Cause and consequence of cancer/testis antigen activation in cancer

Differential expression of preferentially expressed antigen in melanoma (PRAME) in testicular germ cell tumors - A comparative study with SOX17

The accurate identification of different components in testicular germ cell tumors (GCT) is essential for tailoring treatment and informing the clinical prognosis. PRAME (preferentially expressed antigen in melanoma), a member in the family of cancer testis antigens, plays critical roles in regulating pluripotency and suppressing somatic/germ cell differentiation in seminomas (SEM). To investigate the potential diagnostic value of PRAME in testicular GCT, here we comparatively examined the expression patterns of PRAME and SOX17 by immunohistochemistry in both pure and mixed GCT. Tissue microarrays constructed from 66 pure or mixed GCT were examined, including 25 seminomas (13 pure and 12 mixed), 35 embryonal carcinomas (EC; 7 pure and 28 mixed), 23 teratomas (TER; 10 pure and 13 mixed), 15 yolk sac tumors (YST; 1 pure and 14 mixed), and 5 choriocarcinomas (CC; 1 pure and 4 mixed), with 11 germ cell neoplasia in situ (GCNIS) and 6 normal testicular tissue as controls. The expression levels of PRAME or SOX17 were evaluated by a scoring system counting for intensity and extent of staining. PRAME nuclear expression was present in 92% (23/25) of SEM, including all 13 pure SEM, and 10 out of 12 seminomatous component of mixed GCT. In contrast, all EC and TER were completely negative for PRAME, and focal expression was demonstrated in 33.3% of YST and 20% of CC. As for SOX17, 96% of SEM and 73% of YST stained positively, whereas EC and CC were negative. Focal nuclear positivity was identified in the epithelial cell component of 17.4% (4/23) of TER. We found the sensitivity of PRAME to detect SEM to be comparable to SOX17, although SOX17 staining is more diffuse and stronger in the majority of cases. The specificity of PRAME for SEM appeared to be superior to that of SOX17 (92% versus 81%). In conclusion, PRAME is preferentially expressed in SEM or within the seminomatous component of mixed GCT with only focal variable expression in YST and CC, but shows no expression in EC and TER. These findings suggest that PRAME can be explored as a diagnostic marker for SEM.

Spermatogonial Stem Cell-Based Therapies: Taking Preclinical Research to the Next Level

Fertility preservation via biobanking of testicular tissue retrieved from testicular biopsies is now generally recommended for boys who need to undergo gonadotoxic treatment prior to the onset of puberty, as a source of spermatogonial stem cells (SSCs). SSCs have the potential of forming spermatids and may be used for therapeutic fertility approaches later in life. Although in the past 30 years many milestones have been reached to work towards SSC-based fertility restoration therapies, including transplantation of SSCs, grafting of testicular tissue and various in vitro and ex vivo spermatogenesis approaches, unfortunately, all these fertility therapies are still in a preclinical phase and not yet available for patients who have become infertile because of their treatment during childhood. Therefore, it is now time to take the preclinical research towards SSC-based therapy to the next level to resolve major issues that impede clinical implementation. This review gives an outline of the state of the art of the effectiveness and safety of fertility preservation and SSC-based therapies and addresses the hurdles that need to be taken for optimal progression towards actual clinical implementation of safe and effective SSC-based fertility treatments in the near future.

Identification of Tissue-Specific Gene Clusters Induced by DNA Demethylation in Lung Adenocarcinoma: More Than Germline Genes

Simple Summary

Loss of DNA methylation is often observed in human tumors, but how this epigenetic alteration impacts the transcriptome of cancer cells remains largely undefined. So far, DNA hypomethylation in tumors has been associated with aberrant activation of a germline-specific gene expression program. Here, we exploited transcriptomic and methylomic datasets of lung adenocarcinoma to investigate the possibility that other gene expression programs also become ectopically activated in hypomethylated tumors. Remarkably, we found that DNA hypomethylation in lung adenocarcinoma is associated with ectopic activation of not only germline-specific genes, but also gene clusters displaying specific expression in the gastrointestinal tract, or in stratified epithelia. Interestingly, expression of genes in this latter group was of prognostic value. Together, our study brings novel insight into the transcriptomic changes associated with DNA hypomethylation in tumors, and is an incentive to explore the value of hypomethylated DNA sequences as cancer biomarkers.

Abstract

Genome-wide loss of DNA methylation is commonly observed in human cancers, but its impact on the tumor transcriptome remains ill-defined. Previous studies demonstrated that this epigenetic alteration causes aberrant activation of a germline-specific gene expression program. Here, we examined if DNA hypomethylation in tumors also leads to de-repression of gene clusters with other tissue specificities. To this end, we explored transcriptomic and methylomic datasets from human lung adenocarcinoma (LUAD) cell lines, normal lung, and lung alveolar type II cells, considered as the origin of LUAD. Interestingly, DNA demethylation in LUAD cell lines was associated with activation of not only germline-specific (CG) genes, but also gene clusters displaying specific expression in the gastrointestinal tract (GI), or in stratified epithelia (SE). Consistently, genes from all three clusters showed highly specific patterns of promoter methylation among normal tissues and cell types, and were generally sensitive to induction by a DNA demethylating agent. Analysis of TCGA datasets confirmed that demethylation and activation of CG, GI and SE genes also occurs in vivo in LUAD tumor tissues, in association with global genome hypomethylation. For genes of the GI cluster, we demonstrated that HNF4A is a necessary factor for transcriptional activation following promoter demethylation. Interestingly, expression of several SE genes, in particular FAM83A, correlated with both tumor grade and reduced patient survival. Together, our study uncovers novel cell-type specific gene clusters that become aberrantly activated in LUAD tumors in association with genome-wide hypomethylation.

A New Trend in Cancer Treatment: The Combination of Epigenetics and Immunotherapy

In recent years, immunotherapy has become a hot spot in the treatment of tumors. As an emerging treatment, it solves many problems in traditional cancer treatment and has now become the main method for cancer treatment. Although immunotherapy is promising, most patients do not respond to treatment or develop resistance. Therefore, in order to achieve a better therapeutic effect, combination therapy has emerged. The combination of immune checkpoint inhibition and epigenetic therapy is one such strategy. In this review, we summarize the current understanding of the key mechanisms of how epigenetic mechanisms affect cancer immune responses and reveal the key role of epigenetic processes in regulating immune cell function and mediating anti-tumor immunity. In addition, we highlight the outlook of combined epigenetic and immune regimens, particularly the combination of immune checkpoint blockade with epigenetic agents, to address the limitations of immunotherapy alone.

Identification and validation of the high expression of pseudogene TCAM1P in cervical cancer via integrated bioinformatics analysis

Background

HPV as the main cause of cervical cancer has long been revealed, but the detailed mechanism has not yet been elucidated. The role of testis/cancer antigen in cervical cancer has been revealed. However, there are no reports about the statement of testis/cancer-specific non-coding RNA. In this study, we first proposed TCAM1P as a testis/cancer-specific pseudogene, and used a series of experimental data to verify its relationship with HPV, and analyzed its diagnosis value of high-grade cervical lesions and the mechanism of their high expression in cervical cancer. This provides a new direction for the prevention and treatment of cervical cancer.

Methods

The specific expression of pseudogenes in each tissue was calculated by “TAU” formula. ROC curve was used to judge the diagnosed value of TCAM1P for high-grade lesions. The proliferation ability of cells was measured by CCK8. The expression of TCAM1P, HPV E6/E7 were detected by qRT-PCR. The binding for RBPs on TCAM1P was predicted by starbase v2.0 database, then RIP assay was used to verify. Besides, Gene Ontology (GO) and KEGG enrichment analysis were performed with “clusterprofiler” R package.

Results

TCAM1P was specifically high-expressed in normal testicular tissue and cervical cancer. Interesting, with the severity of cervical lesions increased, the expression of TCAM1P increased, and TCAM1P could effectively diagnose high-grade cervical lesions. Besides, the expression of TCAM1P was HPV dependent, with highest expression in HPV-positive cervical cancer tissues. Furthermore, RIP assay showed that EIF4A3 regulated the expression of TCAM1P through binding with it. CCK8 assay showed that TCAM1P promoted the proliferation and the Gene ontology (GO) and KEGG Pathway enrichment analysis same suggested that TCAM1P is involved in multiple ways in cell proliferation including Cell cycle, DNA replication and etc.

Conclusions

In this study, we firstly proposed that TCAM1P is cancer/testis pseudogene and is regulated by HPV E6/E7 and EIF4A3. TCAM1P promotes the proliferation of cervical cancer cells and acts as promoter in cervical cancer. Otherwise, TCAM1P promote proliferation through regulating cell cycle and DNA replication, but more evidence needs to be provided to reveal the mechanism by which TCAM1P plays a role in cervical cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02440-7.

