Quantification of Bcr-Abl transcripts in chronic myelogenous leukemia (CML) using standardized, internally controlled, competitive differential PCR (CD-PCR)

Ephrin-A1 mRNA is associated with poor prognosis of colorectal cancer

We previously studied hypoxic tumor cells from hepatic metastases of colorectal cancer (CRC) and determined several potential prognostic factors, including expression of ephrin-A1 (EFNA1), which was highly induced by hypoxia. Here, we further evaluated the prognostic impact of EFNA1 expression. Samples from a total of 366 CRC patients from 11 institutes were analyzed by either microarray (n=220) or quantitative reverse-transcriptase polymerase chain reaction (n=146). EFNA1 was an independent prognostic factor for CRC (p<0.05). In vitro assays revealed that loss of EFNA1 following siRNA treatment was associated with reduced proliferative activity and decreased invasion and migration of CRC cell lines. EFNA1 expression is a useful marker for predicting high risk of relapse and cancer-related death in patients who have undergone curative resection for CRC.

Upregulation of nuclear PA28γ expression in cirrhosis and hepatocellular carcinoma

We previously reported that proteasome activator 28γ (PA28γ) is an oncogenic protein in hepatitis C virus (HCV) core protein transgenic mice. The aim of this study was to determine the role of PA28γ expression at the protein level in the development and progression of human hepatocarcinogenesis and hepatocellular carcinoma (HCC). Samples from tissues representing a wide spectrum of liver disease were analyzed, including histologically normal livers (n=5), HCV-related chronic hepatitis (CH) (n=15) and cirrhosis (n=31). The level of nuclear PA28γ increased with the progression of liver disease from CH to cirrhosis. The majority of cirrhotic livers (68%; 21/31) displayed high nuclear PA28γ expression. However, in half of the HCCs (50%; 18/36), little or no nuclear PA28γ expression was observed, while the remaining 50% (18/36) of the cases displayed high levels of nuclear PA28γ expression. A clinicopathological survey demonstrated a significant correlation between nuclear PA28γ expression and capsular invasion in HCC (P=0.026); a striking difference was found between nuclear PA28γ expression in non-tumor tissues and shorter disease-free survival (P<0.01). Moreover, nuclear PA28γ expression in non-tumor tissues correlated with the expression of molecules related to the genesis of hepatic steatosis and HCC, such as sterol regulatory element binding protein-1c mRNA. The findings suggest the involvement of nuclear PA28γ expression in the progression and relapse of HCC, and suggest that nuclear PA28γ is a potentially suitable target for the prevention and/or treatment of HCC.

Prophylactic transfer of BCR-ABL–, PR1-, and WT1-reactive donor T cells after T cell–depleted allogeneic hematopoietic cell transplantation in patients with chronic myeloid leukemia

Donor lymphocyte infusions have been effective in patients with chronic myeloid leukemia (CML) relapsing after allogeneic stem cell transplantation, but their use is associated with the risk of graft-versus-host disease. We investigated the effects of prophylactic infusion of in vitro-generated donor T cells reactive against peptides derived from CML-associated antigens. Fourteen CML patients received conditioning therapy followed by CD34+-selected peripheral blood stem cells from matched siblings (n = 7) or unrelated (n = 7) donors. Donor-derived mature dendritic cells generated in vitro from CD14+ monocytes were loaded with human leukocyte Ag-restricted peptides derived from PR1, WT1, and/or B-cell receptor–ABL and used to repetitively stimulate donor CD8+ T cells in the presence of IL-2 and IL-7. Stimulated T cells were infused 28, 56, and 112 days after transplantation. Thirteen patients are alive and 7 remain in molecular remission (median follow-up, 45 months). Interestingly, all 4 patients receiving CD8+ T cells displaying marked cytotoxic activity in vitro and detectable peptide-reactive CD8+ T cells during follow-up have not experienced graft-versus-host disease or relapse. Our study reveals that prophylactic infusion of allogeneic CD8+ T cells reactive against peptides derived from CML-associated antigens is a safe and promising therapeutic strategy. This trial was registered at www.clinicaltrials.gov as #NCT00460629.

