B-Cell Chronic Lymphocytic Leukemia Cells Exposed to the Non-Genotoxic p53 Activator Nutlin-3 Are Characterized by a Specific Gene Expression Signature.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4374-4374
Author(s):  
Michele Dal-Bo ◽  
Paola Secchiero ◽  
Massimo Degan ◽  
Riccardo Bomben ◽  
Dania Benedetti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Differentially Expressed Genes ◽  
Chemotherapeutic Agents ◽  
Lymphocytic Leukemia ◽  
Differentially Expressed ◽  
Specific Gene ◽  
P53 Mutations ◽  
Cell Chronic Lymphocytic Leukemia

Abstract Abstract 4374 Introduction p53 plays a key role in determining the clinical features of B cell chronic lymphocytic leukemia (CLL). Disruption of p53 by point mutations, deletion at 17p13, or both, occurs in a fraction of cases at diagnosis and predicts poor survival and chemorefractoriness. In cells with functional p53, p53 activity is inhibited through interaction with MDM2. In fact, p53 can be activated upon exposure of cells to inhibitors of p53/MDM2 interaction, like Nutlins. Exposure of CLL cells to Nutlin-3 is effective in raising the levels of p53 protein with subsequent induction of cell cycle arrest and/or apoptosis, independently of the most relevant prognostic markers. The aim of the present study was to analyze the gene expression profile (GEP) induced by Nutlin-3 exposure in primary CLL cells from p53wt and p53del/mut cases. Patients and methods purified cells from 24 PB CLL samples, all characterized for IGHV mutational status, CD38 and ZAP-70 and p53 mutations (16 p53wt CLL, 8 p53del/mut CLL of which 6 with del17p13 and p53 mutations, 1 with del17p13 alone, and 1 with p53 mutations alone), were exposed to 10 mM Nutlin-3 for 24 hours. GEP was performed using a dual labelling strategy; the differential expression of the below reported genes were validated by quantitative real-time PCR. Results i) signature of Nutlin-3 exposure in p53wt CLL: 144 differentially expressed genes (143 up-regulated, 1 down-regulated) were correlated with response to Nutlin-3. Among the over-expressed genes, several genes were related to apoptosis (e.g. BAX, BBC3, E124, IKIP, FAS, LRDD, FLJ11259, TRIAP1, GADD45, TP53INP1, ISG20L1, ZMAT3, TNFRS10C, TNFRSF10B/TRAIL-R2), while other genes (e.g. MDM2, CDKN1A, PCNA) were up-regulated by Nutlin-3 as a part of a negative feed-back mechanism. Of note, this signature was not shared by 3/16 p53wt cases (identified as “non-responder” p53wt CLL) and 7/8 p53del/mut cases (identified as “non-responder” p53del/mut CLL); consistently, cells from these cases were also significantly resistant to the in-vitro cytotoxic effects of Nutlin-3; ii) signature of Nutlin-3 “non-responder” p53wt CLL: by comparing the constitutive GEP of 13 “responder” versus 3 “non-responder” p53wt CLL, we obtained 278 differentially expressed genes, 149 up-regulated and 129 down-regulated in “non-responder” p53wt CLL. Among up-regulated genes, we focused on MDM4/MDMX, a gene whose product was known to have an inhibitor activity of p53-dependent transcription and to form Nutlin-3 resistant complexes with p53. Among down-regulated genes, validations were made for BIRC4BP, whose product is known to act as an antagonist of the anti-apoptotic protein XIAP; iii) signature of Nutlin-3 “non-responder” p53del/mut CLL: by comparing the constitutive GEP of 13 “responder” versus 7 “non-responder” p53del/mut cases, we obtained 72 differentially expressed genes, 26 up-regulated and 46 down-regulated (31/46 located at the 17p segment) in “non-responder” p53del/mut CLL. Validations were made for several genes whose products display pro-apoptotic activities (e.g. PSMB6, RPL26 and ZBTB4, located at 17p segment, and GNAZ located at chromosome 22) among down-regulated genes, and ARHGDIA, whose gene product displays anti-apoptotic activities and mediates cellular resistance to chemotherapeutic agents, among up-regulated genes. Notably, CLL cells (n=43) displayed constitutively higher levels of MDM4/MDMX (p<0.0001) and ARHGDIA (p=0.0002) transcripts than purified normal B cells (n=15), irrespectively to the major biologic prognosticators. Conclusions specific gene-sets and GEP were documented to be associated with response or resistance to Nutlin-3 exposure in p53wt or p53del/mut CLL. These findings may help to identify novel molecular targets for CLL therapy. Disclosures: No relevant conflicts of interest to declare.