Beyond immune checkpoint blockade: emerging immunological strategies

The success of checkpoint inhibitors has accelerated the clinical implementation of a vast mosaic of single agents and combination immunotherapies. However, the lack of clinical translation for a number of immunotherapies as monotherapies or in combination with checkpoint inhibitors has clarified that new strategies must be employed to advance the field. The next chapter of immunotherapy should examine the immuno-oncology therapeutic failures, and consider the complexity of immune cell-cancer cell interactions to better design more effective anticancer drugs. Herein, we briefly review the history of immunotherapy and checkpoint blockade, highlighting important clinical failures. We discuss the critical aspects - beyond T cell co-receptors - of immune processes within the tumour microenvironment (TME) that may serve as avenues along which new therapeutic strategies in immuno-oncology can be forged. Emerging insights into tumour biology suggest that successful future therapeutics will focus on two key factors: rescuing T cell homing and dysfunction in the TME, and reappropriating mononuclear phagocyte function for TME inflammatory remodelling. New drugs will need to consider the complex cell networks that exist within tumours and among cancer types.

Seeking the truth behind the myth: Argonaute tales from "nuclearland"

Argonaute proteins have been traditionally characterized as a highly evolutionary conserved family engaged in post-transcriptional gene silencing pathways. The Argonaute family is mainly grouped into the AGO and PIWI clades. The canonical role of Argonaute proteins relies on their ability to bind small-RNAs that recognize complementary sequences on target mRNAs to induce either mRNA degradation or translational repression. However, there is an increasing amount of evidence supporting that Argonaute proteins also exert multiple nuclear functions that subsequently regulate gene expression. In this line, genome-wide studies showed that members from the AGO clade regulate transcription, 3D chromatin organization, and splicing of active loci located within euchromatin. Here, we discuss recent work based on high-throughput technologies that have significantly contributed to shed light on the multivariate nuclear functions of AGO proteins in different model organisms. We also analyze data supporting that AGO proteins are able to execute these nuclear functions independently from small RNA pathways. Finally, we integrate these mechanistic insights with recent reports highlighting the clinical importance of AGO in breast and prostate cancer development.

Role and Clinical Utility of Cancer/Testis Antigens in Head and Neck Squamous Cell Carcinoma

Cancer/testis (CT) antigens exhibit selective expression predominantly in immunoprivileged tissues in non-pathological contexts but are aberrantly expressed in diverse cancers. Due to their expression pattern, they have historically been attractive targets for immunotherapies. A growing number of studies implicate CT antigens in almost all hallmarks of cancer, suggesting that they may act as cancer drivers. CT antigens are expressed in head and neck squamous cell carcinomas. However, their role in the pathogenesis of these cancers remains poorly studied. Given that CT antigens hold intriguing potential as therapeutic targets and as biomarkers for prognosis and that they can provide novel insights into oncogenic mechanisms, their further study in the context of head and squamous cell carcinoma is warranted.

Development of a novel embryonic germline gene-related prognostic model of lung adenocarcinoma

BACKGROUND

Emerging evidence implicates the correlation of embryonic germline genes with the tumor progress and patient's outcome. However, the prognostic value of these genes in lung adenocarcinoma (LUAD) has not been fully studied. Here we systematically evaluated this issue, and constructed a novel signature and a nomogram associated with embryonic germline genes for predicting the outcomes of lung adenocarcinoma.

METHODS

The LUAD cohorts retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database were used as training set and testing set, respectively. The embryonic germline genes were downloaded from the website https://venn.lodder.dev. Then, the differentially expressed embryonic germline genes (DEGGs) between the tumor and normal samples were identified by limma package. The functional enrichment and pathway analyses were also performed by clusterProfiler package. The prognostic model was constructed by the least absolute shrinkage and selection operator (LASSO)-Cox regression method. Survival and Receiver Operating Characteristic (ROC) analyses were performed to validate the model using training set and four testing GEO datasets. Finally, a prognostic nomogram based on the signature genes was constructed using multivariate regression method.

RESULTS

Among the identified 269 DEGGs, 249 were up-regulated and 20 were down-regulated. GO and KEGG analyses revealed that these DEGGs were mainly enriched in the process of cell proliferation and DNA damage repair. Then, 103 DEGGs with prognostic value were identified by univariate Cox regression and further filtered by LASSO method. The resulting sixteen DEGGs were included in step multivariate Cox regression and an eleven embryonic germline gene related signature (EGRS) was constructed. The model could robustly stratify the LUAD patients into high-risk and low-risk groups in both training and testing sets, and low-risk patients had much better outcomes. The multi-ROC analysis also showed that the EGRS model had the best predictive efficacy compared with other common clinicopathological factors. The EGRS model also showed robust predictive ability in four independent external datasets, and the area under curve (AUC) was 0.726 (GSE30219), 0.764 (GSE50081), 0.657 (GSE37745) and 0.668 (GSE72094). More importantly, the expression level of some genes in EGRS has a significant correlation with the progression of LUAD clinicopathology, suggesting these genes might play an important role in the progression of LUAD. Finally, based on EGRS genes, we built and calibrated a nomogram for conveniently evaluating patients' outcomes.

The oncogenic role of meiosis-specific Aurora kinase C in mitotic cells

Aberrant expression of meiosis-specific genes in cancer has recently emerged as a driver of some cancer formation. Aurora kinase C (AURKC) is a member of the Aurora kinase family of proteins known to regulate chromosome segregation during cell divisions. AURKC is normally expressed in meiotic cells; however, elevated levels of AURKC mRNA and protein are frequently measured in cancer cells. To understand the function of AURKC in cancer cells, expression was induced in noncancerous, human retina pigmented epithelial cells. While AURKC expression did not alter cell proliferation over 72 h, it did increase cell migration and anchorage independent growth in soft agar suggesting an oncogenic role in mitotically dividing cells. To evaluate AURKC as a potential therapeutic target, a frameshift mutation in the gene was introduced in U2OS osteosarcoma cells using CRISPR-Cas9 technology resulting in a premature stop codon. Cancer cells lacking AURKC displayed no change in cell proliferation over 72 h but did migrate less and formed fewer colonies in soft agar. Whole transcriptome sequencing analysis uncovered over 400 differentially expressed genes in U2OS cells with and without AURKC. GO analysis revealed alterations in proteinaceous extracellular matrix genes including COL1A1. These data indicate that therapeutics targeting AURKC could decrease cancer cell metastasis and disease progression. Because AURKC is transcriptionally silenced in normal mitotic cells, its disruption could specifically target cancer cells limiting the toxic side effects associated with current therapeutics.

Uev1A promotes breast cancer cell migration by up-regulating CT45A expression via the AKT pathway

Background

UEV1A encodes a ubiquitin-E2 variant closely associated with tumorigenesis and metastasis, but its underlying mechanism in promoting metastasis remains to be investigated.

Methods

In this study, we experimentally manipulated UEV1A and CT45A gene expression and monitored their effects on cancer-related gene expression, cell migration and the signal transduction cascade.

Results

It was found that UEV1A overexpression induces CT45A family gene expression in breast cancer cells. Indeed, ectopic expression of UEV1A was sufficient to induce CT45A and its downstream genes involved in tumorigenesis, epithelial-mesenchymal transition (EMT), stemness and metastasis, and to promote cell migration and EMT signaling. Consistently, depletion of CT45A abolished the above effects, indicating that CT45A is a critical downstream effector of Uev1A. The Uev1A-induced cell migration and EMT signaling was dependent on AKT but independent of NF-κB, indicating that CT45A acts downstream of the AKT pathway.

Conclusions

Based on previous reports and observations in this study, we propose that the Ubc13-Uev1A complex activates AKT through K63-linked polyubiquitination, which leads to enhanced CT45A expression, stimulated cell migration and EMT signaling in breast cells. Since similar effects were also observed in a colorectal cancer cell line, the Ubc13/Uev1A-AKT-CT45A axis may also promote tumorigenesis and metastasis in other tissues.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08750-3.

