Highly efficient, in-vivo Fas-mediated apoptosis of B-cell lymphoma by hexameric CTLA4-FasL

Strong activation of p53 by actinomycin D and nutlin-3a overcomes the resistance of cancer cells to the pro-apoptotic activity of the FAS ligand

The FAS ligand (FASLG) is expressed on lymphocytes, which employ it to activate death receptors on target cells. Cancer cells are generally resistant to apoptosis triggered by FASLG. In this work, we found a way to circumvent this resistance by treatment with actinomycin D (ActD) and nutlin-3a (Nut3a). We selected this drug combination based on our transcriptomic data showing strong activation of proapoptotic genes, including those for receptor-mediated apoptosis, in cells exposed to actinomycin D and nutlin-3a. To test our hypothesis, we pre-exposed cancer cell lines to this drug combination for 45 h and then treated them with recombinant FASLG. This almost instantaneously killed most cells. Actinomycin D and nutlin-3a strongly cooperated in the sensitization because the effect of the drugs acting solo was not as spectacular as the drug combination, which together with FASLG killed more than 99% of cells. Based on the caspase activation pattern (caspase-8, caspase-9, caspase-10), we conclude that both extrinsic and intrinsic pro-apoptotic pathways were engaged. In engineered p53-deficient cells, this pro-apoptotic effect was completely abrogated. Therefore, the combination of ActD + Nut3a activates p53 in an extraordinary way, which overcomes the resistance of cancer cells to apoptosis triggered by FASLG. Interestingly, other combinations of drugs, e.g., etoposide + nutlin-3a, actinomycin D + RG7112, and actinomycin D + idasanutlin had a similar effect. Moreover, normal human fibroblasts are less sensitive to death induced by ActD + Nut3a + FASLG. Our findings create the opportunity to revive the abandoned attempts of cancer immunotherapy employing the recombinant FAS ligand.

Characterizing influence of rCHOP treatment on diffuse large B-cell lymphoma microenvironment through in vitro microfluidic spheroid model

For over two decades, Rituximab and CHOP combination treatment (rCHOP) has remained the standard treatment approach for diffuse large B-cell lymphoma (DLBCL). Despite numerous clinical trials exploring treatment alternatives, few options have shown any promise at further improving patient survival and recovery rates. A wave of new therapeutic approaches have recently been in development with the rise of immunotherapy for cancer, however, the cost of clinical trials is prohibitive of testing all promising approaches. Improved methods of early drug screening are essential for expediting the development of the therapeutic approaches most likely to help patients. Microfluidic devices provide a powerful tool for drug testing with enhanced biological relevance, along with multi-parameter data outputs. Here, we describe a hydrogel spheroid-based microfluidic model for screening lymphoma treatments. We utilized primary patient DLBCL cells in combination with NK cells and rCHOP treatment to determine the biological relevance of this approach. We observed cellular viability in response to treatment, rheological properties, and cell surface marker expression levels correlated well with expected in vivo characteristics. In addition, we explored secretory and transcriptomic changes in response to treatment. Our results showed complex changes in phenotype and transcriptomic response to treatment stimuli, including numerous metabolic and immunogenic changes. These findings support this model as an optimal platform for the comparative screening of novel treatments.

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

MiR-7e-5p downregulation promotes transformation of low-grade follicular lymphoma to aggressive lymphoma by modulating an immunosuppressive stroma through the upregulation of FasL in M1 macrophages

BACKGROUND

In follicular lymphoma (FL), histologic transformation to high-grade FL and diffuse large B-cell lymphoma (DLBCL) is a critical adverse step in disease progression. Activation of the oncogene c-MYC and tumor microenvironment remodeling account for FL progression. A panel of microRNA (miRNA) was downregulated in transformed FL (tFL).

METHODS

Differentially expressed miRNAs were systematically compared in 11 lymph nodes from patients at different stages of disease. Expression of miR-7e-5p was analyzed in 46 B-cell lymphomas, including 30 FL tissues and 16 DLBCL tissues. In FL cells, transcriptional regulation of the oncogene c-MYC on its target miR-7e-5p was revealed by Chromatin Immunoprecipitation (ChIP) assay. Exosome, carrying differentially expressed miR-7e-5p was isolated and visualized by transmission electron microscope and fluorescence tracing. The effect of miR-7e-5p on recipient macrophage was determined by target gene quantification, flow cytometry, and TUNEL method in a cocultured system with miR-7e-5p-mimics or inhibitors treatment. Expression of miR-7e-5p targets, macrophage proportions, and clinical parameters were included for correlation analysis.

RESULTS

We determined that downregulation of miR-7e-5p, driven by c-MYC overexpression, was associated with poorer prognosis in FL patients. The decreased expression of miR-7e-5p in lymphoma cells led to a reduced exosomal transfer to surrounding macrophages. As a result, the target gene of miR-7e-5p, Fas ligand (FasL), was upregulated and activated the caspase signaling, which led to the apoptosis of M1 macrophages in tumor stroma. Finally, in transformed FL tissues, overexpression of FasL and activation of caspase proteins was detected in tumor stromal macrophages. Downregulation of miR-7e-5p was associated with poorer clinical outcomes.

