Lentiviral-mediated Foxp3 RNAi suppresses tumor growth of regulatory T cell-like leukemia in a murine tumor model

Application of lipid-based nanoparticles in cancer immunotherapy

Immunotherapy is revolutionizing the clinical management of patients with different cancer types by sensitizing autologous or allogenic immune cells to the tumor microenvironment which eventually leads to tumor cell lysis without rapidly killing normal cells. Although immunotherapy has been widely demonstrated to be superior to chemotherapies, only a few populations of patients with specific cancer types respond to such treatment due to the failure of systemic immune activation. In addition, severe immune-related adverse events are rapidly observed when patients with very few responses are given higher doses of such therapies. Recent advances of lipid-based nanoparticles (NPs) development have made it possible to deliver not only small molecules but also mRNAs to achieve systemic anticancer immunity through cytotoxic immune cell activation, checkpoint blockade, and chimeric antigen receptor cell therapies, etc. This review summarized recent development and applications of LNPs in anticancer immunotherapy. The diversity of lipid-based NPs would encapsulate payloads with different structures and molecular weights to achieve optimal antitumor immunity through multiple mechanisms of action. The discussion about the components of lipid-based NPs and their immunologic payloads in this review hopefully shed more light on the future direction of anticancer immunotherapy.

FOXP3 knockdown inhibits the proliferation and reduces NOTCH1 expression of T cell acute lymphoblastic leukemia cells

OBJECTIVE

Forkhead box P3 (FOXP3) is a master transcriptional factor of regulatory T-cells (Tregs). Recent studies have shown that FOXP3 is associated with growth inhibition of cancer cells. However, the role of FOXP3 in acute T-lymphoblastic leukemia (T-ALL) cells is not known. It was also reported that NOTCH signaling promoted the expression of FOXP3 in Tregs. However, the effect of FOXP3 on NOTCH expression in T-ALL cells is little known. Therefore, we examined the effect of FOXP3 knockdown on the proliferation of T-ALL cells and NOTCH1 signaling.

RESULTS

Two T-ALL cell lines Jurkat and KOPT-K1, harboring activating NOTCH1 mutations, were transfected with small interfering RNA against FOXP3. Cell growth was assessed with a colorimetric assay and morphology was observed under a microscope. FOXP3 knockdown significantly reduced cell growth and induced morphological changes suggesting apoptosis. Quantitative polymerase chain reaction revealed that FOXP3 knockdown caused the downregulation of mRNA expression of NOTCH1 and HES1. These findings suggest that FOXP3 supports the growth of T-ALL cells although this can not be generalized because we examined only two cell lines. The observed growth suppression can be partly due to the downregulation of NOTCH1 signaling. FOXP3 may be a potential therapeutic target in T-ALL.

Therapeutic Potential of Gene-Modified Regulatory T Cells: From Bench to Bedside

Regulatory T cells (Tregs) are an important subset of adaptive immune cells and control immune reactions for maintaining homeostasis. Tregs are generated upon their encounter with self or non-self-antigen and mediate tolerance or suppress aberrant immune responses. A high level of specificity of Tregs to recognize antigen(s) suggested their instrumental potential to treat various inflammatory diseases. This review will first introduce seminal basic research findings in the field of Tregs over the last two decades pertinent to therapeutic approaches in progress. We will then discuss the previous approaches to use Tregs for therapeutic purposes and the more recent development of gene-modification approaches. The suppressive function of Tregs has been studied intensively in clinical settings, including cancer, autoimmunity, and allotransplantation. In cancer, Tregs are often aberrantly increased in their number, and their suppressor function inhibits mounting of effective antitumor immune responses. We will examine potential approaches of using gene-modified Tregs to treat cancer. In autoimmunity and allotransplantation, chronic inflammation due to inherent genetic defects in the immune system or mismatch between organ donor and recipient results in dysfunction of Tregs, leading to inflammatory diseases or rejection, respectively. Since the recognition of antigen is a central part in Treg function and their therapeutic use, the modulation of T cell receptor specificity will be discussed. Finally, we will focus on future novel strategies employing the therapeutic potential of Tregs using gene modification to broaden our perspective.

Ultrasound-targeted microbubble destruction-mediated Foxp3 knockdown may suppress the tumor growth of HCC mice by relieving immunosuppressive Tregs function

