An emerging research: the role of hepatocellular carcinoma-derived exosomal circRNAs in the immune microenvironment.

Hepatocellular carcinoma (HCC), the most common primary malignancy of the liver, is one of the leading causes of cancer-related death and is associated with a poor prognosis. The tumor microenvironment (TME) of HCC comprises immune, immunosuppressive, and interstitial cells with hypoxic, angiogenic, metabolic reprogramming, inflammatory, and immunosuppressive features. Exosomes are nanoscale extracellular vesicles that secrete biologically active signaling molecules such as deoxyribonucleic acid (DNA), messenger ribonucleic acid (mRNA), microribonucleic acid (miRNA), proteins, and lipids. These signaling molecules act as messengers in the tumor microenvironment, especially the tumor immunosuppressive microenvironment. Exosomal circRNAs reshape the tumor microenvironment by prompting hypoxic stress response, stimulating angiogenesis, contributing to metabolic reprogramming, facilitating inflammatory changes in the HCC cells and inducing tumor immunosuppression. The exosomes secreted by HCC cells carry circRNA into immune cells, which intervene in the activation of immune cells and promote the overexpression of immune checkpoints to regulate immune response, leading tumor cells to acquire immunosuppressive properties. Furthermore, immunosuppression is the final result of a combination of TME-related factors, including hypoxia, angiogenesis, metabolic reprogramming, and inflammation changes. In conclusion, exosomal circRNA accelerates the tumor progression by adjusting the phenotype of the tumor microenvironment and ultimately forming an immunosuppressive microenvironment. HCC-derived exosomal circRNA can affect HCC cell proliferation, invasion, metastasis, and induction of chemoresistance. Therefore, this review aimed to summarize the composition and function of these exosomes, the role that HCC-derived exosomal circRNAs play in microenvironment formation, and the interactions between exosomes and immune cells. This review outlines the role of exosomal circRNAs in the malignant phenotype of HCC and provides a preliminary exploration of the clinical utility of exosomal circRNAs.

Immune gene-viral therapy with triplex efficacy mediated by oncolytic adenovirus carrying an interferon-gamma gene yields efficient antitumor activity in immunodeficient and immunocompetent mice.

Among numerous gene therapeutic strategies for cancer treatment, gene transfer by conditionally replicative adenovirus (CRAd) of interferon-gamma (IFN-gamma) may be useful because of the possibility that it will yield IFN-gamma-mediated antiangiogenesis, immune responses, and CRAd-mediated oncolysis. In this study, we constructed a human TERT promoter-mediated oncolytic adenovirus targeting telomerase-positive cancers and armed with a mouse or human IFN-gamma gene to generate novel immune gene-viral therapeutic systems, CNHK300-mIFN-gamma and CNHK300-hIFN-gamma, respectively. The systems can specifically target, replicate in, and lyse cancer cells, while sparing normal cells. The advantage of these systems is that the number of transgene copies and their expression increase markedly via viral replication within infected cancer cells, and replicated viral progeny can then infect additional cancer cells within the tumor mass. CNHK300-mIFN-gamma induced regression of xenografts in liver cancer models in both immunodeficient and immunocompetent mice by triplex mechanisms including selective oncolysis, antiangiogenesis, and immune responses. We conclude that combining immune gene therapy and oncolytic virotherapy can enhance antitumor efficacy as a result of synergism between CRAd oncolysis and transgene composite antitumor responses.

[CNHK200-hA-a gene-viral therapeutic system and its antitumor effect on lung cancer].

