Calcineurin subunit B upregulates β-interferon production by phosphorylation of interferon regulatory factor 3 via Toll-like receptor 4

The immunostimulatory effects and pro-apoptotic activity of rhCNB against Lewis lung cancer is mediated by Toll-like receptor 4

Background

Recombinant human calcineurin B subunit (rhCNB) has been shown to be an immune‐stimulatory protein promoting cytokine production and inducing phenotypic maturation of Dendritic cells (DCs). In vivo, it has good antitumor efficacy, and has potential as an antitumor drug. Exogenous rhCNB was found to be internalized into tumor cells via the Toll‐like receptor 4 (TLR4) complex, but it was not known whether its immuno‐modulatory and antitumor functions involved entry by this same route.

Methods

The production and secretion of the cytokines and chemokines in innate immune cells induced by rhCNB were determined by ELISA, and the expression of CD40, CD80, CD86, and MHCII was analyzed by FACs. Experimental Lewis lung cancer (LLC) model was prepared in C57 BL/6 wild‐type (WT) mice, TLR4^−/− mice or their littermates by the inoculation of LLCs in their right armpit, and then administrated daily intraperitoneal injections (0.2 mL) of normal saline, rhCNB 20 mg/kg, and rhCNB 40 mg/kg, respectively.

Results

Recombinant human calcineurin B subunit promoted the production of antitumor cytokines by innate immune cells, and culture supernatants of rhCNB‐stimulated immune cells induced apoptosis of LLCs. In addition, rhCNB up‐regulated CD40, CD80, CD86, and MHCII expression in macrophages and DCs in TLR4⁺ cells but failed to do so in TLR4 deficient cells. rhCNB also induced the formation of CD4⁺ and CD8⁺T cells in splenocytes from WT mice, but not from TLR4‐deficient littermates. Intraperitoneal administration of WT C57BL/6 mice with rhCNB resulted in a 50% reduction in LLC tumor growth, but failed to inhibit tumor growth in TLR4^−/− littermates.

Conclusions

The in vivo antitumor and immunomodulatory effects of rhCNB are mediated by the TLR4. This conclusion is important for the further understanding and development of rhCNB as an antitumor drug.

Identification of a targeting-delivery peptide based on rhCNB

Calcineurin B subunit (CNB) is the regulatory subunit of calcineurin (CN), and its classical function is to regulate the activity of CN. Research in our laboratory has revealed that the recombinant human CNB (rhCNB) is a good antitumor candidate and can be internalized by tumor cells via TLR4 receptor complexes and targeted to tumor tissue in nude mice. However, the fragment or domain of rhCNB mediating internalization and target delivery has not been identified. To explore fragment- mediated rhCNB internalization and target delivery, we generated truncated derivatives of rhCNBs by recombinant DNA technology and examined their cellular uptake. Interactions between truncated rhCNBs and the TLR4 receptor were studied by ELISA and co-immunoprecipitation, and targeting of model tumors in nude mice was examined. The results showed that one truncated derivative, Trun3 (124-169aa), was taken up by cells and targeted tumors with almost the same efficiency as intact rhCNB. These results indicate that Trun3 (45aa) contains the major sequence responsible for rhCNB internalization and tumor targeting and might be developed for drug delivery to tumors.

Foot-and-mouth disease virus infection stimulates innate immune signaling in the mouse macrophage RAW 264.7 cells

The innate immune system acts as the first line of defense against invasion by bacterial and viral pathogens. The role of macrophages in innate immune responses to foot-and-mouth disease virus (FMDV) is poorly understood. To determine the mechanism underlying activation of innate immunity after FMDV infection in macrophages, we performed FMDV infection in mouse macrophage RAW 264.7 cells and found that FMDV serotype O infection induced a cytopathic effect. We then evaluated the gene expression profile in macrophage RAW 264.7 cells after FMDV infection using systematic microarray analysis. Gene ontology annotation and enrichment analysis revealed that FMDV promoted expression in a group of genes that are enriched in innate immune response and inflammatory response processes. Further research demonstrated that FMDV serotype O infection enhanced NF-κB, Toll-like, and RIG-I-like receptor signaling pathways and proteins expression and increased transcription and expression of a series of cytokines and interferons, as proved by qRT-PCR, Western blot, ELISA, and dual-luciferase reporter assay. Our study concluded that FMDV infection triggers the innate immune response in macrophages after activation of multiple innate immune pathway receptors and proteins by FMDV serotype O, resulting in activation and secretion of a series of cytokines and interferons.