Jumonji domain containing 1A is a novel prognostic marker for colorectal cancer: in vivo identification from hypoxic tumor cells

PURPOSE

This study aimed to identify novel hypoxia-inducible and prognostic markers in vivo from hypoxic tumor cells.

EXPERIMENTAL DESIGN

Using carbonic anhydrase 9 and CD34 as a guide for hypoxic tumor cells, laser capture microdissection was used to isolate colorectal cancer (CRC) liver metastases. The samples were analyzed by microarray analysis, in parallel with five CRC cell lines cultured under hypoxic conditions. To evaluate the prognostic impact of the expression of certain genes, samples from a total of 356 CRC patients were analyzed by microarray or quantitative reverse transcription-PCR. In vitro mechanistic studies and in vivo therapeutic experiments were also done about a histone H3 Lys(9) demethylase, Jumonji domain containing 1A (JMJD1A).

RESULTS

Several candidate genes were identified by microarray analysis of liver metastases and culturing of CRC cells under hypoxic conditions. Among them, we found that JMJD1A was a novel independent prognostic factor for CRC (P = 0.013). In vitro assays revealed that loss of JMJD1A by small interfering RNA treatment was associated with a reduction of proliferative activity and decrease in invasion of CRC cell lines. Furthermore, treatment with an adenovirus system for antisense JMJD1A construct displayed prominent therapeutic effects when injected into established tumor xenografts of the CRC cell lines HCT116 and DLD1.

CONCLUSIONS

JMJD1A is a useful biomarker for hypoxic tumor cells and a prognostic marker that could be a promising therapeutic target against CRC.

Advances in molecular diagnostics of myeloproliferative disorders

Incremental advances in the molecular pathogenesis of myeloproliferative disorders (MPDs) have had a substantial impact on clinical practice in terms of both diagnosis and treatment. An array of novel molecular methods are being developed and integrated into the current battery of tests for diagnosis and monitoring of treatment response. Primarily, subjective clinico-histologic approaches to diagnosis are being replaced by more objective semimolecular diagnostic algorithms. Furthermore, identification of disease-specific molecular markers has facilitated the development of small-molecule drugs for targeted therapy. This review provides an overview of MPDs with emphasis on molecular diagnostic tests and their incorporation into contemporary diagnostic and therapeutic algorithms.

Construction of a novel DNA decoy that inhibits the oncogenic beta-catenin/T-cell factor pathway

The oncogenic beta-catenin/T-cell factor (TCF) signal is a common trigger inducing expressions of various cancer-related genes and is activated in various types of human malignancy. The aim of this study was to create an effective double-stranded DNA decoy that would interfere with endogenous TCF hyperactivity in tumor cells. We first established the TCF-activated model using nontumor human embryonic kidney 293 (HEK293) cells by introducing a beta-catenin cDNA. Based on a consensus TCF-binding sequence in the cyclin D1 and c-myc promoters, several double-stranded oligodeoxynucleotides were designed and tested for their ability to inhibit TCF activity in the HEK293 model. Among them, the 18-mer oligodeoxynucleotide stably formed double-stranded DNA and efficiently inhibited TCF activity. FITC-labeled oligodeoxynucleotide was efficiently incorporated into the nucleus at 6 hours and remained within cells for up to 72 to 96 hours. When compared with scrambled oligodeoxynucleotide, we found that the 18-mer TCF decoy significantly inhibited TCF activity and promoter activities of the downstream target genes, such as cyclin D1, c-myc, and matrix metalloproteinase 7 in HCT116 colon cancer cells. Reverse transcription-PCR assays indicated that mRNA expression of these genes decreased with treatment of the TCF decoy. Proliferation assay showed that the TCF decoy significantly inhibited growth of HCT116 tumor cells, but not of nontumor HEK293 cells. Our data provide evidence that the TCF decoy reduced both TCF activity and transcriptional activation of downstream target genes. Thus, this TCF decoy is potentially an efficient and nontoxic molecular targeting therapy for controlling malignant properties of cancer cells.