Microarray Gene Expression Profiling of B-Cell Chronic Lymphocytic Leukemia Subgroups Defined by Genomic Aberrations and VH Mutation Status

2004 ◽  
Vol 22 (19) ◽  
pp. 3937-3949 ◽  
Author(s):  
Christian Haslinger ◽  
Norbert Schweifer ◽  
Stephan Stilgenbauer ◽  
Hartmut Döhner ◽  
Peter Lichter ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Differentially Expressed Genes ◽  
Expression Profiling ◽  
Lymphocytic Leukemia ◽  
Differentially Expressed ◽  
Mutational Status ◽  
Genomic Aberrations ◽  
Cell Chronic Lymphocytic Leukemia

Purpose Genomic aberrations and mutational status of the immunoglobulin variable heavy chain (VH) gene have been shown to be among the most important predictors for outcome in patients with B-cell chronic lymphocytic leukemia (B-CLL). In this study, we report on differential gene expression patterns that are characteristic for genetically defined B-CLL subtypes. Materials and Methods One hundred genetically well-characterized B-CLL samples, together with 11 healthy control samples, were analyzed using oligonucleotide arrays, which test for the expression of some 12,000 human genes. Results Aiming at microarray-based subclassification, class predictors were constructed using sets of differentially expressed genes, which yielded in zero or low misclassification rates. Furthermore, a significant number of the differentially expressed genes clustered in chromosomal regions affected by the respective genomic losses/gains. Deletions affecting chromosome bands 11q22-q23 and 17p13 led to a reduced expression of the corresponding genes, such as ATM and p53, while trisomy 12 resulted in the upregulation of genes mapping to chromosome arm 12q. Using an unsupervised analysis algorithm, expression profiling allowed partitioning into predominantly VH-mutated versus unmutated patient groups; however, association of the expression profile with the VH mutational status could only be detected in male patients. Conclusion The finding that the most significantly differentially expressed genes are located in the corresponding aberrant chromosomal regions indicates that a gene dosage effect may exert a pathogenic role in B-CLL. The significant difference in the partitioning of male and female B-CLL samples suggests that the genomic signature for the VH mutational status might be sex-related.

B-Cell Scaffold Protein with Ankyrin Repeats (BANK1) Is Differentially Expressed in ZAP-70 Negative Compared to ZAP-70 Positive Chronic Lymphocytic Leukemia Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2938-2938
Author(s):  
Frank Dicker ◽  
Susanne Schnittger ◽  
Claudia Schoch ◽  
Alexander Kohlmann ◽  
Wei-Min Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Gene Expression Profiling ◽  
Differentially Expressed Genes ◽  
Expression Profiling ◽  
Lymphocytic Leukemia ◽  
Differentially Expressed ◽  
Cell Scaffold

