Effect of 5-Aza-2’-deoxycytidine on immune-associated proteins in exosomes from hepatoma

Role of extracellular vesicle-associated proteins in the progression, diagnosis, and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, characterized by difficulties in early diagnosis, prone to distant metastasis, and high recurrence rates following surgery. Extracellular vesicles (EVs) are a class of cell-derived particles, including exosomes, characterized by a phospholipid bilayer. They serve as effective carriers for intercellular communication cargo, including proteins and nucleic acids, and are widely involved in tumor progression. They are being explored as potential tumor biomarkers and novel therapeutic avenues. We provide a brief overview of the biogenesis and characteristics of EVs to better understand their classification standards. The focus of this review is on the research progress of EV-associated proteins in the field of HCC. EV-associated proteins are involved in tumor growth and regulation in HCC, participate in intercellular communication within the tumor microenvironment (TME), and are implicated in events including angiogenesis and epithelial-mesenchymal transition (EMT) during tumor metastasis. In addition, EV-associated proteins show promising diagnostic efficacy for HCC. For the treatment of HCC, they also demonstrate significant potential including enhancing the efficacy of tumor vaccines, and as targeting cargo anchors. Facing current challenges, we propose the future directions of research in this field. Above all, research on EV-associated proteins offers the potential to enhance our comprehension of HCC and offer novel insights for developing new treatment strategies.

Combined treatment with epigenetic agents enhances anti-tumor activity of MAGE-D4 peptide-specific T cells by upregulating the MAGE-D4 expression in glioma

Objective

The study evaluated the efficacy of combined epigenetic drugs of decitabine (DAC), valproic acid (VPA), and trichostatin A (TSA) on immunotherapy against glioma.

Methods

The expression and prognosis of MAGE-D4 in glioma were analyzed online, and the expression of MAGE-D4 and HLA-A2 in glioma induced by epigenetic drugs was detected by qRT-PCR, Western blot, and flow cytometry. The methylation status of the MAGE-D4 promoter was determined by pyrosequencing. An HLA-A2 restricted MAGE-D4 peptide was predicted and synthesized. An affinity assay and a peptide/HLA complex stability assay were performed to determine the affinity between peptide and HLA. CCK8 assay, CFSE assay, ELISA and ELISPOT were performed to detect the function of MAGE-D4 peptide-specific T cells. Flow cytometry, ELISA, and cytotoxicity assays were used to detect the cytotoxicity effect of MAGE-D4 peptide-specific T cells combined with epigenetic drugs against glioma in vitro. Finally, the glioma-loaded mouse model was applied to test the inhibitory effect of specific T cells on gliomas in vivo.

Results

MAGE-D4 was highly expressed in glioma and correlated with poor prognosis. Glioma cells could be induced to express MAGE-D4 and HLA-A2 by epigenetic drugs. MAGE-D4-associated peptides were found that induce DCs to stimulate the highest T-cell activities of proliferation, IL-2 excretion, and IFN-γ secretion. MAGE-D4 peptide-specific T cells treated with TSA only or combining TSA and DAC had the most cytotoxicity effect, and its cytotoxicity effect on glioma cells decreased significantly after HLA blocking. In vivo experiments also confirmed that MAGE-D4-specific T cells inhibit TSA-treated glioma.

Conclusion

MAGE-D4 is highly expressed in glioma and correlated with the prognosis of glioma. The novel MAGE-D4 peptide identified was capable of inducing MAGE-D4-specific T cells that can effectively inhibit glioma growth, and the epigenetic drug application can enhance this inhibition.

