A previous study showed that this is the case in some Burkitt lymphoma (BL) cell lines, where enhanced translation of mdm2 messenger RNA results in overexpression of the protein that complexes and inactivates wild-type p53.
Activation of endogenous wt p53 in BLs and lymphoblastoid cell lines led to the induction of SAP and this was inhibited by the specific p53 inhibitor pifithrin-alpha.
Additionally, PTEN negatively correlated with p53 expression in FL and CGB DLBCL, whereas NF-κB negatively correlated with WWP2 in GCB DLBCL, but positively associated with PTEN in RFH and c-Myc in BL.
At least three genetic changes are known to contribute to the genesis of Burkitt's lymphoma (BL): the Ig/myc translocation, the presence of Epstein-Barr virus (EBV) in the vast majority of the endemic and a minority of sporadic tumors, and a p53 mutation, present in approximately 60% of the BL-derived lines.
Cells from acute lymphoblastic leukemia (ALL) and Burkitt's lymphoma cell lines express elevated levels of p53, while all examined human acute myeloid leukemia cell lines synthesize negligible p53 protein.
Combined loss of p53 induction and function due to miRNA-mediated regulation of ATM and NLK, together with the upregulation of TFAP4, may be a central role for human miRNAs in eBL oncogenesis.
Further analysis of the BL lines in which p53 had been characterized showed that whereas some lines were essentially resistant to cisplatin, three were rapidly induced to undergo apoptosis.
Here we show that chloroquine, a drug that activates the stress-responsive Atm-p53 tumor-suppressor pathway, preferentially enhances the death of Myc oncogene-overexpressing primary mouse B cells and mouse embryonic fibroblasts (MEFs) and impairs Myc-induced lymphomagenesis in a transgenic mouse model of human Burkitt lymphoma.
Immunohistochemical overexpression of p53 protein was found in 21% of NHL patients, with the highest incidence of p53 immunoreactivity in cases of Burkitt's lymphoma, follicle center lymphoma grade III, and diffuse large B-cell lymphoma.
In addition to confirming a role for the loss of p53 function in tumor progression, the data demonstrate that wt p53 protein can reduce BL tumorigenicity in vivo.
In examining the relative levels of c-Myc and p53 in human Burkitt's lymphomas and other B-lymphoid lines, we found that there is a correlation between the levels of c-Myc protein and p53 mRNA expression.
In hematological malignancies, p53 is most often mutated in Burkitt's lymphoma, with p53 mutations present in 30 to 40% of tumor samples and in 70% of cell lines.
In order to better understand the mechanisms by which chemoresistance is mediated, non-hodgkin's lymphoma (NHL) patients overexpressing p53 mutant protein and resistant to CHOP chemotherapy, NHL patients without p53 overexpression and a Burkitt's lymphoma Raji cell line with p53 overexpression have been evaluated using fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH).
In this study we linked molecular study of the p53 and p16 genes with immunohistochemical analysis of p27 expression in a group of aggressive B-cell lymphomas [large B-cell lymphomas (LBCLs) and Burkitt's lymphomas].
In this study, immunoglobulin variable (Ig V) region genes, c-myc re-arrangement and sequence and p53 status were analyzed in clones derived from a Burkitt's lymphoma cell line (LAM) in which it was previously demonstrated that Epstein-Barr virus (EBV) infection occurred late during lymphomagenesis.