CONCLUSION

Downregulation of exosomal miR-7e-5p induces stromal M1 macrophage apoptosis, which leads to immunosurveillance and transformation of FL.

Toxicology and Pharmacokinetic Studies in Mice and Nonhuman Primates of the Nontoxic, Efficient, Targeted Hexameric FasL: CTLA4-FasL

Cytotoxic T-lymphocyte antigen 4 (CTLA4)-FasL, a homo-hexameric signal converter protein, is capable of inducing robust apoptosis in malignant cells of the B-cell lineage expressing its cognate B7 and Fas targets, while sparing nonmalignant ones. This fusion protein's striking proapoptotic efficacy stems from its complementary abilities to coordinately activate apoptotic signals and abrogate antiapoptotic ones. A limiting factor in translating FasL or Fas receptor agonists into the clinic has been lethal hepatotoxicity. Here, we establish CTLA4-FasL's in vivo efficacy in multiple murine and xenograft models, for both systemic and subcutaneous tumors. Significantly, good laboratory practice (GLP) toxicology studies in mice indicate that CTLA4-FasL given repeatedly at doses up to five times the effective dose was well-tolerated and resulted in no significant adverse events. An equivalent single dose of CTLA4-FasL administered to nonhuman primates was also well-tolerated, albeit with a moderate dose-dependent leukopenia that was completely reversible. Interestingly, monkey peripheral blood mononuclear cells were more sensitive to CTLA4-FasL-induced apoptosis when tested in vitro. In both species, there was short-term elevation in serum levels of IL6, IL2, and IFNγ, although this was not associated with clinical signs of proinflammatory cytokine release, and further, this cytokine elevation could be completely prevented by dexamethasone premedication. Liver toxicity was not observed in either species, as confirmed by serum liver enzyme levels and histopathologic assessment. In conclusion, CTLA4-FasL emerges from animal model studies as an effective and safe agent for targeted FasL-mediated treatment of B7-expressing aggressive B-cell lymphomas.

Intrasplenic Transplantation of Cytotoxic T-Lymphocyte Associated Protein 4-Fas Ligand--Modified Hepatic Oval Cells for Acute Liver Injury in Rats

BACKGROUND

Intrasplenic transplantation of xenogeneic hepatic oval cells (HOCs) may provide metabolic support for acute liver injury. However, xenoreactive lymphocyte-mediated immune response hinders HOCs' survival in the xeno-spleen parenchyma. Cytotoxic T-lymphocyte associated protein 4-Fas ligand (CTLA4.FasL), a fusion product integrating 2 inhibitory elements against lymphocytes into 1 molecule, effectively inhibited the proliferation of allogeneic and autoimmune lymphocytes. The purpose of this study was to explore the effect of CTLA4.FasL on the proliferation of xenoreactive lymphocytes and evaluate the therapeutic efficacy of CTLA4.FasL-modified HOC transplantation on acute liver injury in rats.

METHODS

The effect of CTLA4.FasL-modified mouse liver epithelial progenitor cells (CTLA4.FasL-LEPCs) on the proliferation of rat lymphocytes in xeno-mixed lymphocyte reaction was investigated. Furthermore, CTLA4.FasL-LEPCs were intrasplenically transplanted in carbon tetrachloride- and partial hepatectomy-treated rats, and the therapeutic effect was evaluated using hematoxylin and eosin staining and alanine aminotransferase and aspartate aminotransferase assays. The hepatocytic differentiation of CTLA4.FasL-LEPCs in xenogeneic spleen was monitored by immunohistochemical staining for albumin.

RESULTS

In xeno-mixed lymphocyte reaction, CTLA4.FasL-LEPCs substantially inhibited the rat lymphocytes proliferation. CTLA4.FasL-LEPC transplantation significantly ameliorated liver injury compared with mCherry-modified LEPC and LEPC transplantation, as assessed by hematoxylin and eosin staining, alanine aminotransferase, and aspartate aminotransferase assays. Albumin positive cells appeared only in CTLA4.FasL-LEPCs group, but not in the mCherry-modified LEPCs group and LEPCs group.

CONCLUSIONS

Our results indicate CTLA4.FasL-LEPCs substantially improved liver function and structure in carbon tetrachloride- and partial hepatectomy-induced acute liver injury rats through long-term hepatocytic differentiation.

Site-specific chemical conjugation of human Fas ligand extracellular domain using trans-cyclooctene - methyltetrazine reactions

Background

Fas ligand plays a key role in the human immune system as a major cell death inducing protein. The extracellular domain of human Fas ligand (hFasLECD) triggers apoptosis of malignant cells, and therefore is expected to have substantial potentials in medical biotechnology. However, the current application of this protein to clinical medicine is hampered by a shortage of the benefits relative to the drawbacks including the side-effects in systemic administration. Effective procedures for the engineering of the protein by attaching useful additional functions are required to overcome the problem.

