors and to dasatinib treated patients. On the other hand, up-regulation of ABCF2 was observed after treatment in patients which achieved MMR with dasatinib. ABCF2 might be involved in mechanisms associated with the development of CML or resistance. Further studies are necessary to clarify the role of ABCF2 in CML.
Keyword(s): ABC transporter, Chronic myeloid leukemia, Gene expression, Resistance
Session topic: Publication Only
Type: Publication Only
Background
ABCF2 was previously identified by our group as genes differentially expressed in CML patients which are resistant to imatinib, in samples collected before and after dasatinib treatment (responsive and resistant) in a microarrays analysis study (SILVEIRA, RA et al. Hematology;19(1):31-41,2014). ABCF2 gene is a member of the ATP binding cassette (ABC) transporter family and although its function is not clear, studies with colorectal and breast cancer showed an association of low expression of ABCF2 and poor prognosis and non-response to palliative chemotherapy. The role of ABCF2 in CML pathogenesis is unknown.
Aims
The aim of this study was to analyse the expression profile of ABCF2 in CML patients without previous treatment, in CML patients treated with dasatinib (after imatinib failure) and in healthy donors.
Methods
Total RNA extraction of mononuclear cells from peripheral blood, transcription to cDNA, and qPCR were performed to analyze differential gene expression. ACTB and GAPDH were used as endogenous control. geNorm program was used to estimate the gene expression in arbitrary units (A.U.). Results were expressed as median and compared using non-parametric tests (Mann Whitney or Kruskal-Wallis). We evaluated 13 healthy donors (control group) and 39 CML patients treated with dasatinib in second line after imatinib failure: 25 responsive to dasatinib, all with complete cytogenetic response (CCyR), 15 of them with major molecular response (MMR) and 14 patients resistant to dasatinib. We also analyzed 9 samples collected at CML diagnosis from the group that was responsive to dasatinib. Only one patient of this group had no sample available after dasatinib treatment.
Results
ABCF2 expression was down-regulated in the newly diagnosed CML samples and in patients treated with dasatinib compared to control group (0.15 [0.05 – 0.91] versus (vs.) 0.35 [0.04 – 3.07] versus (vs.) 2.5 [0.61 – 4.84] P< 0.0001). There was no difference of expression between patients at diagnosis and patients treated with dasatinib (all patients) (P=0.09). However, ABCF2 expression was significantly lower in CML dasatinib-resistant patients when compared to dasatinib-responsive patients with MMR (0.35 [0.05 – 2.21] versus (vs.) 1.19 [0.14 – 3.07] P= 0.02). The expression of ABCF2 was down-regulated in 8 CML patients at diagnosis and its expression increased after treatment with dasatinib in patients that achieved MMR (0.22 [0.06 – 0.91] versus (vs.) 1.20 (0.14 – 2.73] P=0.049).
Summary
ABCF2 is down-regulated in newly diagnosed CML when compared to the healthy donors and to dasatinib treated patients. On the other hand, up-regulation of ABCF2 was observed after treatment in patients which achieved MMR with dasatinib. ABCF2 might be involved in mechanisms associated with the development of CML or resistance. Further studies are necessary to clarify the role of ABCF2 in CML.
Keyword(s): ABC transporter, Chronic myeloid leukemia, Gene expression, Resistance
Session topic: Publication Only