Transcriptional overlap links DNA hypomethylation with DNA hypermethylation at adjacent promoters in cancer

Tumor development involves alterations in DNA methylation patterns, which include both gains (hypermethylation) and losses (hypomethylation) in different genomic regions. The mechanisms underlying these two opposite, yet co-existing, alterations in tumors remain unclear. While studying the human MAGEA6/GABRA3 gene locus, we observed that DNA hypomethylation in tumor cells can lead to the activation of a long transcript (CT-GABRA3) that overlaps downstream promoters (GABRQ and GABRA3) and triggers their hypermethylation. Overlapped promoters displayed increases in H3K36me3, a histone mark deposited during transcriptional elongation and known to stimulate de novo DNA methylation. Consistent with such a processive mechanism, increases in H3K36me3 and DNA methylation were observed over the entire region covered by the CT-GABRA3 overlapping transcript. Importantly, experimental induction of CT-GABRA3 by depletion of DNMT1 DNA methyltransferase, resulted in a similar pattern of regional DNA hypermethylation. Bioinformatics analyses in lung cancer datasets identified other genomic loci displaying this process of coupled DNA hypo/hypermethylation, and some of these included tumor suppressor genes, e.g. RERG and PTPRO. Together, our work reveals that focal DNA hypomethylation in tumors can indirectly contribute to hypermethylation of nearby promoters through activation of overlapping transcription, and establishes therefore an unsuspected connection between these two opposite epigenetic alterations.

Sperm proteins and cancer-testis antigens are released by the seminiferous tubules in mice and men

Sperm develop from puberty in the seminiferous tubules, inside the blood-testis barrier to prevent their recognition as "non-self" by the immune system, and it is widely assumed that human sperm-specific proteins cannot access the circulatory or immune systems. Sperm-specific proteins aberrantly expressed in cancer, known as cancer-testis antigens (CTAs), are often pursued as cancer biomarkers and therapeutic targets based on the assumption they are neoantigens absent from the circulation in healthy men. Here, we identify a wide range of germ cell-derived and sperm-specific proteins, including multiple CTAs, that are selectively deposited by the Sertoli cells of the adult mouse and human seminiferous tubules into testicular interstitial fluid (TIF) that is "outside" the blood-testis barrier. From TIF, the proteins can access the circulatory- and immune systems. Disruption of spermatogenesis decreases the abundance of these proteins in mouse TIF, and a sperm-specific CTA is significantly decreased in TIF from infertile men, suggesting that exposure of certain CTAs to the immune system could depend on fertility status. The results provide a rationale for the development of blood-based tests useful in the management of male infertility and indicate CTA candidates for cancer immunotherapy and biomarker development that could show sex-specific and male-fertility-related responses.

Can Immune Suppression and Epigenome Regulation in Placenta Offer Novel Insights into Cancer Immune Evasion and Immunotherapy Resistance?

Cancer is the second leading cause of mortality and morbidity in the developed world. Cancer progression involves genetic and epigenetic alterations, accompanied by aggressive changes, such as increased immune evasion, onset of metastasis, and drug resistance. Similar to cancer, DNA hypomethylation, immune suppression, and invasive cell behaviours are also observed in the human placenta. Mechanisms that lead to the acquisition of invasive behaviour, immune evasion, and drug and immunotherapy resistance are presently under intense investigations to improve patient outcomes. Here, we review current knowledge regarding the similarities between immune suppression and epigenome regulation, including the expression of repetitive elements (REs), endogenous retroviruses (ERVs) and transposable elements (TEs) in cells of the placenta and in cancer, which are associated with changes in immune regulation and invasiveness. We explore whether immune suppression and epigenome regulation in placenta offers novel insights into immunotherapy resistance in cancer, and we also discuss the implications and the knowledge gaps relevant to these findings, which are rapidly being accrued in these quite disparate research fields. Finally, we discuss potential linkages between TE, ERV and RE activation and expression, regarding mechanisms of immune regulation in placenta and cancer. A greater understanding of the role of immune suppression and associated epigenome regulation in placenta could help to elucidate some comparable mechanisms operating in cancer, and identify potential new therapeutic targets for treating cancer.

Cell Therapy With TILs: Training and Taming T Cells to Fight Cancer

The rationale behind cancer immunotherapy is based on the unequivocal demonstration that the immune system plays an important role in limiting cancer initiation and progression. Adoptive cell therapy (ACT) is a form of cancer immunotherapy that utilizes a patient’s own immune cells to find and eliminate tumor cells, however, donor immune cells can also be employed in some cases. Here, we focus on T lymphocyte (T cell)-based cancer immunotherapies that have gained significant attention after initial discoveries that graft-versus-tumor responses were mediated by T cells. Accumulating knowledge of T cell development and function coupled with advancements in genetics and data science has enabled the use of a patient’s own (autologous) T cells for ACT (TIL ACTs). In TIL ACT, tumor-infiltrating lymphocytes (TILs) are collected from resected tumor material, enhanced and expanded ex-vivo, and delivered back to the patient as therapeutic agents. ACT with TILs has been shown to cause objective tumor regression in several types of cancers including melanoma, cervical squamous cell carcinoma, and cholangiocarcinoma. In this review, we provide a brief history of TIL ACT and discuss the current state of TIL ACT clinical development in solid tumors. We also discuss the niche of TIL ACT in the current cancer therapy landscape and potential strategies for patient selection.

Expression of Cancer Testis Antigens in Tumor-Adjacent Normal Liver Is Associated with Post-Resection Recurrence of Hepatocellular Carcinoma

Simple Summary

High recurrence rates after resection of liver cancer (hepatocellular carcinoma) with curative intent impair clinical outcomes of patients diagnosed with liver cancer. Cancer/testis antigens (CTAs) are expressed in cancer and can serve as therapeutic targets. We identified 12 CTAs expressed in 80% of liver cancer patients, and each one individually in at least 10%. Furthermore, we found that patients with expression of CTAs in macroscopically tumor-free liver tissue, experience more tumor recurrence and poor survival after surgical tumor removal. The increased risk of tumor recurrence in patients with CTA expression in tumor-free liver suggests that these patients already have micro-metastasis at the time of operation. These CTA-expressing (pre-)malignant cells may thus be a source of liver cancer recurrence, reflecting the relevance of targeting these to prevent liver cancer recurrence.

Abstract

High recurrence rates after resection of hepatocellular carcinoma (HCC) with curative intent impair clinical outcomes of HCC. Cancer/testis antigens (CTAs) are suitable targets for cancer immunotherapy if selectively expressed in tumor cells. The aims were to identify CTAs that are frequently and selectively expressed in HCC-tumors, and to investigate whether CTAs could serve as biomarkers for occult metastasis. Tumor and paired tumor-free liver (TFL) tissues of HCC-patients and healthy tissues were assessed for mRNA expression of 49 CTAs by RT-qPCR and protein expression of five CTAs by immunohistochemistry. Twelve CTA-mRNAs were expressed in ≥10% of HCC-tumors and not in healthy tissues except testis. In tumors, mRNA and protein of ≥ 1 CTA was expressed in 78% and 71% of HCC-patients, respectively. In TFL, CTA mRNA and protein was found in 45% and 30% of HCC-patients, respectively. Interestingly, CTA-expression in TFL was an independent negative prognostic factor for post-resection HCC-recurrence and survival. We established a panel of 12 testis-restricted CTAs expressed in tumors of most HCC-patients. The increased risk of HCC-recurrence in patients with CTA expression in TFL, suggests that CTA-expressing (pre-)malignant cells may be a source of HCC-recurrence, reflecting the relevance of targeting these to prevent HCC-recurrence.

Oncogenic cancer/testis antigens are a hallmarker of cancer and a sensible target for cancer immunotherapy

Increasing evidence shows that numerous cancer-testis antigens (CTAs) are uniquely overexpressed in various types of cancer and most CTAs are oncogenic. Overexpression of oncogenic CTAs promotes carcinogenesis, cancer metastasis, and drug resistance. Oncogenic CTAs are generally associated with poor prognosis in cancer patients and are an important hallmark of cancer, making them a crucial target for cancer immunotherapy. CTAs-targeted antibodies, vaccines, and chimeric antigen receptor-modified T cells (CAR-T) have recently been used in cancer treatment and achieved promising outcomes in the preclinical and early clinical trials. However, the efficacy of current CTA-targeted therapeutics is either moderate or low in cancer therapy. CTA-targeted cancer immunotherapy is facing enormous challenges. Several critical scientific problems need to be resolved: (1) the antigen presentation function of MHC-I protein is usually deficient in cancer patients, so that very low amounts of intracellular CTA epitopes are presented to tumor cell membrane surface, leading to weak immune response and subsequent immunity to CTAs; (2) various immunosuppressive cells are rich in tumor tissues leading to diminished tumor immunity; (3) the tumor tissue microenvironment markedly reduces the efficacy of cancer immunotherapy. In the current review paper, the authors propose new strategies and approaches to overcome the barriers of CTAs-targeted immunotherapy and to develop novel potent immune therapeutics against cancer. Finally, we highlight that the oncogenic CTAs have high tumor specificity and immunogenicity, and are sensible targets for cancer immunotherapy. We predict that CTAs-targeted immunotherapy will bring about breakthroughs in cancer therapy in the near future.