OBJECTIVE: To develop a novel vector system, which combines the advantages of the gene therapy, antiangiogenic therapy and virus therapy, and to observe its effect on lung cancer. METHODS: Human angiostatin gene hA(k1-5) was inserted into the genome of the replicative virus specific for the tumor cells by virus recombination technology. The expression of hA(k1-5), its effect on tumor growth in vitro and in vivo were studied. RESULTS: A new kind of gene-viral vector system, designated as CNHK200-hA(k1-5), in which the E1b55 000 gene was deleted but the E1a gene of adenovirus preserved, was constructed. The novel vector system possessed the same property as the replicative virus ONYX-015, which replicates in p53- tumor cells but not in normal cells, thus specifically kills tumor cells. In vitro, CNHK200-hA and Ad-hA both could kill A549 tumor cells but the latter needed 100 times more MOI to achieve the same amplitude of cell killing. In vivo, the therapeutic effect of CNHK200-hA on human lung cancer A549 xenograft in nude mice was significantly better than that of Ad-hA and that of tumor-replicative virus ONYX-015. CONCLUSION: CNHK200-hA(k1-5), a novel vector is constructed in which the angiostatin gene is inserted into the genome of the replicative adenovirus cytotoxic to p53-negative tumor cells. It has the advantages of specific tumor targeting, high level gene expression in tumor cells, and potent tumoricidal activity.

Potent antitumor efficacy of an E1B 55kDa-deficient adenovirus carrying murine endostatin in hepatocellular carcinoma.

Data from clinical trails have shown that the antitumoral effect of ONYX-015, an E1B 55kDa-deficient adenovirus, as monotherapy is insufficient. To enhance its efficiency, CNHK200-mE, another E1B 55kDa-deficient adenovirus armed with a mouse endostatin gene was constructed and its antitumoral activities against hepatocellular carcinoma (HCC) in vitro and in vivo were investigated. The selective replication and cytotoxicity of CNHK200-mE in Hep3B and HepGII cells independent of p53 status were confirmed via TCID50 and 3-(4,5dimetylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assays. Potent tumor growth suppression on SMMC-7721 xenografts in nude mice was observed and a synergistic effect of the carrier virus and the therapeutic gene was suggested. Moreover, in comparison with the nonreplicative adenovirus carrying the same therapeutic gene, amplified transgene expression of mouse endostatin in vitro and in vivo were confirmed by Western blotting and ELISA assay. The effective angiogenesis inhibition and replication of CNHK200-mE in nude mice xenografts were demonstrated by immunohistochemistry. In conclusion, the recombinant adenovirus CNHK200-mE is a replication-competent oncolytic virus mediating high expression of therapeutic gene. Because CNHK200-mE is capable of replicating in and lysing HCC cells selectively with effective tumor growth suppression and antiangiogenic activity on HCC xenografts in nude mice, it holds good potential for the treatment of HCC.

Effective gene-viral therapy for telomerase-positive cancers by selective replicative-competent adenovirus combining with endostatin gene.

Gene-viral therapy, which uses replication-selective transgene-expressing viruses to manage tumors, can exploit the virtues of gene therapy and virotherapy and overcome the limitations of conventional gene therapy. Using a human telomerase reverse transcriptase-targeted replicative adenovirus as an antiangiogenic gene transfer vector to target new angiogenesis and making use of its unrestrained proliferation are completely new concepts in tumor management. CNHK300-mE is a selective replication transgene-expressing adenovirus constructed to carry mouse endostatin gene therapeutically. Infection with CNHK300-mE was associated with selective replication of the adenovirus and production of mouse endostatin in telomerase-positive cancer cells. Endostatin secreted from a human gastric cell line, SGC-7901, infected with CNHK300-mE was significantly higher than that infected with nonreplicative adenovirus Ad-mE in vitro (800 +/- 94.7 ng/ml versus 132.9 +/- 9.9 ng/ml) and in vivo (610 +/- 42 ng/ml versus 126 +/- 13 ng/ml). Embryonic chorioallantoic membrane assay showed that the mouse endostatin secreted by CNHK300-mE inhibited angiogenesis efficiently and also induced distortion of pre-existing vasculature. CNHK300-mE exhibited a superior suppression of xenografts in nude mice compared with CNHK300 and Ad-mE. In summary, we provided a more efficient gene-viral therapy strategy by combining oncolysis with antiangiogenesis.

[Treatment of hepatocellular carcinoma by transfecting interleukin-12 and interleukin-2 fusion gene intrasplenically, an experimental study].

