The long-term goal of this application is the development of antisense-based, tumor-specific therapies for the EBV-associated lymphomas. EBV has been implicated in the etiology of a variety of lymphoid malignancies, including AIDS- related, post-transplantation, Burkitt's and Hodgkin's lymphomas, and transformation by the virus may be mediated in part by latent viral gene products that impact on cell growth and death. Two latent viral proteins, EBNA-1 and LMP-1 appear to play a key role in transformation. EBNA-1 is required for episomal viral DNA replication and regulates transcription of other latent viral genes. LMP-1 alters growth properties and confers resistance to apoptosis through induction of anti-apoptotic cellular genes. Given the key functions of EBNA-1 and LMP-1, they represent ideal targets for modulation by antisense strategies as a potential novel anti-tumor strategy. The applicant has demonstrated the feasibility and promise of this approach in in vitro studies using EBNA-1 and LMP-1 targeted antisense oligomers in lymphoblastoid cell lines (LCLs). These studies show that selected antisense oligomers specifically suppress the targeted viral proteins, and, importantly, elicit biological effects. Suppression of EBNA-1 is associated with inhibition of proliferation, decreased viral DNA content, down-regulation of EBNA-2 and LMP-1, and enhanced sensitivity to cytotoxic drugs. Antisense-mediated suppression of LMP-1 not only inhibits proliferation but also down-regulates anti-apoptotic genes, stimulates apoptosis, enhances chemosensitivity, and reverses resistance to cell cycle arrest by TGF-beta. These findings provide the basis for further studies of the biological and anti-tumor effects of antisense- mediated suppression of EBNA-1 and LMP-1. She will extend her in vitro studies using EBNA-1 and LMP-1 targeted antisense to tumor derived cell lines and will explore the susceptibility of EBNA-2 to antisense modulation. To address the therapeutic potential of antisense strategies, she will undertake a detailed investigation of the anti- tumor and chemosensitizing effects of EBNA-1 and LMP-1 targeted antisense using a SCID mouse model of EBV-associated lymphoma. These studies may shed further light on our understanding of the functions of latent viral proteins in the establishment and maintenance of EBV- related lymphomas, and furthermore, may provide the basis for a tumor- specific, non-toxic therapy for EBV-associated lymphomas.
