Recent progress in exosome research: isolation, characterization and clinical applications.

Exosomes, a kind of nano-vesicles released by various cell types, carry a variety of "cargos" including proteins, RNAs, DNAs and lipids. There is substantial evidence that exosomes are involved in intercellular communication by exchanging "cargos" among cells and play important roles in cancer development. Because of the different expressions of "cargos" carried by exosomes in biological fluids under physiological and pathological conditions, exosomes have the potential as a minimally invasive method of liquid biopsy for cancer diagnosis and prognosis. In addition, due to their good biocompatibility, safety, biodistribution and low immunogenicity, exosomes also have potential applications in the development of promising cancer treatment methods. In this review, we summarize the recent progress in the isolation and characterization techniques of exosomes. Moreover, we review the biological functions of exosomes in regulating tumor metastasis, drug resistance and immune regulation during cancer development and outline the applications of exosomes in cancer therapy.

Leonurine promotes the maturation of healthy donors and multiple myeloma patients derived-dendritic cells via the regulation on arachidonic acid metabolism.

Objective: Leonurine is a bioactive alkaloid compound extracted from Leonurus japonicus Houtt, which potentially has immunomodulatory effects. The immunomodulatory effect and mechanism of leonurine on monocyte derived dendritic cells (moDCs) from healthy donors (HDs) and multiple myeloma (MM) patients were investigated for the first time. Methods: Peripheral blood from HDs and MM patients was isolated for peripheral blood mononuclear cells (PBMCs). The generation of moDCs was conducted by the incubation of monocytes from PBMCs in the medium consisting of RPMI 1640 medium, 2 mmol/L L-glutamine, 5% human serum, 800 U/mL GM-CSF, 500 U/mL IL-4, 100 U/mL penicillin and 0.1 mg/mL streptomycin. During the incubation of 7 days, the cells were administrated with 1 µM leonurine or 1 × PBS as the control group. On the 8th day, cells were harvested. The expression of maturation associated surface markers CD40, CD83, and HLA-DR on moDCs was analyzed by flow cytometry. Moreover, moDCs with or without 1 µM leonurine administration were evaluated by LC-MS/MS for metabolomics which was further analyzed for the potential mechanism of leonurine on moDCs. Results: The proportion of moDCs in the harvested cells was significantly higher in the HD group (n = 14) than in the MM patient group (n = 11) (p = 0.000). Leonurine significantly enhanced the median fluorescence intensity of CD83, HLA-DR and CD40 expression on HD-moDCs (n = 14; p = 0.042, p = 0.013, p = 0.084) as well as MM paitent-moDCs (n = 11; p = 0.020, p = 0.006, p = 0.025). The metabolomics data showed that in moDCs (HD, n = 15), 18 metabolites in the pathway of arachidonic acid metabolism showed significant differences between the leonurine group and the control group (VIP all >1 and P all <0.05). To be specific, 6-Keto-PGE1, 8,9-DHET, 11 (R)-HETE, 12-Keto-LTB4, 12-OxoETE, 15 (S)-HETE, 15-Deoxy-Delta12,14-PGJ2, 15-Keto-PGF2a, 20-COOH-LTB4, Lecithin, PGA2, PGB2, PGE2, PGF2a, PGG2, Prostacyclin were significantly upregulated in the leonurine group than in the control group, while Arachidonic Acid and TXB2 were significantly downregulated in the leonurine group than in the control group. Conclusion: Leonurine significantly promotes the maturation of moDCs derived from HDs and MM patients, the mechanism of which is related to arachidonic acid metabolism.

Pomalidomide enhances the maturation of dendritic cells derived from healthy donors and multiple myeloma patients.

