Cycloartenyl ferulate improves natural killer (NK) cell immunity against cancer by binding to IFNγ receptor 1.

Cycloartenyl ferulate (CF) is abundant in brown rice with multiple biologic functions. It has been reported to possess antitumor activity; however, the related mechanism of action of CF has not been clarified. Herein, we unexpectedly uncover the immunological regulation effects of CF and its molecular mechanism. We discovered that CF directly enhanced the killing capacity of natural killer (NK) cells for various cancer cells in vitro. In vivo, CF also improved cancer surveillance in mouse models of lymphoma clearance and metastatic melanoma dependent on NK cells. In addition, CF promoted anticancer efficacy of the anti-PD1 antibody with improvement of tumor immune microenvironment. Mechanistically, we first unveiled that CF acted on the canonical JAK1/2-STAT1 signaling pathway to enhance the immunity of the NK cells by selectively binding to interferon γ receptor 1. Collectively, our results indicate that CF is a promising immunoregulation agent worthy of attention in clinical application in the future. Due to broad biological significance of interferon γ, our findings also provide a capability to understand the diverse functions of CF.

Engineering a HER2-CAR-NK Cell Secreting Soluble Programmed Cell Death Protein with Superior Antitumor Efficacy.

A new therapy strategy for relapsing patients who have received trastuzumab treatment urgently needs to be explored. HER2-specific chimeric antigen receptor (CAR)-expressing NK cells are being rapidly developed for solid tumor therapy, as they have many advantages over HER2-CAR-T cells. Endogenous soluble PD-1 (sPD-1) from the PD-1 extracellular domain blocks PD-1/PD-L1 interaction to promote cancer immunology. Herein, we engineered a new HER2-CAR-NK cell that co-expresses sPD-1 (designed as sPD-1-CAR-NK cells) and assessed its cytotoxic activities toward various cancer cells, activation of immunity and sPD-1 release in vitro and in mouse models bearing breast cancer cells with high HER2 expression, with or without trastuzumab resistance. We demonstrated that sPD-1-CAR-NK cells were able to release bioactive sPD-1, thereby enhancing the cytolytic activities of HER2-CAR-NK cells against HER2 and PD-L1 highly expressing target cells accompanied by increases in the secretion of perforin, granzyme B and IFN-γ. In vivo, sPD-1-CAR-NK cells had superior immunological anticancer efficacy compared to HER2-CAR-NK cells, and they had advantages over HER2-CAR-NK cells in the intraperitoneal injection of sPD-1. Moreover, the infiltration and activation of NK and T cells into tumor tissue were increased in mice with sPD-1-CAR-NK cells. There was no significant change in the body temperature, organ tissue and body weight in all groups except for the group with the PD-1 injection. Together, these data indicate that HER2-specific sPD-1-CAR-NK cells can transport sPD-1 into cancer tissues with high HER2 expression, further improving the efficacy of HER-CAR-NK cells without obvious side effects. sPD-1-CAR-NK is a promising cytotherapeutic agent for patients bearing HER2-positive breast cancer, including those with trastuzumab resistance.

Metformin promotes anticancer activity of NK cells in a p38 MAPK dependent manner.

Metformin, a drug prescribed to treat type 2 diabetes, has been reported to possess antitumor activity via immunity activation. However, the influence of metformin on natural killer (NK) cells is not fully understood. Here, we investigated whether metformin exerts a potent anticancer effect by activating NK cells. The results showed that sustained exposure to metformin enhances the cytolytic activity of NK-92 cells. Moreover, this enhancement of cytotoxicity by metformin was also observed in NK cells from healthy peripheral blood and cancer patient ascites. Mechanistically, metformin induced activation of the JAK1/2/3/STAT5 and AKT/mTOR pathways in a p38 MAPK-dependent manner rather than an AMPK-dependent manner. In vivo experiments, metformin also improved cancer surveillance of NK cells in mouse models of lymphoma clearance and metastatic melanoma. Additionally, combination treatment with metformin and anti-PD-1 antibodies increased the therapy response rates of B16F10 melanoma. Moreover, metformin treatment increased NK cell and T cell infiltration in tumors. Therefore, these results provide a deeper understanding of metformin on the effector function of NK cells and will contribute to the development and applications of metformin in cancer treatment strategies.

VEGF165b augments NK92 cytolytic activity against human K562 leukemia cells by upregulating the levels of perforin and granzyme B via the VEGR1-PLC pathway.

Pro-angiogenic Vascular endothelial growth factors (VEGFs) exert immunosuppressive functions on some immune cells by interacting with VEGF receptors. Blocking the VEGF/VEGFR pathway could reverse the tumor immunosuppressive microenvironment to some degree. We recently demonstrated that the anti-angiogenic VEGF isoform VEGF165b, similar to other anti-angiogenic agents, inhibit the accumulation immunosuppressive cells such as Tregs and MDSCs. However, whether VEGF165b affects the functions of immune effector cells remain unclear. Here, NK92 cell line was utilized as an immune effector cell model. Our results verified that NK92 cells endogenously express VEGF165 and VEGFR1. Further investigation showed that NK92 treatment with VEGF165b augments its killing ability against human K562 leukemia cells by upregulating perforin and granzyme B through the VEGFR1-PLC pathway, whereas VEGF165b had no impact on the proliferation of NK92 cells in vitro. The results of this study improve our understanding of the immunomodulatory function of VEGF165b, which may help in enhancing the efficacy of NK92-based cancer immunotherapy.

