Inhibitory Effects of the AttenuatedSalmonella typhimuriumContaining the IL-2 Gene on Hepatic Tumors in Mice

Abstract

To observe the inhibitory effects of an attenuated S. typhimurium strain carrying IL-2 gene (TPI) on hepatoma cell line (HepG2) and transplanted tumors in mice. TPI, TPG (an attenuated S. typhimurium strain carrying green fluorescent protein gene), and TP (an attenuated S. typhimurium strain) strains were transfected into HepG2 cells. At 48h after transfecting, the transfection rate was 82.58 ± 1.74%. The expression level of IL-2 was (99.5 ± 12.2) ng/1 × 106 cells. Compared with TPG, TP, and normal mouse groups, the proportion of CD4+ T and CD8+ T cells in the blood from the TPI group was higher, the levels of IgM and IgG1 were significantly increased, and the proliferation activity of splenic lymphocyte was significantly stronger. The transplanted tumor weight in the TPI group was significantly smaller than that in the other two groups. The infiltration of lymphocytes increased in the tumor from TPI group mice. TPI was effectively transfected into cancer cells, which expressed the protein of interest. Oral administration of TPI prolonged survival of mice transplanted with hepatoma cell tumours.

Tweak to Treat: Reprograming Bacteria for Cancer Treatment

“…Cytokines that have been delivered by engineered bacteria in preclinical studies include IL-2, IL-4, IL-12, IL-15, IL-18, interferon gamma (IFN-γ), chemokine (C-C motif) ligand 21 (CCL21), granulocyte-macrophage colony-stimulating factor (GM-CSF), FMS-like tyrosine kinase 3 ligand (FLT3L), and tumor necrosis factor superfamily member 14 (TNFSF14) [6,8]. Among these strategies, attenuated S. typhimurium delivery of IL-2 has progressed the furthest, having been tested in mouse [44], veterinary canine [8,37] and human (NCT01099631) i clinical trials. Besides relying on classical cytokines, other molecules can also serve as immunomodulators.…”

Targeted Cancer Therapy Using EngineeredSalmonella typhimurium

“…Attenuated bacteria were have been used as a delivery vehicle to express cargo molecules, such as cytotoxic agents, 21 22 30 31 43 44 45 cytokines, 46 47 48 49 50 51 RNA interference, 52 53 54 55 56 57 and prodrug enzymes, 17 58 59 60 61 62 63 in tumors to enhance BCT ( Fig. 1 ).…”

“…Attenuated S. typhimurium have been engineered to deliver immunocompetent cytokines such as IL-2, IL-18, CCL21, and LIGHT for targeted cancer immunotherapy. 46 47 48 49 50 51 Tumor-specific cytokines produced by bacteria kill cancer cells by triggering the host immune system via upregulation of immune cell activation, proliferation, and migration. IL-2 is a signaling molecule that regulates lymphocyte activity.…”

In Situ Synthesis of an Immune-Checkpoint Blocker from Engineered Bacteria Elicits a Potent Antitumor Response

“…38,39 As one of the most common attenuated Salmonella strains, S. typhimurium VNP20009 has been widely used in synthetic biology for cancer therapy, and some engineered strains are in clinical trials. 40−42 Various strategies have been employed to engineer bacteria to produce antitumor molecules, from cytokines and interleukins, including IL-2 43 and IL-18, 44 to antibodies such as CD47 45 and anti-CTLA−4 monoclonal antibodies, 46 to compounds such as STINGactivation, 47 arginine, 48 and toxins. 49,50 We engineered VNP20009 to synthesize PD-1 single-chain variable fragment antibody (scFv) and Tim-3 scFv to block the immunesuppressive checkpoint receptor and reinvigorate T cells from exhaustion, reviving their antitumor responsiveness.…”

“…The advent of synthetic biology has facilitated the use of bacteria as bioreactors for drug production and targeted drug delivery vehicles . Nonpathogenic bacteria can be genetically designed to perceive and respond to environmental signals by synthetic gene circuits, making them living therapeutics for cancer therapy. , As one of the most common attenuated Salmonella strains, S. typhimurium VNP20009 has been widely used in synthetic biology for cancer therapy, and some engineered strains are in clinical trials. − Various strategies have been employed to engineer bacteria to produce antitumor molecules, from cytokines and interleukins, including IL-2 and IL-18, to antibodies such as CD47 and anti-CTLA–4 monoclonal antibodies, to compounds such as STING-activation, arginine, and toxins. , We engineered VNP20009 to synthesize PD-1 single-chain variable fragment antibody (scFv) and Tim-3 scFv to block the immune-suppressive checkpoint receptor and reinvigorate T cells from exhaustion, reviving their antitumor responsiveness. Engineered bacteria colonize the hypoxic core of the tumor and synthesize PD-1 and Tim-3 scFv in situ , restoring the antitumor immune function of the infiltrated T lymphocytes.…”