Objective: To explore the effect of pomalidomide on the maturation of monocyte-derived dendritic cells (moDCs) from healthy donors (HDs) and multiple myeloma (MM) patients. Methods: MoDCs were generated by the incubation of monocytes from peripheral blood mononuclear cells (PBMCs) for 7 days in a medium consisting of 800 U/ml granulocyte-macrophage colony stimulating factor (GM-CSF), 500 U/ml interleukin-4 (IL-4), RPMI 1,640 medium, 5% human serum, 100 U/ml penicillin and 0.1 mg/ml streptomycin. Meanwhile, the incubation system was administrated with 10 µM pomalidomide or 1 × PBS as the control group. On the eighth day, cells were harvested and analyzed by flow cytometry. The CD80+CD86+ cell population in total cells was gated as moDCs in the FACS analyzing system. After that, the expression of CD40 and HLA-DR on moDCs was analyzed. Meanwhile, the supernatant from the incubation system was evaluated for the secretion of cytokines interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α), and macrophage inflammatory protein 1α (MIP-1α) by enzyme-linked immunosorbent assay (ELISA). Results: When analyzing all the HD-moDCs together (n = 15), pomalidomide significantly increased the mean fluorescence intensity (MFI) of CD40 expression and HLA-DR expression on moDCs compared with the control group (p = 0.003, p = 0.040). Meanwhile, the proportion of CD40+ moDCs and HLA-DR+ moDCs in total moDCs was significantly higher in the pomalidomide group than in the control group (p = 0.008, p = 0.032). When analyzing all MM patient-moDCs together (n = 11), pomalidomide significantly increased the MFI of CD40 expression and HLA-DR expression on moDCs compared with the control group (p = 0.047, p = 0.006). Meanwhile, the proportion of HLA-DR+ moDCs in total DCs was significantly higher in the pomalidomide group than in the control group (p < 0.001). Moreover, HD-moDCs (n = 8) treated with pomalidomide secreted 192% IL-12, 110% TNF-α, and 112% MIP-1α of the untreated moDCs (p = 0.020, p = 0.006, p = 0.055). However, when analyzing MM patient-moDCs (n = 10) together, the secretion of IL-12, TNF-α and MIP-1α from moDCs showed no significant difference between the pomalidomide group and the control group (p = 0.458, p = 0.377, p = 0.248). Conclusion: In vitro, 10 µM pomalidomide enhances the maturation of moDCs derived from both HDs and MM patients. Pomalidomide shows potential to be applied as a DC adjuvant for DC-based immunotherapy, such as the DC vaccine and DC cell therapy in MM.

[Effects of Dasatinib on the Maturation of Monocyte-Derived Dendritic Cells Derived from Healthy Donors and Chronic Myelogenous Leukemia Patients].

OBJECTIVE: To investigate the effects of dasatinib on the maturation of monocyte-derived dendritic cells (moDCs) derived from healthy donors (HDs) and chronic myelogenous leukemia (CML) patients. METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from HDs (n=10) and CML patients (n=10) who had got the remission of MR4.5 with imatinib treatment. The generation of moDCs from PBMCs was completed after 7 days of incubation in DC I culture medium, and another 3 days of incubation in DC II culture medium with or without 25 nmol/L dasatinib. On the 10th day, cells were harvested and expression of molecules of maturation related marker were assessed by flow cytometry. The CD80+CD86+ cell population in total cells was gated as DCs in the fluorescence-activated cell storting (FACS) analyzing system, then the expression of CD83, CD40 or HLA-DR in this population was analyzed respectively. RESULTS: The proportion of CD80+CD86+ cells in total cells didn't show a statistical difference between HD group and patient group (89.46%±9.70% vs 87.39%±9.34%, P=0.690). Dasatinib significantly enhanced the expression of the surface marker CD40 (P=0.008) and HLA-DR (P=0.028) on moDCs derived from HDs compared with the control group, while the expression of CD83 on moDCs didn't show a significant difference between dasatinib group and the control group (P=0.428). Meanwhile, dasatinib significantly enhanced the expression of the surface marker CD40 (P=0.023), CD83 (P=0.038) and HLA-DR (P=0.001) on moDCs derived from patients compared with the control group. CONCLUSION: For CML patients, the same high proportion of moDCs as HDs can be induced in vitro, which provides a basis for the application of DC-based immunotherapy strategy. Dasatinib at the concentration of 25 nmol/L can efficiently promote the maturation of moDCs derived from HDs and CML patients in vitro. Dasatinib shows potential as a DC adjuvant to be applied in DC-based immunotherapy strategies, such as DC vaccine and DC cell-therapy.