OBJECTIVE: To study the inhibitory effect of retroviral packaging cells injected intrasplenically encoding mouse interleukin-12 (mIL-12) and human interleukin-2 (hIL-2) fusion gene on the growth of hepatocellular carcinoma. METHODS: The retroviral vectors encoding mIL-12 gene, hIL-2 gene, and mIL-12 and hIL-2 genes, GCIL12EXPN, GCXEIL2PN, and GCIL12EIL2PN were constructed and then transfected into the retroviral packaging cells PA317 to construct cells PA317-GCIL12EXPN, PA317-GCXEIL2PN, and PA317-GCIL12EIL2PN. Rat hepatocellular carcinoma cells CBRH3 were implanted into the livers of Wistar rats to establish hepatoma animal model. Then the rats were divided into 5 groups to be injected intrasplenically with normal saline one day after the implantation (0.8 ml/rat, group I, n = 10), blank vector PA317-GCXEXPN one day after the implantation (10(7) cells/rat, group II, n = 10), PA317-GCIL12EXPN containing IL-2 gene (1 x 10(7) cells/rat 1, 3, 5, or 7 days after the implantation, group III, n = 40), PA317-GCXEIL2PN containing mIL-12 gene (1 x 10(7) cells/rat 1, 3, 5, or 7 days after the implantation, group IV, n = 40), and PA317-GCIL12EIL2PN containing IL-12-IL-2 fusion gene (1 x 10(7) cells/rat 1, 3, 5, or 7 days after the implantation, group V, n = 40) respectively. The rats surviving longer than 2 months were re-injected with hepatocellular carcinoma cells. The therapeutic effect, immune function and toxic effect were evaluated. CT was conducted on the liver before and after the experiment. Laparotomy was performed 3 and 7 days after treatment to resect some of the carcinoma tissues to undergo pathological examination and OX8 immunohistostaining. Serum mIL-12 and hIL-2 were detected one day before and 3, 7, 30, and 60 days after treatment. RESULTS: The average survival times of the rats treated with IL-12-IL-2 fusion gene at the first, third, fifth and seventh day after tumor implantation were 53.3 +/- 3.7 days, 49.3 +/- 4.2 days, 31.0 +/- 2.1 days, and 24.3 +/- 1.4 days respectively, longer than those treated with IL-2 gene (25.0 +/- 2.5 days, 23.5 +/- 2.0 days, 18.3 +/- 2.4 days, and 12.0 +/- 1.8 days respectively, P < 0.001), and those treated with IL-12 gene (39.0 +/- 4.8 days, 32.0 +/- 3.9 days, 23.0 +/- 2.5 days, and 19.4 +/- 2.1 days respectively, P < 0.001). Long survival (>or= 60 days) rate in the rats treated with IL-12-IL-2 fusion gene on the first and third day was 30%. The serum mIL-12 and hIL-2 levels in these rats remained high on the 60th day after treatment. The pathological study showed that the number of infiltrating lymphocytes in liver tumor tissues was increased in the IL-12-IL-2 fusion gene treatment group. CONCLUSION: The retroviral packaging cell line injected intrasplenically encoding mIL-12 and hIL-2 fusion gene inhibits the growth of hepatocellular carcinoma significantly in rats. The therapeutical efficacy of early administration is superior to that of late one.

[Injection of NKG5SV gene to inhibit growth and metastasis of hepatocellular carcinoma].