Analysis of LAGEs Family Gene Signature and Prognostic Relevance in Breast Cancer

Breast cancer (BRCA) is one of the most complex diseases and involves several biological processes. Members of the L-antigen (LAGE) family participate in the development of various cancers, but their expressions and prognostic values in breast cancer remain to be clarified. High-throughput methods for exploring disease progression mechanisms might play a pivotal role in the improvement of novel therapeutics. Therefore, gene expression profiles and clinical data of LAGE family members were acquired from the cBioportal database, followed by verification using the Oncomine and The Cancer Genome Atlas (TCGA) databases. In addition, the Kaplan-Meier method was applied to explore correlations between expressions of LAGE family members and prognoses of breast cancer patients. MetaCore, GlueGo, and GluePedia were used to comprehensively study the transcript expression signatures of LAGEs and their co-expressed genes together with LAGE-related signal transduction pathways in BRCA. The result indicated that higher LAGE3 messenger (m)RNA expressions were observed in BRCA tissues than in normal tissues, and they were also associated with the stage of BRCA patients. Kaplan-Meier plots showed that overexpression of LAGE1, LAGE2A, LAGE2B, and LAGE3 were highly correlated to poor survival in most types of breast cancer. Significant associations of LAGE family genes were correlated with the cell cycle, focal adhesion, and extracellular matrix (ECM) receptor interactions as indicated by functional enrichment analyses. Collectively, LAGE family members' gene expression levels were related to adverse clinicopathological factors and prognoses of BRCA patients; therefore, LAGEs have the potential to serve as prognosticators of BRCA patients.

Meiotic nuclear divisions 1 (MND1) fuels cell cycle progression by activating a KLF6/E2F1 positive feedback loop in lung adenocarcinoma

Background

Considering the increase in the proportion of lung adenocarcinoma (LUAD) cases among all lung cancers and its considerable contribution to cancer‐related deaths worldwide, we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD.

Methods

The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus (GEO) datasets and The Cancer Genome Atlas (TCGA) data were combined, and a promising risk biomarker called meiotic nuclear divisions 1 (MND1) was selectively acquired. Cell viability assays and subcutaneous xenograft models were used to validate the oncogenic role of MND1 in LUAD cell proliferation and tumor growth. A series of assays, including mass spectrometry, co‐immunoprecipitation (Co‐IP), and chromatin immunoprecipitation (ChIP), were performed to explore the underlying mechanism.

Results

MND1 up‐regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis. In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle. The results of the Co‐IP, ChIP and dual‐luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel‐like factor 6 (KLF6), and thereby protecting E2F transcription factor 1 (E2F1) from KLF6‐induced transcriptional repression. Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner.

Conclusions

MND1, KLF6, and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD. MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.

T-cell-engaging Therapy for Solid Tumors

T-cell engagers (TCE) are a rapidly evolving novel group of treatments that have in common the concurrent engagement of a T-cell surface molecule and a tumoral cell antigen. Bispecific antibodies and genetically engineered adoptive cell therapies, as chimeric antigen receptors or T-cell receptors, have similarities and differences among their mechanisms of action, toxicity profiles, and resistance pathways. Nevertheless, the success observed in the hematologic field has not been obtained with solid tumors yet, as they are biologically more complex and have few truly tumor-specific cell surface antigens that can be targeted with high avidity T cells. Different strategies are under study to improve their short-term perspective, such as new generations of more active TCEs, multi-target or combination of different treatments approaches, or to improve the manufacturing processes. A comprehensive review of TCEs as a grouped treatment class, their current status, and research directions in their application to solid tumors therapeutics are discussed here.

Deficiency of TBL1XR1 causes asthenozoospermia

Transducin (β)-like 1 X-linked receptor 1 (TBL1XR1) is an evolutionarily conserved protein related to spermatozoa. To clarify its role and mechanism of action in spermatozoa, qRT-PCR was used to analyse the expression of TBL1XR1 in human spermatozoa and mouse testes. The mice were established as an animal model by injecting the mice testes with small interfering RNA against TBL1XR1 or control siRNA. Our results indicated that deficiency of TBL1XR1 in mice reduced the motility of spermatozoa and disrupted the histone-to-protamine transition. We also found the decreased expression of TBL1XR1 in the spermatozoa of human patients with asthenozoospermia (AZ) compared with that in the spermatozoa of healthy males. Moreover, we carried out chromatin immunoprecipitation analyses and found that genes downstream of TBL1XR1 were related to sperm motility. Thus, TBL1XR1 might be related to sperm motility and might function through its downstream genes. Our data highlight the role of TBL1XR1 involved in spermatozoa and provide new molecular insights into the intricate systems required for male fertility.

Short H2A histone variants are expressed in cancer

Short H2A (sH2A) histone variants are primarily expressed in the testes of placental mammals. Their incorporation into chromatin is associated with nucleosome destabilization and modulation of alternate splicing. Here, we show that sH2As innately possess features similar to recurrent oncohistone mutations associated with nucleosome instability. Through analyses of existing cancer genomics datasets, we find aberrant sH2A upregulation in a broad array of cancers, which manifest splicing patterns consistent with global nucleosome destabilization. We posit that short H2As are a class of "ready-made" oncohistones, whose inappropriate expression contributes to chromatin dysfunction in cancer.

Does EIF2S3 Retrogene Activation Regulate Cancer/Testis Antigen Expression in Human Cancers?

Cancer/Testis (C/T) antigens are a group of antigens, expressed in almost all types of cancers, which can elicit an immune response in patients whose cancers express these antigens. They are currently of great interest as targets for the development of cancer biomarkers and the creation of immunotherapies that directly target tumors in patients. Currently there are 280 C/T antigens and their variants listed on the C/T antigen data base. All known C/T antigens are encoded for by genes which are normally only expressed in the male testis; specifically during the process of spermatogenesis. They are therefore only expressed in germ cells that are in the process of differentiating into sperm. Expression of C/T antigens in tumors is thus a biological anomaly as, with the exception of germ cell tumors, cancers arise from somatic tissues which are not known to express any of the genes specifically involved in spermatogenesis. How and why C/T antigens are expressed in tumors remains an enigma. In this paper we present a hypothesis which proposes a mechanism for the activation of C/T antigen encoding genes in tumors. We propose that aberrant activation of the human autosomal retrogene, EIF2S3B, which regulates initiation and maintenance of spermatogenesis in males, is responsible for C/T expression. Because both male and females have tumors that express C/T antigens activation of spermatogenesis genes in tumors must involve a non-sex specific pathway. This can be explained by the copy number of EIF2S3 genes uniquely present within the human genome.

Tumors Widely Express Hundreds of Embryonic Germline Genes

We have recently described a class of 756 genes that are widely expressed in cancers, but are normally restricted to adult germ cells, referred to as germ cell cancer genes (GC genes). We hypothesized that carcinogenesis involves the reactivation of biomolecular processes and regulatory mechanisms that, under normal circumstances, are restricted to germline development. This would imply that cancer cells share gene expression profiles with primordial germ cells (PGCs). We therefore compared the transcriptomes of human PGCs (hPGCs) and PGC-like cells (PGCLCs) with 17,382 samples from 54 healthy somatic tissues (GTEx) and 11,003 samples from 33 tumor types (TCGA), and identified 672 GC genes, expanding the known GC gene pool by 387 genes (51%). We found that GC genes are expressed in clusters that are often expressed in multiple tumor types. Moreover, the amount of GC gene expression correlates with poor survival in patients with lung adenocarcinoma. As GC genes specific to the embryonic germline are not expressed in any adult tissue, targeting these in cancer treatment may result in fewer side effects than targeting conventional cancer/testis (CT) or GC genes and may preserve fertility. We anticipate that our extended GC dataset enables improved understanding of tumor development and may provide multiple novel targets for cancer treatment development.

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.

Cancer/Testis Antigens into mitochondria: a hub between spermatogenesis, tumorigenesis and mitochondrial physiology adaptation

Cancer/Testis Antigens (CTAs) genes are expressed only during spermatogenesis and tumorigenesis. Both processes share common specific metabolic adaptation related to energy supply, with a glucose to lactate gradient, leading to changes in mitochondrial physiology paralleling CTAs expression. In this review, we address the role of CTAs in mitochondria (mitoCTAs), by reviewing all published data, and assessing the putative localization of CTAs by screening for the presence of a mitochondrial targeting sequence (MTS). We evidenced that among the 276 CTAs, five were already shown to interfere with mitochondrial activities and 67 display a potential MTS.