Recent progress of dendritic cell-derived exosomes (Dex) as an anti-cancer nanovaccine.

Although cancer vaccines such as dendritic cell (DC) vaccines and peptide vaccines have become appealing and attractive anticancer immunotherapy options in recent decades, some obstacles have hindered their successful application in the clinical setting. The difficulties associated with the high cost of DC preparation, storage of DC vaccines, tumor-mediated immunosuppressive environment, identification of specific tumor antigens, and high degradation of antigen peptides in vivo limit the clinical application and affect the outcomes of these cancer vaccines. Recently, nanocarriers have been considered as a new approach for vaccine delivery. As biogenic nanocarriers, exosomes are small membrane vesicles secreted by cells that carry various proteins, RNAs, and lipids. More importantly, DC-derived exosomes (Dex) express tumor antigens, MHC molecules, and co-stimulatory molecules on their surface, which trigger the release of antigen-specific CD4+ and CD8+ T cells. With their membrane structure, Dex can avoid high degradation while ensuring favorable biocompatibility and biosafety in vivo. In addition, Dex can be stored in vitro for a longer period, which facilitates a significant reduction in production costs. Furthermore, they have shown better antitumor efficacy in preclinical studies compared with DC vaccines owing to their higher immunogenicity and stronger resistance to immunosuppressive effects. However, the clinical efficacy of Dex vaccines remains limited. In this review, we aimed to evaluate the efficacy of Dex as an anticancer nanovaccine.

Recent Progress of Exosomes in Multiple Myeloma: Pathogenesis, Diagnosis, Prognosis and Therapeutic Strategies.

Multiple myeloma (MM) is a hematological malignancy that is still incurable. The bone marrow microenvironment (BMM), with cellular and non-cellular components, can create a favorable environment for the survival, proliferation and migration of MM cells, which is the main reason for the failure of MM therapies. Many studies have demonstrated that exosomes play an important role in the tumor-supportive BMM. Exosomes are nanoscale vesicles that can be released by various cells. Some exosomes contribute to the pathogenesis and progression of MM. MM-derived exosomes act on different cells in the BMM, thereby creating an environment conducive to the survival and growth of MM cells. Owing to the important roles of exosomes in the BMM, targeting the secretion of exosomes may become an effective therapeutic strategy for MM. In addition, the abnormal expression of "cargos" in the exosomes of MM patients may be used to diagnose MM or used as part of a screen for the early prognoses of MM patients. Exosomes also have good biological properties, including safety, biocompatibility, stability and biodegradability. Therefore, the encapsulation of anti-cancer drugs in exosomes, along with surface modifications of exosomes with targeting molecules, are very promising strategies for cancer therapies-particularly for MM. In addition, DC-derived exosomes (DC-EXs) can express MHC-I, MHC-II and T cell costimulatory molecules. Therefore, DC-EXs may be used as a nanocarrier to deliver cancer vaccines in MM. This review summarizes the recent progress of exosome research regarding the pathogenesis of, diagnosis of, prognosis of and therapeutic strategies for MM.

Inhibition of Multiple Myeloma Using 5-Aza-2'-Deoxycytidine and Bortezomib-Loaded Self-Assembling Nanoparticles.

PURPOSE: The aim of this study was to explore the use of self-assembling nanoparticles loaded with two chemotherapy drugs for the treatment of multiple myeloma. MATERIALS AND METHODS: Nanoparticle systems were developed based on amine polyethylene glycol-polycaprolactone (NH2-PEG-PCL) to encapsulate 5-Aza-2'-deoxycytidine and Bortezomib using the self-assemble method. Morphological changes were observed by transmission electron microscopy (TEM), and the size, drug release, long-term stability, and release of reactive oxygen species (ROS) were analyzed. The MTT assay was used to evaluate the effects of drug-loaded nanoparticles (PEG-PCL-DAC-BTZ) in inhibiting the proliferation of multiple myeloma cells (U266 and LP-1), and the TUNEL assay and Western blotting were used to measure the induction of cell apoptosis. RESULTS: Based on the diameter of NH2-PEG-PCL and PEG-PCL-DAC-BTZ, the drug-loaded nanoparticles were successfully prepared. TEM revealed that PEG-PCL-DAC-BTZ was spherically shaped. More than 90% of the drugs were released after 72 h, and PEG-PCL-DAC-BTZ maintained a good stability. U266 and LP-1 cells treated with PEG-PCL-DAC-BTZ showed the highest growth inhibition, release of ROS, and cell apoptosis compared to those treated with unloaded nanoparticles and chemotherapy drugs alone. CONCLUSION: The drug-loaded nanoparticles are a good foundation for the treatment of multiple myeloma as they showed a slow release profile, good stability, and superior anti-cancer effects in vitro.

