MAGE-A, mMage-b, and MAGE-C proteins form complexes with KAP1 and suppress p53-dependent apoptosis in MAGE-positive cell lines

Expression pattern analysis of the MAGE family genes in breast cancer patients and hypomethylation activation in the MCF-7 cells

Melanoma antigen gene (MAGE) families are cancer-testis genes that normally show expression in the testes. However, their expressions have been linked with various types of human cancers, including BC. Therefore, the primary purposes of the present research were to assess the expression of MAGE-A, -B, and -C genes in Saudi female patients with BC and determine their regulation via the epigenetic mechanism. Ten BC samples were analyzed for the expression levels of nine MAGE-A genes, six MAGE-B genes, and three MAGE-C genes using the RT-PCR technique. All 18 evaluated genes except for MAGE-A1, -A3, -A4, and -B5 showed weak band expressions in some BC specimens. MAGE-A6 and -B2 were expressed in 40 % of the BC tissue samples, and MAGE-A9, -A10, and -B6 were expressed in 30 %. The lowest expression levels were found for MAGE-A11, -B1, -B3, -B4, -C1, and -C2 in 10 % of the BC specimens and for MAGE-A9,--B2, and --C3 in 20 % of the samples. The most frequently expressed gene was MAGE-A8 (found in 70 % of the BC samples), which suggests that it may serve as - a marker for screening of BC. In vitro treatment, the 5-aza-2'-deoxycytidine agent led to a significant rise in mRNA expressions for all tested genes related to the MAGE-A family, except for MAGE-A10. By contrast, among the genes in the MAGE-B and -C families, only MAGE-B1 and -C2 exhibited detectable mRNA expression levels after treatment.

Probing the CRL4DCAF12 interactions with MAGEA3 and CCT5 di-Glu C-terminal degrons

Damaged DNA-binding protein-1 (DDB1)- and CUL4-associated factor 12 (DCAF12) serves as the substrate recognition component within the Cullin4-RING E3 ligase (CRL4) complex, capable of identifying C-terminal double-glutamic acid degrons to promote the degradation of specific substrates through the ubiquitin proteasome system. Melanoma-associated antigen 3 (MAGEA3) and T-complex protein 1 subunit epsilon (CCT5) proteins have been identified as cellular targets of DCAF12. To further characterize the interactions between DCAF12 and both MAGEA3 and CCT5, we developed a suite of biophysical and proximity-based cellular NanoBRET assays showing that the C-terminal degron peptides of both MAGEA3 and CCT5 form nanomolar affinity interactions with DCAF12 in vitro and in cells. Furthermore, we report here the 3.17 Å cryo-EM structure of DDB1-DCAF12-MAGEA3 complex revealing the key DCAF12 residues responsible for C-terminal degron recognition and binding. Our study provides new insights and tools to enable the discovery of small molecule handles targeting the WD40-repeat domain of DCAF12 for future proteolysis targeting chimera design and development.

Structural basis for RAD18 regulation by MAGEA4 and its implications for RING ubiquitin ligase binding by MAGE family proteins

MAGEA4 is a cancer-testis antigen primarily expressed in the testes but aberrantly overexpressed in several cancers. MAGEA4 interacts with the RING ubiquitin ligase RAD18 and activates trans-lesion DNA synthesis (TLS), potentially favouring tumour evolution. Here, we employed NMR and AlphaFold2 (AF) to elucidate the interaction mode between RAD18 and MAGEA4, and reveal that the RAD6-binding domain (R6BD) of RAD18 occupies a groove in the C-terminal winged-helix subdomain of MAGEA4. We found that MAGEA4 partially displaces RAD6 from the RAD18 R6BD and inhibits degradative RAD18 autoubiquitination, which could be countered by a competing peptide of the RAD18 R6BD. AlphaFold2 and cross-linking mass spectrometry (XL-MS) also revealed an evolutionary invariant intramolecular interaction between the catalytic RING and the DNA-binding SAP domains of RAD18, which is essential for PCNA mono-ubiquitination. Using interaction proteomics, we found that another Type-I MAGE, MAGE-C2, interacts with the RING ubiquitin ligase TRIM28 in a manner similar to the MAGEA4/RAD18 complex, suggesting that the MAGEA4 peptide-binding groove also serves as a ligase-binding cleft in other type-I MAGEs. Our data provide new insights into the mechanism and regulation of RAD18-mediated PCNA mono-ubiquitination.

Immunization with a multi-antigen targeted DNA vaccine eliminates chemoresistant pancreatic cancer by disrupting tumor-stromal cell crosstalk

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterised by limited responses to chemoimmunotherapy attributed to highly desmoplastic tumor microenvironment. Disrupting the tumor-stromal cell crosstalk is considered as an improved PDAC treatment strategy, whereas little progress has been made due to poor understanding of its underlying mechanism. Here, we examined the cellular role of melanoma associated antigen A isoforms (MAGEA) in regulating tumor-stromal crosstalk mediated chemoresistance.

METHODS

We used clinical samples to explore the correlation between MAGEA expression and patient prognosis in multiple cancers. We utilized cancer cell lines, patient derived organoids and orthotopic PDAC model to examine the function of MAGEA in chemoresistance. We performed biochemical, proteome profiler array and transcriptional analysis to uncover a mechanism that governs tumor-stromal crosstalk. We developed a multi-MAGEA antigen targeted DNA vaccine and tested its effect on PDAC tumor growth.

RESULTS

We establish MAGEA as a regulator of the tumor-stromal crosstalk in PDAC. We provide strong clinical evidence indicating that high MAGEA expression, including MAGEA2, MAGEA3 and MAGEA10, correlates with worse chemotherapeutic response and poor prognosis in multiple cancers, while their expression is up-regulated in chemoresistant PDAC patient derived organoids and cancer cell lines. Mechanistically, MAGEA2 prohibits gemcitabine-induced JNK-c-Jun-p53 mediated cancer cell apoptosis, while gemcitabine stimulated pancreatic stellate cells secretes GDF15 to further enhance the gemcitabine resistance of MAGEA2 expressing cells by activating GFRAL-RET mediated Akt and ERK1/2 dependent survival pathway. Strikingly, immunization with a DNA vaccine that targeting multiple MAGEA antigens, including MAGEA2, MAGEA3 and MAGEA10, elicits robust immune responses against the growth of gemcitabine resistant tumors.

CONCLUSIONS

These findings suggest that targeting MAGEA-mediated paracrine regulation of chemoresistance by immunotherapy can be an improved pancreatic cancer treatment strategy.

Mutational signatures and their association with survival and gene expression in urological carcinomas

Different sources of mutagenesis cause consistently identifiable patterns of mutations and mutational signatures that mirror the various carcinogenetic processes. We used publicly available data from the Cancer Genome Atlas to evaluate the associations between the activity of the mutational signatures and various survival endpoints in six types of urological cancers after adjusting for established prognostic factors. The predictive power of the signatures was evaluated with dynamic area under curve models. In addition, links between mutational signature activities and differences in gene expression patterns were analysed. APOBEC-related signature SBS2 was associated with improved overall survival (OS) and disease-specific survival (DSS) in bladder carcinomas in the multivariate analysis, while clock-like signature SBS1 predicted shortened DSS and progression-free interval (PFI) in clear cell renal cell carcinomas (ccRCC). In papillary renal cell carcinomas (pRCC), SBS45 was a predictor of improved outcomes, and APOBEC-related SBS13 was a predictor of worse outcomes. Gene expression analyses revealed various enriched pathways between the low- and high-signature groups. Interestingly, in both the ccRCC and pRCC cohorts, the genes of several members of the melanoma antigen (MAGE) family were highly upregulated in the signatures, which predicted poor outcomes, and downregulated in signatures, which were associated with improved survival. To summarize, SBS signatures provide substantial prognostic value compared with just the traditional prognostic factors in certain cancer types. APOBEC-related SBS2 and SBS13 seem to provide robust prognostic information for particular urological cancers, maybe driven by the expression of specific groups of genes, including the MAGE gene family.