Molecular monitoring of BCR-ABL as a guide to clinical management in chronic myeloid leukaemia

Molecular monitoring of BCR-ABL transcript levels by real-time quantitative PCR is increasingly used to assess treatment response in patients with chronic myeloid leukaemia (CML). This has become particularly relevant in the era of imatinib therapy when residual levels of leukaemia usually fall below the level of detection by bone marrow cytogenetic analysis. Studies of imatinib-treated patients have determined that BCR-ABL levels measured early in therapy can predict subsequent response and the probability of acquired resistance. The defining of a molecular level of response that indicates a high probability of progression-free survival highlights the relevance of molecular analysis for clinical management. Small increases in the BCR-ABL level can identify patients with kinase domain mutations that lead to imatinib resistance. Therefore, these assays can be used as a screening strategy for mutation analysis. As second generation kinase inhibitors commence clinical trials, the molecular response will be a primary end-point that determines efficacy.

Stabilization of mRNA Expression in Whole Blood Samples

Background: Accurate quantification of mRNA in whole blood is made difficult by the simultaneous degradation of gene transcripts and unintended gene induction caused by sample handling or uncontrolled activation of coagulation. This study was designed to compare a new blood collection tube (PAXgeneTM Blood RNA System) and a companion sample preparation reagent set with a traditional sample collection and preparation method for the purpose of gene expression analysis.

Methods: We collected parallel blood samples from healthy donors into the new sample collection tubes and control EDTA tubes and performed serial RNA extractions on samples stored for 5 days at room temperature and for up to 90 days at 4 and 20 °C. Samples were analyzed by Northern blot analysis or reverse transcription-PCR (RT-PCR).

Results: Specific mRNA concentrations in blood stored in EDTA tubes at any temperature changed substantially, as determined by high-precision RT-PCR. These changes were eliminated or markedly reduced when whole blood was stored in PAXgene tubes. Loss of specific mRNAs, as measured by RT-PCR, reflected total RNA depletion as well as specific mRNA destruction demonstrated by Northern blot analysis. The salutary effects of PAXgene on mRNA stabilization extended to blood samples from eight unrelated donors.

Conclusions: Compared with whole blood collected in EDTA tubes and extracted by an organic method, the PAXgene Blood RNA System reduced RNA degradation and inhibited or eliminated gene induction in phlebotomy whole blood samples. Storage of whole blood samples in PAXgene tubes can be recommended for clinically related blood samples that will be analyzed for total or specific RNA content.

Minimal residual disease in chronic myeloid leukaemia patients

In many ways, chronic myeloid leukaemia (CML) serves as a paradigm for the utility of molecular methods in the diagnosis of malignancy or for monitoring the response of the patient to therapy. The Philadelphia (Ph) translocation provides an elegant example of how cytogenetic findings provided the starting point for understanding the genetic mechanisms involved in leukaemogenesis. The degree of reduction in tumour load after therapy is an important prognostic factor for CML patients. Several approaches have been introduced that can specifically detect the Ph translocation or its products; these approaches include fluorescent in situ hybridization, Southern blotting, western blotting and reverse transcriptase polymerase chain reaction (RT-PCR). Because non-quantitative RT-PCR analysis after therapy gives only limited information, quantitative or semiquantitative RT-PCR assays have been developed that enable the kinetics of residual BCR-ABL transcripts to be monitored over time in patients after allogeneic stem cell transplantation, interferon-alpha, or STI571 therapy.

Quantifying porphobilinogen deaminase mRNA in microdissected nephron segments by a modified RT-PCR

BACKGROUND

Quantifying mRNA levels by reverse transcription-polymerase chain reaction (RT-PCR), although widely exercised, is still difficult.

METHODS

A modified quantitative RT-PCR in which genomic DNA was used as standard was developed. The quantity of mRNA was expressed as the ratio of the PCR product from cDNA and that from genomic DNA (CG ratio). Nephron distribution of porphobilinogen deaminase (PBGD) mRNA was examined in microdissected nephron segments using the method. The enzyme activity and mRNA quantity of PBGD also were measured in tissue homogenates.

RESULTS

Tubular segments expressed substantially more PBGD mRNA than glomeruli (expressed as CG ratios, 1.04 +/- 0.10 in glomeruli, 4.53 +/- 0.32 in PCT, 5.71 +/- 0.25 in PST, 5.13 +/- 0.52 in mTAL, 5.29 +/- 0.20 in cTAL, 4.05 +/- 0.35 in DCT, 2.88 +/- 0.25 in CCD, and 4.90 +/- 0.24 in OMCD). PBGD mRNA level in liver homogenate (3.17 +/- 0.36) was much higher than glomeruli but lower than most of the tubular segments. The enzyme activity in tissue homogenates correlated well with mRNA levels.