PIWI-interacting RNAs in human cancer

P-element-induced wimpy testis (PIWI) interacting RNAs (piRNAs) are a class of small regulatory RNAs mechanistically similar to but much less studied than microRNAs and small interfering RNAs. Today the best understood function of piRNAs is transposon control in animal germ cells, which has earned them the name 'guardians of the germline'. Several molecular/cellular characteristics of piRNAs, including high sequence diversity, lack of secondary structures, and target-oriented generation seem to serve this purpose. Recently, aberrant expressions of piRNAs and PIWI proteins have been implicated in a variety of malignant tumors and associated with cancer hallmarks such as cell proliferation, inhibited apoptosis, invasion, metastasis and increased stemness. Researchers have also demonstrated multiple mechanisms of piRNA-mediated target deregulation associated with cancer initiation, progression or dissemination. We review current research findings on the biogenesis, normal functions and cancer associations of piRNAs, highlighting their potentials as cancer diagnostic/prognostic biomarkers and therapeutic tools. Whenever applicable, we draw connections with other research fields to encourage intercommunity conversations. We also offer recommendations and cautions regarding the general process of cancer-related piRNA studies and the methods/tools used at each step. Finally, we call attention to some issues that, if left unsolved, might impede the future development of this field.

Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse

Personalized cancer immunotherapy targeting patient-specific cancer/testis antigens (CTA) and neoantigens may benefit from large-scale tumor human leukocyte antigen (HLA) peptidome (immunopeptidome) analysis, which aims to accurately identify antigens presented by tumor cells. Although significant efforts have been invested in analyzing the HLA peptidomes of fresh tumors, it is often impossible to obtain sufficient volumes of tumor tissues for comprehensive HLA peptidome characterization. This work attempted to overcome some of these obstacles by using patient-derived xenograft tumors (PDX) in mice as the tissue sources for HLA peptidome analysis. PDX tumors provide a proxy for the expansion of the patient tumor by re-grafting them through several passages to immune-compromised mice. The HLA peptidomes of human biopsies were compared with those derived from PDX tumors. Larger HLA peptidomes were obtained from the significantly larger PDX tumors as compared with the patient biopsies. The HLA peptidomes of different PDX tumors derived from the same source tumor biopsy were very reproducible, even following subsequent passages to new naïve mice. Many CTA-derived HLA peptides were discovered, as well as several potential neoantigens/variant sequences. Taken together, the use of PDX tumors for HLA peptidome analysis serves as a highly expandable and stable source of reproducible and authentic peptidomes, opening up new opportunities for defining large HLA peptidomes when only small tumor biopsies are available. This approach provides a large source for tumor antigens identification, potentially useful for personalized immunotherapy.

Human cancer germline antigen-specific cytotoxic T cell-what can we learn from patient

In this review, we will highlight the importance of cancer germline antigen-specific cytotoxic CD8+ T lymphocytes (CTL) and the factors affecting antitumor CTL responses. In light of cancer immunotherapy, we will emphasis the need to further understand the features, characteristics, and actions of modulatory receptors of human cancer germline-specific CTLs, in order to determine the optimal conditions for antitumor CTL responses.

SPANXN2 functions a cell migration inhibitor in testicular germ cell tumor cells

Background

SPANX family members are thought to play an important role in cancer progression. The SPANXN2 is a gene expressed mainly in normal testis, but its role in testicular germ cell tumors (TGCTs) has yet to be investigated. TGCT is one of the most common solid tumors in young men and is associated with poor prognosis; however, effective prognostic indicators remain elusive. Therefore, we investigated the role of SPANXN2 in TGCT development.

Methods

SPANXN2 expression levels were validated by quantitative real-time polymerase chain reaction (qRT-PCR) analyses of 14 TGCT samples and five adjacent normal tissue samples. SPANXN2 was transiently overexpressed in TGCT cells to study the consequences for cell function. The effects of SPANXN2 on cell migration were evaluated in transwell and wound healing assays. The effects on cloning ability were evaluated in colony formation assays. MTT assays and cell cycle analysis were used to detect the effects of SPANXN2 on cell proliferation. The expression levels of EMT- and AKT-related proteins in cells overexpressing SPANXN2 were analyzed by Western blotting.

Results

Compared with adjacent normal tissues, the Gene Expression Profiling Interactive Analysis database showed SPANXN2 expression was downregulated in TGCTs which was consistent with the qRT-PCR analysis. SPANXN2 overexpression reduced cell migration and colony formation capability and downregulated expression of EMT- and AKT-related proteins, Vimentin, Snail, AKT, and p-AKT.

Conclusion

Our results suggest that SPANXN2 regulates TGCT cell migration via EMT- and AKT-related proteins although its role in the occurrence and development of TGCT remains to be fully elucidated.

The testis protein ZNF165 is a SMAD3 cofactor that coordinates oncogenic TGFβ signaling in triple-negative breast cancer

Cancer/testis (CT) antigens are proteins whose expression is normally restricted to germ cells yet aberrantly activated in tumors, where their functions remain relatively cryptic. Here we report that ZNF165, a CT antigen frequently expressed in triple-negative breast cancer (TNBC), associates with SMAD3 to modulate transcription of transforming growth factor β (TGFβ)-dependent genes and thereby promote growth and survival of human TNBC cells. In addition, we identify the KRAB zinc finger protein, ZNF446, and its associated tripartite motif protein, TRIM27, as obligate components of the ZNF165-SMAD3 complex that also support tumor cell viability. Importantly, we find that TRIM27 alone is necessary for ZNF165 transcriptional activity and is required for TNBC tumor growth in vivo using an orthotopic xenograft model in immunocompromised mice. Our findings indicate that aberrant expression of a testis-specific transcription factor is sufficient to co-opt somatic transcriptional machinery to drive a pro-tumorigenic gene expression program in TNBC.

Cancer Epigenetics, Tumor Immunity, and Immunotherapy

Epigenetic mechanisms, including DNA methylation, histone post-translational modifications, and chromatin structure regulation, are critical for the interactions between tumor and immune cells. Emerging evidence shows that tumors commonly hijack various epigenetic mechanisms to escape immune restriction. As a result, the pharmaceutical modulation of epigenetic regulators, including 'writers', 'readers', 'erasers', and 'remodelers', is able to normalize the impaired immunosurveillance and/or trigger antitumor immune responses. Thus, epigenetic targeting agents are attractive immunomodulatory drugs and will have major impacts on immuno-oncology. Here, we discuss epigenetic regulators of the cancer-immunity cycle and current advances in developing epigenetic therapies to boost anticancer immune responses, either alone or in combination with current immunotherapies.

The ectopic expression of meiCT genes promotes meiomitosis and may facilitate carcinogenesis

Cancer meiomitosis is defined as the concurrent activation of both mitotic and meiotic machineries in neoplastic cells that confer a selective advantage together with increased genomic instability. MeiCT (meiosis-specific cancer/testis) genes that perform specialized functions in the germline events required for the first meiotic division are ectopically expressed in several cancers. Here we describe the expression profiles of meiCT genes and proteins across a number of cancers and review the proposed mechanisms that increase aneuploidy and elicit reduction division in polyploid cells. These mechanisms are centered on the overexpression and function of meiCT proteins in cancers under various conditions that includes a response to genotoxic stress. Since meiCT genes are transcriptionally repressed in somatic cells, their target offers a promising therapeutic approach with limited toxicity to healthy tissues. Throughout the review, we provide a detailed description of the roles for each gene in the context of meiosis and we discuss proposed functions and outcomes resulting from their ectopic reactivation in cancer.

Systematic analysis of genetic variants in cancer-testis genes identified two novel lung cancer susceptibility loci in Chinese population

Cancer-testis (CT) genes played important roles in the progression of malignant tumors and were recognized as promising therapeutic targets. However, the roles of genetic variants in CT genes in lung cancer susceptibility have not been well depicted. This study aimed to evaluate the associations between genetic variants in CT genes and lung cancer risk in Chinese population. A total of 22,556 qualified SNPs from 268 lung cancer associated CT genes were initially evaluated based on our previous lung cancer GWAS (Genome-wide association studies) with 2,331 cases and 3,077 controls. As a result, 17 candidate SNPs were further genotyped in 1,056 cases and 1,053 controls using Sequenom platform. Two variants (rs6941653, OPRM1, T > C, screening: OR = 1.24, 95%CI: 1.12-1.38, P = 2.40×10^-5; validation: OR = 1.18, 95%CI: 1.01-1.37, P = 0.039 and rs402969, NLRP8, C > T, screening: OR = 1.15, 95%CI: 1.04-1.26, P = 0.006; validation: OR = 1.16, 95%CI: 1.02-1.33, P = 0.028) were identified as novel lung cancer susceptibility variants. Stratification analysis indicated that the effect of rs6941653 was stronger in lung squamous cell carcinoma (OR = 1.36) than that in lung adenocarcinoma (OR = 1.15, I² = 77%, P = 0.04). Finally, functional annotations, differential gene expression analysis, pathway and gene ontology analyses were performed to suggest the potential functions of our identified variants and genes. In conclusion, this study identified two novel lung cancer risk variants in Chinese population and provided deeper insight into the roles of CT genes in lung tumorigenesis.

