Differences between BCL2-break positive and negative follicular lymphoma unraveled by whole-exome sequencing

Depending on disease stage follicular lymphoma (FL) lack the t(14;18) in ~15-~50% of cases. Nevertheless, most of these cases express BCL2. To elucidate mechanisms triggering BCL2 expression and promoting pathogenesis in t(14;18)-negative FL, exonic single-nucleotide variant (SNV) profiles of 28 t(14;18)-positive and 13 t(14;18)-negative FL were analyzed, followed by the integration of copy-number changes, copy-neutral LOH and published gene-expression data as well as the assessment of immunoglobulin N-glycosylation sites. Typical FL mutations also affected t(14;18)-negative FL. Curated gene set/pathway annotation of genes mutated in either t(14;18)-positive or t(14;18)-negative FL revealed a strong enrichment of same or similar gene sets but also a more prominent or exclusive enrichment of immune response and N-glycosylation signatures in t(14;18)-negative FL. Mutated genes showed high BCL2 association in both subgroups. Among the genes mutated in t(14;18)-negative FL 555 were affected by copy-number alterations and/or copy-neutral LOH and 96 were differently expressed between t(14;18)-positive and t(14;18)-negative FL (P<0.01). N-glycosylation sites were detected considerably less frequently in t(14;18)-negative FL. These results suggest a diverse portfolio of genetic alterations that may induce or regulate BCL2 expression or promote pathogenesis of t(14;18)-negative FL as well as a less specific but increased crosstalk with the microenvironment that may compensate for the lack of N-glycosylation.

NOTCH1-mutated chronic lymphocytic leukemia cells are characterized by a MYC-related overexpression of nucleophosmin 1 and ribosome-associated components

In chronic lymphocytic leukemia (CLL), the mechanisms controlling cell growth and proliferation in the presence of NOTCH1 mutations remain largely unexplored. By performing a gene expression profile of NOTCH1-mutated (NOTCH1-mut) versus NOTCH1 wild-type CLL, we identified a gene signature of NOTCH1-mut CLL characterized by the upregulation of genes related to ribosome biogenesis, such as nucleophosmin 1 (NPM1) and ribosomal proteins (RNPs). Activation of NOTCH1 signaling by ethylenediaminetetraacetic acid or by coculture with JAGGED1-expressing stromal cells increased NPM1 expression, and inhibition of NOTCH1 signaling by either NOTCH1-specific small interfering RNA (siRNA) or γ-secretase inhibitor reduced NPM1 expression. Bioinformatic analyses and in vitro activation/inhibition of NOTCH1 signaling suggested a role of MYC as a mediator of NOTCH1 effects over NPM1 and RNP expression in NOTCH1-mut CLL. Chromatin immunoprecipitation experiments performed on NOTCH1 intracellular domain (NICD)-transfected CLL-like cells showed the direct binding of NOTCH1 to the MYC promoter, and transfection with MYC-specific siRNA reduced NPM1 expression. In turn, NPM1 determined a proliferation advantage of CLL-like cells, as demonstrated by NPM1-specific siRNA transfection. In conclusion, NOTCH1 mutations in CLL are associated with the overexpression of MYC and MYC-related genes involved in protein biosynthesis including NPM1, which are allegedly responsible for cell growth and/or proliferation advantages of NOTCH1-mut CLL.

NOTCH1 mutations associate with low CD20 level in chronic lymphocytic leukemia: evidence for a NOTCH1 mutation-driven epigenetic dysregulation

In chronic lymphocytic leukemia (CLL), NOTCH1 mutations have been associated with clinical resistance to the anti-CD20 rituximab, although the mechanisms behind this peculiar behavior remain to be clarified. In a wide CLL series (n=692), we demonstrated that CLL cells from NOTCH1-mutated cases (87/692) were characterized by lower CD20 expression and lower relative lysis induced by anti-CD20 exposure in vitro. Consistently, CD20 expression by CLL cells was upregulated in vitro by γ-secretase inhibitors or NOTCH1-specific small interfering RNA and the stable transfection of a mutated (c.7541-7542delCT) NOTCH1 intracellular domain (NICD-mut) into CLL-like cells resulted in a strong downregulation of both CD20 protein and transcript. By using these NICD-mut transfectants, we investigated protein interactions of RBPJ, a transcription factor acting either as activator or repressor of NOTCH1 pathway when respectively bound to NICD or histone deacetylases (HDACs). Compared with controls, NICD-mut transfectants had RBPJ preferentially complexed to NICD and showed higher levels of HDACs interacting with the promoter of the CD20 gene. Finally, treatment with the HDAC inhibitor valproic acid upregulated CD20 in both NICD-mut transfectants and primary CLL cells. In conclusion, NOTCH1 mutations are associated with low CD20 levels in CLL and are responsible for a dysregulation of HDAC-mediated epigenetic repression of CD20 expression.

