Marketa Kalinova

Real-time quantitative PCR detection of WT1 gene expression in children with AML: prognostic significance, correlation with disease status and residual disease detection by flow cytometry

The clinical significance of WT1 gene expression at diagnosis and during therapy of AML has not yet been resolved. We analysed WT1 expression at presentation in an unselected group of 47 childhood AML patients using real-time quantitative reverse-transcription PCR. We also showed that within the first 30 h following aspiration RQ-RT-PCR results were not influenced by transportation time. We observed lower levels of WT1 transcript in AML M5 (P = 0.0015); no association was found between expression levels and sex, initial leukocyte count and karyotype-based prognostic groups. There was significant correlation between very low WT1 expression at presentation and excellent outcome (EFS P = 0.0014). Combined analysis of WT1 levels, three-colour flow cytometry residual disease detection and the course of the disease in 222 samples from 28 children with AML showed remarkable correlation. Fourteen patients expressed high WT1 levels at presentation. In eight of them, who suffered relapse or did not reach complete remission, dynamics of WT1 levels clearly correlated with the disease status and residual disease by flow cytometry. We conclude that very low WT1 levels at presentation represent a good prognostic factor and that RQ-RT-PCR-based analysis of WT1 expression is a promising and rapid approach for monitoring of MRD in approximately half of paediatric AML patients.

TEL/AML1 positivity in childhood ALL: average or better prognosis?

The presence of TEL/AML1 fusion gene in childhood acute lymphoblastic leukaemia (ALL) defines a subgroup of patients with better than average outcome. However, the prognostic significance of this aberration has recently been disputed by the Berlin–Frankfurt–Münster (BFM) study group due to its relatively high incidence found in relapsed patients (19.6% and 21.9%, in two cohorts). In contrast, only four out of 45 (8.9%) unselected relapsed patients (all of whom had been treated according to BFM protocols) in the Czech Republic carry this fusion. From March 1995 to June 1998, 41 out of 190 (21.6%) newly diagnosed children with ALL were TEL/AML1-positive. There is a statistically significant difference between the incidence of TEL/AML1 fusion at diagnosis and at relapse within our group (P = 0.035). Interim analysis of the minimal residual disease (MRD) detection shows heterogeneity within the group of newly diagnosed TEL/AML1-positive leukaemias – 10 out of 24 patients tested at the end of induction therapy had detectable levels of MRD. However, only one of these patients reached relapse-predictive level (10−3) of MRD. In conclusion, we corroborate low frequency of TEL/AML1 positivity among relapsed patients with ALL among Czech children who are treated by the BFM protocols. Moreover, we demonstrate different patterns of bone marrow clean-up in TEL/AML1-positive patients.

Upregulation of asparagine synthetase fails to avert cell cycle arrest induced by L-asparaginase in TEL/AML1-positive leukaemic cells

L-Asparaginase is a standard component in chemotherapy of childhood acute lymphoblastic leukaemia (ALL). Leukaemic cells carrying TEL/AML1 fusion gene are more sensitive to treatment with L-asparaginase compared to other subtypes of ALL. We demonstrate in vitro the prolonged growth suppression of TEL/AML1[+] cells compared to TEL/AML1[−] leukaemic cells after L-asparaginase treatment simulating treatment protocol. Cell cycle analysis revealed TEL/AML1[+] cells to accumulate in G1/G0 phase (81–98%) compared to TEL/AML1[−] cells (47–60%). Quantitative analysis of asparagine synthetase (AsnS) expression showed the ability of TEL/AML1[+] cells to increase AsnS mRNA levels after L-asparaginase treatment to the same extent as TEL/AML1[−] leukaemic and nonleukaemic lymphoid cells. We hypothesise that TEL/AML1[+] cells are unable to progress into the S phase of cell cycle under nutrition stress caused by L-asparaginase, despite the ability of AsnS upregulation. Significantly higher expression of AsnS was found in untreated leukaemic cells from children with TEL/AML1[+] ALL (n=20) in comparison with the group of age-matched children with ALL bearing no known fusion gene (n=25; P=0.0043). Interestingly, none of the TEL/AML1[+] patients with high AsnS level relapsed, whereas 10/15 patients with AsnS below median relapsed (P=0.00028). Therefore, high AsnS levels in TEL/AML1[+] patients correlate with better prognosis, possibly reflecting the stretched metabolic demand of the lymphoblast.