VEGF165b and its mutant demonstrate immunomodulatory, not merely anti-angiogenic functions, in tumor-bearing mice.

A great deal of evidence has shown that anti-angiogenic molecules and antibodies targeting the VEGF-A/VEGFRs signal pathway can also reverse tumor-induced immunosuppression to an extent. VEGF165b, an anti-angiogenic VEGF-A isoform, has demonstrated capacity as an efficacious anti-tumor therapy in mice as an anti-angiogenic agent. However, whether VEGF165b also plays an immunomodulatory role in anti-tumor field remains unclear. mVEGF165b effect on regulatory T cells (Tregs) in vitro were evaluated using flow cytometry and Cell Counting Kit-8 (CCK-8) methods. Its effects on Tregs (or Foxp3 expressing cells) and myeloid-derived suppressor cells (MDSCs) were analyzed in vivo using flow cytometry and immunostaining techniques. In this study, we found VEGF165b and its mutant (its half-life in plasma was extended 10 times while retaining its bioactivity; the VEGF165b mutant is called mVEGF165b for short) inhibited the proliferation of Tregs in vitro. In addition, mVEGF165b dramatically inhibited the accumulation of MDSCs and Tregs (or Foxp3 expressing cells) in the spleen and tumor in tumor-bearing mice. In conclusion, our findings demonstrated for the first time that VEGF165b and its mutant has immunoregulatory functions. It may be used as a potential immunomodulatory agent, beyond its anti-angiogenic capacities, in cancer therapies.

Utilizing VEGF165b mutant as an effective immunization adjunct to augment antitumor immune response.

Compelling evidence has shown that blocking VEGF via monoclonal antibodies may be beneficial in that it not only inhibits tumor angiogenesis but also reduces immune suppression and promotes T cell infiltration into tumors. Herein, we determined whether our recently generated VEGF165b mutant could be used as a co-immunization adjunct to augment the peptide cancer-vaccine- induced immune response in a mouse model of breast cancer. When co-immunized mVEGF165b with the peptide-based cancer vaccine (MUC1, a T-cell epitope dominant peptide vaccine from Mucin1), the VEGF antibody titers increased approximately 600,000-fold in mice. Moreover, the anti-VEGF antibody also reduced the frequency of regulatory T cells (Tregs) in both preventive and therapeutic scenarios. Mechanistically, the decrease of the Tregs population was associated with a remarkably increased MUC-1-specific IFN-γ-producing CD8+ T cells and anti-MUC1 humoral response. Finally, this combination co-immunization produced a superior antitumor response and significantly prolonged survival of tumor-bearing mice. In conclusion, our findings suggest that mVEGF165b may be an ideal immunization adjunct to enhance the immune efficacy of peptide-based tumor vaccines by overcoming immune tolerance.

VEGF165b mutant with a prolonged half-life and enhanced anti-tumor potency in a mouse model.

VEGF165b has been shown to be an effective anti-cancer agent; however, its short half-life limits further application in the clinical field. The development of a mutant VEGF165b with a prolonged half-life is urgently needed for its future application. A mutant VEGF165b was generated by inactivation of its plasmin cleavage site. The mutant and native VEGF165b proteins without purification tags were expressed via the Pichia pastoris expression system followed by purification with a HiTrap heparin affinity chromatography column through optimization of the purification conditions. Furthermore, its binding affinity with VEGF Receptors and its functions in vitro and in vivo were examined. Results showed that the half-life of mutant VEGF165b increased to approximately 10 times (Intravenous), 9.1 times (Intraperitoneal) and 5.4 times (Subcutaneous) greater than that of VEGF165b, and the mutation did not cause significant alteration of VEGFR1 and VEGFR2 binding affinity. Mutant VEGF165b inhibited the proliferation and migration of HUVECs in vitro, similar to the native VEGF165b. In a mouse melanoma model, mutant VEGF165b exhibited stronger anti-tumor activity in comparison with its native counterpart. These results indicate that the mutant VEGF165b had a prolonged half-life and retained the anti-angiogenic activity of the native VEGF165b, suggesting that this novel mutant VEGF165b may be a stronger anti-cancer agent.

[Over-expressed HER2 enhances proliferation, migration and invasion of melanoma B16 cells].

Objective To establish a melanoma B16 cell line stably over-expressing the HER2 (ErbB2) gene and study its effect on the proliferation, migration and invasion of melanoma cells. Methods The recombinant plasmid pCMV3-ErbB2 was transfected into B16 melanoma cell line by cationic liposome. The positive clones were screened with hygromycin B. Real-time quantitative PCR (qRT-PCR) was utilized to determine the expression of ErbB2 mRNA. Immunofluorescence was used to evaluate the expression of ErbB2 protein. MTT assay was applied to detect the cell proliferation ability. The cell migration ability was examined by a scratch assay. TranswellTM assay was performed to determine the effect of HER2 over-expression on the capability of B16s invasion. Results The cell line over-expressing HER2 was successfully established as showed by qRT-PCR. Over-expression of HER2 remarkably enhanced the proliferation, invasion and migration of B16 cells. Conclusion Over-expression of HER2 can enhance the growth and invasion of B16 cells.