Recent progress of graphene oxide as a potential vaccine carrier and adjuvant.

Vaccine is one of the most effective strategies for preventing and controlling infectious diseases and some noninfectious diseases, especially cancers. Adjuvants and carriers have been appropriately added to the vaccine formulation to improve the immunogenicity of the antigen and induce long-lasting immunity. However, there is an urgent need to develop new all-purpose adjuvants because some adjuvants approved for human use have limited functionality. Graphene oxide (GO), widely employed for the delivery of biomolecules, excels in loading and delivering antigen and shows the potentiality of activating the immune system. However, GO aggregates in biological liquid and induces cell death, and it also exhibits poor biosolubility and biocompatibility. To address these limitations, various surface modification protocols have been employed to integrate aqueous compatible substances with GO to effectively improve its biocompatibility. More importantly, these modifications render functionalized-GO with superior properties as both carriers and adjuvants. Herein, the recent progress of physicochemical properties and surface modification strategies of GO for its application as both carriers and adjuvants is reviewed. STATEMENT OF SIGNIFICANCE: Due to its unique physicochemical properties, graphene oxide is widely employed in medicine for purposes of photothermal treatment of cancer, drug delivery, antibacterial therapy, and medical imaging. Our work describes the surface modification of graphene oxide and for the first time summarizes that functionalized graphene oxide serves as a vaccine carrier and shows significant adjuvant activity in activating cellular and humoral immunity. In the future, it is expected to be introduced into vaccine research to improve the efficacy of vaccines.

Effects of dasatinib on CD8+T, Th1, and Treg cells in patients with chronic myeloid leukemia.

OBJECTIVE: To investigate the immunomodulatory effects of the tyrosine kinase inhibitor (TKI) dasatinib on T-cell subtypes in patients with chronic myeloid leukemia (CML). METHODS: T helper (Th) 1, Th2, regulatory T (Treg), and CD8+T cell levels were detected in patients with CML (n = 9) before and after dasatinib treatment. The corresponding response level at the time of a blood test was evaluated. RESULTS: After dasatinib treatment, six patients achieved a better response level, while three did not show improved response levels. Among the total nine patients, there were no significant differences in Th1, Th2, and Treg cell levels, whereas CD8+T cell levels were significantly increased after dasatinib treatment compared with before treatment. When we analyzed the six patients who obtained a better response level, Th1 and CD8+T cell levels were significantly increased after dasatinib treatment, but Th2 and Treg cell levels did not change. The other three patients who did not have improved response levels showed decreased Th1 cell levels and increased Treg cell levels after treatment. CONCLUSIONS: Dasatinib may increase Th1 and CD8+T cell levels, and decrease Treg cell levels in patients with CML. This finding might be associated with a good therapeutic response to this drug.

Increased expression of miR-27 predicts poor prognosis and promotes tumorigenesis in human multiple myeloma.