OBJECTIVE: To study the injection of NKG5SV gene to inhibit growth and metastasis of hepatocellular carcinoma (HCC). METHODS: NKG5SV gene was inserted into retroviral vector pLXSN by normal methods. LacZ gene was used as control. LCI-D20 tumor together with saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was subcutaneously inoculated to the nude mice. Tumor formation rate and tumor size were noted 35 days after inoculation. LCI-D20 tumor was inoculated subcutaneously. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was intratumorally injected respectively 10 days after inoculation. Tumor growth was observed 35 days after inoculation. Liver cancer was resected 22 days after intrahepatic inoculation. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was respectively injected at incisal margin or intraspleen. Mice were killed 35 days after inoculation to observe tumor recurrence at incisal margin, intrahepatic metastasis and extrahepatic metastasis. RESULTS: Tumor formation rate and tumor diameter(cm) were 1.76 +/- 0.11, 1.51 +/- 0.34, 0.33 +/- 0.04 in the control group, LacZ group, NKG5SV group respectively when tumor and different cDNA were inoculated together. Tumor diameter(cm) and weight(g) were 0.87 +/- 0.08, 0.83 +/- 0.05, 0.26 +/- 0.04; 0.43 +/- 0.06, 0.38 +/- 0.04, 0.08 +/- 0.06 in the control group, LacZ group, NKG5SV group respectively when different cDNA were injected into the LCI-D20 tumor. Sites with extrahepatic metastasis nidi, incisal margin recurrence tumor size(cm), intrahepatic metastasis nidi, metastasis involved hepatic lobes in the control group, LacZ group, NKG5SV group were 4.25 +/- 1.48, 4.25 +/- 1.04, 0.63 +/- 0.51; 1.51 +/- 0.27, 1.35 +/- 0.17, 0.81 +/- 0.17; 2.50 +/- 1.41, 2.38 +/- 1.06, 1.25 +/- 0.71; 2.13 +/- 0.99, 2.00 +/- 0.75, 1.38 +/- 0.74 respectively when NK cells were injected at incise margin. They were 4.38 +/- 1.85, 4.25 +/- 1.48, 1.00 +/- 0.75; 1.13 +/- 0.23, 0.97 +/- 0.29, 0.76 +/- 0.16; 2.50 +/- 1.41, 2.05 +/- 1.12, 0; 2.13 +/- 0.83, 1.75 +/- 0.88, 0 respectively when NK cell were injected intrasplenicly. CONCLUSIONS: NKG5SV gene can inhibit HCC growth and postoperative metastasis and recurrence.

[High-level mIL-12 expression and replication of replicating adenovirus carrying mIL12 gene in naso-pharyngeal carcinoma cells].

OBJECTIVE: To enhance the therapeutic effects on nasopharyngeal carcinoma by combining treatment with selectively replicating adenovirus and IL12. METHODS: Replicating adenovirus with mouse IL12 gene insert (CNHK200-mIL12) was constructed to transfect nasopharyngeal carcinoma cell lines CNE3 and 915. Adenovirus hexon was detected by immunohistochemical staining and flow cytometry (FCM), and mIL12 expression examined by enzyme-linked immunosorbent assay (ELISA). The replication rates of CNHK200-mIL12 and dl1520 was determined by 50% tissue culture infectious dose (TCID50). RESULTS: Twenty-four hours after transfection with CNHK200-mIL12, most of cells were positive for adenovirus hexon and FCM demonstrated increased positivity rates of 39% and 4% among CNE3 and 915 cells respectively. It was observed that CNHK200-mIL12 replication increased by 1 000 folds with mIL12 expression level reaching as high as 84.5+/-4.6 ng in CNE3 cells and 75.6+/-3.4 ng in 915 cells as determined 72 h after transfection with 1x10(5) PFU CNHK200-mIL12 into 1x10(4) cells. CONCLUSION: CNHK200-mIL12 can replicate in vitro in nasopharyngeal carcinoma cells (dl1520 cells, for instance) with high mIL12 expression, which suggests that CNHK200-mIL12 may potentially be used to treat nasopharyngeal carcinoma.

Gene-viral vectors: a promising way to target tumor cells and express anticancer genes simultaneously.