Wnt Signaling Drives Ectopic Gene Expression and Larval Arrest in the Absence of the Caenorhabditis elegans DREAM Repressor Complex

Establishment and maintenance of proper gene expression is a requirement for normal growth and development. The DREAM complex in Caenorhabditis elegans functions as a transcriptional repressor of germline genes in somatic cells. At 26°, DREAM complex mutants show increased misexpression of germline genes in somatic cells and High Temperature Arrest (HTA) of worms at the first larval stage. To identify transcription factors required for the ectopic expression of germline genes in DREAM complex mutants, we conducted an RNA interference screen against 123 transcription factors capable of binding DREAM target promoter loci for suppression of the HTA phenotype in lin-54 mutants. We found that knock-down of 15 embryonically expressed transcription factors suppress the HTA phenotype in lin-54 mutants. Five of the transcription factors found in the initial screen have associations with Wnt signaling pathways. In a subsequent RNAi suppression screen of Wnt signaling factors we found that knock-down of the non-canonical Wnt/PCP pathway factors vang-1, prkl-1 and fmi-1 in a lin-54 mutant background resulted in strong suppression of the HTA phenotype. Animals mutant for both lin-54 and vang-1 showed almost complete suppression of the HTA phenotype, pgl-1 misexpression, and fertility defects associated with lin-54 single mutants at 26°. We propose a model whereby a set of embryonically expressed transcription factors, and the Wnt/PCP pathway, act opportunistically to activate DREAM complex target genes in somatic cells of DREAM complex mutants at 26°.

Tumor-Specific Transcripts Are Frequently Expressed in Hepatocellular Carcinoma With Clinical Implication and Potential Function

Hepatocellular carcinoma (HCC) is a highly lethal cancer and its underlying etiology remains understudied. The immense diversity and complexity of the cancer transcriptome hold the potential to yield tumor-specific transcripts (TSTs). Here, we showed that hundreds of TSTs are frequently expressed in HCC by an assembling spliced junction analysis of RNA sequencing raw data from approximately 1,000 normal and HCC tissues. Many of the TSTs were found to be unannotated and noncoding RNAs. We observed that intergenic TSTs are generated from transcription initiation sites frequently harboring long terminal repeat (LTR) elements. The strong presence of TSTs indicates significantly poor prognoses in HCC. Functional screening revealed a noncoding TST (termed TST1), which acted as a regulator of HCC cell proliferation and tumorigenesis. TST1 is generated from an LTR12C promoter regulated by DNA methylation and retinoic-acid-related drugs. Additionally, we observed that TSTs may be detected in the blood extracellular vesicles of patients with HCC. Conclusion: Our findings suggest an abundance of TSTs in HCC and their potential in clinical settings. The identification and characterization of TSTs may help toward the development of strategies for cancer diagnosis and treatment.

Cancer-Related Increases and Decreases in Calcium Signaling at the Endoplasmic Reticulum-Mitochondria Interface (MAMs)

Endoplasmic reticulum (ER)-mitochondria regions are specialized subdomains called also mitochondria-associated membranes (MAMs). MAMs allow regulation of lipid synthesis and represent hubs for ion and metabolite signaling. As these two organelles can module both the amplitude and the spatiotemporal patterns of calcium (Ca²⁺) signals, this particular interaction controls several Ca²⁺-dependent pathways well known for their contribution to tumorigenesis, such as metabolism, survival, sensitivity to cell death, and metastasis. Mitochondria-mediated apoptosis arises from mitochondrial Ca²⁺ overload, permeabilization of the mitochondrial outer membrane, and the release of mitochondrial apoptotic factors into the cytosol. Decreases in Ca²⁺ signaling at the ER-mitochondria interface are being studied in depth as failure of apoptotic-dependent cell death is one of the predominant characteristics of cancer cells. However, some recent papers that linked MAMs Ca²⁺ crosstalk-related upregulation to tumor onset and progression have aroused the interest of the scientific community.In this review, we will describe how different MAMs-localized proteins modulate the effectiveness of Ca²⁺-dependent apoptotic stimuli by causing both increases and decreases in the ER-mitochondria interplay and, specifically, by modulating Ca²⁺ signaling.

TEX19 promotes ovarian carcinoma progression and is a potential target for epitope vaccine immunotherapy

AIMS

Testis Expressed 19 (TEX19) is one of cancer/testis antigens identified in recent years and is related to the oncogenesis and progress of several cancers. This study aimed to reveal the role of TEX19 in ovarian cancer (OC) and searched for potential candidate epitope peptides of TEX19 to facilitate clinical application.

MAIN METHODS

TEX19 levels were evaluated by immunohistochemistry (IHC) in 98 human ovarian tissue samples. The correlation of TEX19 levels with patients' clinicopathological features was assessed. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting analysis were utilized to detect TEX19 levels in ovarian cell lines and TEX19-deficient cells. The level of TEX19 in OVCAR-3 and A2780 was knocked down by small interfering RNA (siRNA), and loss-of-function assays were used to determine the biological effects of TEX19 on the proliferation, migration, and invasion of OC cells. Subsequently, candidate epitope peptides from TEX19 were predicted and verified by the IEDB database, pepsite2 website, MOE software, and T2 cell binding assay.

KEY FINDINGS

TEX19 was significantly upregulated in OC which correlated to higher TNM stage, lymph node involvement, and invasiveness. Knockdown of TEX19 inhibited proliferation, migration, and invasion of OC cells. Additionally, we screened four peptides derived from TEX19 and found TL to be the dominant peptide with the greatest affinity with HLA-A*0201.

SIGNIFICANCE

Our data indicated a cancer-promoting effect of TEX19 in OC and demonstrated that TL could be a potential candidate for an anti-tumor epitope vaccine of OC, suggesting that TEX19 is a promising biomarker and immunotherapeutic target for OC.

Diagnostic and prognostic value of the cancer-testis antigen lactate dehydrogenase C4 in breast cancer

BACKGROUND

Lactate dehydrogenase C4 (LDH-C4) as a cancer/testis antigen (CTA) is abnormally expressed in some malignant tumors. However, the expression and clinical significance of LDH-C4 in breast cancer (BC) has not been characterized.

METHODS

We determined LDHC mRNA expression in serum and serum-derived exosomes of BC patients by quantitative RT-PCR. We also evaluated the protein expression of LDH-C4 in BC tissues using high-throughput tissue microarray analysis and immunohistochemistry.

RESULTS

Our results showed high mRNA expression level of LDHC in serum and serum-derived exosomes of BC patients. The LDHC level in serum and exosomes could distinguish BC cases from healthy individuals based on their AUCs of 0.9587 and 0.9464, respectively. Besides, the LDHC level in exosomes of BC patients associated with tumor size, and positively correlated with HER2 and Ki-67 expressions (all with P < 0.05). Serum and exosomal level of LDHC negatively correlated with medical treatment and positively with the recurrence of BC. Survival analysis showed that LDH-C4 expression negatively correlated with BC prognosis.

CONCLUSION

Serum and exosomal LDHC may be an effective indicator for the diagnosis, efficacy evaluation, and monitoring the recurrence of BC. LDH-C4 may act as a biomarker that predicts BC prognosis.

Cancer-testis specific gene OIP5: a downstream gene of E2F1 that promotes tumorigenesis and metastasis in glioblastoma by stabilizing E2F1 signaling

Background

The cancer-testis specific gene Opa interacting protein 5 (OIP5) is reactivated in many human cancers, but its functions in glioblastoma remain unclear. Here, we assessed the significance of OIP5 in the tumorigenesis and metastasis of glioblastoma for the first time.

Methods

An immunohistochemistry assay was performed to detect OIP5 expression changes in glioblastoma patients. Overall survival analysis was performed to evaluate the prognostic significance of OIP5. Growth curve, colony formation, and transwell assays were used to analyze cell proliferation and metastasis. Tumorigenicity potential was investigated in orthotopic tumor models, and immunoprecipitation, chromatin immunoprecipitation, and luciferase assays were employed to explore the mechanisms underlying the activation of OIP5 expression by E2F transcription factor 1 (E2F1) to stabilize and maintain E2F1 signaling.

