Dataset Information

Advantages of digital PCR in the detection of low abundance BCR-ABL1 gene in patients with chronic myeloid leukemia.

ABSTRACT: Quantitative monitoring of BCR-ABL1 IS gene using reverse transcription quantitative-PCR (RT-qPCR) is an important method for evaluating the treatment effects in patients with chronic myeloid leukemia (CML). Digital-PCR (dPCR) can be applied to detect the BCR-ABL1 gene with high sensitivity. In the present study, the results of the Clarity™ dPCR system were compared with those of the RT-qPCR in order to determine whether dPCR can be applied in the clinical setting. A total of 83 patients were included in the present study, and they were divided into two groups according to the results of BCR-ABL1 IS during ongoing monitoring. A total of 43 patients with undetectable BCR-ABL1 IS where enrolled in group A. BCR-ABL1 testing was performed using the dPCR system on the same peripheral blood samples of patients from group A, and the association between dPCR results and relapse was analyzed. The RT-qPCR platform and dPCR system were used simultaneously to detect the BCR-ABL1 gene of another 40 patients who achieved either partial cytogenetic response (PCyR) or further response. Among patients with undetectable BCR-ABL1 IS, patients with dPCR-positive disease (BCR-ABL1 >0.1%) were more likely to undergo molecular relapse (P=0.018). The results of dPCR detection of BCR-ABL1% were consistent with the RT-qPCR results (R2=0.9510) in patients who achieved PCyR or further response. For samples with BCR-ABL1 IS <1.0%, the consistency of the dPCR and RT-qPCR results was better than that of BCR-ABL1 IS >1.0% (R2=0.9488 vs. R2=0.9264 for BCR-ABL1 IS). The detection results of the BCR-ABL1 gene in patients with CML using dPCR matched well with those from the RT-qPCR. To conclude, the results of the dPCR system can be applied as a supplement to the RT-qPCR platform, particularly for those with BCR-ABL1 IS <1.0%.

SUBMITTER: Yan Z

PROVIDER: S-EPMC6781637 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Advantages of digital PCR in the detection of low abundance BCR-ABL1 gene in patients with chronic myeloid leukemia.

Yan Zhiling Z Sun Qian Q Zhang Huanxin H Han Yahui Y Qiao Jianlin J Niu Mingshan M Zhu Shengyun S Zhao Kai K Wu Qingyun Q Cheng Hai H Cao Jiang J Zeng Lingyu L Li Zhenyu Z Xu Kailin K

Oncology letters 20190912 5

Quantitative monitoring of BCR-ABL1 IS gene using reverse transcription quantitative-PCR (RT-qPCR) is an important method for evaluating the treatment effects in patients with chronic myeloid leukemia (CML). Digital-PCR (dPCR) can be applied to detect the BCR-ABL1 gene with high sensitivity. In the present study, the results of the Clarity™ dPCR system were compared with those of the RT-qPCR in order to determine whether dPCR can be applied in the clinical setting. A tot ...[more]

PMID: 31612025

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Project description:Although the use of ATP-competitive tyrosine kinase inhibitors of oncoprotein BCR-ABL1 has enabled durable responses in patients with chronic myeloid leukemia (CML), issues of drug resistance and residual leukemic stem cells remain. To test whether the degradation of BCR-ABL1 kinase could offer improved response, we developed a series of proteolysis-targeting chimera (PROTAC) that allosterically target BCR-ABL1 protein and recruit the E3 ligase Von Hippel-Lindau, resulting in ubiquitination and subsequent degradation of the oncogenic fusion protein. In both human CML K562 cells and murine Ba/F3 cells expressing BCR-ABL1, lead compound GMB-475 induced rapid proteasomal degradation and inhibition of downstream biomarkers, such as STAT5, and showed increased sensitivity compared with diastereomeric controls lacking degradation activity. Notably, GMB-475 inhibited the proliferation of certain clinically relevant BCR-ABL1 kinase domain point mutants and further sensitized Ba/F3 BCR-ABL1 cells to inhibition by imatinib, while demonstrating no toxicity toward Ba/F3 parental cells. Reverse phase protein array analysis suggested additional differences in levels of phosphorylated SHP2, GAB2, and SHC associated with BCR-ABL1 degradation. Importantly, GMB-475 reduced viability and increased apoptosis in primary CML CD34+ cells, with no effect on healthy CD34+ cells at identical concentrations. GMB-475 degraded BCR-ABL1 and reduced cell viability in primary CML stem cells. Together, these findings suggest that combined BCR-ABL1 kinase inhibition and protein degradation may represent a strategy to address BCR-ABL1-dependent drug resistance, and warrant further investigation into the eradication of persistent leukemic stem cells, which rely on neither the presence nor the activity of the BCR-ABL1 protein for survival. SIGNIFICANCE: Small-molecule-induced degradation of BCR-ABL1 in CML provides an advantage over inhibition and provides insights into CML stem cell biology. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/18/4744/F1.large.jpg.

Project description:Beta Catenin signaling is critical for the self-renewal of leukemic stem cells in chronic myeloid leukemia. It is driven by multiple events, enhancing beta catenin stability and promoting its transcriptional co-activating function. We investigated the impact of BCR-ABL1 on Chibby1, a beta catenin antagonist involved in cell differentiation and transformation. Relative proximity of the Chibby1 encoding gene (C22orf2) on chromosome 22q12 to the BCR breakpoint (22q11) lets assume its involvement in beta catenin activation in chronic myeloid leukemia as a consequence of deletions of distal BCR sequences encompassing one C22orf2 allele. Forty patients with chronic myeloid leukemia in chronic phase were analyzed for C22orf2 relocation and Chibby1 expression. Fluorescent in situ hybridization analyses established that the entire C22orf2 follows BCR regardless of chromosomes involved in the translocation. In differentiated hematopoietic progenitors (bone marrow mononuclear cell fractions) of 30/40 patients, the expression of Chibby1 protein was reduced below 50% of the reference value (peripheral blood mononuclear cell fractions of healthy persons). In such cell context, Chibby1 protein reduction is not dependent on C22orf2 transcriptional downmodulation; however, it is strictly dependent upon BCR-ABL1 expression because it was not observed at the moment of major molecular response under tyrosine kinase inhibitor therapy. Moreover, it was not correlated with the disease prognosis or response to therapy. Most importantly, a remarkable Chibby1 reduction was apparent in a putative BCR-ABL1+ leukemic stem cell compartment identified by a CD34+ phenotype compared to more differentiated hematopoietic progenitors. In CD34+ cells, Chibby1 reduction arises from transcriptional events and is driven by C22orf2 promoter hypermethylation. These results advance low Chibby1 expression associated with BCR-ABL1 as a component of beta catenin signaling in leukemic stem cells.

Dataset Information

Advantages of digital PCR in the detection of low abundance BCR-ABL1 gene in patients with chronic myeloid leukemia.

Publications

Advantages of digital PCR in the detection of low abundance <i>BCR-ABL1</i> gene in patients with chronic myeloid leukemia.

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