CONCLUSION

The method reported here is simple and reliable, and especially suitable for quantitating specific mRNA amounts in minute tissue samples such as microdissected nephron segments.

Rapid Quantification of Human ABCA1 mRNA in Various Cell Types and Tissues by Real-Time Reverse Transcription-PCR

Background: The ABCA1 gene encodes for a member of subfamily A of the ATP-binding cassette transporters that plays an important role in cellular export of cholesterol and phospholipids; therefore, quantification of the ABCA1 mRNA is critical in many studies related to its expression and regulation by metabolic factors, nutritional status, and new antiatherogenic drug candidates. We developed a rapid, sensitive, specific, and reproducible real-time reverse transcription-PCR (RT-PCR) method for detection and quantification of ABCA1 transcripts in total RNA isolated from cultured human cells and tissues.

Methods: To quantify ABCA1 mRNA, we generated a calibration curve from serial dilutions of in vitro-transcribed RNA corresponding to an amplified ABCA1 cDNA 205-bp fragment (homologous calibrator). Two pairs of fluorescent hybridization probes were used to detect the ABCA1 and porphobilinogen deaminase (PBGD) mRNAs; the latter served as an internal control. PCR was performed as real-time amplification of ABCA1 mRNA in 100 ng of total RNA isolated from various human tissues, and cultured cells were calculated from the calibration curve. In addition, normalized values of target (ABCA1/PBGD ratio) were calculated.

Results: Using this method, we quantified ABCA1 transcripts in various human tissue samples as well as in monocytes, THP-1 cells, fibroblasts, and adipocytes. We demonstrated ABCA1 mRNA up-regulation during human adipocyte and monocyte differentiation. In addition, we examined the effect of cholesterol loading and deloading on ABCA1 expression in monocytes, THP-1 cells, and fibroblasts.

Conclusions: Our RT-PCR assay allows the specific and highly reproducible detection and quantification of minute amounts of human ABCA1 mRNA. This new method is more accurate, more informative, and less laborious than the classic RT-PCR methods and Northern blot; it therefore could simplify all studies on ABCA1 mRNA expression.

Clinical significance of CDC25A and CDC25B expression in squamous cell carcinomas of the oesophagus

CDC25A, CDC25B and CDC25C belong to a family of protein phosphatases which activate the cyclin-dependent kinase at different points of the cell cycle. According to accumulating evidence, CDC25A and CDC25B seem to possess oncogenic properties. We have analysed these expressions by immunohistochemistry, western blot and RT-PCR in a series of 100 patients with squamous cell carcinoma of the oesophagus. When compared with non-cancerous cells, CDC25A and CDC25B were strongly expressed in the cytoplasm of cancer cells, with positive (+) classification in 46% (46 cases) and 48% (48 cases), respectively. There was no significant correlation between CDC25A and CDC25B expression, nor was there any association with the expression of other cell cycle-regulating molecules, including cyclin D1, Rb, p16(INK4), p27(KIP1)and PCNA (proliferating cell nuclear antigen). CDC25A (+), as well as CDC25B (+), was more frequently found in patients with deeper tumour invasion and lymph node metastasis, while tumour size was correlated only with CDC25A expression. Postoperative survival was significantly poorer for CDC25A (+) patients than CDC25A (-) patients, but was not affected by the CDC25B status. Nuclear localization of CDC25A was observed in 51 cases (51%), regardless of its cytoplasmic expression, and was not associated with clinico-pathological factors or prognosis. Multivariate analysis revealed only the CDC25A status to be an independent significant prognostic factor among these biological and clinico-pathological factors. CDC25A but not CDC25B may be a new prognostic factor for squamous cell carcinoma of the oesophagus. Thus, regulation of the G1 checkpoint in the cell cycle may be important in oesophageal carcinogenesis, which may also involve many other oncogenes.

