Objective: To detect the C-Myc, Bcl-2 and Bcl-6 gene rearrangements in diffuse large B cell lymphoma with C-Myc/Bcl-2 co-expression, also known as double expression Lymphoma (DEL), and explore the correlation between the above three gene rearrangements and the clinicopathological characteristics of DEL patients, as well as the impact on the prognosis.
Methods: Patients diagnosed as DLBCL by the Department of Pathology of affiliated Hospital of Guizhou Medical University from January 1, 2010 to December 31, 2018 were collected. Immunohistochemical (IHC) staining was used to detect the C-Myc and Bcl-2 expression, and 39 cases were screened out for the study. The expression of p65 was detected by immunohistochemical staining, gene rearrangements of C-Myc, Bcl-2 and Bcl-6 were detected by fluorescence in situ hybridization, and the expression of Epstein-Barr Virus encode RNA (Eber) was detected by ordinary hybridization in situ. Clinicopathological and follow-up data were collected. According to the results of gene rearrangement detected by FISH, these cases were divided into C-Myc, Bcl-2 and Bcl-6 gene rearrangement positive group, negative group and DHL/THL group. Fisher's exact test was performed on the experimental data, the Kaplan-Meier method was used to draw the overall survival (OS) curve of the patients, and the log-rank test was used for survival analysis. The survival curves were compared, and the prognostic factors were analyzed using the COX proportional hazards regression model.
Results: According to the results of IHC, 39 cases with double expression of C-Myc and Bcl-2 protein were included in the study. The detection results of the three gene rearrangements showed that the detection rates of C-Myc, Bcl-2 and Bcl-6 gene rearrangements were 23.08% (9/39), 23.08% (9/39) and 30.77% (12/39). C-Myc gene rearrangement was detected at the same time as Bcl-2 or Bcl-6 rearrangement (double-hit lymphoma, DHL) in 3 cases, 3 gene rearrangements were detected at the same time (triple-hit lymphoma, THL) in 2 cases, high-grade B-cell lymphoma (high grade B cell lymphoma, HGBL) (including DHL and THL) accounted for 12.80%. In 39 cases of DEL, the incidence of Bcl-2 and Bcl-6 gene rearrangement in germinal center B-cell-like double expression lymphoma (GCB-DEL) was significantly higher than that of non-germinal center B-cell like double expression lymphoma (non-GCB-DEL) (P < 0.05); HGBL also mainly occurred in non-GCB-DEL. Among 39 cases of DEL, the detection rate of C-Myc gene rearrangement and HGBL was significantly higher in cases under 60 years old (< 60 years old) was significantly higher than in cases over 60 years old (≥60 years old). The positive expression rateof nuclear factor-κB (nuclear factor-κB, NF-κB) (p65) was 53.84% (21/39), p65 positive expression rate in the non-GCB-DEL (16/23) was significantly higher than in GCB-DEL (5/16) (P < 0.05). There was no statistically significant difference in p65 positive expression between the C-Myc gene rearrangement, Bcl-2 gene and Bcl-6 gene rearrangement positive group and the negative group DEL. Among 39 cases of DEL, the survival status of Bcl-6 gene rearrangement positive cases was significantly worse than that of negative cases, while there was no statistically significant difference in survival status between the positive and negative groups of C-Myc and Bcl-2 gene rearrangement, and between HGBL and other DEL cases. There was no statistically significant difference in clinical stage, gender, primary site, bone marrow, IPI score, serum lactate dehydrogenase (LDH) and EBER expression between the positive and negative groups of C-Myc and Bcl-2 gene rearrangement, and between HGBL and other DEL cases.
Conclusion: There is a higher incidence of C-Myc, Bcl-2 and Bcl-6 gene rearrangements in DEL cases, and it is related to the patient’s age and Hans classification. The occurrence of different gene rearrangements has a certain impact on the clinical process and prognosis of DEL, Bcl-6 rearrangement is associated with poor prognosis of DEL, and the detection of three gene rearrangements should be routinely performed to provide a basis for the determination of clinical treatment plans and prognostic evaluation.