Obstruction of Transcription at Tumorigenic Chromosomal Translocations as Therapy
This proposal describes a novel approach by which unique gene sequences in cancer cells can be targeted as a therapeutic intervention. In the long run this project could lead to the ‘bench to bedside’ development of peptide nucleic acid (PNA) oligomers that can be delivered systemically to bind a targeted gene sequence irreversibly in a cell. Peptide nucleic acid oligomers are able to target DNA sequences because they bind more avidly to a DNA target and displace the complementary DNA strand. This strand displacement disrupts transcription, and in this manner obstructs gene expression. To deliver PNA oligomers into cells we conjugate them to peptides capable of transporting them into the nucleus where they are then capable of gene suppression at nanomolar concentrations. Therefore PNA oligomers have the ability to interfere with transcription or possibly obstructing replication of a fusion or mutated oncogene and offer a novel strategy to treat cancer. Any cancer with an activating oncogene mutation, eg. RAS, or fusion oncogene, eg. BCR/ABL, is potentially amenable to this strategy. Chemotherapeutic effectiveness for solid malignancies lag far behind those for hematopoietic malignancies. And furthermore, in the case for liposarcomas the limited recourse to effective chemotherapies provides further impetus for application of other strategies. Thus fusion-related sarcomas represent an important and neglected malignancy for targeted drug development. We will focus our preliminary work on the pathogenic FUS/CHOP gene fusion in myxoid-round cell liposarcomas. We believe that a more permanent and irreversible covalent attachment of invading PNA oligomer strand to target sequence would offer more effective suppression of functional translocation expression and thus more effective obstruction of oncogene transcription. Effectively, sufficient downregulation of the FUS/CHOP fusion gene would abrogate the tumorigenic phenotype. Initial aims would include: 1) demonstrating FUS/CHOP suppression with strand-invading PNA delivered to FUS/CHOP type-II cell line by lipofection, and optimizing suppression by varying frameshift over the target region; 2) demonstrating FUS/CHOP suppression with PNA conjugated to nuclear locating peptides and optimizing by varying composition of the transport peptide; 3) modifying PNA and PNA-peptides with alkylating moieties for covalent attachment to target, assess suppression and evidence for covalent attachment.