Problems with interphase fluorescence in situ hybridization in detecting BCR/ABL-positive cells in some patients using a novel technique with extra signals

Interphase fluorescence in situ hybridization (I-FISH) is frequently used to monitor the response to therapy in various hematological malignancies. We performed a comparison of I-FISH, metaphase FISH (C-FISH), conventional cytogenetics, spectral karyotyping (SKY) and PCR for the detection of the t(9;22) and the BCR/ABL rearrangement in 32 patients with chronic myelogenous leukemia (CML). FISH was done using a novel commercial probe set (VYSIS LSI BCR/ABL ES), which is designed to reduce the rate of false-positive results by marking the argininosuccinate synthetase (ASS) gene and thus providing an extra signal on chromosome 9. Our data indicate, that a substantial number of BCR/ABL-positive patients (n=5 patients, 3 with Ph, 2 with masked Ph) present negative results using this probe set in I-FISH analyses, because they did not fulfill the scoring criteria. In fact, the ASS region, which usually remains on 9q in Ph+ CML, appears to be lost or translocated. Due to these results we recommend that the initial diagnosis as well as the follow-up of patients with Ph+ leukemias should not be based on a single technique but should integrate results of cytogenetics and molecular biology.

Isolation of a novel human lung-specific gene, LUNX, a potential molecular marker for detection of micrometastasis in non-small-cell lung cancer

We have isolated a novel human lung-specific gene, LUNX (lung-specific X protein), by differential-display mRNA analysis. The full-length cDNA contained 1,015 nucleotides including an open reading frame of 768 nucleotides encoding 256 amino acids. We localized the gene to chromosomal region 20p11.1-q12 by radiation hybrid mapping. Using an RT-PCR assay specific for LUNX mRNA, 35 non-small-cell lung-cancer (NSCLC) tumors and 0 of 16 normal lymph nodes were positive. Furthermore, LUNX mRNA expression was enhanced in 26 (84%) of 31 NSCLC tumors vs. corresponding cancer-free lung tissues by semi-quantitative analyses with multiplex RT-PCR. We assessed the possibility of LUNX mRNA as a molecular marker for detection of micrometastasis in dissected lymph nodes obtained from 20 patients with NSCLC tumors. LUNX mRNA was detected in 16 (80%) of 20 histologically positive lymph nodes and 21 (25%) of 84 histologically negative lymph nodes. Comparative analyses of the conventional histological examination and the RT-PCR detection assay for LUNX mRNA showed that the detection rate of metastases in lymph nodes by the RT-PCR assay was higher in 12 and consistent in 6 of the total 20 NSCLC patients. We demonstrate that the LUNX RT-PCR assay is a potential diagnostic method for detection of micrometastases in lymph nodes of NSCLC patients.

Detection and quantification of residual disease in chronic myelogenous leukemia

The degree of tumor load reduction after therapy is an important prognostic factor for patients with CML. Conventional metaphase analysis has been considered to be the 'gold standard' for evaluating patient response to treatment but this technique normally requires bone marrow aspiration and is therefore invasive. The frequency of cytogenetic analyses can be considerably reduced if patients are also monitored by molecular methods, which can be performed on peripheral blood specimens. Of the various techniques available, most attention has been paid to RT-PCR for BCR-ABL mRNA since this is by far the most sensitive. Simple, non-quantitative RT-PCR analysis gives only limited information on patients after treatment. Quantitative RT-PCR assays have been developed to monitor the kinetics of residual BCR-ABL transcripts over time. Variables in the quantitative PCR assay may be controlled for by quantification of transcripts of a normal gene (eg ABL or glucose-6-phosphate dehydrogenase, G6PD) as an internal standard. After allogeneic stem cell transplantation, most patients become RT-PCR negative, often after a period of low level positivity that may persist for several months. Those patients destined to relapse are characterized by the reappearance and/or rising levels of BCR-ABL transcripts. In contrast, for patients treated with interferon-alpha (IFN) residual disease is rarely, if ever, eliminated. The actual level of minimal residual disease in complete cytogenetic responders to IFN correlates with the probability of relapse. New quantitative real time procedures promise to simplify the protocols that are currently in use, but standardization and the introduction of rigorous, internationally accepted controls are required to enable RT-PCR to become a robust and routine basis for therapeutic decisions.