Kita-Kyushu Lung Cancer Antigen-1 (KK-LC-1): A Promising Cancer Testis Antigen

Cancer has always been a huge problem in the field of human health, and its early diagnosis and treatment are the key to solving this problem. Cancer testis antigens (CTAs) are a family of multifunctional proteins that are specifically expressed in male spermatozoa and tumor cells but not in healthy somatic cells. Studies have found that CTAs are involved in the occurrence and development of tumors, and some CTAs trigger immunogenicity, which suggests a possibility of tumor immunotherapy. The differential expression and function of CTAs in normal tissues and tumor cells can promote the screening of tumor markers and the development of new immunotherapies. This article introduces the expression of Kita-Kyushu lung cancer antigen-1 (KK-LC-1), a new member of the CTA family, in different types of tumors and its role in immunotherapy.

Extracellular Chaperones as Novel Biomarkers of Overall Cancer Progression and Efficacy of Anticancer Therapy

Exosomal heat shock proteins (Hsps) are involved in intercellular communication both in physiological and pathological conditions. They play a role in key processes of carcinogenesis including immune system regulation, cell differentiation, vascular homeostasis and metastasis formation. Thus, exosomal Hsps are emerging biomarkers of malignancies and possible therapeutic targets. Adolescents and young adults (AYAs) are patients aged 15–39 years. This age group, placed between pediatric and adult oncology, pose a particular challenge for cancer management. New biomarkers of cancer growth and progression as well as prognostic factors are desperately needed in AYAs. In this review, we attempted to summarize the current knowledge on the role of exosomal Hsps in selected solid tumors characteristic for the AYA population and/or associated with poor prognosis in this age group. These included malignant melanoma, brain tumors, and breast, colorectal, thyroid, hepatocellular, lung and gynecological tract carcinomas. The studies on exosomal Hsps in these tumors are limited; however; some have provided promising results. Although further research is needed, there is potential for future clinical applications of exosomal Hsps in AYA cancers, both as novel biomarkers of disease presence, progression or relapse, or as therapeutic targets or tools for drug delivery.

Exosome plays an important role in the development of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most malignant cancers around the world. However, the early biomarkers for its detection and treatment are limited currently. Exosomes, classified as intercellular messenger shuttling their cargoes between cells, regulate cell differentiation and tissue development. They contain messenger RNA (mRNA), microRNA (miRNA), long non-coding RNA (lncRNA), circular RNA (circRNA), proteins, lipids and transcription factors. Therefore, exosomes play a crucial role in the development of HCC. In this review, we highlight the exosomal cargoes which could serve as biomarkers for the prediction and diagnosis of HCC. Exosomes are involved in metastases of HCC and they show great potential in immunotherapy and drug resistance mechanism. In summary, exosome suggests new clues in clinical application of HCC.

The functional role of exosome in hepatocellular carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide with limited therapeutic options. Exosome is a member of extracellular vesicles that can be released by different cells in liver to communicate with other cells. HCC development has been characterized by a dysfunction of exosome regulation through many molecular mechanisms. The aim of the present review is to summarize the literature on exosomes in HCC, their roles in hepatocarcinogenesis from liver disease, molecules exchange between tumor cells and neighboring cells, metastasis, chemoresistant, immunosuppression, early diagnose and therapy application.

METHODS

Literatures about HCC and exosomes from PubMed databases were reviewed in this article.

RESULTS

As our review described, exosomes can induce malignant transformation of liver disease via promoting viral diffusion and inflammation, exchange oncogenic factors between tumor cells, sustain tumor growth by neighboring stromal cells, play a important role in metastasis, trigger chemoresistance through transmitting long noncoding RNAs, stimulate immune activation as well as immune evasion, be utilized in biomarkers discovery and therapeutic options.

CONCLUSIONS

Available data suggested that exosomes may play an important role in HCC development. More studies on the way that exosomes mediated the HCC progression are needed to promote the clinical utilization of exosomes.