Abstract The lack of somatic mutations of the immunoglobulin variable heavy chain (IgVH) gene has been established as poor prognostic marker for chronic lymphocytic leukemia (CLL) patients at early stage disease. Expression of the non receptor tyrosine kinase zeta chain associated protein (ZAP-70) was proposed as a surrogate marker for an unmutated IgVH, however, up to 30% discordant samples have been reported depending on the respective study. B cell receptor (BCR) mediated signaling is enhanced by ZAP-70 expression in CLL cells in vitro and ZAP-70 expression also tends to decrease the time from diagnosis to treatment irrespective of the IgVH status. Therefore, we wanted to identify differentially expressed genes between the ZAP-70 positive and negative CLLs by gene expression profiling of peripheral blood mononuclear cells (PBMCs) using Affymetrix microarrays (HG-U133 Plus 2.0). ZAP-70 expression was analyzed by quantitative real time PCR of CD19 purified (purity &gt; 99%) PBMCs (n=62) using a LightCycler instrument. Expression of ZAP-70 mRNA was normalized against the housekeeping gene ABL and a relative quantitation against Jurkat T cells as a calibrator was performed. Results are expressed as normalized ratio and a cut-off of 0.5 normalized ratio gave the best correlation to the IgVH status with 77% concordant samples between ZAP-70 expression and the IgVH status. The discordant samples consisted of 5 unmutated IgVHs in the ZAP-70 negative group and 9 mutated in the ZAP-70 positive group. In a second step PBMCs of the same samples were analyzed by gene expression profiling and differentially expressed genes were identified by t-test. Among the two best genes that could be used in a classification algorithm (SVM) to distinguish between the 2 subsets with 92% accuracy were ZAP-70 and B cell scaffold protein with ankyrin repeats (BANK1). The expression of BANK1 was increased 3–4-fold in the ZAP-70 negative compared to the ZAP-70 positive CLL subset (P = 0,001). In the literature, BANK1 has been identified in human BCR expressing B cells and seems to be B cell restricted. In B cells the scaffolding protein BANK1 enhances BCR-mediated Ca2+-signaling, a signaling pathway that is also enhanced by ZAP-70 expression in CLL B cells. Based on these data we show that increased BANK1 expression correlates with a ZAP-70 negative status in CLL B cells. The functional consequences of BANK1 expression in the ZAP-70 negative subset of CLL B cells, which are usually associated with a more favorable prognosis, still need to be established further.

B-Cell Prolymphocytic Leukemia (B-PLL) and Chronic Lymphocytic Leukemia (CLL) Express Distinct Genomic Profiles.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4372-4372
Author(s):  
Ilaria Del Giudice ◽  
Nnenna Osuji ◽  
Tim Dexter ◽  
Estella Matutes ◽  
Vasantha Brito-Babapulle ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Clinical Features ◽  
Mononuclear Cells ◽  
Expression Profiles ◽  
Lymphocytic Leukemia ◽  
Differentially Expressed ◽  
Specific Gene ◽  
Prolymphocytic Leukemia

