High BCL6 expression predicts better prognosis, independent of BCL6 translocation status, translocation partner, or BCL6-deregulating mutations, in gastric lymphoma.
To investigate the role of BCL6 in the pathogenesis of gastric lymphoma, we analyzed the BCL6 promoter region for BCL6 translocations, somatic hypermutations, and deregulating mutations in 43 gastric lymphomas, including 4 extranodal marginal-zone B-cell lymphomas of mucosa-associated lymphoid tissues (MALT lymphomas), 33 diffuse large B-cell lymphomas (DLBCLs), and 6 composite DLBCLs with residual MALT lymphoma (DLCLMLs). BCL6 promoter substitutions by immunoglobulin (Ig) and non-Ig translocation partners, resulting in its deregulation, were frequently involved in DLBCL (36.4%) and DLCLML (50%). Two novel BCL6 translocation partner genes, 28S rRNA and DMRT1, and a new BCL6 translocation breakpoint in intron 2 were also identified. Deregulating mutations were found only in DLBCL (24.2%), which correlated significantly with high BCL6 protein expression. Significantly, high BCL6 expression correlated strongly with longer overall survival (OS), independent of mechanism in gastric DLBCL and DLCLML. Gastric DLBCLs were further subclassified into germinal center B-cell-like (GCB) and non-GCB subgroups immunohistochemically. High BCL6 expression was detected in all GCB cases, irrespective of BCL6 genetic alterations. In the non-GCB subgroup, BCL6-deregulating mutations correlated significantly with high BCL6 expression level. No significant correlation was found between the BCL6 expression level and OS in the non-GCB subgroup, which had significantly poorer prognosis than the GCB subgroup.
Chen
Yun-Wen
YW
Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
Hu
Xiao-Tong
XT
Liang
Anthony C
AC
Au
Wing-Yan
WY
So
Chi-Chiu
CC
Wong
Michelle L
ML
Shen
Lijun
L
Tao
Qian
Q
Chu
Kent-Man
KM
Kwong
Yok-Lam
YL
Liang
Raymond H
RH
Srivastava
Gopesh
G
D001483:Base Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D008223:Lymphoma / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D051560:Proto-Oncogene Proteins c-bcl-6; D012689:Sequence Homology, Nucleic Acid; D013274:Stomach Neoplasms / Q000235:genetics*
C084103:BCL6 protein, human; D004268:DNA-Binding Proteins; D007136:Immunoglobulins; D051560:Proto-Oncogene Proteins c-bcl-6