Imaging of angiogenesis of human umbilical vein endothelial cells by uptake of exosomes secreted from hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a typical hyper-vascular tumor, so the understanding the mechanisms of angiogenesis in HCC is very important for its treatment. However, the influence of the exosomes secreted from HCC cells (HCC-exosomes) on angiogenesis remains poorly understood. We herein examined the effects of the exosomes secreted from HepG2 cells (HepG2-exosomes) on the lumen formation of human umbilical vein endothelial cells (HUVECs) by the imaging of angiogenesis. The degree of lumen formation of HUVECs was dependent on the number of HepG2-exosomes. The HepG2-exosomes expressed NKG2D, an activating receptor for immune cells, and HSP70, a stress-induced heat shock protein associated with angiogenesis through the vascular endothelial growth factor (VEGF) receptor. In addition, the HepG2-exosomes contained several microRNAs (miRNAs) reported to exist in the serum of HCC patients. These results suggest that the HCC-exosomes play an important role in angiogenesis. Further studies on the function of HCC-exosomes may provide a new target for HCC treatment.

Exosomes: small vesicles with big roles in hepatocellular carcinoma

Despite improvements in the diagnosis and treatment of hepatocellular carcinoma (HCC), the prognosis is still poor. Pioneering work has demonstrated a potential role for tumour cell-derived exosomes (TEXs) in HCC. TEXs can mediate immune responses, antigen presentation and intracellular communication by serving as vehicles for the transfer of proteins, viruses, lipids and RNA between cells. An improved understanding of the roles played by exosomes could lead to a powerful new strategy for preventing and treating HCC. In this review, we summarise current understanding on the topic. The literature points to two faces of TEXs in HCC: 1) They can promote invasion, metastasis, immune evasion and modulation and 2) they can act as diagnostic and prognostic biomarkers, and can be used in anti-cancer drug resistance and immunotherapy in the future.

Role of exosomes and exosomal microRNAs in hepatocellular carcinoma: Potential in diagnosis and antitumour treatments (Review)

Communication between hepatocellular carcinoma (HCC) cells and their environment is essential for the development and progression of HCC. Exosomes, which are microvesicles secreted by a number of cell types, are carriers of intercellular information and regulate the tumour microenvironment. Studies have demonstrated that exosomes are involved in the communication between HCC cells, endothelial cells and stem cells, and that they serve important roles in the metastasis and invasion, immune evasion and immunotherapy of HCC. In addition, the mechanism of HCC-derived exosome-mediated microRNA (miRNA) transfer is important in the environmental modulation of HCC growth and progression. As exosomes can be used for detecting and monitoring HCC, they can potentially serve as specific biomarkers for early-stage tumours and the tumour metastasis of HCC. Moreover, mesenchymal stem cell-derived exosomes can be transfected with miRNAs to inhibit HCC development. Therefore, as nucleic acid delivery vehicles, exosomes show a tremendous potential for effective treatment against HCC. In the present review, recent advances in our understanding of the source, composition and function of exosomes in HCC, and their potential value in the early diagnosis and treatment of HCC, are summarized.

Effects of Decitabine on Invasion and Exosomal Expression of miR-200c and miR-141 in Oxaliplatin-Resistant Colorectal Cancer Cells

The effects of decitabine (DAC), a DNA methyltransferase (DNMT) inhibitor, on metastasis and exosomal expression of microRNAs were examined in SW620/OxR cells, a human colorectal cancer (CRC) cell line (SW620) with acquired resistance to oxaliplatin. This cell line shows an invasive phenotype by epithelial-mesenchymal transition. Two CRC cell lines, SW480, derived from primary CRC, and SW620, derived from lymph node metastasis, which were obtained from the same patient, as well as SW620/OxR, were also used in the present study. Cytarabine (Ara-C), a non-DNMT-inhibiting cytidine analog, was used as negative control of DAC. No significant difference was observed in the invasion abilities of SW480 cells treated with DAC or Ara-C. On the other hand, invasion ability was suppressed by treatment with DAC in SW620 and SW620/OxR cells. Up-regulated expression of E-cadherin, microRNA-200c (miR-200c), and miR-141 following DAC treatment indicated the acquisition of epithelial cell-like characteristics in SW620 and SW620/OxR cells. Exosomal expression levels of miR-200c and miR-141 were also up-regulated by DAC treatment in SW620 and SW620/OxR but not in SW480 cells. This increase in exosomal miRNA expression negatively correlated with invasion ability. These results suggest that DNA demethylation treatment caused acquisition of epithelial cell-like characteristics in SW620 and SW620/OxR cells. Furthermore, the observed increased exosomal expression of miR-200c and miR-141 may be an indicator or biomarker candidate for mesenchymal-epithelial transition of CRC cells.