Abstract B-cell prolymphocytic leukemia (B-PLL) is a rare disease, originally described in the early seventies and now recognized as a specific entity by the WHO classification. Diagnosis is based on clinical features and lymphocyte morphology (>55% circulating prolymphocytes), as no specific immunophenotypic or cytogenetic marker is available. According to WHO, cases of chronic lymphocytic leukemia (CLL) with increased prolymphocytes (CLL/PL) (>10% and <55%) should not be considered as B-PLL, because they have different genetic features. However, the existence of B-PLL as a separate entity from CLL has been questioned. We investigated the gene expression profiles of B-PLL and CLL to identify key genetic differences potentially useful for the diagnosis or involved in their different natural history. We retrospectively selected cryopreserved samples from 10 de-novo B-PLL and 10 untreated CLL. Diagnosis was well-defined by clinical features, lymphocyte morphology and immunophenotype. Matutes immunophenotypic score was 4–5 in all CLL; 3 cases showed CLL/PL morphology. B-PLL scored 0–3, with 3 CD5+ cases. Diagnosis of B-PLL was corroborated by excluding a leukemic form of MCL; t(11;14) assessed by fluorescent in situ hybridization (FISH) was absent in all but one case which, originally diagnosed as B-PLL, was reclassified as leukemic MCL. Five B-PLL and 2 CLL showed del(p53) by FISH. Total RNA was extracted from frozen blood mononuclear cells containing ≥95% purity of malignant cells, determined by flow cytometry. cDNA synthesis followed by biotin-labelled cRNA synthesis was carried out as per Affymetrix protocols. Microarray experiments were performed by MRC geneservice (UK HGMP Resource Centre), using the Affymetrix Human U133PLUS2 GeneChip array (54K probes). Hierarchical clustering was performed on samples using a filtered set of 9878 genes with >4 different algorithms. Prediction analysis for microarray (PAM) and significance analysis of microarray data (SAM) were used to evaluate class performance, and to partition genes using a priori defined labels of morphology, immunophenotype and cytogenetics. Unsupervised analysis reproducibly partitioned samples into two homogeneous distinct groups, corresponding to the diagnoses of B-PLL and CLL. SAM analysis identified 3957 differentially expressed transcripts (false discovery rates <1%), >77% of which showed an over 2-fold difference in expression between the groups. PAM analysis refined a sub-group of 46 genes which most efficiently differentiated the two diseases. Differentially expressed genes included those encoding surface antigens, oncogenes, transcription factors, adhesion molecules or involved in cell cycle/cell proliferation, lipidic metabolism and catalytic protein activity. Comparison of CD5 positive (13) versus CD5 negative (7) cases and cases with (7) or without (13) del(p53) showed no reliable class prediction. Our study formally demonstrates that B-PLL and CLL are two distinct diseases, each showing a specific gene expression. B-PLL has a homogeneous genomic profile irrespective of its heterogeneity in laboratory features. Validation of a model based on the expression of few genes predictive of diagnosis is on going. Further analysis of these data may also identify specific genes involved in B-PLL pathogenesis and drug resistance.

scholarly journals Relation of Gene Expression Phenotype to Immunoglobulin Mutation Genotype in B Cell Chronic Lymphocytic Leukemia

2001 ◽  
Vol 194 (11) ◽  
pp. 1639-1648 ◽  
Author(s):  
Andreas Rosenwald ◽  
Ash A. Alizadeh ◽  
George Widhopf ◽  
Richard Simon ◽  
R. Eric Davis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Germ Line ◽  
Gene Expression Signature ◽  
Lymphocytic Leukemia ◽  
Common Mechanism ◽  
Human Leukemia ◽  
Mutational Status ◽  
Cell Chronic Lymphocytic Leukemia

The most common human leukemia is B cell chronic lymphocytic leukemia (CLL), a malignancy of mature B cells with a characteristic clinical presentation but a variable clinical course. The rearranged immunoglobulin (Ig) genes of CLL cells may be either germ-line in sequence or somatically mutated. Lack of Ig mutations defined a distinctly worse prognostic group of CLL patients raising the possibility that CLL comprises two distinct diseases. Using genomic-scale gene expression profiling, we show that CLL is characterized by a common gene expression “signature,” irrespective of Ig mutational status, suggesting that CLL cases share a common mechanism of transformation and/or cell of origin. Nonetheless, the expression of hundreds of other genes correlated with the Ig mutational status, including many genes that are modulated in expression during mitogenic B cell receptor signaling. These genes were used to build a CLL subtype predictor that may help in the clinical classification of patients with this disease.