Recent Advances in Molecular Mechanisms of Cancer Immunotherapy

Cancer is among the current leading causes of death worldwide, despite the novel advances that have been made toward its treatment, it is still considered a major public health concern. Considering both the serious impact of cancer on public health and the significant side effects and complications of conventional therapeutic options, the current strategies towards targeted cancer therapy must be enhanced to avoid undesired toxicity. Cancer immunotherapy has become preferable among researchers in recent years compared to conventional therapeutic options, such as chemotherapy, surgery, and radiotherapy. The understanding of how to control immune checkpoints, develop therapeutic cancer vaccines, genetically modify immune cells as well as enhance the activation of antitumor immune response led to the development of novel cancer treatments. In this review, we address recent advances in cancer immunotherapy molecular mechanisms. Different immunotherapeutic approaches are critically discussed, focusing on the challenges, potential risks, and prospects involving their use.

Biology of Cancer-Testis Antigens and Their Therapeutic Implications in Cancer

Tumour-specific antigens have been an area of interest in cancer therapy since their discovery in the middle of the 20th century. In the era of immune-based cancer therapeutics, redirecting our immune cells to target these tumour-specific antigens has become even more relevant. Cancer-testis antigens (CTAs) are a class of antigens with an expression specific to the testis and cancer cells. CTAs have also been demonstrated to be expressed in a wide variety of cancers. Due to their frequency and specificity of expression in a multitude of cancers, CTAs have been particularly attractive as cancer-specific therapeutic targets. There is now a rapid expansion of CTAs being identified and many studies have been conducted to correlate CTA expression with cancer and therapy-resistant phenotypes. Furthermore, there is an increasing number of clinical trials involving using some of these CTAs as molecular targets in pharmacological and immune-targeted therapeutics for various cancers. This review will summarise the current knowledge of the biology of known CTAs in tumorigenesis and the regulation of CTA genes. CTAs as molecular targets and the therapeutic implications of these CTA-targeted anticancer strategies will also be discussed.

The Melanoma-Associated Antigen Family A (MAGE-A): A Promising Target for Cancer Immunotherapy?

Early efforts to identify tumor-associated antigens over the last decade have provided unique cancer epitopes for targeted cancer therapy. MAGE-A proteins are a subclass of cancer/testis (CT) antigens that are presented on the cell surface by MHC class I molecules as an immune-privileged site. This is due to their restricted expression to germline cells and a wide range of cancers, where they are associated with resistance to chemotherapy, metastasis, and cancer cells with an increasing potential for survival. This makes them an appealing candidate target for designing an effective and specific immunotherapy, thereby suggesting that targeting oncogenic MAGE-As with cancer vaccination, adoptive T-cell transfer, or a combination of therapies would be promising. In this review, we summarize and discuss previous and ongoing (pre-)clinical studies that target these antigens, while bearing in mind the benefits and drawbacks of various therapeutic strategies, in order to speculate on future directions for MAGE-A-specific immunotherapies.

MAGED4B Promotes Glioma Progression via Inactivation of the TNF-α-induced Apoptotic Pathway by Down-regulating TRIM27 Expression

MAGED4B belongs to the melanoma-associated antigen family; originally found in melanoma, it is expressed in various types of cancer, and is especially enriched in glioblastoma. However, the functional role and molecular mechanisms of MAGED4B in glioma are still unclear. In this study, we found that the MAGED4B level was higher in glioma tissue than that in non-cancer tissue, and the level was positively correlated with glioma grade, tumor diameter, Ki-67 level, and patient age. The patients with higher levels had a worse prognosis than those with lower MAGED4B levels. In glioma cells, MAGED4B overexpression promoted proliferation, invasion, and migration, as well as decreasing apoptosis and the chemosensitivity to cisplatin and temozolomide. On the contrary, MAGED4B knockdown in glioma cells inhibited proliferation, invasion, and migration, as well as increasing apoptosis and the chemosensitivity to cisplatin and temozolomide. MAGED4B knockdown also inhibited the growth of gliomas implanted into the rat brain. The interaction between MAGED4B and tripartite motif-containing 27 (TRIM27) in glioma cells was detected by co-immunoprecipitation assay, which showed that MAGED4B was co-localized with TRIM27. In addition, MAGED4B overexpression down-regulated the TRIM27 protein level, and this was blocked by carbobenzoxyl-L-leucyl-L-leucyl-L-leucine (MG132), an inhibitor of the proteasome. On the contrary, MAGED4B knockdown up-regulated the TRIM27 level. Furthermore, MAGED4B overexpression increased TRIM27 ubiquitination in the presence of MG132. Accordingly, MAGED4B down-regulated the protein levels of genes downstream of ubiquitin-specific protease 7 (USP7) involved in the tumor necrosis factor-alpha (TNF-α)-induced apoptotic pathway. These findings indicate that MAGED4B promotes glioma growth via a TRIM27/USP7/receptor-interacting serine/threonine-protein kinase 1 (RIP1)-dependent TNF-α-induced apoptotic pathway, which suggests that MAGED4B is a potential target for glioma diagnosis and treatment.

The role of tripartite motif-containing 28 in cancer progression and its therapeutic potentials

Tripartite motif-containing 28 (TRIM28) belongs to tripartite motif (TRIM) family. TRIM28 not only binds and degrades its downstream target, but also acts as a transcription co-factor to inhibit gene expression. More and more studies have shown that TRIM28 plays a vital role in tumor genesis and progression. Here, we reviewed the role of TRIM28 in tumor proliferation, migration, invasion and cell death. Moreover, we also summarized the important role of TRIM28 in tumor stemness sustainability and immune regulation. Because of the importance of TRIM28 in tumors, TIRM28 may be a candidate target for anti-tumor therapy and play an important role in tumor diagnosis and treatment in the future.

Identification of hub genes in AR-induced tamoxifen resistance in breast cancer based on weighted gene co-expression network analysis

BACKGROUND

Approximately 30% of patients with oestrogen receptor (ER)-positive breast cancer (BC) exhibit intrinsic or recurrent resistance to tamoxifen (TAM) adjuvant endocrine therapy. The androgen receptor (AR) is expressed in about 90% of ER-positive patients. Our previous studies found that BC patients with an AR:ER expression ratio ≥ 2.0 are more susceptible to TAM resistance. However, the specific mechanism by which a high AR:ER ratio promotes TAM resistance remains unknown.

METHODS

RNA sequencing was performed on 10 cases of BC tissues with AR:ER ratios ≥ 2.0 and 3 cases with AR:ER ratios < 2.0. We then compared our data with the screened TAM-resistant and TAM-sensitive cases from the TCGA BC database. Bioinformatics methods were used to screen differentially expressed genes (DEGs) and to perform gene enrichment analysis. Weighted correlation network analysis (WGCNA) was used to screen hub genes in the AR-induced TAM resistance process.

RESULTS

PAM50 analysis showed that the molecular phenotype of BC patients with AR:ER ratios ≥ 2.0 was similar to that of triple-negative breast cancer (TNBC), whereas the BC samples with AR:ER ratios < 2.0 were classified as the luminal subtype. Among the AR:ER ratio ≥ 2.0 and AR:ER < 2.0 BC tumours, 1855 DEGs were identified. Gene enrichment analysis showed that DEGs were enriched mainly in proliferation-related molecular pathways, such as the cell cycle, necroptosis, metabolic pathways and DNA replication. WGCNA analysis showed that SEC14L2, RIIAD1, STC2 and MAGEA6 served as hub genes in AR-induced TAM resistance and were associated with BC survival prognosis in the TCGA cohort.

CONCLUSIONS

A high AR:ER expression ratio is a biomarker for patients who might develop TAM resistance, and AR expression seems to be a possible mechanism of resistance to endocrine therapy.

The Transcriptome and Proteome Networks of Malignant Tumours Reveal Atavistic Attractors of Polyploidy-Related Asexual Reproduction

The expression of gametogenesis-related (GG) genes and proteins, as well as whole genome duplications (WGD), are the hallmarks of cancer related to poor prognosis. Currently, it is not clear if these hallmarks are random processes associated only with genome instability or are programmatically linked. Our goal was to elucidate this via a thorough bioinformatics analysis of 1474 GG genes in the context of WGD. We examined their association in protein-protein interaction and coexpression networks, and their phylostratigraphic profiles from publicly available patient tumour data. The results show that GG genes are upregulated in most WGD-enriched somatic cancers at the transcriptome level and reveal robust GG gene expression at the protein level, as well as the ability to associate into correlation networks and enrich the reproductive modules. GG gene phylostratigraphy displayed in WGD+ cancers an attractor of early eukaryotic origin for DNA recombination and meiosis, and one relative to oocyte maturation and embryogenesis from early multicellular organisms. The upregulation of cancer-testis genes emerging with mammalian placentation was also associated with WGD. In general, the results suggest the role of polyploidy for soma-germ transition accessing latent cancer attractors in the human genome network, which appear as pre-formed along the whole Evolution of Life.

