Our analysis provided a novel look on the transition range between FL and DLBCL, on DLBCL with poor prognosis showing expression patterns resembling that of Burkitt's lymphoma and particularly on 'double-hit' MYC and BCL2 transformed lymphomas.
Based on drug response, we identified cell line specific sensitivities, i.e. to venetoclax driven by BCL2 overexpression and partitioned subsets of BL driven by response to kinase inhibitors.
BCL-W expression was highly selected for in patient samples of Burkitt lymphoma (BL), with 88.5% expressing BCL-W. BCL-W knockdown in BL cell lines induced apoptosis, and its overexpression conferred resistance to BCL-2 family-targeting BH3 mimetics.
We recently discovered BCLW, an antiapoptotic BCL2 family member thought only to contribute to spermatogenesis, was overexpressed in diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma.
An independent cohort of 17 BL with expression of BCL2 were analysed molecularly, with 13 of 17 cases classified as molecularly defined BL (Burkitt Lymphoma) using gene expression profiling on formalin-fixed paraffin-embedded tissues.
This system mediates the efficient, temporally controlled deletion of MCL-1, both in vitro and in vivo, in human Burkitt lymphoma cell lines that require this anti-apoptotic BCL-2 protein for sustained survival and growth.
MYC gene alterations in diffuse large B-cell lymphomas and in B-cell lymphomas, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma are frequently associated with BCL2 or/and BCL6 translocations conferring a very aggressive behavior.
Five of six cases had an immunophenotype corresponding to the germinal center B cells, and only one was positive for BCL2, an immunophenotype reminiscent of that of Burkitt lymphoma.
Most cases of MYC/BCL2 DHL morphologically resemble diffuse large B-cell lymphoma (DLBCL) or B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma.
Double-hit (DH) lymphomas with MYC and either BCL2 (DH-BCL2/MYC) or BCL6 (DH-BCL6/MYC) rearrangements are considered very aggressive, many of which are now included in the category B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL) (DLBCL/BL).
The antitumor activities and apoptosis of the two types of Bcl-2 shRNA plasmid were evaluated in BALB/c nude mice bearing Burkitt's lymphoma inoculated with Raji cells.
A high Ki-67 proliferation index and positive bcl-2 staining (on cytospin slides or cell block material) of cases not conforming to typical Burkitt lymphoma morphology should prompt FISH analysis for c-MYC and/or IGH-BCL2 rearrangements to identify DHL, particularly if tissue biopsy is not expected.
Our data indicates that ATO can inhibit the proliferation of BL cell lines through 1) arresting the cell cycle; 2) decreasing the respiratory function and transmembrane potential of mitochondrial; and 3) downregulating the expressions of Survivin, Bcl-2, MCL-1, and VEGF.
The expression of CD10 and BCL6 but not BCL2, a high Ki-67 PI (>90%) and a C-MYC rearrangement but not BCL2 or BCL6 rearrangement are the features of BL.
EBERs (EBER1 and EBER2) contribute to the clonal proliferation of EBV-negative Burkitt's lymphoma (BL) cells in soft agar, tumorigenicity in SCID mice, up-regulation of the bcl-2 oncoprotein, resistance to apoptosis, and maintenance of malignant phenotypes in BL cells.
In contrast to BL, MYC aberrations in DLBCL are usually associated with multiple cytogenetic abnormalities and other genetic lesions, such as concurrent BCL2 translocations.
BCL2(+)/MYC(+) lymphomas were diagnosed as B-cell lymphoma unclassifiable (BCLU; n = 36) with features intermediate between Burkitt lymphoma and diffuse large B-cell lymphoma (DLBCL); DLBCL (n = 17), or follicular lymphoma (n = 1).
We suggest that, concordant with the WHO classification to be published in 2008, the diagnosis of BL should be restricted to cases with expression of CD10 and BCL6, absence or very weak expression of BCL2 protein, a homogeneously very high proliferation index and a proven IG-MYC translocation without evidence of a chromosomal translocation typical for other lymphoma entities.
This work therefore provides the first evidence that BHRF1, the EBV bcl2 homologue, is constitutively expressed as a latent protein in growth-transformed cells in vitro and, in the context of Wp-restricted BL, may contribute to virus-associated lymphomagenesis in vivo.
There were statistically significant differences in the expression of CD10 (28/28 vs 1/16), bcl-2 (3/28 vs 11/16), MUM1 (5/28 vs 15/16), a PI of 95.0% or more (27/28 vs 2/16), and combined CD10+/bcl-2-/bcl-6+ (24/28 vs 1/16) between BLs and DLBCL-HPSSs.