The aim of the present study was to investigate the effect of Forkhead family transcription factor P3 (Foxp3) knockdown on the function of cluster of differentiation (CD)4⁺CD25⁺ regulatory T cell (Tregs) and the tumor growth of a hepatocellular carcinoma (HCC) mouse model. CD4⁺CD25⁺ Tregs and CD4⁺CD25^- T cells were sorted from peripheral blood mononuclear cells (PBMCs) of patients with HCC. Then, ultrasound-targeted microbubble destruction (UTMD)-mediated Foxp3-microRNA (miRNA) was transfected into Tregs. Subsequently, CD4⁺CD25^- T cells were co-cultured with PBMC and Tregs without Foxp3-miRNA (Foxp3⁺Tregs) or Tregs with Foxp3-miRNA (Foxp3^-Tregs) and the proliferation-inhibition ratio of CD4⁺CD25^- T cells was detected using a Cell Counting Kit-8. Additionally, HCC mice were treated with UTMD-mediated Foxp3-shRNA, the tumor volume was calculated and the content of CD4⁺ and CD25⁺ T cells in the blood were detected using flow cytometry. The content of interferon-γ (IFN-γ), interleukin (IL)-2, IL-10, transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) in cultural supernatant and serum were detected by ELISA analysis. Foxp3^-Tregs significantly reduced the inhibition effect of Foxp3⁺Tregs on the proliferation of CD4⁺CD25^- T cells (P<0.01). The content of IFN-γ and IL-2 significantly increased, while IL-10 and TGF-β significantly decreased in the co-cultured system of Foxp3^-Tregs compared with the co-cultured system of Foxp3⁺Tregs (P<0.01). Following treatment with Foxp3-shRNA, the average tumor volume, ratio of Tregs/CD4⁺ T cells and level of IL-10, TGF-β and VEGF significantly decreased, however, the level of IFN-γ and IL-2 significantly increased compared with un-treated HCC mice (P<0.05). Foxp3 knockdown may suppress the tumor growth of HCC mice through relieving the immunosuppressive function of Tregs.

Amygdalin ameliorates the progression of atherosclerosis in LDL receptor‑deficient mice

Previous studies have demonstrated that regulatory T cells (Tregs) are pivotal in the regulation of T cell-mediated immune responses in atherosclerosis, a chronic autoimmune-like disease. In the authors' previous studies, it was demonstrated that amygdalin ameliorated atherosclerosis by the regulation of Tregs in apolipoprotein E-deficient (ApoE^−/−) mice. Therefore, the aim of the present study was to investigate the therapeutic effect of amygdalin on low-density lipoprotein (LDL) receptor deficient (LDLR^−/−) mice, and to examine its immune regulatory function by the stimulation of Tregs. To establish an atherosclerosis mouse model, the LDLR^−/− mice were fed a high fat and high cholesterol diet then the total plasma cholesterol, triglyceride, LDL and chemokines levels were measured by an ELISA. Following sacrificing the mice, the upper sections of the aorta were stained by hematoxylin and eosin, and Oil red O to assess the plaque area. Then western blotting and reverse transcription polymerase chain reactions were performed to analysis the expression levels of cluster of differentiation 68, monocyte chemoattractant protein-1, matrix metalloproteinase (MMP)-2, MMP-9 and forkhead box P3 (Foxp3). To further confirm the activation of FOXP3 by amygdalin, lentiviruses carrying Foxp3 shRNA were injected into the mice, and the serum cytokines levels were measured by ELISA. Following feeding of the mice with a high-fat/high-cholesterol diet, the LDLR^−/− mice demonstrated comparatively higher levels of triglyceride, total cholesterol and LDL, compared with levels in the amygdalin-treated mice. By comparing the vessel area, lumen area, plaque area, and percentage aortic plaque coverage, the effects of amygdalin on pre-existing lesions were assessed. In addition, the levels of CD68, monocyte chemoattractant protein-1, MMP-2 and MMP-9 were analyzed, and analysis of the expression of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α indicated that the mice treated with amygdalin had decreased expression of pro-inflammatory cytokines. The mRNA and protein levels of Foxp3 were also quantified, and the mice treated with amygdalin demonstrated an increased number of Tregs. The knockdown of Foxp3mRNA resulted in the increased secretion of IL-1β, IL-6 and TNF-α. Therefore, the data indicated that amygdalin regulated the formation of atherosclerosis and stabilized the plaque by suppressing inflammatory responses and promoting the immune-modulation function of Tregs. Taken together, the results demonstrated the therapeutic effect of amygdalin on atherosclerosis.

Therapeutic blockade of Foxp3 in experimental breast cancer models

PURPOSE

Regulatory T cells (Tregs) impair the clinical benefit of cancer immunotherapy. To optimize the antitumor efficacy of therapeutic dendritic cell (DC) vaccines, we aimed to inhibit Foxp3, a transcription factor required for Treg function.

METHODS

Mice bearing established syngeneic LM3 and 4T1 breast tumors were treated with antitumor DC vaccines and a synthetic peptide (P60) that has been shown to inhibit Foxp3.

RESULTS

Treatment with P60 improved the therapeutic efficacy of DC vaccines in these experimental models. In addition, monotherapy with P60 inhibited tumor growth in immunocompetent as well as in immuno-compromised animals bearing established tumors. We found expression of Foxp3 in human and murine breast tumor cells. P60 inhibited IL-10 secretion in breast cancer cells that expressed Foxp3.