Slower molecular response to treatment predicts poor outcome in patients with TEL/AML1 positive acute lymphoblastic leukemia: Prospective real-time quantitative reverse transcriptase-polymerase chain reaction study

The translocation t(12;21)(p13;q22), which produces the TEL/AML1 fusion gene, is the most frequent chromosomal abnormality in patients with childhood acute lymphoblastic leukemia (ALL) and generally is associated with a favorable prognosis. Furthermore, real‐time quantitative‐polymerase chain reaction (RQ‐PCR)‐based detection of TEL/AML1 represents an accurate technique for the reproducible assessment of minimal residual disease (MRD).

ETV6/RUNX1 (TEL/AML1) is a frequent prenatal first hit in childhood leukemia

To the editor: We read with interest the report by Lausten-Thomsen et al in this issue of Blood .[1][1] The study challenges the previous report by Mori et al describing ∼ 1% frequency of TEL/AML1 ( ETV6/RUNX1 )–positive cord blood in healthy newborns and questions the hypothesis of TEL/AML1

A novel quantitative PCR of proliferation markers (Ki-67, topoisomerase IIα, and TPX2): an immunohistochemical correlation, testing, and optimizing for mantle cell lymphoma

A clinical course of patients with mantle cell lymphoma (MCL) is aggressive, and the disease is rarely curable. Proliferation rate is the most important prognostic factor. We developed a novel, reliable, rapid, and routinely applicable approach allowing a precise quantitative assessment of three proliferation markers, Ki-67, topoisomerase IIα, and TPX2. A total of 95 lymphoma specimens were measured in the study by real-time reverse transcription PCR (RQ-RT-PCR). We tested the reproducibility and accuracy of the assay and correlated the results with the immunohistochemical staining of the corresponding proteins. The results obtained indicated individual variability of the mRNA expression levels, reflecting heterogeneity of the proliferation rate in individual patients. In general, we observed the highest mRNA expression in the group of Burkitt lymphomas and the lowest in patients with reactive lymphadenopathies. We found increased proliferation rate in MCLs with high cyclin D1 mRNA, indicating a quantitative control of the cell cycle. We observed a correlation between mRNA expression level and the immunohistochemical staining of corresponding proteins, which significantly argues for the prognostic significance of the mRNA expression measuring. We confirmed the accuracy of the current assay for a precise quantitative examination of the proliferation activity. Real-time RT-PCR provides a novel approach applicable for clinical trials, and it represents a potent approach allowing to stratify MCL patients for entry into clinical trials according to the expression of the proliferation signature genes in their tumors. This approach may contribute to improved and individualized therapeutic options respecting the individual progression risk of patients with MCL.

Quantitative monitoring of cyclin D1 expression: A molecular marker for minimal residual disease monitoring and a predictor of the disease outcome in patients with mantle cell lymphoma

In mantle cell lymphoma (MCL), minimal residual disease (MRD) is an indicator of the disease outcome. Quantitative methods used so far do not provide a suitable molecular marker in 30–70% patients with MCL (depending on the technique used). We tested cyclin D1 as a marker for quantitative MRD monitoring. The real‐time PCR of cyclin D1 mRNA was performed in 144 bone marrow (BM) specimens including 95 BMs from MCL patients, 39 BMs from patients with other B‐cell non‐Hodgkins lymphomas and 10 BMs from healthy volunteer donors. In 73 BMs obtained from 20 MCL patients we examined the cyclin D1 level during the treatment and follow‐up period. We detected a cyclin D1 overexpression exclusively in BMs infiltrated with MCL, including minimal residual infiltration. Dynamics of cyclin D1 correlated with the patients clinical status in 69/73 BMs. Individual monitoring of patients during the disease course showed cyclin D1 quantitative changes accompanying either the disease relapse or a successful treatment response or the disease‐free survival (remission) and it showed a predictive significance. Cyclin D1 detection is a promising approach for the quantitative MRD monitoring in MCL patients, and the individual monitoring of the cyclin D1 dynamics represents a suitable indicator of the disease course.