Kinetics of the Graft-Versus-Leukemia Response After Donor Leukocyte Infusions for Relapsed Chronic Myeloid Leukemia After Allogeneic Bone Marrow Transplantation

Little is known about the mechanisms and the kinetics of the so-called graft-versus-leukemia (GVL) response induced by donor lymphocyte infusions (DLI) in patients with leukemic relapse after allogeneic bone marrow transplantation (BMT). We sought to elucidate this problem by sequentially studying three patients with relapsed chronic myeloid leukemia after sex-mismatched BMT from time before donor leukocyte infusion until achievement of complete molecular remission. Lineage-specific chimerism was assessed longitudinally by a combined fluorescent immunophenotyping and sex chromosome-specific in situ hybridization approach. Results were related to quantitative detection of bcr-abl transcripts by competitive differential reverse transcriptase-polymerase chain reaction (RT-PCR), qualitative bcr-abl RT-PCR, and multiplex PCR-based DNA donor/recipient chimerism. All patients had predominant donor lymphopoiesis at the time of DLI, suggesting a state of tolerance to recipient leukemic and/or normal cells. In contrast, granulopoiesis and erythropoiesis were mainly recipient derived in both patients with hematologic relapse and partly recipient derived in the patient with molecular relapse. Eighty percent, 90%, and 8% of CD34+cells, respectively, were found to be of recipient origin at relapse, and few donor stem cells predicted for cytopenia post-DLI. Responses were seen after a time lag of 5 to 13 weeks after DLI and resulted in reversal to full donor chimerism within a critical switch period of 4 to 5 weeks. A sudden decrease in recipient cells was paralleled by a sharp decrease in bcr-abl transcript numbers detectable several weeks before achievement of molecular remission and onset of clinical graft-versus-host disease (GVHD). This response pattern was confirmed by retrospective RT-PCR analysis in an additional five patients. Prospective monitoring of stem cell chimerism and response may enable us to individually tailor adoptive immunotherapy in the future.

Kinetics of the Graft-Versus-Leukemia Response After Donor Leukocyte Infusions for Relapsed Chronic Myeloid Leukemia After Allogeneic Bone Marrow Transplantation

Little is known about the mechanisms and the kinetics of the so-called graft-versus-leukemia (GVL) response induced by donor lymphocyte infusions (DLI) in patients with leukemic relapse after allogeneic bone marrow transplantation (BMT). We sought to elucidate this problem by sequentially studying three patients with relapsed chronic myeloid leukemia after sex-mismatched BMT from time before donor leukocyte infusion until achievement of complete molecular remission. Lineage-specific chimerism was assessed longitudinally by a combined fluorescent immunophenotyping and sex chromosome-specific in situ hybridization approach. Results were related to quantitative detection of bcr-abl transcripts by competitive differential reverse transcriptase-polymerase chain reaction (RT-PCR), qualitative bcr-abl RT-PCR, and multiplex PCR-based DNA donor/recipient chimerism. All patients had predominant donor lymphopoiesis at the time of DLI, suggesting a state of tolerance to recipient leukemic and/or normal cells. In contrast, granulopoiesis and erythropoiesis were mainly recipient derived in both patients with hematologic relapse and partly recipient derived in the patient with molecular relapse. Eighty percent, 90%, and 8% of CD34+cells, respectively, were found to be of recipient origin at relapse, and few donor stem cells predicted for cytopenia post-DLI. Responses were seen after a time lag of 5 to 13 weeks after DLI and resulted in reversal to full donor chimerism within a critical switch period of 4 to 5 weeks. A sudden decrease in recipient cells was paralleled by a sharp decrease in bcr-abl transcript numbers detectable several weeks before achievement of molecular remission and onset of clinical graft-versus-host disease (GVHD). This response pattern was confirmed by retrospective RT-PCR analysis in an additional five patients. Prospective monitoring of stem cell chimerism and response may enable us to individually tailor adoptive immunotherapy in the future.