Clinical Outcome of B-Cell Chronic Lymphocytic Leukemia Following Alemtuzumab Therapy: Retrospective Study within Various Cytogenetic Risk Categories

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3164-3164
Author(s):  
Michael Fiegl ◽  
Martin Erdel ◽  
Inge Tinhofer ◽  
Georg Hopfinger ◽  
Karin Eigenberger ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Chemotherapeutic Agents ◽  
Lymphocytic Leukemia ◽  
Cox Regression Analysis ◽  
Trisomy 12 ◽  
11Q Deletion ◽  
Cell Chronic Lymphocytic Leukemia ◽  
13Q Deletion

Abstract B-cell chronic lymphocytic leukemia (CLL) with 17p deletion responds poorly to chemotherapeutic agents. This retrospective study evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced CLL, categorized by cytogenetic profile. Methods: This is the largest data base with efficacy analysis of alemtuzumab in CLL stratified according to cytogenetics. Detailed data analysis was done in 138 CLL patients, in whom cytogenetic analysis was performed by FISH using the standard CLL analysis categorized according to Doehner et al. (N Engl J Med343, 1910; 2000). Responses were evaluated according to the NCI criteria; progression-free survival (PFS) and overall survival (OS) were also assessed. Results: 73% of the patients were male. At start of alemtuzumab therapy, the median age was 64 years (range, 46–92); 12% were in Rai stage I, 18% in stage II, 20% in stage III, and 50% in stage IV. The median number of two prior therapies was 2 (range, 0–10); of the patients who received prior fludarabine (F) (n=113), 70% were F-refratory, 25% sensitive, and in 5% this was unknown. 30% and 17% of patients had bulky lymphadenopathy (&gt;5 cm) and giant splenomegaly (&gt;20 cm), respectively. Cytogenetic abnormalities were as follows: 13q deletion 14%; trisomy 12, 12%, 11q deletion 20%; 17p deletion, 33%, none of these, 22%. The overall response rate (ORR) was 38% in the total cohort. ORR was 53%, 56%, 21%, and 44% in the subgroup of 13q deletion, trisomy 12, 11q deletion, and 17p deletion, respectively; patients without any of these abnormalities had an ORR of 27%. From start of alemtuzumab, median PFS and OS for the whole cohort was 6.9 months and 30 months, respectively. Notably, PFS and OS in 17p deletion patients was 7.1 months and 19.1 months, respectively, an encouraging outcome when considering the unfavourable risk profile in these patients. In 17p deletion patients, response was remarkable also in disease involved lymph nodes (78%). Patients with F-resistant disease and 17p deletion, an extraordinarily poor prognostic group (n=25), had encouraging ORR, PFS, and OS rates (28%; 7.2 months; and 19.1 months, respectively), which did not differ from those in F-resistant patients with good risk cytogenetics. In a multivariate Cox regression analysis, independent risk factors for shorter OS were anemia (hazard ratio [HR] = 2.48; 95% CI, 1.50–4.11; P &lt;.001), ≥3 of prior lines of therapy (HR = 2.00; 95% CI, 1.24–3.24, P =.005), and poor risk cytogenetics ([17p deletion and 11q deletion], HR = 2.23; 95% CI 1.35–3.69, P =.002). Conclusion: Alemtuzumab was effective in CLL across all cytogenetic categories evaluated. In patients with favorable cytogenetics, we observed that alemtuzumab is a highly effective therapy even when conventional chemotherapy has failed. Patients with 17p deletion achieved quite favorable ORR and OS upon alemtuzumab. Thus, the 17p deletion group can often be shifted to an “intermediate” risk CLL, and responding patients are frequently re-treated with alemtuzumab.

Mevalonate pathway inhibitors in the treatment of B-cell chronic lymphocytic leukemia.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 6561-6561
Author(s):  
Ravi Kiran Bobba ◽  
Indira Benakanakere ◽  
Smitha Bearelly ◽  
Monica Arya ◽  
Richard Sleigtholm ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Viability ◽  
B Cell ◽  
Combination Treatment ◽  
Mevalonate Pathway ◽  
Chemotherapeutic Agents ◽  
Lymphocytic Leukemia ◽  
Cell Chronic Lymphocytic Leukemia