MAGE-I proteins and cancer-pathways: A bidirectional relationship

Data emerged from the last 20 years of basic research on tumor antigens positioned the type I MAGE (Melanoma Antigen GEnes - I or MAGE-I) family as cancer driver factors. MAGE-I gene expression is mainly restricted to normal reproductive tissues. However, abnormal re-expression in cancer unbalances the cell status towards enhanced oncogenic activity or reduced tumor suppression. Anomalous MAGE-I gene re-expression in cancer is attributed to altered epigenetic-mediated chromatin silencing. Still, emerging data indicate that MAGE-I can be regulated at protein level. Results from different laboratories suggest that after its anomalous re-expression, specific MAGE-I proteins can be regulated by well-known signaling pathways or key cellular processes that finally potentiate the cancer cell phenotype. Thus, MAGE-I proteins both regulate and are regulated by cancer-related pathways. Here, we present an updated review highlighting the recent findings on the regulation of MAGE-I by oncogenic pathways and the potential consequences in the tumor cell behavior.

High Expression of POGK Predicts Poor Prognosis in Patients with Hepatocellular Carcinoma

OBJECTIVE

Kruppel-associated box (KRAB) proteins reportedly play a dual role in neoplastic transformation. At present, little is known about the function of the proteins encoded by the human pogo transposable element derived with KRAB domain (POGK) gene. Herein, we evaluated the prognostic significance of POGK expression in patients with hepatocellular carcinoma (HCC).

METHODS

The data of HCC patients was downloaded from The Cancer Genome Atlas (TCGA) database. To determine the relationship between POGK and clinical features, logistic regression was applied. Cox regression and Kaplan-Meier analyses were used to evaluate the correlation between POGK and survival rates. Gene ontology (GO) analysis and Gene set enrichment analysis (GSEA) were conducted to identify the enriched pathways and functions associated with POGK.

RESULTS

A total of 374 HCC patients were identified in TCGA. POGK was significantly upregulated in HCC and correlated with tumor status (p = 0.036), race (p = 0.025), weight (p = 0.002), body mass index (p = 0.033), histologic grade (p < 0.001), and alpha-fetoprotein (p < 0.001). High POGK expression in HCC patients correlated with a poor outcome in terms of overall survival (p = 0.0018), progression-free survival (p = 0.0087), relapse-free survival (p = 0.045), and disease-specific survival (p = 0.014), according to Kaplan-Meier analysis. Receiver operating characteristic curve analysis showed that the area under the curve of POGK expression for HCC diagnosis was 0.891. GSEA showed that high POGK expression might activate mitotic prometaphase, kinesins, homologous DNA pairing and strand exchange, MET activates PTK2 signaling pathway, G1 to S cell cycle control, Aurora B pathway, ncRNAs involved in WNT signaling pathway, hepatitis C, and ncRNAs involved in the STAT3 signaling pathway. POGK expression correlated with the abundance of adaptive and innate immunocytes in HCC.

CONCLUSION

High expression of POGK has high diagnostic and prognostic values in patients with HCC. Moreover, POGK expression is correlated with immune infiltration in HCC.

Alterations in Gene Pair Correlations as Potential Diagnostic Markers for Colon Cancer

Colorectal cancer (CRC) is a leading cause of death from cancer in Canada. Early detection of CRC remains crucial in managing disease prognosis and improving patient survival. It can also facilitate prevention, screening, and treatment before the disease progresses to a chronic stage. In this study, we developed a strategy for identifying colon cancer biomarkers from both gene expression and gene pair correlation. Using the RNA-Seq dataset TCGA-COAD, a panel of 71 genes, including the 20 most upregulated genes, 20 most downregulated genes and 31 genes involved in the most significantly altered gene pairs, were selected as potential biomarkers for colon cancer. This signature set of genes could be used for early diagnosis. Furthermore, this strategy could be applied to other types of cancer.

Chemical complementarity between tumor resident, T-cell receptor CDR3s and MAGEA3/6 correlates with increased melanoma survival: Potential relevance to MAGE vaccine auto-reactivity

Cancer testis antigens have been of interest as possible targets for cancer immunotherapies. To better understand the opportunities for the use of such immunotherapy targets, we used a chemical complementarity scoring algorithm and an original web tool to establish aspects of electrostatic complementarity of the CTAs, MAGEA3 and MAGEA6, with melanoma specimen resident, T-cell receptor (TCR) complementarity determining region 3 (CDR3) amino acid sequences. Greater electrostatic complementarity between T-cell receptor CDR3 and tumor CTAs MAGEA3/6 was associated with a greater probability of overall survival, for both the cancer genome atlas and Moffitt Cancer Center samples; and was associated with high levels of T-cell cytotoxicity-related gene expression. Most importantly, this approach allowed for the highly efficient screening of specific segments of the MAGEA3/6 antigens which indicated that certain MAGE segments would have either more or less risk of auto-reactivity. In sum, the chemical complementarity algorithm, and its efficient application via the web tool, adaptivematch.com, offers a convenient opportunity to identify likely parameters important for immunotherapy considerations and melanoma patient risk stratifications.

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.

Generation of TRIM28 Knockout K562 Cells by CRISPR/Cas9 Genome Editing and Characterization of TRIM28-Regulated Gene Expression in Cell Proliferation and Hemoglobin Beta Subunits

TRIM28 is a scaffold protein that interacts with DNA-binding proteins and recruits corepressor complexes to cause gene silencing. TRIM28 contributes to physiological functions such as cell growth and differentiation. In the chronic myeloid leukemia cell line K562, we edited TRIM28 using CRISPR/Cas9 technology, and the complete and partial knockout (KO) cell clones were obtained and confirmed using quantitative droplet digital PCR (ddPCR) technology. The amplicon sequencing demonstrated no off-target effects in our gene editing experiments. The TRIM28 KO cells grew slowly and appeared red, seeming to have a tendency towards erythroid differentiation. To understand how TRIM28 controls K562 cell proliferation and differentiation, transcriptome profiling analysis was performed in wild-type and KO cells to identify TRIM28-regulated genes. Some of the RNAs that encode the proteins regulating the cell cycle were increased (such as p21) or decreased (such as cyclin D2) in TRIM28 KO cell clones; a tumor marker, the MAGE (melanoma antigen) family, which is involved in cell proliferation was reduced. Moreover, we found that knockout of TRIM28 can induce miR-874 expression to downregulate MAGEC2 mRNA via post-transcriptional regulation. The embryonic epsilon-globin gene was significantly increased in TRIM28 KO cell clones through the downregulation of transcription repressor SOX6. Taken together, we provide evidence to demonstrate the regulatory network of TRIM28-mediated cell growth and erythroid differentiation in K562 leukemia cells.

Kap1 Regulates the Stability of Lin28A in Embryonic Stem Cells

Lin28A is an RNA-binding protein that controls mammalian development and maintenance of the pluripotency of embryonic stem cells (ESCs) via regulating the processing of the microRNA let-7. Lin28A is highly expressed in ESCs, and ectopic expression of this protein facilitates reprogramming of somatic cells to induced pluripotent stem cells. However, the mechanisms underlying the post-translational regulation of Lin28A protein stability in ESCs remain unclear. In the present study, we identified Kap1 (KRAB-associated protein 1) as a novel Lin28A-binding protein using affinity purification and mass spectrometry. Kap1 specifically interacted with the N-terminal region of Lin28A through its coiled-coil domain. Kap1 overexpression significantly attenuated Lin28A ubiquitination and increased its stability. However, small interfering RNA-mediated knockdown of Kap1 promoted the ubiquitination of Lin28A, leading to its proteasomal degradation. Trim71, an E3 ubiquitin ligase, induced Lin28A degradation and Kap1 knockdown accelerated the Trim71-dependent degradation of Lin28A. Mutation of the lysine 177 residue of Lin28A to arginine abrogated the ubiquitination and degradation of Lin28A which were accelerated by Kap1 silencing. Moreover, Kap1 overexpression led to the accumulation of Lin28A in the cytoplasm, but not in the nucleus, and reduced the levels of let-7 subtypes. These results suggest that Kap1 plays a key role in regulation of the stability of Lin28A by modulating the Trim71-mediated ubiquitination and subsequent degradation of Lin28A, thus playing a pivotal role in the regulation of ESC self-renewal and pluripotency.