Exposure of B cell chronic lymphocytic leukemia (B-CLL) cells to nutlin-3 induces a characteristic gene expression profile, which correlates with nutlin-3-mediated cytotoxicity

By analyzing the cDNA obtained from 16 B-cell chronic lymphocytic leukemia (B-CLL) patient samples, we found that Nutlin-3, a small molecule inhibitor of MDM2/p53 interaction, induced a characteristic gene expression profile (GEP) signature in 13 out of 16 B-CLL samples. The lack of Nutlin-3-induced GEP signature in 3 out of 16 B-CLL samples was not due to p53 deletion and/or mutation, as demonstrated by FISH analysis and p53 sequencing. Of note, the 3 B-CLL samples in which Nutlin-3 did not elicit the GEP signature were also less susceptible to Nutlin-3-mediated cytotoxicity with respect to the remaining 13 B-CLL samples. However, the partial lack of response in these p53 wild-type B-CLL samples was not due to defects in the ability of Nutlin-3 to promote p53 induction, as confirmed by the rapid accumulation of p53 protein at Western blot analysis in response to Nutlin-3 in all samples examined. Upon exposure to Nutlin-3, the genes up-regulated with the highest score in the majority of B-CLL cells were all known p53-target genes, including genes involved in apoptotic pathways, such as FAS and BAX, as well as MDM2. Taken together, our data indicate that the ability of Nutlin-3 to induce a characteristic GEP signature correlates with its cytotoxic potential in p53 wild-type B-CLL cells. However, in some p53 wild-type B-CLL samples, the response to Nutlin-3 cannot be predicted on the basis of FISH analysis or p53 sequencing.

Correlation of high CD49d expression with disease progression and need for therapy in chronic lymphocytic leukemia (CLL) patients

7091

Background: CD49d mediates interaction of lymphocytes with microenvironmental components. We and others reported the correlated expression of CD49d and CD38 by CLL cells, and the complementary value of these molecules in predicting overall survival for CLL patients. However, nothing is known on the relationship of CD49d with other prognosticators and its impact in predicting disease progression and need for therapy in CLL. Methods: The study includes 232 CLLs (median age 64 yrs), all characterized for Rai stages, lymphocyte doubling time (LDT), CD49d, CD38 and ZAP-70 expression, serum levels for sCD23 and beta2-microglobulin (beta2-m), IgVH mutations (139/232), cytogenetics (151/232; FISH for 17p, 11q, 13q, 12). CD49d was measured in CD19/CD5 cells by three-color flow cytometry, choosing a 30% cut-off to discriminate CD49d-low vs. CD49d-high CLLs. NCI-working group criteria were used for CLL diagnosis, progression and therapy need. Results: Median time-to-progression (TTP) was 136 and 56 months in CD49d-low and CD49d-high CLL patients (p=0.00008), respectively; similarly, median time-to-treatment (TTT) was 108 and 46 months for the same patient groups (p=0.000008). Correlations were also observed among CD49d and CD38 (p=2.2x10exp-16) or ZAP-70 (p=0.00009) expression, sCD23 serum level (p=0.0017), LDT (p=0.0037), Rai stages (p=0.019), cytogenetics (p=0.011), IgVH mutations (p=0.00008). TTT and TTP were significantly shorter in CLLs in advanced Rai stages, or with high CD38 and ZAP-70 or low IgVH mutations. Within these cases, significantly longer TTP/TTT were observed in subsets expressing low CD49d. Serum levels of sCD23 and beta2-m, LDT, and FISH analyses had also predictive value for progression and treatment in our series. Within the better prognosis groups (i.e. <70 U/ml sCD23, 12 months, or a normal karyotype), high CD49d expression identified a subset of patients with significantly shorter TTP/TTT. Overall, the capability of CD49d to predict disease progression and need for therapy was statistically significant in younger patients (<64 y.o.; 115 cases; p=0.0001), but not in those older than 64 yrs (117 cases; p=0.09). Conclusions: We propone to include evaluation of CD49d expression in the prognostic assessment of CLL patients.

