Abstract
Fas-associated protein with death domain (FADD), a pivotal adaptor protein transmitting apoptotic signals, is indispensable for the induction of extrinsic apoptosis. However, overexpression of FADD can form large, filamentous aggregates, termed death effector filaments (DEFs) by self-association and initiate apoptosis independent of receptor cross-linking. A mutant of FADD, which is truncated of the C-terminal tail (m-FADD, 182–205 aa) named N-FADD (m-FADD, 1–181 aa), can dramatically up-regulate the strength of FADD self-association and increase apoptosis. In this study, it was found that over-expression of FADD or N-FADD caused apoptosis of B16F10 cells in vitro, even more, N-FADD showed a more potent apoptotic effect than FADD. Meanwhile, Attenuated Salmonella Typhimurium strain VNP20009 was engineered to express FADD or N-FADD under the control of a hypoxia-induced NirB promoter and each named VNP-pN-FADD and VNP-pN-N-FADD. The results showed both VNP-pN-FADD and VNP-pN-N-FADD delayed tumor growth in B16F10 mice model, while VNP-pN-N-FADD suppressed melanoma growth more significantly than VNP-pN-FADD. Additionally, VNP-pN-FADD and VNP-pN-N-FADD induced apoptosis of tumor cells by activating caspase-dependent apoptotic pathway. Our results show that N-FADD is a more potent apoptotic inducer and VNP20009-mediated targeted expression of N-FADD provides a possible cancer gene therapeutic approach for the treatment of melanoma.
Highlights
Apoptosis is an active, genetically controlled process and is important for homeostasis of the body[1,2,3]
A mutant of mouse Fas associated protein with death domain (FADD) (m-FADD, 1–181 aa), which is truncated of the C-terminal tail (m-FADD, 182–205 aa) similar to human N-FADD (h-FADD, 1–182 aa), was constructed and VNP20009 was engineered to express FADD or N-FADD (VNP-pN-FADD, VNP-pN-N-FADD) under the control of a hypoxia-induced NirB promoter in tumor tissues
The death domain (DD) and death effector domain (DED) of FADD are essential for interaction with death receptors and transmission of the apoptotic signal, while the DED and DD are highly conserved across all species examined (Fig. 1A)
Summary
Genetically controlled process and is important for homeostasis of the body[1,2,3]. Over-expression of FADD or its variants can self-induced apoptosis of tumor cells, making the potential of FADD or its variants used as anti-tumor agents. For the apoptosis deficiency in tumor cells, we hypothesized that tumor-specific delivery of FADD or its variant by VNP20009 with the potential to enhance apoptosis and improve the antitumor effect of VNP20009. A mutant of mouse FADD (m-FADD, 1–181 aa), which is truncated of the C-terminal tail (m-FADD, 182–205 aa) similar to human N-FADD (h-FADD, 1–182 aa), was constructed and VNP20009 was engineered to express FADD or N-FADD (VNP-pN-FADD, VNP-pN-N-FADD) under the control of a hypoxia-induced NirB promoter in tumor tissues. After intraperitoneal injection of genetically engineered Salmonella strains into mice carrying melanoma xenografts, it was found that VNP-pN-N-FADD significantly suppressed tumor growth and prolonged survival time of mouse, suggesting a potential strategy for melanoma therapy
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