Trim28 acts as restriction factor of prototype foamy virus replication by modulating H3K9me3 marks and destabilizing the viral transactivator Tas

Background

Prototype foamy virus (PFV) is nonpathogenic complex retroviruses that express a transcriptional transactivator Tas, which is essential for the activity of viral long terminal repeat (LTR) promoter and internal promoter (IP). Tripartite motif-containing protein 28 (Trim28) is well known as a scaffold protein normally enriched in gene promoter region to repress transcription. We sought to determine if whether Trim28 could be enriched in PFV promoter region to participate the establishment of PFV latency infection.

Results

In this study, we show that Trim28 restricts Tas-dependent transactivation activity of PFV promoter and negatively regulates PFV replication. Trim28 was found to be enriched in LTR instead of IP promoter regions of PFV genome and contribute to the maintenance of histone H3K9me3 marks on the LTR promoter. Furthermore, Trim28 interacts with Tas and colocalizes with Tas in the nucleus. Besides, we found that Trim28, an E3 ubiquitin ligase, binds directly to and promotes Tas for ubiquitination and degradation. And the RBCC domain of Trim28 is required for the ubiquitination and degradation of Tas.

Conclusions

Collectively, our findings not only identify a host factor Trim28 negatively inhibits PFV replication by acting as transcriptional restriction factor enriched in viral LTR promoter through modulating H3K9me3 mark here, but also reveal that Trim28 mediated ubiquitin proteasome degradation of Tas as a mechanism underlying Trim28 restricts Tas-dependent transcription activity of PFV promoter and PFV replication. These findings provide new insights into the process of PFV latency establishment.

Graphical Abstract

MAGEH1 interacts with GADD45G and induces renal tubular cell apoptosis

BACKGROUND

Melanoma-associated antigen H1 (MAGEH1) is a protein that belongs to melanoma-associated antigen (MAGE) superfamily. Growth arrest and DNA damage 45G (GADD45G) is a member of the DNA damage-inducible gene family which responds to environmental stresses. We have previously shown that GADD45G is a protein that promotes apoptosis of renal tubular cells in response to a nephrotoxic injury. In this study, we show evidence that MAGEH1 interacts with GADD45G and is involved in the induction of nephrotoxin-induced apoptosis of renal tubular cells.

METHODS

Primary human renal tubular epithelial (HRE) cells and human kidney 2 (HK-2) cells were used in this study. To produce stable cell lines in which MAGEH1 expression was silenced, HRE cells were transduced with a lentiviral vector encoding a single guide RNA construct targeting the MAGEH1 gene. To knockdown GADD45G expression in HRE cells, a vector containing short hairpin RNA (shRNA) was used. We used short interfering RNAs (siRNA) to achieve transient silencing of genes in HK-2 cells. Recombinant adenoviruses were synthesized to overexpress MAGEH1 and GADD45G proteins. Human protein microarray was used to identify proteins that binds to GADD45G. Co-immunoprecipitation assays were then performed to confirm microarray results. Cell death was induced by cyclosporine A (CsA). Real-time quantitative PCR assay was used to evaluate gene expression levels. The degree of apoptosis and necrosis of cultured cells was evaluated by flow cytometry. Expression levels of caspases were examined using western blot analysis.

RESULTS

We found that GADD45G bound to one protein spotted in the protein microarray, which was subsequently identified as MAGEH1. We confirmed the interaction between GADD45G and MAGEH1 protein using the co-immunoprecipitation assay. MAGEH1 gene expression was not altered by CsA-induced cytotoxic injury, whereas GADD45G gene expression was increased significantly upon CsA treatment. MAGEH1 expression was significantly downregulated in GADD45G knockdown HRE stable cells suggesting that MAGEH1 expression may be dependent on GADD45G expression. CsA-induced apoptosis was significantly reduced in MAGEH1 knockdown HRE stable cells which led to an increased survival of these cells. Similar results were observed in GADD45G knockdown HRE stable cells. Accordingly, CsA-induced apoptosis was significantly decreased in MAGEH1 siRNA and GADD45G siRNA transfected HK-2 cells. CsA-induced activation of caspase-7 and caspase-9 was inhibited in MAGEH1 knockdown HRE stable cells, and similarly in GADD45G knockdown HRE stable cells.

CONCLUSIONS

To the best of our knowledge, this is the first study to show that MAGEH1 interacts with GADD45G and that MAGEH1 is involved in caspase-dependent apoptosis of renal tubular cells induced by nephrotoxic drugs.

Pathogenicity of the MAGE family

The melanoma antigen gene (MAGE) protein family is a group of highly conserved proteins that share a common homology domain. Under normal circumstances, numerous MAGE proteins are only expressed in reproduction-related tissues; however, abnormal expression levels are observed in a variety of tumor tissues. The MAGE family consists of type I and II proteins, several of which are cancer-testis antigens that are highly expressed in cancer and serve a critical role in tumorigenesis. Therefore, this review will use the relationship between MAGEs and tumors as a starting point, focusing on the latest developments regarding the function of MAGEs as oncogenes, and preliminarily reveal their possible mechanisms.

Prognostic Value of Melanoma-Associated Antigen-A (MAGE-A) Gene Expression in Various Human Cancers: A Systematic Review and Meta-analysis of 7428 Patients and 44 Studies

Background

Members of the melanoma-associated antigen-A (MAGE-A) subfamily are overexpressed in many cancers and can drive cancer progression, metastasis, and therapeutic recurrence.

Objective

This study is the first comprehensive meta-analysis evaluating the prognostic utility of MAGE-A members in different cancers.

Methods

A systematic literature search was conducted in PubMed, Google Scholar, Science Direct, and Web of Science. The pooled hazard ratios with 95% confidence intervals were estimated to evaluate the prognostic significance of MAGE-A expression in various cancers.

Results

In total, 44 eligible studies consisting of 7428 patients from 11 countries were analysed. Univariate and multivariate analysis for overall survival, progression-free survival, and disease-free survival showed a significant association between high MAGE-A expression and various cancers (P < 0.00001). Additionally, subgroup analysis demonstrated that high MAGE-A expression was significantly associated with poor prognosis for lung, gastrointestinal, breast, and ovarian cancer in both univariate and multivariate analysis for overall survival.

Conclusion

Overexpression of MAGE-A subfamily members is linked to poor prognosis in multiple cancers. Therefore, it could serve as a potential prognostic marker of poor prognosis in cancers.

Electronic supplementary material

The online version of this article (10.1007/s40291-020-00476-5) contains supplementary material, which is available to authorized users.

Oncogenic activity and cellular functionality of melanoma associated antigen A3

Cancer testis antigen Melanoma associated antigen A3 (MAGE-A3) has been subject of research for many years. Being expressed in various tumor types and influencing proliferation, metastasis, and tumor pathogenicity, MAGE-A3 is an attractive target for cancer therapy, particularly because in healthy tissues, MAGE-A3 is only expressed in testes and placenta. MAGE-A3 acts as a cellular master regulator by stimulating E3 ubiquitin ligase tripartite motif-containing protein 28 (TRIM28), resulting in regulation of various cellular targets. These include tumor suppressor protein p53 and cellular energy sensor AMP-activated protein kinase (AMPK). The restricted expression of MAGE-A3 in tumor cells makes MAGE-A3 an attractive target for vaccine-based immune therapy. However, although phase I and phase II clinical trials involving MAGE-A3-specific immunotherapeutic interventions were promising, large phase III studies failed. This article gives an overview about the role of MAGE-A3 as a cellular master switch and discusses approaches to improve MAGE-A3-based immunotherapies.