Multiple myeloma (MM) is an incurable hematological malignancy characterized by abnormal infiltration of plasma cells in the bone marrow. MicroRNAs (miRNAs) have emerged as crucial regulators in human tumorigenesis and tumor progression. miR-27, a novel cancer-related miRNA, has been confirmed to be implicated in multiple types of human tumors; however, its biological role in MM remains largely unknown. The present study aimed to characterize the biological role of miR-27 in MM and elucidate the potential molecular mechanisms. Here we found that miR-27 was significantly up-regulated in MM samples compared with normal bone marrow samples from healthy donors. Moreover, the log-rank test and Kaplan-Meier survival analysis displayed that MM patients with high miR-27 expression experienced a significantly shorter overall survival than those with low miR-27 expression. In the current study, we transfected MM cells with miR-27 mimics or miR-27 inhibitor to manipulate its expression. Functional studies demonstrated that miR-27 overexpression promoted MM cell proliferation, facilitated cell cycle progression, and expedited cell migration and invasion; whereas miR-27 knockdown inhibited cell proliferation, induced cell cycle arrest, and slowed down cell motility. Mechanistic studies revealed that Sprouty homolog 2 (SPRY2) was a direct target of miR-27 and that rescuing SPRY2 expression reversed the promoting effects of miR-27 on MM cell proliferation, migration, and invasion. Besides, miR-27 ablation suppressed tumorigenecity of MM cells in mouse xenograft models. Collectively, our data indicate that miR-27 exerts its oncogenic functions in MM by targetting SPRY2 and that miR-27 may be used as a promising candidate target in MM treatment.

Antibody-drug conjugates of 7-ethyl-10-hydroxycamptothecin: Sacituzumab govitecan and labetuzumab govitecan.

Monoclonal antibody (mAb), cytotoxins, and linker technology are three essential elements for developing a successful antibody-drug conjugate (ADC). In the research and development of ADCs industry, selected cytotoxins, such as auristatins and maytansines, are commonly tubulin inhibitors which are widely put into clinical use. Thereafter, with the booming development of ADCs, a large number of pharmaceutical companies have expanded a wide range of selectable cytotoxin product lines as well. Recently, the cytotoxic substance of 7-ethyl-10-hydroxycamptothecin (SN-38) conjugated to the monoclonal antibody by linker technology is developed as the second-generation ADCs. Here, the SN-38 families together with sacituzumab govitecan and labetuzumab govitecan are reviewed, whose features of metabolic pathway and toxicity in vivo are well-known. In sum, these methodology and technology would be convenient and flexible to be applied for developing the novel class of cytotoxins in ADCs industry.

[Effects of Tyrosine Kinase Inhibitors on the Th1 and Treg Cells of CML Patients].

OBJECTIVE: To compare the immunomodulatory effects of the 2nd generation of tyrosine kinase inhibitors (TKIs)-dasatinib and nilotinib as well as the 1st generation of TKI-imatinib on chronic myeloid leukemia (CML) patients. METHOD: To evaluate the T cell subtypes by flow cytometry on the CML patients of our center who received the treatment with dasatinib (n=10), nilotinib (n=26) or imatinib (n=44) for more than 3 months, and to analyze and correlate these data with the clinical remission situations and prognosis. RESULTS: 80.0% of the patients in dasatinib group, 16.6% of the patients in nilotinib group and 27.5% of the patients in imatinib group respectively had a Th1 proportion in the peripheral blood (Th1/CD4+ T) above the upper limit of normal. More specifically, the Th1 proportion in dasatinib group (30.86%±9.75%) was significantly higher than that in nilotinib group(17.37%±9.35%) (P<0.001) and that in imatinib group (20.79%±9.01%) (P<0.001). Among the 3 groups, both the CD8+ T cell proportion (CD8+ T/Lymphocyte) and the Th2 proportion (Th2/CD4+ T) in the peripheral blood did not show a statistically significant difference. The Treg proportion (Treg/CD4+ T) in dasatinib group (1.31%±0.10%) was significantly lower than that in nilotinib group (2.65%±0.97%) (P<0.001) and that in imatinib group(2.99%±1.40%) (P<0.001).Among all the CML patients analyzed, for CML patients who had a Th1 proportion above the upper limit of normal(25.8%) (n=28), 84.62% of these patients obtained CCyR (complete cytogenetic response), 71.43% of these patients obtained MMR (major molecular response), 71.43% of these patients obtained MR4.5; for CML patients who had the Th1 proportion in the normal range(11.8%-25.8%) (n=45), 90.7% of these patients obtained CCyR, 75.56% of these patients obtained MMR, and 75.56% of these patients obtained MR4.5; for CML patients who had the Th1 proportion below the lower limit of normal (11.8%) (n=21), 57.14% of these patients obtained CCyR, 47.62% of these patients obtained MMR, and 47.62% of these patients obtained MR4.5. The above-mentioned data shows that the patients in high Th1 group and the normal Th1 group obtained the higher remission rate as well as the deeper remission level. CONCLUSION: This study shows that during the CML treatment with TKIs, the increased or normal Th1 proportion indicates a bigger chance for CCyR, MMR, and MR4.5. Dasatinib may significantly increase the level of Th1 while decrease the level of Treg in the patients, as compared with nilotinib and imatinib.

