Session: 625. Lymphoma - Pre-Clinical - Chemotherapy and Biologic Agents: Novel In vivo Models of Lymphoma Therapy
Methods: To accomplish this, we developed a biomimetic spherical nanoparticle (HDL-NP) with surface chemical properties similar to natural HDL, including the ability to sequester cholesterol. Biomimetic HDL-NPs are synthesized using a 5 nm diameter gold (Au) nanoparticle (NP) as a size- and shape-restrictive template on which to assemble the surface chemical components of natural HDLs, including phospholipids and the HDL-defining apolipoprotein A1 (Apo A1). Importantly, the core AuNP template occupies the real estate in natural cholesterol-rich HDLs reserved for esterified cholesterol, which inherently limits the ability of HDL-NPs to deliver cholesterol. We incubated the HDL-NPs with various lymphoma cell lines, and similarly tested the HDL-NPs in a xenograft model.
Results: We first examined gene expression profiles of diffuse large B-cell lymphoma (DLBCL), Burkitt Lymphoma (BL) and normal B cells from patient samples in a database generated using Affymetrix U133plus 2.0 arrays in order to establish the prevalence of SR-B1 expression. We compared the expression of SR-B1 in BL cases (n=20), and DLBCL cases (n=40) that were further subdivided as activated B-cell (ABC)-like DLBCL (n=20), and germinal center (GC)-like DLBCL (n=20) to normal naive (n=3) and memory (n=3) B cells obtained from healthy donors. We found that SR-B1 was expressed at two to four-fold higher levels in the lymphomas (ABC and GC) compared with normal B cells. Next, we determined the expression of SR-B1 in lymphoma cell lines and normal peripheral lymphocytes by immunoblotting, and we found that SR-B1 is expressed in multiple B cell lymphoma cell lines, but not in Jurkat, a T-cell line, and is not expressed by normal human lymphocytes. Incubation of HDL-NP with Ramos, LY-3 and SUDHL-4 resulted in a dose-dependent decrease in cell viability and apoptosis (Figure 1) of the Ramos and SUDHL-4 cells, less so in LY-3 cells, and not in the Jurkat line. This required the nanoparticle construct and could not be duplicated by individual components of that construct, and was reversible with addition of acetylated low-density lipoprotein, indicating that the SR-B1 receptor was targeted. Xenograft experiments with SCID beige mice (C.B-Igh-1b/GbmsTac-Prkdcscid-Lystbg N7) bearing Ramos and Jurkat flank tumor xenografts confirmed the activity of the HDL-NP (Figure 2).
Conclusion: We report a template-directed and bio-functional therapeutic nanostructure that could shift the paradigm for treating lymphoma and other cancers. A combination of SR-B1 binding and manipulation of cholesterol flux is responsible for selective induction of apoptosis in B cell lymphoma.
Figure 1 Figure 2
Disclosures: Thaxton: Aurasense: Employment, Equity Ownership.
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