Results

OIP5 was found to be upregulated in glioblastoma patients and to impair patient survival, and the increased expression of OIP5 was positively correlated with tumor stage. Compared with short hairpin green fluorescent protein cells, cells in which OIP5 was knocked down exhibited significantly reduced proliferation, metastasis, colony formation, and tumorigenicity abilities, whereas OIP5 recovery enhanced these abilities. OIP5 was highly correlated with cell cycle progression but had no obvious effects on apoptosis. Notably, we demonstrated a feedback loop in which E2F1 activates the expression of OIP5 to stabilize and maintain E2F1 signaling and promote the E2F1-regulated gene expression that is required for aggressive tumor biology.

Conclusions

Collectively, our findings demonstrate that OIP5 promotes glioblastoma progression and metastasis, suggesting that OIP5 is a potential target for anticancer therapy.

Cancer stem-like cells with increased expression of NY-ESO-1 initiate breast cancer metastasis

Breast cancer stem-like cells (BCSLCs) with a CD44⁺/CD24^−/low phenotype initiate the invasion and metastasis of breast cancer. The expression of New York oesophageal squamous cell carcinoma 1 (NY-ESO-1), one of the most immunogenic cancer-testicular antigens, is largely restricted to cancer and germ cells/placental trophoblasts, with little to no expression in normal adult somatic cells. Currently, few studies have reported the expression or function of NY-ESO-1 in BCSLCs. In the present study, immunohistochemistry indicated enhanced expression levels of NY-ESO-1/CD44 (P<0.01) and decreased expression levels of CD24 (P<0.01) in metastatic breast cancer tissues (MBCT) compared with non-MBCT. Additionally, the co-localization of CD44, CD24 and NY-ESO-1 in tissue samples was determined using immunofluorescence analysis. The results revealed that the expression of NY-ESO-1/CD44/CD24 was associated with breast cancer metastasis. Moreover, Spearman's rank correlation analysis indicated that CD44/CD24 expression was significantly correlated with that of NY-ESO-1. In the present study, mammosphere culture, a valuable method of BCSLC enrichment, was used to enrich MCF-7 and SK-BR-3 BCSLCs; immunofluorescence, western blotting and flow cytometry demonstrated increased expression levels of NY-ESO-1 and CD44, and low expression levels of CD24 in BCSLCs. Furthermore, the cell migration and invasion assays verified that BCSLCs with an increased NY-ESO-1 expression level exhibited greater invasive and migratory capacity compared with parental breast cancer cells. In addition to previously reported findings from the Oncomine database, it was ascertained that CD44⁺/CD24^−/low BCSLCs with an increased level of NY-ESO-1 expression initiated the invasion and metastasis of breast cancer; therefore, NY-ESO-1 may serve as a novel target for metastatic breast cancer immunotherapy.

The immune microenvironment and expression of PD-L1, PD-1, PRAME and MHC I in salivary duct carcinoma

AIMS

Salivary duct carcinoma (SDC) is an aggressive salivary malignancy that results in high mortality rates and is often resistant to chemotherapy. Anti-programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) checkpoint inhibitors have led to dramatic improvements in patients with various cancers. Other immunotherapeutic approaches, e.g. cancer vaccines, have shown promising results. Cancer testis antigens, e.g. preferentially expressed antigen in melanoma (PRAME), are regarded as promising vaccine targets because of their tumour-specific expression pattern.

METHODS AND RESULTS

We analysed the immunoexpression of PD-L1, PD-1, major histocompatibility complex class I (MHC I) and PRAME in 53 SDCs. The immunoexpression levels of PD-L1 in tumour cells (TCs) and immune cells (ICs), PD-1 in ICs, PRAME in TCs and MHC I in TCs were analysed, and were correlated with outcome. PRAME expression was seen in 83% of SDCs. No PRAME staining was present in normal salivary gland tissue. With the three established diagnostic algorithms proposed for head and neck squamous cell carcinoma, the criteria being a combined positive score of ≥1, TC% ≥1%, and TC% ≥25%, 35 (66%), 17 (32%) and three cases (6%), respectively, were deemed to be positive for PD-L1. PD-1-positive ICs were seen in 35 (66%) cases. MHC I down-regulation was seen in 82% of SDCs. There was a significant correlation among PD-L1 expression in ICs, PD-1 expression in ICs, and PRAME expression in TCs. PD-L1 expression in TCs and lack of PD-1 expression in ICs were associated with decreased disease-specific survival in SDC patients.

CONCLUSIONS

Alterations of the tumour immune microenvironment are common in SDCs, including expression of PD-1/PD-L1 and PRAME, which opens the way to potential novel immune therapies, such as cancer vaccination and PD-1/PD-L1 blockade, in these tumours.

A cis-eQTL genetic variant in PLK4 confers high risk of hepatocellular carcinoma

Purpose

The overexpression and knockdown of PLK4 were both reported to generate aneuploidy. Thus, we aimed to investigate whether genetic variants in PLK4 contribute to the development of hepatocellular carcinoma (HCC).

Methods

We evaluated associations of common variants in PLK4 and its promoter for the risk of HCC in our association study (1300 cases and 1344 controls). The genotype‐tissue expression (GTEx) and The cancer genome atlas (TCGA) databases were used to quantify the expression of PLK4. Cell proliferation and migration affected by PLK4 in HCC were assessed in vitro. Drug susceptibility testing (DST) model was used to assess the sensibility of PLK4‐activated HCC to CFI‐400945, a small molecule inhibitor of PLK4.

Results

Herein, we found a significant association between rs3811741, located in the PLK4 intron, and liver cancer risk (OR = 1.26, P = 9.81 × 10⁻⁵). Although PLK4 expressed at lower levels in somatic tissues compared to the testis, the risk allele A of rs3811741 was associated with increased PLK4 expression in liver cancer tissues. Additionally, PLK4 high expression was remarkably associated with shortened survival of HCC (HR = 1.97, P = .001). Furthermore, overexpression of PLK4 promoted, while knockdown of PLK4 suppressed cancer cell proliferation, migration, and invasion. DST model demonstrated that CFI‐400945 can effectively suppress rampant proliferation of HCC with highly expressed PLK4.

Conclusion

Taken together, our study demonstrated that PLK4 is a susceptibility gene and plays an oncogenic role in HCC. Furthermore, we identified that PLK4 sensitives HCC to CFI‐400945, which may be an ideal therapy target for HCC.

Hypomethylation-activated cancer-testis gene SPANXC promotes cell metastasis in lung adenocarcinoma

Many studies have shown that there were similarity between tumorigenesis and gametogenesis. Our previous work found that cancer-testis (CT) genes could serve as a novel source of candidate of cancer. Here, by analysing The Cancer Genome Atlas (TCGA) database, we characterized a CT gene, SPANXC, which is expressed only in testis. The SPANXC was reactivated in lung adenocarcinoma (LUAD) tissues. And the expression of SPANXC was associated with prognosis of LUAD. We also found that the activation of SPANXC was due to the promoter hypomethylation of SPANXC. Moreover, SPANXC could modulate cell metastasis both in vitro and in vivo. Mechanistically, we found that SPANXC could bind to ROCK1, a metastasis-related gene, and thus SPANXC may regulate cell metastasis partly through interaction with ROCK1 in LUAD. Together, our results demonstrated that the CT expression pattern of SPANXC served as a crucial role in metastasis of LUAD. And these data further corroborated the resemblance between processes of germ cell development and tumorigenesis, including migration and invasion.

Validation of immunogenic PASD1 peptides against HLA-A*24:02 colorectal cancer

Colorectal cancer is the third commonest malignancy in Asia including Malaysia. The immunogenic cancer-testis antigens, which are expressed in a variety of cancers but with limited expression in normal tissues except the testis, represent an attractive approach to improve treatment options for colorectal cancer. We aimed to validate four PASD1 peptides as the immunotherapeutic targets in colorectal cancer. First, PASD1 mRNA and protein expression were determined via real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. The PASD1 peptides specific to HLA-A*24:02 were investigated using IFN-y-ELISpot assay, followed by the cytolytic and granzyme-B-ELISpot assays to analyze the cytolytic effects of CD8⁺ T cells. Gene and protein expressions of PASD1 were detected in 20% and 17.3% of colorectal cancer samples, respectively. PASD1(4) peptide was shown to be immunogenic in colorectal cancer samples. CD8⁺ T cells raised against PASD1(4) peptide were able to lyze HLA-A*24:02+ PASD1+ cells. Our results reveal that PASD1(4) peptide represents a potential target for colorectal cancer.