Molecular and immunohistochemical analyses of BCL2, KI-67, and cyclin D1 expression in synovial sarcoma

Synovial sarcoma (SS) is a highly aggressive soft tissue sarcoma that causes death in more than half of the affected patients. An immunohistochemical and molecular study of the BCL2, MKI67, and CCND1 genes (expressing the BCL2, KI-67, and cyclin D1 proteins, respectively) was performed to determine the expression profiles in correlation with mRNA levels, and to assess the possible utility of these genes as a potential target for the treatment. Cyclin D1 staining was identified in 18 of 30 cases (60%), and CCND1 mRNA was overexpressed in 15 of 32 cases (47%). KI-67 nuclear immunoreactivity was found in 14 of 29 cases (48%), and MKI67 mRNA was overexpressed in 12 of 32 cases (37.5%). The high level of MKI67 mRNA was observed predominantly in monophasic SS. BCL2, a negative regulator of apoptosis, was expressed in all 32 cases. The intensity of the BCL2 protein expression correlated well with the mRNA level (P<0.0001). The high level of BCL2 mRNA correlated with a high level of CCND1 mRNA, but not with MKI67 mRNA level. Despite advances in therapy of sarcomas, the prognosis of patients with SS remains unfavorable, and a search for an improved therapy approach remains necessary. The strong immunopositivity of BCL2 in SS correlates well with a high level of BCL2 mRNA. Treatment with antisense BCL2 (G3139) may therefore represent an appropriate alternative therapy for patients with BCL2-positive synovial sarcomas.

Quantitative measurement of cyclin D1 mRNA, a potent diagnostic tool to separate mantle cell lymphoma from other B-cell lymphoproliferative disorders.

Cyclin D1 overexpression as a result of t(11;14) is a specific marker for diagnosis of mantle cell lymphoma (MCL) and plays an important role in MCL pathogenesis. To set a highly reliable cutoff value that discriminates MCL from other B-cell lymphoproliferative disorders, we performed a retrospective study of cyclin D1 expression. We established cyclin D1 expression level in 116 frozen and formalin-fixed, paraffin-embedded primary tumors from patients diagnosed with a variety of B-cell lymphoproliferative disorders. We used real time quantitative reverse-transcription polymerase chain reaction to quantify levels of cyclin D1 mRNA. The range of cyclin D1 expression in MCLs exceeded the range found in other lymphomas and reactive lymph nodes by a considerable margin. Cyclin D1 overexpression was found in 60/61 MCLs and in none of the other lymphomas, except for 12/19 mucosa-associated lymphoid tissue lymphomas from the lungs and stomach, which also revealed cyclin D1 overexpression. As epithelial tissues are known to express cyclin D1, an admixture of non-neoplastic epithelial cells present in the extranodal specimens probably influenced the quantitative reverse-transcription polymerase chain reaction result. Quantitative cyclin D1 monitoring provides a diagnostic test and an approach for studying MCL pathogenesis and may be of clinical importance.

Array-based analysis of gene expression in childhood acute lymphoblastic leukemia

Gene expression profiles of 10 children with acute lymphoblastic leukemia (ALL) were detected using cDNA arrays. Total RNAs were isolated from peripheral blood leukocytes of the patients at diagnosis. For detection of expression profiles we used Atlas Human Cancer cDNA Arrays (Clontech) with 588 genes. Although the study revealed variability of gene expression in many genes, we identified a number of genes with the same expression changes (up-regulation: PCNA, ERCC1; down-regulation: jun-B, BCL-2 related protein A1, CRAF-1, PBP) in most examined patients. Our objective was to identify genes that were differentially expressed in ALL and might contribute to development (and characterization) of the disease.