OBJECTIVE: To develop a new kind of vector system called gene-viral vector, which combines the advantages of gene and virus therapies. METHODS: Using recombinant technology, an anti-tumor gene was inserted into the genome of replicative virus specific for tumor cells. The cell killing effect, reporter gene expression of the green fluorescence protein, anti-tumor gene expression of mouse interleukin-12 (mIL-12) and replication of virus were observed by the methods of cell pathology, fluorescence microscopy, ELISA and electron microscopy, respectively. RESULTS: A new kind of gene-viral vector system of adenovirus, in which the E1b-55 kD gene was deleted but the E1a gene was preserved, was constructed. The vector system, like the replicative virus ONYX-015, replicated and proliferated in tumor cells but not in normal ones. Our vector had an advantage over ONYX-015 in that it carried different kinds of anti-tumor genes to enhance its therapeutic effect. The reporter gene expression of the green fluorescence protein in tumor cells was much better than the adenovirus vector employed in conventional gene the rapy, and the expression in our vector system was as low as or even less than that in the conventional adenovirus gene therapy system. Similar results were observed in experiments with this vector system carrying the anti-tumor gene mIL-12. Replication and proliferation of the virus carrying the mIL-12 gene in tumor cells were confirmed by electron microscopy. CONCLUSIONS: Gene-viral vectors are new vectors with an anti-tumor gene inserted into the genome of replicative virus specific for tumor cells. Because of the specific replication and proliferation of the virus in tumor cells, expression of the anti-tumor gene is increased hundreds to thousands of times. This approach takes full advantages of gene therapy and virus therapy to enhance the effect on the tumor. It overcomes the disadvantages of conventional gene therapy, such as low transfer rate, low gene expression, lack of target tropism, and low anti-tumor activity. We believe that this is a promising means for future tumor treatment.

[Development of gene-viral vector and its anti-tumor effect, a primary study].

OBJECTIVE: To develop a new kind of vector system, named as gene-viral vector, which combines the advantages of the gene therapy and virus therapy. METHOD: An anti-tumor gene was inserted into the genome of the replicative virus specific for the tumor cells by virus recombination technology. The killing effect, report gene expression of the green fluorescence protein, expression of the anti-tumor gene of mouse IL12, and the replication of the virus were observed respectively by cell pathology, fluorescence microscopy, ELISA and electron microscopy. RESULTS: A new kind of gene-viral vector system, in which the E1b-55 000 gene is deleted but the E1a gene of adenovirus is preserved, was constructed. The vector system possessed the same characteristics as the replicative virus ONYX-015, replication and proliferation in the tumor cells but not in the normal cells, thus specifically killing the tumor cells. Besides, it carried many kinds of anti-tumor genes. When carrying the report gene of the green fluorescence protein it made the expression of this gene in tumor cells far more effectively than the adenovirus vector employed in the traditional gene therapy did. However in the normal cells the expression of green fluorescence protein caused by this vector system was as little as or even less than that by the traditional adenovirus system. The similar result was also observed in the experiments of this vector system carrying the anti-tumor gene, gene of mouse IL12. The replication and proliferation of the virus carrying the gene of mouse IL12 in the tumor cells were confirmed by electron microscopy. CONCLUSION: Gene-viral vector is a new kind of vector in which the anti-tumor gene is inserted into the genome of the replicative virus specific for the tumor cells. It increases the expression of the anti-tumor gene by hundreds even tens of thousand times. It posseses all the advantages of gene therapy and virus therapy, thus further enhancing the curative effect and it overcomes such disadvantages as low transfer rate, low expression, lack of target tropism and low anti-tumor activity. It will become one of the most promising means in tumor treatment.

In situ detection of tumor infiltrating lymphocytes expressing perforin and fas ligand genes in human HCC.

AIM:To investigate the expression of perforin and fas-ligand (fas-L) of tumor infiltrating lymphocytes (TILs) in human hepatocellular carcinoma (HCC).METHODS:By in situ hybridization and immunohistochemistry, the perforin and fas-L gene expression of TILs was studied in 20 HCC cases.RESULTS: Positive expression of perforin and fas-L genes was detected in 16 HCC cases. One patient had expression of perforin and fas-L genes in the majority of TILs and survived 1.5 years after tumor resection without HCC relapse.This seems that the presence of a large number of activated T cells might be beneficial for the antitumor immunity. In other cases, less than 10% of TILs were able to express perforin and fas-L genes.CONCLUSION:Although there were a number of T cells in HCC, only few of them were immunoactive and able to kill tumor cells. It seems important to promote further proliferation of these activated T cells in vitro or in vivo.