TRIM28 variants and Wilms' tumour predisposition

TRIM28 was recently identified as a Wilms' tumour (WT) predisposition gene, with germline pathogenic variants identified in around 1% of isolated and 8% of familial WT cases. TRIM28 variants are associated with epithelial WT, but the presence of other tumour components or anaplasia does not exclude the presence of a germline or somatic TRIM28 variant. In children with WT, TRIM28 acts as a classical tumour suppressor gene, with both alleles generally disrupted in the tumour. Therefore, loss of TRIM28 (KAP1/TIF1beta) protein expression in tumour tissue by immunohistochemistry is an effective strategy to identify patients carrying pathogenic TRIM28 variants. TRIM28 is a ubiquitously expressed corepressor that binds transcription factors in a context‐, species‐, and cell‐type‐specific manner to control the expression of genes and transposable elements during embryogenesis and cellular differentiation. In this review, we describe the inheritance patterns, histopathological and clinical features of TRIM28‐associated WT, as well as potential underlying mechanisms of tumourigenesis during embryonic kidney development. Recognizing germline TRIM28 variants in patients with WT can enable counselling, genetic testing, and potential early detection of WT in other children in the family. A further exploration of TRIM28‐associated WT will help to unravel the diverse and complex mechanisms underlying WT development. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

MageC2 protein is upregulated by oncogenic activation of MAPK pathway and causes impairment of the p53 transactivation function

Normal-to-tumor cell transition is accompanied by changes in gene expression and signal transduction that turns the balance toward cancer-cell phenotype, eluding by different mechanisms, the response of tumor-suppressor genes. Here, we observed that MageC2, a MAGE-I protein able to regulate the p53 tumor-suppressor, is accumulated upon MEK/ERK MAPK activation. Overexpression of H-RasV12 oncogene causes an increase in MageC2 protein that is prevented by pharmacologic inhibition of MEK. Similarly, decrease in MageC2 protein levels is shown in A375 melanoma cells (which harbor B-RafV600E oncogenic mutation) treated with MEK inhibitors. MageC2 protein levels decrease when p14ARF is expressed, causing an Mdm2-independent upregulation of p53 transactivation. However, MageC2 is refractory to p14ARF-driven downregulation when H-RasV12 is co-expressed. Using MageC2 knockout A375 cells generated by CRISPR/CAS9 technology, we demonstrated the relevance of MageC2 protein in reducing p53 transcriptional activity in cells containing hyperactive MEK/ERK signaling. Furthermore, gene expression analysis performed in cancer-genomic databases, supports the correlation of reduced p53 transcriptional activity and high MageC2 expression, in melanoma cells containing Ras or B-Raf driver mutations. Data presented here suggest that MageC2 can be a functional target of the oncogenic MEK/ERK pathway to regulate p53.

MAGE-A3 is a prognostic biomarker for poor clinical outcome in cutaneous squamous cell carcinoma with perineural invasion via modulation of cell proliferation

Perineural invasion is a pathologic process of neoplastic dissemination along and invading into the nerves. Perineural invasion is associated with aggressive disease and a greater likelihood of poor outcomes. In this study, 3 of 9 patients with cutaneous squamous cell carcinoma and perineural invasion exhibited poor clinical outcomes. Tumors from these patients expressed high levels of MAGE-A3, a cancer testis antigen that may contribute to key processes of tumor development. In addition to perineural invasion, the tumors exhibited poor differentiation and deep invasion and were subsequently classified as Brigham and Women's Hospital tumor stage 3. Cyclin E, A and B mRNA levels were increased in these tumors compared with normal skin tissues (102.93±15.03 vs. 27.15±4.59, 36.83±19.41 vs. 11.59±5.83, 343.77±86.49 vs. 95.65±29.25, respectively; p<0.05). A431 cutaneous squamous cell carcinoma cells pretreated with MAGE-A3 antibody exhibited a decreased percentage S-phase cells (14.13±2.8% vs. 33.97±1.1%; p<0.05) and reduced closure in scratch assays (43.88±5.49% vs. 61.17±3.97%; p = 0.0058). In a syngeneic animal model of squamous cell carcinoma, immunoblots revealed overexpression of MAGE-A3 and cyclin E, A, and B protein in tumors at 6 weeks. However, knockout of MAGE-A3 expression caused a reduction in tumor growth (mean tumor volume 155.3 mm3 vs. 3.2 mm3) compared with parental cells. These results suggest that MAGE-A3 is a key mediator in cancer progression. Moreover, elevated collagen XI and matrix metalloproteases 3, 10, 11, and 13 mRNA levels were observed in poorly differentiated cutaneous squamous cell carcinoma with perineural invasion compared with normal skin tissue (1132.56±882.7 vs. 107.62±183.62, 1118.15±1109.49 vs. 9.5±5, 2603.87±2385.26 vs. 5.29±3, 957.95±627.14 vs. 400.42±967.66, 1149.13±832.18 vs. 19.41±35.62, respectively; p<0.05). In summary, this study highlights the potential prognostic value of MAGE-A3 in clinical outcomes of cutaneous squamous cell carcinoma patients.

Emerging roles of the MAGE protein family in stress response pathways

The melanoma antigen (MAGE) proteins all contain a MAGE homology domain. MAGE genes are conserved in all eukaryotes and have expanded from a single gene in lower eukaryotes to ∼40 genes in humans and mice. Whereas some MAGEs are ubiquitously expressed in tissues, others are expressed in only germ cells with aberrant reactivation in multiple cancers. Much of the initial research on MAGEs focused on exploiting their antigenicity and restricted expression pattern to target them with cancer immunotherapy. Beyond their potential clinical application and role in tumorigenesis, recent studies have shown that MAGE proteins regulate diverse cellular and developmental pathways, implicating them in many diseases besides cancer, including lung, renal, and neurodevelopmental disorders. At the molecular level, many MAGEs bind to E3 RING ubiquitin ligases and, thus, regulate their substrate specificity, ligase activity, and subcellular localization. On a broader scale, the MAGE genes likely expanded in eutherian mammals to protect the germline from environmental stress and aid in stress adaptation, and this stress tolerance may explain why many cancers aberrantly express MAGEs Here, we present an updated, comprehensive review on the MAGE family that highlights general characteristics, emphasizes recent comparative studies in mice, and describes the diverse functions exerted by individual MAGEs.

T cell receptor therapy against melanoma-Immunotherapy for the future?

Malignant melanoma has seen monumental changes in treatment options the last decade from the very poor results of dacarbazine treatment to the modern-day use of targeted therapies and immune checkpoint inhibitors. Melanoma has a high mutational burden making it more capable of evoking immune responses than many other tumours. Even when considering double immune checkpoint blockade with anti-CTLA-4 and anti-PD-1, we still have far to go in melanoma treatment as 50% of patients with metastatic disease do not respond to current treatment. Alternative immunotherapy should therefore be considered. Since melanoma has a high mutational burden, it is considered more immunogenic than many other tumours. T cell receptor (TCR) therapy could be a possible way forward, either alone or in combination, to improve the response rates of this deadly disease. Melanoma is one of the cancers where TCR therapy has been frequently applied. However, the number of antigens targeted remains fairly limited, although advanced personalized therapies aim at also targeting private mutations. In this review, we look at possible aspects of targeting TCR therapy towards melanoma and provide an implication of its use in the future.

Structural basis for substrate recognition and chemical inhibition of oncogenic MAGE ubiquitin ligases

Testis-restricted melanoma antigen (MAGE) proteins are frequently hijacked in cancer and play a critical role in tumorigenesis. MAGEs assemble with E3 ubiquitin ligases and function as substrate adaptors that direct the ubiquitination of novel targets, including key tumor suppressors. However, how MAGEs recognize their targets is unknown and has impeded the development of MAGE-directed therapeutics. Here, we report the structural basis for substrate recognition by MAGE ubiquitin ligases. Biochemical analysis of the degron motif recognized by MAGE-A11 and the crystal structure of MAGE-A11 bound to the PCF11 substrate uncovered a conserved substrate binding cleft (SBC) in MAGEs. Mutation of the SBC disrupted substrate recognition by MAGEs and blocked MAGE-A11 oncogenic activity. A chemical screen for inhibitors of MAGE-A11:substrate interaction identified 4-Aminoquinolines as potent inhibitors of MAGE-A11 that show selective cytotoxicity. These findings provide important insights into the large family of MAGE ubiquitin ligases and identify approaches for developing cancer-specific therapeutics.