CONCLUSIONS

Our results suggest that Foxp3 blockade improves the therapeutic efficacy of DC vaccines by inhibition of Tregs and through a direct antitumor effect. This strategy could prove useful to neutralize the immunosuppressive microenvironment and to boost antitumor immunity in breast cancer.

Silencing of Foxp3 enhances the antitumor efficacy of GM-CSF genetically modified tumor cell vaccine against B16 melanoma

The antitumor response after therapeutic vaccination has a limited effect and seems to be related to the presence of T regulatory cells (Treg), which express the immunoregulatory molecules CTLA4 and Foxp3. The blockage of CTLA4 using antibodies has shown an effective antitumor response conducing to the approval of the human anti-CTLA4 antibody ipilimumab by the US Food and Drug Administration. On the other hand, Foxp3 is crucial for Treg development. For this reason, it is an attractive target for cancer treatment. This study aims to evaluate whether combining therapeutic vaccination with CTLA4 or Foxp3 gene silencing enhances the antitumor response. First, the "in vitro" cell entrance and gene silencing efficacy of two tools, 2'-O-methyl phosphorotioate-modified oligonucleotides (2'-OMe-PS-ASOs) and polypurine reverse Hoogsteen hairpins (PPRHs), were evaluated in EL4 cells and cultured primary lymphocytes. Following B16 tumor transplant, C57BL6 mice were vaccinated with irradiated B16 tumor cells engineered to produce granulocyte-macrophage colony-stimulating factor (GM-CSF) and were intraperitoneally treated with CTLA4 and Foxp3 2'-OMe-PS-ASO before and after vaccination. Tumor growth, mice survival, and CTLA4 and Foxp3 expression in blood cells were measured. The following results were obtained: 1) only 2'-OMe-PS-ASO reached gene silencing efficacy "in vitro"; 2) an improved survival effect was achieved combining both therapeutic vaccine and Foxp3 antisense or CTLA4 antisense oligonucleotides (50% and 20%, respectively); 3) The blood CD4⁺CD25⁺Foxp3⁺ (Treg) and CD4⁺CTLA4⁺ cell counts were higher in mice that developed tumor on the day of sacrifice. Our data showed that tumor cell vaccine combined with Foxp3 or CTLA4 gene silencing can increase the efficacy of therapeutic antitumor vaccination.

Imaging and therapy of liver fibrosis using bioreducible polyethylenimine/siRNA complexes conjugated with N-acetylglucosamine as a targeting moiety

Diagnosis and therapy of early stage liver fibrosis is very important for the treatment of fatal liver diseases. Here, we report on the targeted imaging and therapy of activated hepatic stellate cells (HSCs) and fibrotic liver tissue using N-acetylglucosamine (GlcNAc)- and indocyanine green (ICG)-conjugated PEI/siRNA complexes. The conjugation of a disulfide bond to PEI (PEI-D) was achieved by Michael addition. We modified PEI with N-acetylglucosamine (PEI-D-GlcNAc), which can specifically interact with desmin on activated HSCs, using the EDC coupling method. Confocal microscopic analysis showed that the PEI-D-GlcNAc/siRNA was internalized by HSCs upon interaction with surface desmin. In vitro western blot analysis confirmed that PEI-D-GlcNAc provided strong protein knock-down after transfection with TGFβ1siRNA into HSCs. After a tail vein injection of ICG-conjugated complexes, the PEI-D-GlcNAc-ICG/siRNA complex accumulated to a greater extent in the livers of fibrotic mice than in normal mice over an extended duration. Moreover, immunohistofluorescence analysis confirmed that the PEI-D-GlcNAc-ICG/siRNA complex specifically colocalized with HSCs, which are desmin-positive cells, in fibrotic liver tissues. In vivo TGFβ1siRNA delivery also resulted in superior protein knock-down when using the PEI-D-GlcNAc complex. These results demonstrate that the PEI-D-GlcNAc-ICG/TGFβ1siRNA complex is a useful tool for imaging and treatment of liver fibrosis.

MED19 promotes proliferation and tumorigenesis of lung cancer

MED19 is a subunit of Mediator that is an essential component of RNA polymerase II-mediated transcription machinery. High expression levels of MED19 were examined in human lung adenocarcinoma tissues by immunohistochemical assay. MED19-specific short hairpin RNA (shRNA) expressing lentivirus was constructed and infected lung cancer cell line A549. MED19 mRNA and protein expression levels were downregulated in A549 cells as evidenced by real-time PCR and western blot assays. Importantly, MED19 inhibition resulted in impaired proliferation and colony formation, and induced accumulation of G1-phase cells and mitigated invasiveness of cells. More importantly, downregulation of MED19 expression reduced the tumorigenicity of A549 cells in vivo. It was suggested that MED19 is a novel proliferation regulator that promotes growth of lung cancer cells, thereby indicating that MED19 may serve as a new molecular target for lung cancer therapy.