Restoring FAS Expression via Lipid-Encapsulated FAS DNA Nanoparticle Delivery Is Sufficient to Suppress Colon Tumor Growth In Vivo.

Alyssa D Merting,Natasha M Savage,Honglin Li,Huidong Shi,Chunwan Lu,Kebin Liu,Michael T Redman,Dakota B Poschel,Mitzi Montgomery,Eric Chapdelaine,Dafeng Yang,Asha Nayak-Kapoor,John D Klement

doi:10.3390/cancers14020361

Alyssa D Merting, Natasha M Savage + Show 11 more

Open Access

https://doi.org/10.3390/cancers14020361

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Journal: Cancers	Publication Date: Jan 12, 2022
Citations: 8	License type: CC BY 4.0

Affiliation: Augusta University, Charlie Norwood VA Medical Center

Abstract

Simple SummaryA key feature of human colorectal tumor is loss of FAS expression. FAS is the death receptor for FASL of activated T cells. Loss of FAS expression therefore may promote tumor cell immune escape. We aimed at determining whether restoring FAS expression is sufficient to suppress colorectal tumor growth. Mouse and human FAS cDNA was synthesized and encapsulated into cationic lipid nanoparticle DOTAP-Cholesterol to formulate DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Restoring FAS expression in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS+ tumor cells in vitro and suppressed colon-tumor growth and progression in tumor-bearing mice in vivo. Restoring FAS expression induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells in vitro. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. Tumor-selective delivery of FAS DNA nanoparticle is potentially an effective therapy for human colorectal cancer.A hallmark of human colorectal cancer is lost expression of FAS, the death receptor for FASL of cytotoxic T lymphocytes (CTLs). However, it is unknown whether restoring FAS expression alone is sufficient to suppress csolorectal-cancer development. The FAS promoter is hypermethylated and inversely correlated with FAS mRNA level in human colorectal carcinomas. Analysis of single-cell RNA-Seq datasets revealed that FAS is highly expressed in epithelial cells and immune cells but down-regulated in colon-tumor cells in human colorectal-cancer patients. Codon usage-optimized mouse and human FAS cDNA was designed, synthesized, and encapsulated into cationic lipid to formulate nanoparticle DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Overexpression of codon usage-optimized FAS in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS+ tumor cells in vitro, suppressed colon tumor growth, and increased the survival of tumor-bearing mice in vivo. Overexpression of codon-optimized FAS-induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. DOTAP-Chol-mFAS therapy exhibited no significant liver toxicity. Our data determined that tumor-selective delivery of FAS DNA nanoparticles is sufficient for suppression of human colon tumor growth in vivo.

Highlights

The five-year survival rate for human colorectal cancer is 92%, but this rate drops to 7% if the cancer has metastasized to the liver
It has been reported that FAS mediates non-apoptotic signaling pathways to promote tumor growth under certain cellular context [9], tumoral FAS expression plays a key role for CAR-T cell efficacy [10], and it alone predicts survival of chimeric antigen receptor (CAR)-T-treated patients in a large clinical trial [11]
A recent CRISPR screen identified an essential role for FAS-FASL in antigen-specific T cell killing, and tumor-cell eradication by tumor-specific cytotoxic T lymphocytes (CTLs) and CAR-T cells was abrogated in FAS-deficient target cells despite the presence of activated and functional CTLs in vitro and in vivo [11]

Summary

Introduction

The five-year survival rate for human colorectal cancer is 92%, but this rate drops to 7% if the cancer has metastasized to the liver. Advances in chemotherapeutic and biological agents, combined with liver resection, have increased the survival of patients with metastatic colorectal cancer to 50% [2]. The mechanism underlying human colorectal-cancer progression and metastasis is still elusive, but down-regulation of the death receptor FAS is a hallmark of metastatic human colorectal cancer [4,5]. CD8+ cytotoxic T lymphocytes (CTLs) are the primary immune cells that kill tumor cells via the FAS-FASL [6,7] and perforin-granzyme [8] pathways. FAS is a death receptor expressed on the tumor cell surface, and its physiological ligand FASL is expressed on activated CTL and NK cell surfaces [7].

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