Immunological and functional aspects of MAGEA3 cancer/testis antigen

Identification of ectopic gene activation in cancer cells serves as a basis for both gene signature-guided tumor targeting and unearthing of oncogenic mechanisms to expand the understanding of tumor biology/oncogenic process. Proteins expressed only in germ cells of testis and/or placenta (immunoprivileged organs) and in malignancies are called cancer testis antigens; they are antigenic because of the lack of antigen presentation by those specific cell types (germ cells), which limits the exposure of the proteins to the immune cells. Since the Cancer Testis Antigens (CTAs) are immunogenic and expressed in a wide variety of cancer types, CT antigens have become interesting target for immunotherapy against cancer. Among CT antigens MAGEA family is reported to have 12 members (MAGEA1 to MAGEA12). The current review highlights the studies on MAGEA3 which is a CT antigen and reported in almost all types of cancer. MAGEA3 is well tried for cancer immunotherapy. Recent advances on its functional and immunological aspect warranted much deliberation on effective therapeutic approach, thus making it a more interesting target for cancer therapy.

A comprehensive analysis of the MAGE family as prognostic and diagnostic markers for hepatocellular carcinoma

The Melanoma Antigen Gene (MAGE) family is a large, highly conserved group of proteins which was reported to participate in the progression of multiple cancers in humans. However, the function of distinct MAGE genes in hepatocellular carcinoma (HCC) is largely unclear. In this study, we comprehensively evaluated the expression, clinical significance, genetic alteration, interaction network and functional enrichment of MAGEs in HCC. Our research showed that many MAGE genes were dysregulated in HCC. Among them, MAGEA1, MAGEC2, MAGED1, MAGED2, MAGEF1 and MAGEL2 were significantly associated with clinical stage and differentiation of HCC. MAGED1, MAGED2, MAGEA6, MAGEA12, MAGEA10, MAGEB4, MAGEL2 and MAGEC3 significantly correlated with HCC prognosis. Further functional enrichment analysis suggested the dysregulated MAGEs may play important roles in signal transduction. These results indicate that multiple dysregulated MAGEs might play important roles in the development of HCC and can be exploited as useful biomarkers for diagnosis and treatment in HCC.

Inhibition of MAGEA2 regulates pluripotency, proliferation, apoptosis, and differentiation in mouse embryonic stem cells

Mouse embryonic stem cells (mESCs) exhibit self-renewal and pluripotency, can differentiate into all three germ layers, and serve as an essential model in stem cell research and for potential clinical application in regenerative medicine. Melanoma-associated antigen A2 (MAGEA2) is not expressed in normal somatic cells but rather in different types of cancer, especially in undifferentiated cells, such as in the testis, differentiating cells, and ESCs. However, the role of MAGEA2 in mESCs remains to be clarified. Accordingly, in this study, we examined the expression and functions of MAGEA2 in mESCs. MAGEA2 messenger RNA (mRNA) expression was decreased during mESCs differentiation. MAGEA2 function was then evaluated in knockdown mESC. MAGEA2 knockdown resulted in decreased pluripotency marker gene expression in mESCs consequent to increased Erk1/2 phosphorylation. Decreased MAGEA2 expression inhibited mESC proliferation via S phase cell cycle arrest with a subsequent decrease in cell cycle-associated genes Cdk1, Cdk2, Cyclin A1, Cyclin D1, and Cdc25a. Apoptotic mESCs markedly increased along with cleaved forms of caspases 3, 6, and 7 and PARP expression, confirming caspase-dependent apoptosis. MAGEA2 knockdown significantly decreased embryoid body size in vitro when cells were differentiated naturally and teratoma size in vivo, concomitant with decreased ectoderm marker gene expression. These findings suggested that MAGEA2 regulates ESC pluripotency, proliferation, cell cycle, apoptosis, and differentiation. The enhanced understanding of the regulatory mechanisms underlying diverse mESC characteristics will facilitate the clinical application of mESCs.

Aberrantly enhanced melanoma-associated antigen (MAGE)-A3 expression facilitates cervical cancer cell proliferation and metastasis via actuating Wnt signaling pathway

BACKGROUND

The over-expression of melanoma-associated antigen (MAGE)-A3 in cervical cancer (CC) has been observed in our previous study, suggesting that it possibly take a vital role during the development and metastasis of CC. The present study aimed to investigate the biological function of MAGE-A3 in the progression of CC and explore how it executes its roles.

METHODS

The mRNA expression of MAGE-A3 in End1/E6E7 and CC cell lines (HeLa, SiHa and C33A) was measured by real-time quantitative reverse transcription PCR (qRT-PCR). Loss- and gain-of-function methods were used to assess the effect of MAGE-A3 on the proliferative, migratory and invasive abilities of HeLa and SiHa cells. Western blot was performed to measure the expression levels of proteins related to epithelial-mesenchymal transition (EMT) and proteins in the Wnt signaling pathway. In vivo tumorigenesis assay was conducted to evaluate the effect of MAGE-A3 on tumor growth.

RESULTS

MAGE-A3 expression was significantly up-regulated in CC cell lines (HeLa, SiHa and C33A) compared with that in End1/E6E7 cell line. Knockdown of MAGE-A3 could significantly suppress migration, invasion and proliferation in HeLa cells; whereas, overexpression of MAGE-A3 in SiHa cells presented the opposite results. Moreover, knockdown of MAGE-A3 presented a suppressive effect on the activation of EMT and Wnt signaling pathway in HeLa cells, whilst up-regulation of MAGE-A3 exhibited the opponent outcomes in SiHa cells. Through in vivo tumorigenesis assay, we further verified that MAGE-A3 acted as a facilitator in tumor growth.

CONCLUSIONS

MAGE-A3 is overexpressed in CC cells and possibly facilitates the viability and motility of CC cells via modulating EMT and Wnt signaling. This study implied that MAGE-A3 might be a potential therapeutic target as well as a prognosis predictor for patients with CC.

Cancer testis antigens in sarcoma: Expression, function and immunotherapeutic application

Sarcomas are a group of heterogeneous malignancies of mesenchymal origin. Patient outcomes remain especially grim for those with recurrent or metastatic disease, and current therapeutic strategies have not significantly improved outcomes over the past few decades. This has led to a number of studies assessing novel therapies. Cancer testis antigens (CTAs) are tumor-associated antigens with physiologic expression in the testis and various malignancies, including sarcomas. Genes encoding CTAs include MAGE, NY-ESO-1, PRAME, TRAG-3/CSAGE, and SSX. The importance and function of CTAs in tumorigenesis have gained recognition in recent years. They are also proving as robust diagnostic and prognostic biomarkers. Therapeutically, antigens derived from CTAs are highly recognizable by T lymphocytes and therefore capable of generating a potent antitumor immune response. CTAs are, therefore, promising targets for novel immunotherapies. Here we review the emerging works on expression, function, and immunotherapeutic application of CTAs in sarcoma therapy.

KAP1 is an antiparallel dimer with a functional asymmetry

This study reveals the architecture of human KAP1 by integrating molecular modeling with small-angle X-ray scattering and single-molecule experiments. KAP1 dimers feature a structural asymmetry at the C-terminal domains that has functional implications for recruitment of HP1.

KAP1 (KRAB domain–associated protein 1) plays a fundamental role in regulating gene expression in mammalian cells by recruiting different transcription factors and altering the chromatin state. In doing so, KAP1 acts both as a platform for macromolecular interactions and as an E3 small ubiquitin modifier ligase. This work sheds light on the overall organization of the full-length protein combining solution scattering data, integrative modeling, and single-molecule experiments. We show that KAP1 is an elongated antiparallel dimer with an asymmetry at the C-terminal domains. This conformation is consistent with the finding that the Really Interesting New Gene (RING) domain contributes to KAP1 auto-SUMOylation. Importantly, this intrinsic asymmetry has key functional implications for the KAP1 network of interactions, as the heterochromatin protein 1 (HP1) occupies only one of the two putative HP1 binding sites on the KAP1 dimer, resulting in an unexpected stoichiometry, even in the context of chromatin fibers.