Results

A procedure for the site-specific chemical conjugation of hFasLECD with a fluorochrome and functional proteins was devised using an inverse-electron-demand Diels-Alder reaction between trans-cyclooctene group and methyltetrazine group. The conjugations in the present study were attained by using much less molar excess amounts of the compounds to be attached as compared with the conventional chemical modification reactions using maleimide derivatives in the previous study. The isolated conjugates of hFasLECD with sulfo-Cy3, avidin and rabbit IgG Fab’ domain presented the functional and the structural integrities of the attached molecules without impairing the specific binding activity toward human Fas receptor extracellular domain.

Conclusions

The present study provided a new fundamental strategy for the production of the engineered hFasLECDs with additional beneficial functions, which will lead to the developments of the improved diagnostic systems and the effective treatment methods of serious diseases by using this protein as a component of novel molecular tools.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-017-0381-2) contains supplementary material, which is available to authorized users.

Inhibition of MicroRNA-149-5p Induces Apoptosis of Acute Myeloid Leukemia Cell Line THP-1 by Targeting Fas Ligand (FASLG)

Background

This study was aimed to reveal the role of miR-149-5p in acute myeloid leukemia (AML) cells apoptosis and the possible mechanism involved.

Material/Methods

The expression of miR-149-5p in leukemia cell lines, as well as the blood and bone marrow (BM) samples from leukemia patients, were monitored by reverse-transcription polymerase chain reaction (RT-PCR). AML cell line THP-1 was transfected with miR-149-5p mimic or inhibitor, and then cell apoptosis was determined using the APO Percentage assay kit. The target of miR-149-5p was predicted by using the microRNA.org database, and verified by RT-PCR, Western blot, and Dual-Luciferase reporter assays. Further, small interfering RNA (siRNA) against the target gene was co-transfected with miR-149-5p inhibitor, and then the cell apoptosis and the expression of apoptosis-related proteins were assessed.

Results

MiR-149-5p was significantly up-regulated in leukemia cell lines and samples from leukemia patients (P<0.01 or P<0.001), especially in THP-1 cells and samples from AML patients. Cell apoptosis was significantly decreased by miR-149-5p overexpression (P<0.01) and increased by miR-149-5p suppression (P<0.05). Fas Ligand (FASLG) was a direct target of miR-149-5p, and was negatively regulated by miR-149-5p. More importantly, the inductive effects of miR-149-5p suppression on cell apoptosis were abrogated by si-FASLG (P<0.01). Furthermore, the up-regulative effects of miR-149-5p suppression on the phosphorylated form of Fas-associated via death domain (p-FADD), caspase-8, caspase-2, caspase-3, and the cleaved forms of these caspases were abrogated by si-FASLG.

Conclusions

Inhibition of miR-149-5p can induce apoptosis in THP-1 cells. These inductive effects might be via targeting FASLG and activating FADD and caspases.

Molecular alterations in the TCR signaling pathway in patients with aplastic anemia

Background

A previous study has demonstrated a significantly increased CD3ζ gene expression level in aplastic anemia (AA). However, the mechanism underlying the upregulated CD3ζ mRNA expression level and that of T cell activation signaling molecules in AA patients remains unclear. Thus, we investigated the expression levels of the CD3ζ, CD28, CTLA-4, and Cbl-b genes, the SNP rs231775 in the CTLA-4 gene, and the distribution of the CD3ζ 3′-UTR splice variant in AA patients.

Methods

CD3ζ 3′-UTR splice variants were identified in peripheral blood mononuclear cells (PBMCs) from 48 healthy individuals and 67 patients with AA [37 cases of severe aplastic anemia (SAA) and 30 cases of non-sever aplastic anemia (NSAA)] by RT-PCR. CD3ζ, CD28, CTLA-4, and Cbl-b gene expression was analyzed by real-time quantitative PCR. The SNP rs231775 in CTLA-4 gene was analyzed by PCR-RFLP.

Results

CD3ζ and CD28 expression was significantly higher, while CTLA-4 and Cbl-b expression was significantly lower in AA patients compared with healthy individuals. Significantly higher CD3ζ expression was found in the NSAA subgroup compared with the SAA subgroup. 64 % of the AA samples had the same genotype (WT⁺AS⁺CD3ζ 3′-UTR); 22 % of the AA patients had a WT⁺AS⁻CD3ζ 3′-UTR genotype, and 14 % of the AA patients had a WT⁻AS⁺CD3ζ 3′-UTR genotype. The CD3ζ expression level of WT⁻AS⁺ subgroup was the highest in the SAA patients. A significantly higher frequency of the GG genotype (mutant type, homozygous) of SNP rs231775 in CTLA-4 gene was found in the AA patients. Positive correlation between the CTLA-4 and Cbl-b gene expression levels was found in healthy individuals with the AA and AG genotypes, but not in the AA patients.

Conclusions

This is the first study analyzing the expression characteristics of the CD28, CTLA-4, and Cbl-b genes in AA. Our results suggest that aberrant T cell activation may be related to the first and second signals of T cell activation in AA. The GG genotype of SNP rs231775 in CTLA-4 gene might be associated with AA risk in the Chinese population. The characteristics of CD3ζ 3′-UTR alternative splicing may be an index for evaluating the T cell activation status in AA patients, particularly in SAA patients.