@article{ShiKuaiLeietal.2016, author = {Shi, Yaoyao and Kuai, Yue and Lei, Lizhen and Weng, Yuanyuan and Berberich-Siebelt, Friederike and Zhang, Xinxia and Wang, Jinjie and Zhou, Yuan and Jiang, Xin and Ren, Guoping and Pan, Hongyang and Mao, Zhengrong and Zhou, Ren}, title = {The feedback loop of LITAF and BCL6 is involved in regulating apoptosis in B cell non-Hodgkin's-lymphoma}, series = {Oncotarget}, volume = {7}, journal = {Oncotarget}, number = {47}, doi = {10.18632/oncotarget.12680}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166500}, pages = {77444-77456}, year = {2016}, abstract = {Dysregulation of the apoptotic pathway is widely recognized as a key step in lymphomagenesis. Notably, LITAF was initially identified as a p53-inducible gene, subsequently implicated as a tumor suppressor. Our previous study also showed LITAF to be methylated in 89.5\% B-NHL samples. Conversely, deregulated expression of BCL6 is a pathogenic event in many lymphomas. Interestingly, our study found an oppositional expression of LITAF and BCL6 in B-NHL. In addition, LITAF was recently identified as a novel target gene of BCL6. Therefore, we sought to explore the feedback loop between LITAF and BCL6 in B-NHL. Here, our data for the first time show that LITAF can repress expression of BCL6 by binding to Region A (-87 to +65) containing a putative LITAF-binding motif (CTCCC) within the BCL6 promoter. Furthermore, the regulation of BCL6 targets (PRDM1 or c-Myc) by LITAF may be associated with B-cell differentiation. Results also demonstrate that ectopic expression of LITAF induces cell apoptosis, activated by releasing cytochrome c, cleaving PARP and caspase 3 in B-NHL cells whereas knockdown of LITAF robustly protected cells from apoptosis. Interestingly, BCL6, in turn, could reverse cell apoptosis mediated by LITAF. Collectively, our findings provide a novel apoptotic regulatory pathway in which LITAF, as a transcription factor, inhibits the expression of BCL6, which leads to activation of the intrinsic mitochondrial pathway and tumor apoptosis. Our study is expected to provide a possible biomarker as well as a target for clinical therapies to promote tumor cell apoptosis.}, language = {en} }