Comparison of ultracentrifugation and density gradient separation methods for isolating Tca8113 human tongue cancer cell line-derived exosomes

The aim of the present study was to compare the method of ultracentrifugation and density gradient separation for isolating Tca8113 human tongue squamous cell carcinoma cell line-derived exosomes. The exosomes were obtained from the culture supernatant of cultured Tca8113 cells, respectively, followed by identification with transmission electron microscopy observation and western blot analysis. The two different methods were then compared by the morphology, the distribution range of the particle size and the concentration of proteins of the extracted exosomes. In vitro, Tca8113 cells can secrete a large amount of vesicle-like structures, which are identified as exosomes by the presence of the surface markers, Hsp-70 and Alix. The protein profile of the two products are almost the same, however the particle size distribution of the exosomes extracted with density gradient centrifugation are more limited, between 40–120 nm, and these have a higher protein concentration. The results indicate that Tca8113 cells can secrete exosomes in vitro, and the density gradient separation methods for purifying exosomes is improved, which is helpful for future research and application of exosomes.

Pharmacokinetic and pharmacodynamic analysis of 5-aza-2'-deoxycytidine (decitabine) in the design of its dose-schedule for cancer therapy

5-Aza-2′-deoxycytidine (5-AZA-CdR, decitabine), an epigenetic drug that inhibits DNA methylation, is currently used to treat myelodysplastic syndrome (MDS), and is under investigation for treating acute myeloid leukemia (AML) and other malignancies. 5-AZA-CdR can reactivate tumor suppressor genes silenced by aberrant DNA methylation, a frequent event in all types of cancer. Because this epigenetic change is reversible, it is a good target for 5-AZA-CdR therapy. We have reviewed the preclinical data of 5-AZA-CdR to analyze the concentrations and exposure times required to eradicate cancer stem cells. We analyzed the dose-schedules used in animal models that show potent antineoplastic activity of 5-AZA-CdR. We attempted to correlate the preclinical data with the responses obtained in clinical trials of 5-AZA-CdR in patients with cancer. The pharmacokinetics and drug distribution of 5-AZA-CdR are key parameters because adequate therapeutic drug levels are required to eliminate cancer stem cells in all anatomic compartments. The plasma half-life of 5-AZA-CdR in humans is approximately 20 minutes due to the high levels in the liver of cytidine deaminase, the enzyme that inactivates this analogue. This provides a rationale to use an inhibitor of cytidine deaminase in combination with 5-AZA-CdR. Low-dose 5-AZA-CdR is effective for MDS and AML and can induce complete remissions (CR). However, maintenance of CR with low-dose 5-AZA-CdR is difficult. Based on analyses of preclinical and clinical data, low dose 5-AZA-CdR has the potential to be an effective form of therapy in some patients with cancer. For patients who do not respond to low dose therapy we recommend dose-intensive treatment with 5-AZA-CdR. Patients who are candidates for intensive dose 5-AZA-CdR should have a good bone marrow status so as to permit adequate recovery from myelosuppression, the major toxicity of 5-AZA-CdR. Solid tumors are also interesting targets for therapy with 5-AZA-CdR. Both low dose and intensive therapy with 5-AZA-CdR can reduce the proliferative potential of tumor stem cells in animal models. We propose novel dose schedules of 5-AZA-CdR for investigation in patients with cancer. The full chemotherapeutic potential of 5-AZA-CdR to treat cancer merits further clinical investigation and can only be realized when its optimal dose-schedule is determined.