Evaluation of cancer testis antigen (CT10, PRAME) and MHC I expression in high-grade urothelial carcinoma of the bladder

Immunotherapeutic strategies are increasingly used in the treatment of a number of malignancies including high grade urothelial carcinoma (HGUC) of the bladder. Because of this, detailed and accurate assessment of the tumour immune microenvironment is paramount. In this study, we aimed to correlate the composition of the tumour immune microenvironment with oncologic outcome and the expression of two cancer testis antigens (CTAs), CT10 and PRAME, potential cancer vaccine targets, as well as major histocompatibility complex I (MHC I), a molecule associated with tumour immune escape and resistance to immunotherapy.

Triplicate tissue microarrays (TMAs) were constructed using 207 cases of HGUC of the bladder. Oncologic outcome data was gathered for each case. Consecutive sections from the TMA blocks were stained with CD3, CD4, CD8, FOXP3, PD1, PD-L1, CT10, PRAME, and MHC I. 21% and 15% of cases expressed CT10 and PRAME, respectively. 88% of cases showed absent or decreased MHC I expression. CT10-expressing tumours showed a significantly worse disease specific survival (p = 0.007, hazard ratio 2.245, confidence interval 1.223–4.122). CT10, PRAME, and MHC I expression significantly correlated with other some immune parameters. CT10 and PRAME are expressed in a subset of HGUC and CTA and MHC I expression correlate with a number of important immune parameters. Together, these findings highlight the potential for exploring novel immune therapeutic strategies in HGUC. Additional studies evaluating the clinical relevance of these findings are warranted.

Serum Antibody Against NY-ESO-1 and XAGE1 Antigens Potentially Predicts Clinical Responses to Anti-Programmed Cell Death-1 Therapy in NSCLC

INTRODUCTION

Programmed cell death-1 (PD-1) inhibitors effectively treat NSCLC and prolong survival. Robust biomarkers for predicting clinical benefits of good response and long survival with anti-PD-1 therapy have yet to be identified; therefore, predictive biomarkers are needed to select patients with benefits.

METHODS

We conducted a prospective study to explore whether serum antibody against NY-ESO-1 and/or XAGE1 cancer-testis antigens predicted primarily good clinical response and secondarily long survival with anti-PD-1 therapy for NSCLC. The serum antibody was detected by enzyme-linked immunosorbent assay, and tumor immune microenvironment and mutation burden were analyzed by immunohistochemistry and next-generation sequencing.

RESULTS

In the discovery cohort (n = 13), six antibody-positive NSCLC cases responded to anti-PD-1 therapy (two complete and four partial responses), whereas seven antibody-negative NSCLC cases did not. Antibody positivity was associated with good response and survival, regardless of tumor programmed death ligand 1 (PD-L1) expression, mutation burden, and CD8⁺ T-cell infiltration. In the validation cohort (n = 75), 17 antibody-positive NSCLC cases responded well to anti-PD-1 therapy as compared with 58 negative NSCLC cases (objective response rate 65% versus 19%, p = 0.0006) and showed significantly prolonged progression-free survival and overall survival. Antibody titers highly correlated with tumor reduction rates. In the multivariate analysis, response biomarkers were tumor programmed death ligand 1 expression and antibody positivity, and only antibody positivity was a significantly better predictive biomarker of progression-free survival (hazard ratio = 0.4, p = 0.01) and overall survival (hazard ratio = 0.2, p = 0.004).

CONCLUSIONS

Our results suggest that NY-ESO-1 and/or XAGE1 serum antibodies are useful biomarkers for predicting clinical benefits in anti-PD-1 therapy for NSCLC and probably for other cancers.

Cancer-testis antigens as biomarkers for Merkel cell carcinoma: Pitfalls and opportunities

BACKGROUND

The prognosis and treatment options for metastatic Merkel cell carcinoma (MCC) are poor. The immune-privileged status of cancer-testis (CT) antigens imparts tumor specificity, making them ideal candidates for targeted immunotherapy. We investigate the usefulness of the CT antigens SPA17 (sperm protein-17 [SP-17]), IGF2BP3 (insulin-like growth factor-II mRNA-binding protein 3 [IMP-3]), and transmembrane protein with epidermal growth factor (EGF)-like and two follistatin-like domains 1 (TMEFF1) as potential MCC biomarkers and evaluate their possible utility in immunotherapy and molecularly targeted image-guided treatment.

METHODS

The CT antigens SP-17, IMP-3, and TMEFF1 were selected using transcriptome profiling to identify CT antigens expressed in MCC tumors. Antibodies directed against these CT antigens were stained. Twelve normal skin tissue samples were used as a control. The average percentage of positive cells in each tumor was computed.

RESULTS

Twelve of 14 (86%) MCC cases showed crisp nuclear staining for SP-17, with 2.06% of cells staining positive. IMP-3 showed crisp, perinuclear staining in all 14 MCC cases, with 52.93% MCC cells staining positive. TMEFF1 showed perinuclear staining in all 14 MCC cases, with 96.51% of tumor cells staining positive.

CONCLUSIONS

CT antigens were found to be expressed in both MCC and some control tissues. SP-17 was the most specific yet the least sensitive. IMP-3 and TMEFF1 were both sensitive but not specific. CT antigens may represent valuable treatment targets in MCC.

Molecular Basis of Tumor Heterogeneity in Endometrial Carcinosarcoma

Endometrial carcinosarcoma (ECS) represents one of the most extreme examples of tumor heterogeneity among human cancers. ECS is a clinically aggressive, high-grade, metaplastic carcinoma. At the morphological level, intratumor heterogeneity in ECS is due to an admixture of epithelial (carcinoma) and mesenchymal (sarcoma) components that can include heterologous tissues, such as skeletal muscle, cartilage, or bone. Most ECSs belong to the copy-number high serous-like molecular subtype of endometrial carcinoma, characterized by the TP53 mutation and the frequently accompanied by a large number of gene copy-number alterations, including the amplification of important oncogenes, such as CCNE1 and c-MYC. However, a proportion of cases (20%) probably represent the progression of tumors initially belonging to the copy-number low endometrioid-like molecular subtype (characterized by mutations in genes such as PTEN, PI3KCA, or ARID1A), after the acquisition of the TP53 mutations. Only a few ECS belong to the microsatellite-unstable hypermutated molecular type and the POLE-mutated, ultramutated molecular type. A common characteristic of all ECSs is the modulation of genes involved in the epithelial to mesenchymal process. Thus, the acquisition of a mesenchymal phenotype is associated with a switch from E- to N-cadherin, the up-regulation of transcriptional repressors of E-cadherin, such as Snail Family Transcriptional Repressor 1 and 2 (SNAI1 and SNAI2), Zinc Finger E-Box Binding Homeobox 1 and 2 (ZEB1 and ZEB2), and the down-regulation, among others, of members of the miR-200 family involved in the maintenance of an epithelial phenotype. Subsequent differentiation to different types of mesenchymal tissues increases tumor heterogeneity and probably modulates clinical behavior and therapy response.

EWSR1-FLI1 Activation of the Cancer/Testis Antigen FATE1 Promotes Ewing Sarcoma Survival

Ewing sarcoma is characterized by a pathognomonic chromosomal translocation that generates the EWSR1-FLI1 chimeric transcription factor. The transcriptional targets of EWSR1-FLI1 that are essential for tumorigenicity are incompletely defined. Here, we found that EWSR1-FLI1 modulates the expression of cancer/testis (CT) antigen genes, whose expression is biased to the testes but is also activated in cancer. Among these CT antigens, fetal and adult testis expressed 1 (FATE1) is most robustly induced. EWSR1-FLI1 associates with the GGAA repeats in the proximal promoter of FATE1, which exhibits accessible chromatin exclusively in mesenchymal progenitor cells (MPCs) and Ewing sarcoma cells. Expression of EWSR1-FLI1 in non-Ewing sarcoma cells and in MPCs enhances FATE1 mRNA and protein expression. Conversely, depletion of EWSR1-FLI1 in Ewing sarcoma cells leads to a loss of FATE1 expression. Importantly, we found that FATE1 is required for survival and anchorage-independent growth in Ewing sarcoma cells via attenuating the accumulation of BNIP3L, a BH3-only protein that is toxic when stabilized. This action appears to be mediated by the E3 ligase RNF183. We propose that engaging FATE1 function can permit the bypass of cell death mechanisms that would otherwise inhibit tumor progression.