Cancer/testis antigen HCA587-derived long peptide vaccine generates potent immunologic responses and antitumor effects in mouse model

MAGEC2 Correlates With Unfavorable Prognosis And Promotes Tumor Development In HCC Via Epithelial-Mesenchymal Transition

Purpose

Although MAGEC2 was first cloned from a human hepatocellular carcinoma (HCC) cDNA library by serum screening, the detailed attributes of MAGEC2 in HCC have rarely been elucidated.

Patients and methods

In this study, The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases were consulted to analyse the expression of MAGEC2 mRNA in liver cancer. Immunohistochemistry (IHC) analysis was performed to detect MAGEC2 expression in HCC, and the relationship between MAGEC2 expression and the clinicopathological characteristics of HCC patients was evaluated. Then, we employed the short hairpin (sh)RNA-mediated knockdown of MAGEC2 in HCC cell lines to explore the function of MAGEC2 in HCC development. Finally, the expression of epithelial-mesenchymal transition (EMT) markers in HCC xenografts and clinical samples was investigated.

Results

The results showed a remarkably higher level of MAGEC2 expression in HCC tissues than in noncancerous tissues, and MAGEC2 expression could be used as an independent prognostic factor for overall survival in HCC. Moreover, sh-MAGEC2 inhibited a series of HCC malignant behaviours both in vitro and in vivo. Finally, decreased MAGEC2 expression and low levels of EMT markers were detected in sh-MAGEC2 xenografts, while increased MAGEC2 expression and high levels of EMT markers were observed in invasive and metastatic HCC samples.

Conclusion

Taken together, our data imply that MAGEC2 is a novel prognostic marker for HCC and that MAGEC2 significantly promotes HCC tumourigenesis by inducing EMT. Targeting MAGEC2 may provide a promising therapeutic strategy for HCC treatment.

Post-transcriptional regulation of cancer/testis antigen MAGEC2 expression by TRIM28 in tumor cells

BACKGROUND

Cancer/testis antigen MAGEC2 (also known as HCA587) is highly expressed in a wide variety of tumors and plays an active role in promoting growth and metastasis of tumor cells. However, little is known for the regulation of MAGEC2 expression in cancer cells.

METHODS

Western blotting and quantitative RT-PCR were performed to analyze MAGEC2 expression. Co-immunoprecipitation assay was applied for detecting the endogenous interaction of MAGEC2 and TRIM28 in tumor cells. Overexpression and knockdown assays were used to examine the effects of TRIM28 on the expression of MAGEC2 protein. Immunohistochemistry (IHC) staining was performed in hepatocellular carcinoma patients to evaluate the association between the expression of MAGEC2 and TRIM28. Proteasome inhibitors MG132 or PS-341 and lysosome inhibitor Chloroquine (CQ) were used to inhibit proteasomal or lysosomal-mediated protein degradation respectively.

RESULTS

We demonstrate that MAGEC2 interacts with TRIM28 in melanoma cells and MAGEC2 expression in tumor cells depends on the expression of TRIM28. The expression level of MAGEC2 protein was significantly reduced when TRIM28 was depleted in tumor cells, and no changes were observed in MAGEC2 mRNA level. Furthermore, expression levels of MAGEC2 and TRIM28 are positively correlated in MAGEC2-positive human hepatocellular carcinoma tissues (p = 0.0011). Mechanistic studies indicate that the regulatory role of TRIM28 on MAGEC2 protein expression in tumor cells depends on proteasome-mediated pathway.

CONCLUSIONS

Our findings show that TRIM28 is necessary for MAGEC2 expression in cancer cells, and TRIM28 may serve as a new potential target for immunotherapy of cancer.

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity

Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I), a putative heat shock protein (EL PGI II), Spa32 (EL PGI III), IcsB (EL PGI IV) and a hypothetical protein (EL PGI V). These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP) and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

Novel cancer antigens for personalized immunotherapies: latest evidence and clinical potential

The clinical success of monoclonal antibody immune checkpoint modulators such as ipilimumab, which targets cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the recently approved agents nivolumab and pembrolizumab, which target programmed cell death receptor 1 (PD-1), has stimulated renewed enthusiasm for anticancer immunotherapy, which was heralded by Science as 'Breakthrough of the Year' in 2013. As the potential of cancer immunotherapy has been recognized since the 1890s when William Coley showed that bacterial products could be beneficial in cancer patients, leveraging the immune system in the treatment of cancer is certainly not a new concept; however, earlier attempts to develop effective therapeutic vaccines and antibodies against solid tumors, for example, melanoma, frequently met with failure due in part to self-tolerance and the development of an immunosuppressive tumor microenvironment. Increased knowledge of the mechanisms through which cancer evades the immune system and the identification of tumor-associated antigens (TAAs) and negative immune checkpoint regulators have led to the development of vaccines and monoclonal antibodies targeting specific tumor antigens and immune checkpoints such as CTLA-4 and PD-1. This review first discusses the established targets of currently approved cancer immunotherapies and then focuses on investigational cancer antigens and their clinical potential. Because of the highly heterogeneous nature of tumors, effective anticancer immunotherapy-based treatment regimens will likely require a personalized combination of therapeutic vaccines, antibodies and chemotherapy that fit the specific biology of a patient's disease.

A Comprehensive Preclinical Model Evaluating the Recombinant PRAME Antigen Combined With the AS15 Immunostimulant to Fight Against PRAME-expressing Tumors

The PRAME tumor antigen is a potential target for immunotherapy. We assessed the immunogenicity, the antitumor activity, and the safety and the tolerability of a recombinant PRAME protein (recPRAME) combined with the AS15 immunostimulant (recPRAME+ AS15) in preclinical studies in mice and Cynomolgus monkeys. Four groups of 12 CB6F1 mice received 4 injections of phosphate-buffered saline (PBS), recPRAME, AS15, or recPRAME+AS15. Immunized mice were injected with tumor cells expressing PRAME (CT26-PRAME) 2 weeks or 2 months after the last injection. The mean tumor surface was measured twice a week. Two groups of 10 monkeys received 7 injections of saline or recPRAME+ AS15. T-cell responses were measured by flow cytometry using intracellular cytokine staining (ICS). In CB6F1 mice, repeated injections of recPRAME+ AS15 induced high PRAME-specific antibody titers and mostly CD4+ T cells producing cytokines. This immune response was long-lasting in these animals and was associated with protection against a challenge with PRAME-expressing tumor cells (CT26-PRAME) applied either 2 weeks or 2 months after the last injection; these data indicate the induction of an immune memory. In HLA-A02.01/HLA-DR1 transgenic mice, recPRAME+ AS15 induced both CD4+ and CD8+ T-cell responses, indicating that this antigen can be processed by the human leukocyte antigen and is potentially immunogenic in humans. In addition, a repeated-dose toxicity study in monkeys showed that 7 biweekly injections of recPRAME+ AS15 were well tolerated, and induced PRAME-specific antibodies and T cells. In conclusion, these preclinical data indicate that repeated injections of the PRAME cancer immunotherapeutic are immunogenic and have an acceptable safety profile.