Hypoxia Targeted Infectious Knockdown for the Treatment of Solid Tumors

Introduction

Intratumoral hypoxia is a characteristic feature of solid tumors. The management of tumor cells in hypoxic regions is a critical barrier in oncology, as they have a slow metabolism, and are resistant to chemotherapy and radiation. HIF-1 and CREB provide a survival advantage to tumors in the hypoxic tumor microenvironment. We have previously shown that knockdown of either CREB or HIF-1 inhibits tumor progression. To date, there are no effective treatments for metastatic uveal melanoma (UM). ‎The aim of this study ‎is to test the effect of infectious knockdown of CREB and HIF-1 on UM.

Material and method

Uveal melanoma cells expressing luciferase and infected with a ‎MuLV-based replication competent retroviral (RCR) vector expressing shRNA targeting either ‎ CREB or HIF-1 were tested for knockdown efficiency in vitro. The effect of the armed viruses on subcutaneous tumor growth in mice was monitored weekly via bioluminescence (IVIS). 5 weeks post-implantation, tumors were excised and analyzed.

Results and discussion

Infection with the armed viruses resulted in an efficient knockdown CREB, HIF-1, and downstream genes. The efficient knockdown resulted in an inhibition of cell growth in vitro. Subcutaneous xenografts infected with armed viruses ‎had a halted growth rate as opposed to the steady fast growth of the control ‎tumors. In correlation with the non-invasive luciferase-based method, at the end of the experiment, the mean weight of the tumors ‎infected with an armed virus knocking down HIF-1 was only 42% of the mean ‎tumor weight of the control tumors, and the mean weight of the tumors ‎infected with an armed virus knocking down CREB was only 16% of the mean ‎control tumor.

Conclusion

Infectious knockdown via armed viruses targeting the hypoxia regulators ‎CREB and HIF-1 is effective against metastatic uveal melanoma in vitro and in vivo. These results indicate that armed viruses controlling the cellular response to hypoxia may be the basis of a new treatment modality for solid tumors.