A stochastic individual-based model to explore the role of spatial interactions and antigen recognition in the immune response against solid tumours

Spatial interactions between cancer and immune cells, as well as the recognition of tumour antigens by cells of the immune system, play a key role in the immune response against solid tumours. The existing mathematical models generally focus only on one of these key aspects. We present here a spatial stochastic individual-based model that explicitly captures antigen expression and recognition. In our model, each cancer cell is characterised by an antigen profile which can change over time due to either epimutations or mutations. The immune response against the cancer cells is initiated by the dendritic cells that recognise the tumour antigens and present them to the cytotoxic T cells. Consequently, T cells become activated against the tumour cells expressing such antigens. Moreover, the differences in movement between inactive and active immune cells are explicitly taken into account by the model. Computational simulations of our model clarify the conditions for the emergence of tumour clearance, dormancy or escape, and allow us to assess the impact of antigenic heterogeneity of cancer cells on the efficacy of immune action. Ultimately, our results highlight the complex interplay between spatial interactions and adaptive mechanisms that underpins the immune response against solid tumours, and suggest how this may be exploited to further develop cancer immunotherapies.

Regulation of MAGE-A3/6 by the CRL4-DCAF12 ubiquitin ligase and nutrient availability

Melanoma antigen genes (MAGEs) are emerging as important oncogenic drivers that are normally restricted to expression in male germ cells but are aberrantly expressed in cancers and promote tumorigenesis. Mechanistically, MAGEs function as substrate specifying subunits of E3 ubiquitin ligases. Thus, the activation of germline-specific genes in cancer can drive metabolic and signaling pathways through altered ubiquitination to promote tumorigenesis. However, the mechanisms regulating MAGE expression and activity are unclear. Here, we describe how the MAGE-A3/6 proteins that function as repressors of autophagy are downregulated in response to nutrient deprivation. Short-term cellular starvation promotes rapid MAGE-A3/6 degradation in a proteasome-dependent manner. Proteomic analysis reveals that degradation of MAGE-A3/6 is controlled by the CRL4-DCAF12 E3 ubiquitin ligase. Importantly, the degradation of MAGE-A3/6 by CRL4-DCAF12 is required for starvation-induced autophagy. These findings suggest that oncogenic MAGEs can be dynamically controlled in response to stress to allow cellular adaptation, autophagy regulation, and tumor growth and that CRL4-DCAF12 activity is responsive to nutrient status.

The expression of melanoma-associated antigen A (MAGE-A) in oral squamous cell carcinoma: an evaluation of the significance for tumor prognosis

OBJECTIVES

Melanoma-associated antigens A had been detected repeatedly in oral squamous cell carcinoma, but not in healthy mucosa. Additionally, patients with MAGE-A expressing cancers are regarded to have a worse survival prognosis, so that MAGE-A are supposed to be part of carcinogenesis. Which role these antigens fulfill within OSCC is still, up today, largely unknown. This study examines the hypothesis that MAGE-A is being produced in OSCC but not in mucosa tissue and if MAGE-A has any correlation to clinical patient's parameters like tumor size, lymph node metastasis, distant metastasis, overall survival, and recurrence.

MATERIALS AND METHODS

For this purpose, 50 tumor samples and 39 mucosa samples were analyzed by means of PCR and immunohistochemical staining with the antibody 6C1.

RESULTS

Forty of 41 stained tumor samples showed a positive antibody reaction with a maximum staining rate of 53%. Sixteen mucosa samples showed a mild positive reaction. The PCR revealed a linear expression pattern of MAGE-A in which the genes are proportionally expressed in OSCC. We did not find any relationship between MAGE-A and tumor size, overall survival, or recurrence. There was also no connection between MAGE-A and tumor parameters Hif-1 and LDH. Their expression was detected tendentially in tumors with higher staging, advanced lymph node metastasis, and rising age of the patients. The genes MAGE-A3+6 and MAGE-A4 had a statistically significant correlation with lymph node metastasis (p = 0.007 and p = 0.004). Patients got distant metastasis and influence of MAGE-A on metastatic behavior could not be verified. The genes MAGE-A3 and -A4 are consequently qualified as tumor markers in the field of diagnosis and follow-up of OSCC.

CONCLUSIONS AND CLINICAL RELEVANCE

Two genes have great potential as target proteins in immunotherapy. The genes MAGE-A3+6 and MAGE-A4 had a statistically significant correlation with lymph node metastasis.

Expression dynamics of Mage family genes during self-renewal and differentiation of mouse pluripotent stem and teratocarcinoma cells

The biological roles of cancer-testis antigens of the Melanoma antigen (Mage) family in mammalian development, stem cell differentiation and carcinogenesis are largely unknown. In order to understand the involvement of the Mage family genes in maintenance of normal and cancer stem cells, the expression patterns of Mage-a, Mage-b, Mage-d, Mage-e, Mage-h and Mage-l gene subfamilies were analyzed during the self-renewal and differentiation of mouse pluripotent stem and teratocarcinoma cells. Clustering analysis based on the gene expression profiles of undifferentiated and differentiating cell populations revealed strong correlations between Mage expression patterns and differentiation and malignant states. Gene co-expression analysis disclosed the potential contributions of Mage family members in self-renewal and differentiation of pluripotent stem and teratocarcinoma cells. Two gene clusters including Mage-a4 and Mage-a8, Mageb1, Mage-d1, Mage-d2, Mage-e1, Mage-l2 were identified as functional antagonists with opposing roles in the regulation of proliferation and differentiation of mouse pluripotent stem and teratocarcinoma cells. The identified aberrant expression patterns of Mage-a2, Mage-a6, Mage-b4, Mageb-16 and Mage-h1 in teratocarcinoma cells can be considered as specific teratocarcinoma biomarkers promoted the malignant phenotype. Our study first provides a model for the involvement of Mage family members in regulatory networks during the self-renewal and early differentiation of normal and cancerous stem cells for further research of the predicted functional modules and the development of new cancer treatment strategies.

ZFP30 promotes adipogenesis through the KAP1-mediated activation of a retrotransposon-derived Pparg2 enhancer

Krüppel-associated box zinc finger proteins (KZFPs) constitute the largest family of mammalian transcription factors, but most remain completely uncharacterized. While initially proposed to primarily repress transposable elements, recent reports have revealed that KFZPs contribute to a wide variety of other biological processes. Using murine and human in vitro and in vivo models, we demonstrate here that one poorly studied KZFP, ZFP30, promotes adipogenesis by directly targeting and activating a retrotransposon-derived Pparg2 enhancer. Through mechanistic studies, we further show that ZFP30 recruits the co-regulator KRAB-associated protein 1 (KAP1), which, surprisingly, acts as a ZFP30 co-activator in this adipogenic context. Our findings provide an understanding of both adipogenic and KZFP-KAP1 complex-mediated gene regulation, showing that the KZFP-KAP1 axis can also function in a non-repressive manner.

Downregulation of DCC sensitizes multiple myeloma cells to bortezomib treatment

Multiple myeloma (MM) is an incurable disease; a better understanding of the molecular aspects of this hematological malignancy could contribute to the development of new treatment strategies and help to improve the survival rates of patients with MM. Previously, the methylation status of the deleted in colorectal cancer (DCC) gene was correlated with the survival rate of patients with MM, thus the main goal of this study was to understand DCC contribution to MM tumorigenesis, and to assess the impact of DCC inhibition in the MM response to treatment with bortezomib. Our results demonstrated that hypermethylation of the DCC promoter inhibits gene expression, and DCC silencing is significantly correlated with a reduction in cell viability and an increase in cell death induced by bortezomib. In conclusion, our results suggested that hypermethylation is an important mechanism of DCC expression regulation in MM and that the absence of DCC contributes to the enhanced sensitivity to treatment with bortezomib.

A Designer Cross-reactive DNA Immunotherapeutic Vaccine that Targets Multiple MAGE-A Family Members Simultaneously for Cancer Therapy

PURPOSE

Cancer/testis antigens have emerged as attractive targets for cancer immunotherapy. Clinical studies have targeted MAGE-A3, a prototype antigen that is a member of the MAGE-A family of antigens, in melanoma and lung carcinoma. However, these studies have not yet had a significant impact due to poor CD8⁺ T-cell immunogenicity, platform toxicity, or perhaps limited target antigen availability. In this study, we develop an improved MAGE-A immunogen with cross-reactivity to multiple family members.

EXPERIMENTAL DESIGN

In this study, we analyzed MAGE-A expression in The Cancer Genome Atlas and observed that many patients express multiple MAGE-A isoforms, not limited to MAGE-A3, simultaneously in diverse tumors. On the basis of this, we designed an optimized consensus MAGE-A DNA vaccine capable of cross-reacting with many MAGE-A isoforms, and tested immunogenicity and antitumor activity of this vaccine in a relevant autochthonous melanoma model.

