Distant Bystander Effect of REIC/DKK3 Gene Therapy Through Immune System Stimulation in Thoracic Malignancies.

BACKGROUND

Reduced expression in immortalized cell (REIC)/Dickkoph-3 (DKK3) is a tumor-suppressor gene, and its overexpression by adenovirus vector (Ad-REIC) exhibits a remarkable therapeutic effect on various human cancer types through a mechanism triggered by endoplasmic reticulum stress.

MATERIALS AND

METHODS

We examined the direct anti-tumor effect of Ad-REIC gene therapy on lung cancer and malignant mesothelioma cell lines in vitro, and the distant bystander effect using immunocompetent mouse allograft models with bilateral flank tumors.

RESULTS

Ad-REIC treatment showed antitumor effect in many lung cancer and malignant mesothelioma cell lines in vitro. In an in vivo model, Ad-REIC treatment inhibited the growth not only of directly treated tumors but also of distant untreated tumors. By immunohistochemical analysis, infiltration of T-cells and natural killer (NK) cells and expression of the major histocompatibility complex (MHC) class I molecules were observed in bilateral tumors.

CONCLUSION

Ad-REIC treatment not only had a direct antitumor effect but also an indirect bystander effect through stimulation of the immune system.