Yin Yang 1 expression predicts a favourable survival in diffuse large B-cell lymphoma.

AIMS: Yin Yang 1 (YY1) is a multifunctional transcription factor that plays an important role in tumour development and progression, while its clinical significance in diffuse large B-cell lymphoma (DLBCL) remains largely unexplored. This study aimed to investigate the expression and clinical implications of YY1 in DLBCL.

METHODS: YY1 expression in 198 cases of DLBCL was determined using immunohistochemistry. The correlation between YY1 expression and clinicopathological parameters as well as the overall survival (OS) and progression-free survival (PFS) of patients was analyzed.

RESULTS: YY1 protein expression was observed in 121 out of 198 (61.1 %) DLBCL cases. YY1 expression was significantly more frequent in cases of the GCB subgroup than in the non-GCB subgroup ( P  = 0.005). YY1 was positively correlated with the expression of MUM1, BCL6, pAKT and MYC/BCL2 but was negatively associated with the expression of CXCR4. No significant relationships were identified between YY1 and clinical characteristics, including age, sex, stage, localization, and B symptoms. Univariate analysis showed that the OS ( P  = 0.003) and PFS ( P  = 0.005) of patients in the YY1-negative group were significantly worse than those in the YY1-positive group. Multivariate analysis indicated that negative YY1 was a risk factor for inferior OS ( P  < 0.001) and PFS ( P  = 0.017) independent of the international prognostic index (IPI) score, treatment and Ann Arbor stage. Furthermore, YY1 is more powerful for stratifying DLBCL patients into different risk groups when combined with MYC/BCL2 double-expression (DE) status.

CONCLUSIONS: YY1 was frequently expressed in DLBCL, especially in those of GCB phenotype and with MYC/BCL2-DE. As an independent prognostic factor, YY1 expression could predict a favourable outcome in DLBCL. In addition, a complex regulatory mechanism might be involved in the interactions between YY1 and MYC, pAKT as well as CXCR4 in DLBCL, which warrants further investigation.