No significant financial relationships to disclose.

Gene and surface-antigen expression profilings concordantly identify alpha4-integrin/CD49d as a marker for unmutated (UM) bad prognosis B-cell chronic lymphocytic leukemia (B-CLL)

10076

Background: The highly heterogeneous clinical courses of B-CLL can be foreseen by investigating IgVH gene mutations or expression of specific prognosticators. Gene and surface-antigen expression profilings (GEP and SEP) have been both employed for identifying molecules of prognostic relevance in B-CLL. Methods: i) GEP - Purified B-CLL cells from 19 UM and 38 mutated (M) cases were investigated for differential GEP by using a two-color Operon Human Genome Oligo Set 2.1 platform with normal B cells as common reference and by applying, after data pre-processing, the LIMMA (Linear Model for MicroArray) package with two combined cutoffs (Bayesian log-odds>1; adjusted p value for false discovery rate <10e−4); ii) SEP - B-CLL cells from 60 UM and 101 M cases were investigated for the expression of 36 surface markers by flow cytometry. Results: i) GEP - 77 probes (32 duplicates) were overexpressed in M B-CLLs (UM/M log-ratio range −0.79/−3.62; p range 6.72e−5/3.6e−10) and 81 probes (46 duplicates) in UM B-CLLs (UM/M log-ratio range 0.87/4.57; p range 9.49e−5/3.01e−12); the CD49d gene was overexpressed in UM cases with UM/M log-ratio of 3.21 (p=8.3e-10). ii) SEP - Six markers significantly discriminated UM to M B-CLLs (t-test, p<10ed-3) and separated most UM (49/60) from M B-CLLs by hierarchical clustering; among them, CD49d was significantly overexpressed in UM cases (median % positive cells 71.2±36 vs. 10.0±31; p=2.1e−10). By applying standardized log-rank statistics in 95 pts, all with CD49d expression and survival data, 30% of positive cells was judged optimal cutoff for identifying two groups with different survivals, 41 CD49dhigh pts showing worse prognosis than 54 CD49dlow cases (p=7.4×10e−5). Similarly, 46 UM B-CLLs had shorter survival than 77 M cases (p=1.4×10e−5). By combining IgVH mutations and CD49d expression, 42 concordant M/CD49dlow pts had better prognosis than 25 concordant UM/CD49dhigh cases (p=1.8×10e−5); noteworthy, among 28 discordant cases, 16 with a M/CD49dhigh phenotype had survival similar to bad prognosis cases. Conclusions: CD49d is a novel prognosticator for B-CLL. Given its high expression level in bad prognosis subsets, CD49d may be a promising therapeutic target.

No significant financial relationships to disclose.

[Laryngeal mask vs tracheal tube in pediatric anesthesia in the presence of upper respiratory tract infection]

BACKGROUND

The aim of this report is to assess the incidence of postoperative respiratory complications in patients recently suffering from inflammation of the upper respiratory tract in whom a LMA or an uncuffed orotracheal tube have been used.

METHODS

Four hundred patients were enrolled aged 6 months to 12 years undergoing general anaesthesia for elective body surface surgery with insertion of the LMA (group M) or the uncuffed tube (group T). Acute inflammation of the upper airways (URI) was assessed, defined by the presence of at least two of the following symptoms, rhinorrhea, coughing, pharyngodynia, disphony, fever, malaise. The appearance of post-surgical adverse respiratory events (ARE), such as laryngospasm, stridor, disphony, excessive coughing was detected. Patients were divided into four groups in relation to the management of the airway and the presence or otherwise of URI (M URI, M NO URI, T URI, T NO URI).

RESULTS

In NO URI patients, the presence of ARE was 9.6% in the M and 36.9% in the T group (p < 0.001); in URI patients, these figures were respectively 31.5% and 73.9% (p < 0.001).

CONCLUSIONS

The frequency of ARE increases significantly in URI patients with both LMA and the tracheal tube, but with the former is far lower than with the latter. Despite the appearance of only minor and transient complications, it is confirmed that the tracheal intubation is an additional risk factor as a result of the mechanical airway simulation. In recent URI, it would seem appropriate to avoid tracheal intubation, if possible, preferring the LMA.