Combination of calcineurin B subunit (CnB) and 5-fluorouracil reverses 5-fluorouracil-induced immunosuppressive effect and enhances the antitumor activity in hepatocellular carcinoma

Five-fluorouracil (5-FU) is a widely used chemotherapeutic agent for digestive system tumors; however, continuous use of 5-FU may cause severe side effects, including myelosuppression and immunosuppression. Our previous study revealed that calcineurin B subunit (CnB), an innovative genetic engineering antitumor protein, possesses tumor-suppressive effects with low toxicity. CnB can bind to and activate integrin αM on macrophages, subsequently promoting the expression, and secretion of TNF-related apoptosis-inducing ligand, a specific proapoptotic cytokine. In the present study, whether the combined use of CnB and 5-FU can reverse the myelosuppression, and immunosuppressive effects of 5-FU by reactivating the immune system thus increasing antitumor efficacy, was investigated. It was demonstrated that combined treatment of 5-FU and CnB led to increased tumor-suppressive effects, as indicated by reduced tumor volume and weight when compared with 5-FU or CnB treatment alone in a hepatoma xenograph model. In addition, it was demonstrated that combined treatment inhibited the proliferation of hepatoma cells. Notably, the addition of CnB to 5-FU-based therapy completely reversed the immunosuppressive effect of 5-FU. The spleen index and total number of white blood cells in the combination group were higher compared with that of the 5-FU alone group. Furthermore, pathological examinations indicated that CnB attenuated 5-FU-induced organ damage. Based on these findings, it is proposed that CnB may serve as a novel and promising drug candidate for the improvement of 5-FU-based chemotherapy.

Pimecrolimus increases the expression of interferon-inducible genes that modulate human coronary artery cells proliferation

The pharmacodynamics of the loaded compounds defines clinical failure or success of a drug-eluting device. Various limus derivatives have entered clinics due to the observed positive outcome after stent implantation, which is explained by their antiproliferative activity resulting from inhibition of the cytosolic immunophilin FK506-binding protein 12. Although pimecrolimus also binds to this protein, pimecrolimus-eluting stents failed in clinics. However, despite its impact on T lymphocytes little is known about the pharmacodynamics of pimecrolimus in cultured human coronary artery cells. We were able to show that pimecrolimus exerts antiproliferative activity in human smooth muscle and endothelial cells. Furthermore in those cells pimecrolimus induced transcription of interferon-inducible genes which in part are known to modulate cell proliferation. Modulation of gene expression may be part of an interaction between calcineurin, the downstream target of the pimecrolimus/FK506-binding protein 12-complex, and the toll-like receptor 4. In accordance are our findings showing that silencing of toll-like receptor 4 by siRNA in A549 a lung carcinoma cell line reduced the activation of interferon-inducible genes upon pimecrolimus treatment in those cells. Based on our findings we hypothesize that calcineurin inhibition may induce the toll-like receptor 4 mediated activation of type I interferon signaling finally inducing the observed effect in endothelial and smooth muscle cells. The crosstalk of interferon and toll-like receptor signaling may be a molecular mechanism that contributed to the failure of pimecrolimus-eluting stents in humans.

Cellular uptake of exogenous calcineurin B is dependent on TLR4/MD2/CD14 complexes, and CnB is an endogenous ligand of TLR4

Our previous research showed that recombinant calcineurin B (rhCnB) stimulates cytokine secretion by immune cells, probably through TLR4. Exogenous CnB can be incorporated into many different tumour cells in vitro, but the mode of uptake and receptors required remain unknown. Here, we report that exogenous CnB is taken up by cells in a time- and concentration-dependent manner via clathrin-dependent receptor-mediated internalization. Our findings further confirm that uptake is mediated by the TLR4/MD2 complex together with the co-receptor CD14. The MST results revealed a high affinity between CnB and the TLR4 receptor complex. No binding was detected between CnB and LPS. CnB inhibited the uptake of LPS, and LPS also inhibited the uptake of CnB. These results indicate that the uptake of exogenous CnB did not occur through LPS and that CnB was not a chaperone of LPS. Thus, we conclude that TLR4 receptor complexes were required for the recognition and internalization of exogenous CnB. CnB could be a potential endogenous ligand of TLR4 and function as an agonist of TLR4. These properties of CnB support its potential for development as an anti-cancer drug.

miR-190a inhibits epithelial-mesenchymal transition of hepatoma cells via targeting the long non-coding RNA treRNA

treRNA is a long non-coding RNA (lncRNA) involved in cancer progression. In this study, we show that miR-190a can silence treRNA post-transcriptionally. Suppression of treRNA by miR-190a led to significant changes of mesenchymal-epithelial transition markers and impaired migration and invasion capability of hepatoma cells. TCGA data indicated that miR-190a exhibited lower expression in hepatoma tissues, especially from patients with vascular tumor invasion, compared to normal tissues. Our results reveal the involvement of miR-190a-treRNA axis in hepatoma progression and shed light on lncRNA-based cancer therapies for hepatoma patients at high risk of metastasis.