6561 Background: B-cell chronic lymphocytic leukemia (CLL) cells are arrested in G0/G1 phase of the cell cycle and are resistant to programmed cell death, hypothesized to contribute to the resistance of CLL cells to standard chemotherapy with curative intent. Methods: Mec-2 cells and Wac-3 cells are CLL cells that have been shown to be resistant to fludarabine and rituximab. We tested a novel enzyme inhibitor’s ability to render CLL cells sensitive to fludarabine and rituximab. Results: BIBB515, a lanosterol synthase inhibitor, at a concentration of 10μM, was able to reduce the cell viability from 82% in controls to 65% after 72 hours. Fludarabine 10μM alone did not reduce the cell viability, 82 % in controls compared to 80%. BIBB515+ fludarabine treatment for 72 hours, at the dose of 10μM each decreased the cell viability to 37%. Cell proliferation by MTT assay was 0.66±0.010 in control compared to 0.37±0.01 in BIBB515+fludarbine and 0.21±0.01 in BIBB515+ fludarabine+ rituximab. There is a 68% down-regulation of cell proliferation using this treatment. There was a two fold induction of CD 20 with combination treatment, and BIBB515 treatment. The mechanism of cell death in the combination treatment of BIBB515 and fludarabine may be due to the up regulation of cell surface marker CD-20. WAC-3 is another CLL cell line that is sensitive to fludarabine, and resistant to rituximab. BIBB515 sensitizes WAC-3 cells to CD 20 antibody rituximab. There is a 68.7% decrease in cell proliferation with combination treatment of BIBB515 and rituximab. Proliferation of Mec-2 cells were inhibited by 60µM and 30µM terbinafine. Ro-48-8071, showed dose-dependent activity, alone or in combination to fludarabine was seen to induce cell death in Mec-2 cells. Fludarabine alone did not have any effect on these cells. Conclusions: Inhibitors of the mevalonate pathway make resistant CLL cells sensitive to current chemotherapeutic agents. Exploiting this mechanism could alter the current treatment regimens, leading to control of the disease in advanced stages by either inducing the leukemic cells to be static or to regress. This strategy may also limit the toxicities involved with chemotherapy.

scholarly journals p53 gene mutation in B-cell chronic lymphocytic leukemia is associated with drug resistance and is independent of MDR1/MDR3 gene expression

Blood ◽  
1993 ◽  
Vol 82 (11) ◽  
pp. 3452-3459 ◽  
Author(s):  
S el Rouby ◽  
A Thomas ◽  
D Costin ◽  
CR Rosenberg ◽  
M Potmesil ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Gene Mutations ◽  
P53 Gene ◽  
Lymphocytic Leukemia ◽  
P53 Mutations ◽  
P53 Gene Mutation ◽  
P53 Gene Mutations ◽  
Cell Chronic Lymphocytic Leukemia

We studied 53 patients with B-cell chronic lymphocytic leukemia (B-CLL) and found mutations of the p53 gene in 15%. Patients with p53 gene mutations were found to have an aggressive form of B-CLL disease characterized by advanced Rai stage, rapid lymphocyte doubling time (LDT), and resistance to chemotherapy. While 27 of 29 treated patients (93%) without p53 mutations achieved a partial remission, only one of seven treated patients (14%) with p53 mutations achieved a partial remission (P = .00009). Adjusting for prognostic factors (age, sex, race, and Rai stage), patients with p53 gene mutations had a 13-fold greater risk of death than patients without p53 mutations (P = .013). In addition to examining the clinical relevance of p53 gene mutations in B-CLL, we investigated the possible role of p53 gene regulation in the expression of the multidrug resistance genes MDR1 and MDR3. We quantitated MDR1 and MDR3 mRNA expression by reverse transcription- polymerase chain reaction (RT-PCR). Expression of both the MDR1 and MDR3 genes was independent of p53 gene mutation or prior drug treatment, and did not predict for clinical response. Our findings indicate that p53 gene mutations in B-CLL are associated with a poor clinical outcome and may be a prognostic indicator for drug resistance.