Lack of Interferon Consensus Sequence Binding Protein (ICSBP) Transcripts in Human Myeloid Leukemias

Interferon consensus sequence binding protein (ICSBP) was first identified as a transcription factor of the interferon (IFN) regulatory factor family (IRF) which regulates expression of IFN-dependent genes by binding to DNA at specific sites, IFN-stimulated responsive elements. Analysis of ICSBP-deficient mice showed hematologic alterations similar to chronic myelogenous leukemia (CML) in humans and suggested a novel role for ICSBP in regulating proliferation and differentiation of hematopoietic progenitor cells. Here we show that ICSBP-mRNA expression is impaired in human myeloid leukemias: 27 of 34 CML patients (79%) and 21 of 32 patients with acute myeloid leukemia (AML) (66%) showed very low or absent transcript numbers of ICSBP. In contrast, only 2 of 33 normal volunteers (6%) showed low transcription of ICSBP(P < .0001 both for CML and AML values). The lack of expression was not associated with lack of lymphatic cells, which normally have been shown to express ICSBP at the highest level. More detailed analysis showed an absence of ICSBP-mRNA also in sorted B cells derived from CML patients. To analyze whetherICSBP may be induced in leukemic cells, ex vivoexperiments using a known inducer of ICSBP, IFN-γ, were performed. Ex vivo treatment of primary CML cells using IFN-γ resulted in induction of ICSBP transcripts. Furthermore, samples of CML patients during IFN-α treatment were analyzed. In 11 of 12 CML patients ICSBP-mRNA was inducible upon in vivo treatment with IFN-α, but decreased with progression of CML. Stable transfection of K-562 cell line with ICSBP led to no difference in bcr-abl expression in vitro, although two patients showed an inverse correlation between bcr-abl andICSBP in vivo. These data suggest that lack of ICSBPmay have an important role also in human myeloid leukemogenesis.

Lack of Interferon Consensus Sequence Binding Protein (ICSBP) Transcripts in Human Myeloid Leukemias

Interferon consensus sequence binding protein (ICSBP) was first identified as a transcription factor of the interferon (IFN) regulatory factor family (IRF) which regulates expression of IFN-dependent genes by binding to DNA at specific sites, IFN-stimulated responsive elements. Analysis of ICSBP-deficient mice showed hematologic alterations similar to chronic myelogenous leukemia (CML) in humans and suggested a novel role for ICSBP in regulating proliferation and differentiation of hematopoietic progenitor cells. Here we show that ICSBP-mRNA expression is impaired in human myeloid leukemias: 27 of 34 CML patients (79%) and 21 of 32 patients with acute myeloid leukemia (AML) (66%) showed very low or absent transcript numbers of ICSBP. In contrast, only 2 of 33 normal volunteers (6%) showed low transcription of ICSBP(P < .0001 both for CML and AML values). The lack of expression was not associated with lack of lymphatic cells, which normally have been shown to express ICSBP at the highest level. More detailed analysis showed an absence of ICSBP-mRNA also in sorted B cells derived from CML patients. To analyze whetherICSBP may be induced in leukemic cells, ex vivoexperiments using a known inducer of ICSBP, IFN-γ, were performed. Ex vivo treatment of primary CML cells using IFN-γ resulted in induction of ICSBP transcripts. Furthermore, samples of CML patients during IFN-α treatment were analyzed. In 11 of 12 CML patients ICSBP-mRNA was inducible upon in vivo treatment with IFN-α, but decreased with progression of CML. Stable transfection of K-562 cell line with ICSBP led to no difference in bcr-abl expression in vitro, although two patients showed an inverse correlation between bcr-abl andICSBP in vivo. These data suggest that lack of ICSBPmay have an important role also in human myeloid leukemogenesis.

Adaptor-tagged competitive PCR: a novel method for measuring relative gene expression

A simple and reliable PCR-based method to quantitate gene expression is described. Following the digestion of double-stranded cDNA by a restriction enzyme, an adaptor is ligated to a cDNA from a first RNA sample, and another adaptor to a second RNA sample. The two adaptors share a common sequence at the outer region, but differ in size. Equal amounts of the ligated samples are mixed, and amplified by an adaptor-primer and a primer specific to the gene of interest. Products derived from the two sources differ in size, and can be separated by denaturing polyacrylamide gel electrophoresis. The ratio of the two products reveals the relative level of gene expression. Since the technique avoids the need to construct internal standards, it is especially useful for the analysis of many different gene transcripts.