Lentiviral vector transduction provides nonspecific immunogenicity for syngeneic tumor models

Abstract

Lentivirus-based transduction systems are widely used in biological science and cancer biology, including cancer immunotherapy. However, in in vivo transplanted tumor model, the immunogenicity of these transduced cells was not appropriately addressed. Here, we used empty vector-transduced mouse melanoma (B16) and carcinoma (lewis lung carcinoma) cells transplanted tumor model to study the immune response due to the transduction processes. We showed that the overall in vivo tumor growth rate gets reduced in transduced cells only in immune-competent mice but not in nude mice. This data indicate the involvement of the immune system in the in vivo tumor growth restriction in the transduced group. Further studies showed that specific activation of CD8⁺ T cells might be responsible for restricted tumor growth. Mechanistically, transduced tumor cells show the higher activity of type I interferon, which might play an essential role in this activation. Overall, our data indicate the modulation of the immune system by lentiviral vector transduced tumor cells, which required further studies to explore the mechanisms and better understand the biological significance. Our data also indicate the importance of considering the immunogenicity of transduced cells when analyzing in vivo results, especially in studies related to immunotherapy.

Keywords: CD8+ T cells; lentivirus; type I interferon.

Figure 1:. Empty vector-induced tumor cell lines showed lower tumor growth.

A. Schematic diagram of vector transduction. B. Tumor volume curve. C. Representative image of tumor growth in PAR-LLC and EVT-LLC groups. D. Bar diagram indicates mean tumor weight ± SEM E. Histological representation of the PAR-LLC and EVT-LLC group tumor sample. F. Representative image of colony formation assay. G. bar diagram indicates the mean % cell death ± SEM. H. Tumor cell proliferation by MTT assay± SEM. I. tumor volume curve for B16 melanoma model*<0.05, **<0.005.

Figure 2.. Activated CD8 T cells prevent EVT tumor growth.

A. Representative flowcytometry graph. B. Bar diagram indicates the mean percent cell population ± SEM C. Bar diagram indicates mean fold change ± SEM D. Tumor growth curve in nude mice. Graph indicates tumor growth in day dependent manner. Every data point indicates average tumor volume ± SEM E. Representative tumor growth in nude mice. F. Bar diagram indicates mean tumor volume ± SEM in nude mice. G. Bar diagram indicates fold change ± SEM in mRNA expression of different chemokine *<0.05, **<0.005, ***<0.0002, ****<0.0001

Figure 3.. Effect of the supernatant on splenocytes.

A. Schematic diagram of experimental design. B. Bar diagram indicates average T cells activation ± SEM. C. Bar diagram indicates ave age tumor cell death ± SEM.

Figure 4.. EVT tumor secret IFNγ.

A. & B. Bar diagram indicates the mean ± SEM fold change of mRNA expression of anti-viral sensor pathway of cell line and tumor respectively. C. Representative Flow cytometry data indicates the CD137 marker. Bar diagram indicates the mean percentage of CD137 ± SEM. *<0.05; **<0.005; ***<0.001.