RESULTS

Immunization of this MAGE-A vaccine by electroporation in C57Bl/6 mice generated robust IFNγ and TNFα CD8⁺ T-cell responses as well as cytotoxic CD107a/IFNγ/T-bet triple-positive responses against multiple isoforms. Furthermore, this MAGE-A DNA immunogen generated a cross-reactive immune response in 14 of 15 genetically diverse, outbred mice. We tested the antitumor activity of this MAGE-A DNA vaccine in Tyr::CreER;BRAF^Ca/+;Pten^lox/lox transgenic mice that develop melanoma upon tamoxifen induction. The MAGE-A DNA therapeutic vaccine significantly slowed tumor growth and doubled median mouse survival.

CONCLUSIONS

These results support the clinical use of consensus MAGE-A immunogens with the capacity to target multiple MAGE-A family members to prevent tumor immune escape.

Emerging Contributions of Cancer/Testis Antigens to Neoplastic Behaviors

Tumors of nearly every origin activate the expression of genes normally restricted to gametogenic cells. These genes encode proteins termed cancer/testis (CT) antigens, since expression outside of their naturally immune-privileged site can evoke an immune response. Despite extensive efforts to exploit CT antigens as immunotherapeutic targets, investigation of whether these proteins participate in tumorigenic processes has lagged. Here, we discuss emerging evidence that demonstrates that CT antigens can confer a selective advantage to tumor cells by promoting oncogenic processes or permitting evasion of tumor-suppressive mechanisms. These advances indicate the inherent flexibility of tumor cell regulatory networks to engage aberrantly expressed proteins to promote neoplastic behaviors, which could ultimately present novel therapeutic entry points.

The role of Cancer/Testis Antigens in Multiple Myeloma pathogenesis and their application in disease monitoring and therapy

A unique group of genes, encoding tumour associated antigens, known as the Cancer/Testis Antigens (CTAs), have been explored as novel markers of disease progression and as targets of immunotherapy in several cancers, including the haematological malignancy Multiple Myeloma (MM). This review aims to update the knowledge of CTA involvement in MM pathogenesis and how their potential as biomarkers for disease monitoring and targets of immunotherapy has been explored in the MM disease arena. Despite the initial promise of these antigens, their use as immunotherapy targets has not been successful, yet with a greater understanding of their role in disease pathogenesis they may still have a significant role to play as biomarkers of disease and therapeutic targets.

Epigenetic regulation of MAGE family in human cancer progression-DNA methylation, histone modification, and non-coding RNAs

The melanoma antigen gene (MAGE) proteins are a group of highly conserved family members that contain a common MAGE homology domain. Type I MAGEs are relevant cancer-testis antigens (CTAs), and originally considered as attractive targets for cancer immunotherapy due to their typically high expression in tumor tissues but restricted expression in normal adult tissues. Here, we reviewed the recent discoveries and ideas that illustrate the biological functions of MAGE family in cancer progression. Furthermore, we also highlighted the current understanding of the epigenetic mechanism of MAGE family expression in human cancers.

The potential immune-eliciting cancer testis antigens in colorectal cancer

The identification of cancer testis antigens (CTAs) has been an important finding in the search of potential targets for cancer immunotherapy. CTA is one of the subfamilies of the large tumor-associated antigens groups. It is aberrantly expressed in various types of human tumors but is absent in normal tissues except for the testis and placenta. This CTAs-restricted pattern of expression in human malignancies together with its potential immunogenic properties, has stirred the interest of many researchers to use CTAs as one of the ideal targets in cancer immunotherapy. To date, multiple studies have shown that CTAs-based vaccines can elicit clinical and immunological responses in different tumors, including colorectal cancer (CRC). This review details our current understanding of CTAs and CRC in regard to the expression and immunological responses as well as some of the critical hurdles in CTAs-based immunotherapy.

Cancer-testis antigens: Unique cancer stem cell biomarkers and targets for cancer therapy

Cancer-testis antigens (CTAs) are considered as unique and promising cancer biomarkers and targets for cancer therapy. CTAs are multifunctional protein group with specific expression patterns in normal embryonic and adult cells and various types of cancer cells. CTAs are involved in regulating of the basic cellular processes during development, stem cell differentiation and carcinogenesis though the biological roles and cell functions of CTA families remain largely unclear. Analysis of CTA expression patterns in embryonic germ and somatic cells, pluripotent and multipotent stem cells, cancer stem cells and their cell descendants indicates that rearrangements of characteristic CTA profiles (aberrant expression) could be associated with cancer transformation and failure of the developmental program of cell lineage specification and germ line restriction. Therefore, aberrant CTA profiles can be used as panels of biomarkers for diagnoses and the selection of cancer treatment strategies. Moreover, immunogenic CTAs are prospective targets for cancer immunotherapy. Clinical trials testing broad range of cancer therapeutic vaccines against antigens of MAGEA and NY-ESO-1 families for treating various cancers have shown mixed clinical efficiency, safety and tolerability, suggesting the requirement of in-depth research of CTA expression in normal and cancer stem cells and extensive clinical trials for improving cancer immunotherapy technologies. This review focuses on recent advancement in study of CTAs in normal and cancer cells, particularly in normal and cancer stem cells, and provides a new insight into CTA expression patterns during normal and cancer stem cell lineage development. Additionally, new approaches in development of effective CTA-based therapies exclusively targeting cancer stem cells will be discussed.

Cancer/testis antigens (CTAs) expression in resected lung cancer

Background

Increasing evidence shows cancer/testis antigens (CTAs) play a key role in oncogenesis. Our pre-study finds that MAGEA1, MAGEA10, MAGEB2, KK-LC-1, and CTAG1A/B have high expression frequencies at the protein level. We aim to explore their prognostic role and correlations with clinical characteristics in resected lung cancer at the mRNA level.

Methods

Thirty-eight surgical lung cancer samples were included. Validation study was performed based on The Cancer Genome Atlas database. The prognostic roles of CTAs were evaluated by Kaplan–Meier and multivariate analysis.

Results

High expression of MAGEA1 (16.7% vs 65.0%, P=0.004), MAGEA10 (61.1% vs 95.0%, P=0.016), MAGEB2 (55.6% vs 95.0%, P=0.007), and KK-LC-1 (16.7% vs 55.0%, P=0.020) was closely correlated with lymph node metastasis at diagnosis. Patients with TNM stage II or III had a higher expression of MAGEA10 (57.1% vs 91.7%, P=0.034) and KK-LC-1 (14.3% vs 50.0%, P=0.039) compared with patients in TNM stage I. High CTAG1A/B expression showed unfavorable prognosis in all cases (P<0.05). Subgroup analysis showed high CTAG1A/B expression was a negative prognostic factor of survival (P=0.031) in patients with TNM stage II or III. Although no statistical significance was reached, high CTAG1A/B also showed a similar prognostic trend in lung adenocarcinoma (ADC) and squamous cell carcinoma. The Cancer Genome Atlas database showed the negative prognostic role of CTAG1A/B was mainly induced by CTAG1B (NY-ESO-1, P=0.047) and high CTAG1B expression (hazard ratio =2.733, 95% CI: 1.348–5.541, P=0.005) was an independent negative prognostic factor of lung ADC.

Conclusion

CTAs represent potential candidate targets for immunotherapy and their expression was closely correlated with tumor stage. High CTAG1B expression was an independent negative prognostic factor of lung ADC.

Cancer testis antigens as immunogenic and oncogenic targets in breast cancer

Breast cancer cells frequently express tumor-associated antigens that can elicit immune responses to eradicate cancer. Cancer-testis antigens (CTAs) are a group of tumor-associated antigens that might serve as ideal targets for cancer immunotherapy because of their cancer-restricted expression and robust immunogenicity. Previous clinical studies reported that CTAs are associated with negative hormonal status, aggressive tumor behavior and poor survival. Furthermore, experimental studies have shown the ability of CTAs to induce both cellular and humoral immune responses. They also demonstrated the implication of CTAs in promoting cancer cell growth, inhibiting apoptosis and inducing cancer cell invasion and migration. In the current review, we attempt to address the immunogenic and oncogenic potential of CTAs and their current utilization in therapeutic interventions for breast cancer.