Inhibition of human diffuse large B-cell lymphoma growth by JC polyomavirus-like particles delivering a suicide gene

Abstract

Background: Diffuse large B-cell lymphoma (DLBCL) is one of the most common types of aggressive B-cell non-Hodgkin lymphoma. About one-third of patients are either refractory to the treatment or experience relapse afterwards, pointing to the necessity of developing other effective therapies for DLBCL. Human B-lymphocytes are susceptible to JC polyomavirus (JCPyV) infection, and JCPyV virus-like particles (VLPs) can effectively deliver exogenous genes to susceptible cells for expression, suggesting the feasibility of using JCPyV VLPs as gene therapy vectors for DLBCL.

Methods: The JCPyV VLPs packaged with a GFP reporter gene were used to infect human DLBCL cells for gene delivery assay. Furthermore, we packaged JCPyV VLPs with a suicide gene encoding thymidine kinase (TK) to inhibit the growth of DLBCL in vitro and in vivo.

Results: Here, we show that JCPyV VLPs effectively entered human germinal center B-cell-like (GCB-like) DLBCL and activated B-cell-like (ABC-like) DLBCL and expressed the packaged reporter gene in vitro. As measured by the MTT assay, treatment with tk-VLPs in combination with gancyclovir (GCV) reduced the viability of DLBCL cells by 60%. In the xenograft mouse model, injection of tk-VLPs through the tail vein in combination with GCV administration resulted in a potent 80% inhibition of DLBCL tumor nodule growth.

Conclusions: Our results demonstrate the effectiveness of JCPyV VLPs as gene therapy vectors for human DLBCL and provide a potential new strategy for the treatment of DLBCL.

Figure 1

Transduction of the green fluorescent protein gene into human DLBCL cells by JCPyV VLPs in vitro . GCB-like, Toledo (A) and HT (B), and ABC-like, SU-DHL-2 (C), DLBCL cells were infected with control VLPs or with gfp-VLPs. The expression of green fluorescent protein in the infected cells was visualized with a fluorescence microscope.

Figure 2

Transduction of the green fluorescent protein gene into human DLBCL tumor nodules by JCPyV VLPs in a xenograft mouse model. Human DLBCL–xenografted mice were administered control VLPs or gfp-VLPs intravenously. The DLBCL tumor nodules were frozen-sectioned, and the expression of green fluorescent protein was visualized with a fluorescence microscope.

Figure 3

Cytotoxic effect of tk-VLPs on human DLBCL cells. The viability of DLBCL cells at different days after various treatments was assessed by the MTT assay. The treatment combinations included PBS followed by PBS (PBS/PBS), PBS followed by GCV (PBS/GCV), control VLPs followed by GCV (VLP/GCV), the pUMVC1‐tk plasmid followed by GCV (tk/GCV), tk-VLPs followed by PBS (tk‐VLP/PBS) and tk-VLPs followed by GCV (tk-VLP/GCV).

Figure 4

Inhibition of human DLBCL tumor nodule growth by tk-VLPs in a xenograft mouse model. The human DLBCL–xenografted mice were intravenously administered control VLPs or tk-VLPs in the presence or absence of GCV. (A) Gross pictures of tumor nodules from each treatment group. (B) Quantification of tumor weights for the different treatment groups. *, P < 0.05.