# Project 2 Josefowicz

> **NIH NIH P01** · WEILL MEDICAL COLL OF CORNELL UNIV · 2024 · $411,265

## Abstract

PROJECT 2: SUMMARY/ABSTRACT
Activated B cell-like diffuse large B-cell lymphoma (ABC-DLBCL) and Epstein Barr virus associated viral
lymphomas (EBV+ lymphoma) have in common that they are among the most aggressive and difficult to treat
lymphomas and both hijack potent signaling cascades to drive aggressive growth, survival, and resistance to
treatment. These hijacked signaling programs flip a potent epigenetic switch that results in activation of positive-
selection and differentiation programs that are characteristic of aged autoimmune B cells (AAB) (P3). This
chromatin program involves loss of PRC2/H3K27me3 and stimulation of CREBBP (P4), KMT2D (P1) and is
highly active at ABC-DLBCL and EBV+ lymphoma signature genes. The mechanisms by which immune synapse
signaling, viral oncogenes, or ABC-DLBCL mutations activate these epigenetic programs have not been
characterized. Our preliminary data show that histone H3 phosphorylation (H3ph) at both residue S28 (H3S28ph)
and residue 31 (H3.3S31ph), downstream of immune synapse signaling, can potently disrupt and reshape
chromatin states, acting as a sensitive signaling scaffold. Normally absent in resting B cells, we find constitutive
high-level H3ph at lymphoma signature genes in ABC-DLBCL and EBV+ lymphoma. Further, in human
lymphomas we found that H3S28ph high tumors are associated with decreased survival and that both ABC-
DLBCL and EBV+ lymphoma cells are selectively sensitive to histone kinase inhibition. Based on these
preliminary data, we hypothesize that ABC-DLBCL signaling mutations and EBV oncoproteins signal through
histone kinases and H3ph to constitutively switch on chromatin at lymphoma driver genes. To pursue this
hypothesis we will first use mechanistic, biochemical, and epigenetic studies of murine and human models of
ABC-DLBCL and EBV+ lymphoma to determine the sequence of epigenetic events that activate gene expression
downstream from Myd88 and Cd79b mutations or EBV oncoproteins, respectively, expecting that H3ph is an
initiating and dominant epigenetic event (Aim 1). Next, we will determine the direct contribution of H3ph to
malignant transformation of GC B cells by employing first-of-their-kind histone functional mutagenesis
approaches that confer constitutive activation or suppression of H3ph in mouse and human lymphoma (Aim 2).
Finally, we will determine whether chromatin kinases and histone phosphorylation are required for maintenance
of ABC-DLBCL and viral lymphomas using small-molecule inhibitors and inducible knock-down of MSK and
IKKa, and CRISPR editing of histone genes in well-characterized models of ABC-DLBCL and EBV+ lymphoma.
We expect to find that ABC-DLBCL and EBV+ lymphoma require histone kinases and H3ph for
lymphomagenesis and are addicted to their constitutive activity for maintenance. We anticipate that these studies
will establish histone kinases as novel dependencies for these aggressive lymphomas for which there are
currently few treatment options.

## Key facts

- **NIH application ID:** 10847989
- **Project number:** 1P01CA272295-01A1
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** Steven Zvi Josefowicz
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $411,265
- **Award type:** 1
- **Project period:** 2024-08-12 → 2029-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10847989

## Citation

> US National Institutes of Health, RePORTER application 10847989, Project 2 Josefowicz (1P01CA272295-01A1). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10847989. Licensed CC0.

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