Role of SUMO-1, MDM2 and P53 in 5-flurouracil-induced apoptosis of HepG2 cells

AIM: To investigate the role of small ubiquitin-like modifier-1 (SUMO-1), murine double minute gene 2 (MDM2) and P53 in 5-flurouracil (5-Fu)-induced apoptosis of HepG2 cells.

METHODS: Non-transfected HepG2 cells and HepG2 cells transfected with pMDM2 and pSUMO-1 plasmids, alone or both, were treated with different concentrations of 5-Fu for 36 hours. The expression of endogenous P53 protein in HepG2 cells was detected by Western blot.

RESULTS: Treatment with 5-Fu significantly increased the relative expression level of endogenous P53 protein and the apoptosis rate of HepG2 cells in a concentration-dependent manner (90.15% ± 4.22% vs 11.27% ± 1.18%, 33.61% ± 3.15% vs 3.22% ± 0.60%, both P < 0.05). Cells transfected with the pMDM2 plasmid had an apparent resistance to 5-Fu-induced apoptosis of HepG2 cells. The relative expression level of P53 protein and the apoptosis rate in cells transfected with the pMDM2 plasmid were much lower than those in non-transfected cells treated with the same concentration of 5-Fu (51.80% ± 0.78% vs 90.15% ± 4.22%; 20.45% ± 2.23% vs 33.61% ± 3.15%, both P < 0.05). No significant differences were noted in the relative expression level of P53 protein and the apoptosis rate between cells co-transfected with the pSUMO-1 and pMDM2 plasmids and non-transfected cells (78.85% ± 2.43% vs 51.80% ± 0.78%, 29.83% ± 0.53% vs 20.45% ± 2.23%, both P < 0.05).

CONCLUSION: SUMO-1 could inhibit MDM2-induced degradation of P53 protein and enhance the nuclear expression of P53, thus promoting 5-Fu-induced cell apoptosis and elevating chemosensitivity.

Let-7 microRNA family is selectively secreted into the extracellular environment via exosomes in a metastatic gastric cancer cell line

BACKGROUND

Exosomes play a major role in cell-to-cell communication, targeting cells to transfer exosomal molecules including proteins, mRNAs, and microRNAs (miRNAs) by an endocytosis-like pathway. miRNAs are small noncoding RNA molecules on average 22 nucleotides in length that regulate numerous biological processes including cancer pathogenesis and mediate gene down-regulation by targeting mRNAs to induce RNA degradation and/or interfering with translation. Recent reports imply that miRNAs can be stably detected in circulating plasma and serum since miRNAs are packaged by exosomes to be protected from RNA degradation. Thus, profiling exosomal miRNAs are in need to clarify intercellular signaling and discover a novel disease marker as well.

METHODOLOGY/PRINCIPAL FINDINGS

Exosomes were isolated from cultured cancer cell lines and their quality was validated by analyses of transmission electron microscopy and western blotting. One of the cell lines tested, a metastatic gastric cancer cell line, AZ-P7a, showed the highest RNA yield in the released exosomes and distinctive shape in morphology. In addition, RNAs were isolated from cells and culture media, and profiles of these three miRNA fractions were obtained using microarray analysis. By comparing signal intensities of microarray data and the following validation using RT-PCR analysis, we found that let-7 miRNA family was abundant in both the intracellular and extracellular fractions from AZ-P7a cells, while low metastatic AZ-521, the parental cell line of AZ-P7a, as well as other cancer cell lines showed no such propensity.

CONCLUSIONS/SIGNIFICANCE

The enrichment of let-7 miRNA family in the extracellular fractions, particularly, in the exosomes from AZ-P7a cells may reflect their oncogenic characteristics including tumorigenesis and metastasis. Since let-7 miRNAs generally play a tumor-suppressive role as targeting oncogenes such as RAS and HMGA2, our results suggest that AZ-P7a cells release let-7 miRNAs via exosomes into the extracellular environment to maintain their oncogenesis.