Lenalidomide overcomes the immunosuppression of regulatory CD8+CD28- T-cells.

Although lenalidomide and pomalidomide are well-established treatment options in patients with multiple myeloma, their immune-modulating effects are not fully understood. While CD8+CD28- regulatory T-cells in patients with hematologic disorders display a known immune-escape mechanism, we show that lenalidomide can overcome the immunosuppressive impact of CD8+CD28- T-cells. We analyzed in vitro the antigen-specific T-cell responses of healthy donors and patients with multiple myeloma with or without the addition of autologous CD8+CD28- T-cells in the absence and presence of lenalidomide. We found that lenalidomide enhances the antigen-specific secretion of IFN-γ and Granzyme B despite the addition of CD8+CD28- T-cells. Furthermore, we showed that lenalidomide inhibits the IL-6 secretion of mononuclear cells, triggered by CD8+CD28- T-cells. The addition of IL-6 counteracts the action of lenalidomide based stimulation of IFN-γ secretion and induction of T-cell maturation but not the secretion of Granzyme B. Surprisingly, pomalidomide failed to induce IL-6 suppression and displayed immunostimulating effects only after a prolonged incubation time. Analysis of the IL-6 modulating cereblon-binding protein KPNA2 showed the similar degradation capacity of lenalidomide and pomalidomide without explaining the divergent effects. In conclusion, we showed that IL-6 and lenalidomide, but not pomalidomide, are opponents in a myeloma-antigen specific T-cell model.

Mechanisms of tetrandrine and 5-bromotetrandrine in reversing multidrug resistance may relate to down-regulation of multidrug resistance associated protein 7 expression.

Both tetrandrine (Tet) and 5-bromotetrandrine (BrTet) can effectively reverse P-glycoprotein (P-gp)-mediated multidrug resistance (MDR). The structure of multidrug resistance associated protein 7 (MRP7) has its own specificity and difference compared with other members of the MRP family. This study was aimed to investigate whether Tet and BrTet can inhibit the expression level of MRP7 so as to further look into the mechanisms of the reversal effects of Tet and BrTet on MDR. The inhibitory effects of daunorubicin (DNR) used alone on the proliferation of K562 and K562/A02 cells were evaluated by MTT assay, the IC(50) of DNR and drug resistant folds were calculated. The mRNA level of MRP7 was tested by real-time PCR, and the protein levels of MRP7 and P-gp were tested by Western blot. The DNR accumulation was analyzed by flow cytometry (FCM). The results showed that the resistance of K562/A02 cells to DNR was 23.65-folds of that of K562 cells. After administration of 1 µmol/L Tet or 2 µmol/L BrTet, the mRNA level of MRP7 in the K562/A02 cells decreased to 2% and 12% respectively, and the protein level of MRP7 decreased by 53.2% and 83.7% respectively. The protein level of P-gp decreased by 58.47% and 52.20% in the 1 µmol/L Tet and 2 µmol/L BrTet groups. FCM detection showed that 1 µmol/L Tet and 2 µmol/L BrTet significantly increased the accumulation of DNR in K562/A02 cells by 94.32% and 271% respectively. It is concluded that Tet and BrTet both can reverse MDR in vitro. The mechanisms may be related to the inhibition of MRP7 overexpression and the increase of anticancer drug concentration in cells. At the same molar concentration, the effects of Tet and BrTet in inhibiting the protein level of MRP7 expression do not show significant difference.