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Diffuse large B-cell lymphomas (DLBCL) are aggressive tumors that arise from germinal center B-cells (GCB). Post GCB are noted for their heterogeneity and variable clinical outcomes. In previous genome wide studies we found profound alterations in the cytosine methylation patterning of DLBCL and that the expression of activation-induced deaminase (AID) was associated with the loss of methylation in DLBCL patients. AID functions as demethylase during embryonic development, which led us to ask whether AID has demethylase activity during the transit of B-cells through the germinal center, and if over expression contributes to lymphomagenesis through the disruption of DNA methylation.
This question was addressed in an abstract during the 56th annual meeting of the American Society of Hematology (ASH). We studied the epigenetic function of AID in GCB and germinal center-derived lymphomas. Our preliminary results indicate that high AID expression is correlated with a more aggressive phenotype of the disease. We are currently analyzing the epigenetic targets of AID in both normal GCB and tumors, in order to find genes that could be epigenetically deregulated and contribute to the formation of lymphomas. These results demonstrate – for the first time – that AID functions as a demethylase in GCB in vivo. This suggests that the epigenetic role of AID could contribute to lymphomagenesis.
Diffuse large B cell lymphoma (DLBCL) is a common aggressive lymphoma that represents 30-40% of newly diagnosed cases of non-Hodgkin lymphoma, but accounts for up to 80% of lymphoma-related deaths. Although R-CHOP remains the standard first line therapy, it has more recently been associated with a frequent lack of response in DLBCL patients. This lack of response has enforced the necessity for finding alternate therapeutic targets.
At the 2014 meeting of the American Association for Cancer Research researchers from Weill Cornell Medical College reported on their recent findings. In a late breaking abstract the Shaknovich Lab reported on the potential of the IL10 receptor as a new biomarker and therapeutic target in DLBCL. The hypothesis is that DLBCL is dependent on the feed-forward autostimulatory loop that begins from the autocrine IL10 secretion and stimulation of overexpressed receptors leading to cell proliferation and that blocking the receptor would lead to cell death.
The research team of postdoctoral fellow Wendy Beguelin and research associate Seema Sawh determined that blocking IL10R results in specific inhibition of signaling through JAK1/2 and loss of phosphorylation at STAT3Y705 immediately after treatment. The inhibition of signaling through MAPK and phosphorylation of STAT3S727 came at a later time in treatment. The inhibition of signaling was sustained for days with only one drug treatment leading to induction of apoptosis. Anti-IL10R treatment resulted in significant downregulation of IL10 and IL10RA transcription, leading to interruption of IL10-IL10R autostimulatory loop.
IL10R is a novel therapeutic target in DLBCL that allows for easy detection and targeting. Shaknovich Lab is planning further animal studies and hopes to develop therapeutic antibody for clinical use in patients.