Biological and Clinical Relevance of Surrogate Markers of IgVH Mutational Status in B-Cell Chronic Lymphocytic Leukemia.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1062-1062
Author(s):  
Fortunato Morabito ◽  
Marta Lionetti ◽  
Giovanna Cutrona ◽  
Katia Todoerti ◽  
Serena Matis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Candidate Genes ◽  
Lymphocytic Leukemia ◽  
Surrogate Markers ◽  
Rt Pcr ◽  
Mutation Status ◽  
Expression Levels ◽  
Cell Chronic Lymphocytic Leukemia

Abstract B-cell chronic lymphocytic leukemia (B-CLL) is a heterogeneous disease; some patients have a rapidly progressing disease and others exhibit an indolent course and survive for many years without treatment. Mutation status of IgVH genes utilized by CLL cells represents a very reliable predictor of clinical outcome in B-CLL, but its analysis is expensive and beyond the capacities of most diagnostic laboratories. To identify surrogate markers we performed a gene expression profiling analysis of CD19+ purified cells from 80 B-CLL untreated patients in Binet stage A, by means of Affymetrix GeneChip® HGU133A arrays. The comparison of 46 IgVH-unmutated versus 34 mutated samples using the Prediction Analysis of Microarrays software identified 78 differentially expressed probes, specific for 59 well-characterized genes. Specifically, 43 genes had a higher and 16 genes a lower average expression in the IgVH unmutated group. These genes are involved in cellular functions, including cell cycle regulation (SEPT7, SEPT10, CDK2AP1), cell proliferation (SLAMF1, LDOC1), apoptosis (CD63, IFT57, P2RX1, RNF130, TNFRSF1B), cell adhesion (CNTNAP2, C1orf38, PCDH9), immune response (ZAP70, IFI44), signal transduction (AKAP13, RASGRP1, USP6NL, TGFBR3, AKAP12), lipid metabolism and fatty-acid degradation (FADS3, LPL, LASS6), cell-cell signalling (FCRL2), phospholipid biosynthetic process (AYTL2), regulation of circadian rhythm (EGR3, CRY1, OPN3), DNA-dependent regulation of transcription (MYBL1, NR4A2, NRIP1, ZBTB20), muscle development (VAMP5, SRI, DMD). The expression signature identified in the proprietary database was then validated by means of a meta-analysis of a publicly available gene expression dataset of 100 B-CLL (Haslinger et al., 2005), showing classification accuracy measures leading to a global classification rate of 82.93% of the test set and thus suggesting the strength of the identified expression signature. The expression levels of 11 genes (LPL, ZBTB20, ZAP70, CRY1, COBLL1, SEPT10, LDOC1, TNFRSF1B, DMD, SRI, NRIP1) were confirmed by means of quantitative real-time PCR (Q-RT-PCR) in a subset of 40 CLL patients. The prognostic impact for Time To Treatment (TTT) of the 59 candidate genes of our classifier model was investigated in 77 patients. Forty-nine (36.4%) of these received treatment after a median follow up of 4 years. As expected, patients with unmutated IgVH genes had a risk of therapy requirement that was about 3 times higher (HR: 3.1,95% C.I. 1.6–5.8, p&lt;0.0001) than those with mutated IgVH. Based on microarray expression levels, 43/59 genes significantly predicted TTT with a HR ranging from 1.5 (LPL gene) to 4.2 (SRI gene) (value for ZAP-70 = HR: 1.9, 95% C.I. 1.0–3.4, p=0.039). The same analysis performed in the panel of the 11 genes validated by Q-RT-PCR revealed 4 candidate genes which significantly predicted TTT. Specifically, Cox univariate analysis confirmed ZAP-70 as a predictor of disease outcome and underscored the prognostic role of the LPL, TNFRSF1B and CRY1 genes. The predictive power of the novel putative surrogate markers for the IgVH mutation status is now being further validated at protein expression level.

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