BCL6 and BCL2 inverse correlation is disrupted in patients with BCL2 translocations. (A) A series of DLBCLs (columns) is plotted in a heatmap and distributed according to their abundance of BCL6 transcript (data from Lenz et al33 ). BCL2 mRNA is generally negatively correlated with BCL6. Cases with BCL2 translocations are indicated by the red boxes in the top row. (B) Expression of BCL2 and BCL6 was examined in a series of 157 DLBCL patients by immunohistochemistry. The top bar represents patients without BCL2 translocation; bottom bar, BCL2 translocated cases. In each case, the black bar represents the percentage of patients who express both BCL6 and BCL2, whereas the gray bar represents the percentage of tumors that express either BCL2 or BCL6 exclusively. (C) Immunohistochemistry shows that DLBCL cases with t(14;18) translocations (left panel) typically exhibit malignant cells with dual BCL2 (blue) and BCL6 (brown) protein expression (right panel). FISH results were visualized using a Zeiss LSM510 Multiphoton confocal microscope (Carl Zeiss Microimaging) equipped with 40×/0.75/0.72 and 60×/0.80/0.3 objectives and one 25-mW argon laser exciting at 458, 488, and 514 nm and one 1-mW helium-neon laser exciting at 543 nm; proprietary image acquisition software was used for image analysis. (D) The DLBCL cell lines Farage (which expresses BCL6 and has wild-type BCL2 locus) and Toledo (which is BCL6-negative) were exposed for the indicated times to the specific BCL6 peptidomimetic inhibitor RI-BPI. The y-axis represents the fold increase of mRNA change induced by RI-BPI versus a control peptide. Cells were treated as indicated, and the data were from 3 independent experiments. Error bars represent the SEM for triplicates.
