Identification of a meiosis-specific protein as a member of the class of cancer/testis antigens

Next-generation cancer vaccines and emerging immunotherapy combinations

Therapeutic cancer vaccines have been a subject of research for several decades as potential new weapons to tackle malignancies. Their goal is to induce a long-lasting and efficient antitumour-directed immune response, capable of mediating tumour regression, preventing tumour progression, and eradicating minimal residual disease, while avoiding major adverse effects. Development of new vaccine technologies and antigen prediction methods has led to significant improvements in cancer vaccine efficacy. However, for their successful clinical application, certain obstacles still need to be overcome, especially tumour-mediated immunosuppression and escape mechanisms. In this review, we introduce therapeutic cancer vaccines and subsequently discuss combination approaches of next-generation cancer vaccines and existing immunotherapies, particularly immune checkpoint inhibitors (ICIs) and adoptive cell transfer/cell-based immunotherapies.

The cancer testes antigen, HORMAD1, limits genomic instability in cancer cells by protecting stalled replication forks

Tumors anomalously induce the expression of meiotic genes, which are otherwise restricted only to developing gametes. If and how these aberrantly expressed meiotic proteins influence DNA metabolism is not clear, but could have important implications for how tumors acquire and mitigate genomic instability. HORMAD1 is a highly conserved meiotic protein that is frequently expressed in lung adenocarincoma where its expression correlates with reduced patient survival and increased mutation burden. Here, we find that HORMAD1 associates with the replisome and is critical for protecting stalled DNA replication forks. Loss of HORMAD1 leads to nascent DNA strand degradation, an event which is mediated by the MRE11-DNA2-BLM pathway. We find that these phenotypes are due to limited RAD51 loading onto stalled replication forks in the absence of HORMAD1. Ultimately, loss of HORMAD1 leads to increased DNA breaks and chromosomal defects, which is exacerbated dramatically by induction of replication stress. Tumor cells proliferate despite encountering chronic replication stress, placing them on the precipice of catastrophic genomic damage. Our data support the hypothesis that the aberrant expression of HORMAD1 is engaged to attenuate the accumulation of excessive DNA damage due to chronic replication stress, which may otherwise lead to accumulation of toxic levels of genomic instability.

Cancer/testis antigens: promising immunotherapy targets for digestive tract cancers

Digestive tract cancers, including esophageal, gastric, and colorectal cancers, are the major cause of death among cancer patients worldwide due to the heterogeneity of cancer cells, which limits the effectiveness of traditional treatment methods. Immunotherapy represents a promising treatment strategy for improving the prognosis of patients with digestive tract cancers. However, the clinical application of this approach is limited by the absence of optimal targets. Cancer/testis antigens are characterized by low or absent expression in normal tissues, but high expression in tumor tissues, making them an attractive target for antitumor immunotherapy. Recent preclinical trials have shown promising results for cancer/testis antigen-targeted immunotherapy in digestive cancer. However, practical problems and difficulties in clinical application remain. This review presents a comprehensive analysis of cancer/testis antigens in digestive tract cancers, covering their expression, function, and potential as an immunotherapy target. Additionally, the current state of cancer/testis antigens in digestive tract cancer immunotherapy is discussed, and we predict that these antigens hold great promise as an avenue for breakthroughs in the treatment of digestive tract cancers.

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.

Gene-based cancer-testis antigens as prognostic indicators in hepatocellular carcinoma

Cancer/testis antigens (CTAs) are reproductive tissue-restricted genes, frequently ectopic expressed in tumors. CTA genes associate with a poor prognosis in some solid tumors, due to their potential roles in the tumorigenesis and progression. However, whether CTAs relate with hepatocellular carcinoma (HCC) remains unclear. In this study, the prognostic signatures based on CTA genes were investigated and validated in three cohorts including Chinese HCC patients with hepatitis B virus infection (CHCC-HBV), International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA) cohorts. Univariate, LASSO, and multivariate Cox regression analyses were used to screen prognostic genes and develop the prognostic gene signature. A prognosis model was established with six CTA genes (SSX1, CTCFL, OIP5, CEP55, NOL4, and TPPP2) in CHCC-HBV cohort, and further validated in the ICGC and TCGA cohorts. The CTA signature was an essential prognostic predictor independent of other clinical pathological factors. High-risk group exhibited up-regulated cell cycle-related and tumor-related pathways and more M0 macrophage, activated mast cell, activated memory CD4⁺ T cell, and memory B cell infiltration. Furthermore, CTA signature correlated with the sensitivity to multiple chemotherapy drugs. Our results highlighted that the CTA gene profiling was a prognostic assessment tool for HCC patients.

The Cancer Testes Antigen, HORMAD1, is a Tumor-Specific Replication Fork Protection Factor

Tumors frequently activate the expression of genes that are only otherwise required for meiosis. HORMAD1, which is essential for meiotic recombination in multiple species, is expressed in over 50% of human lung adenocarcinoma cells (LUAD). We previously found that HORMAD1 promotes DNA double strand break (DSB) repair in LUAD. Here, we report that HORMAD1 takes on an additional role in protecting genomic integrity. Specifically, we find HORMAD1 is critical for protecting stalled DNA replication forks in LUAD. Loss of HORMAD1 leads to nascent DNA degradation, an event which is mediated by the MRE11-DNA2-BLM pathway. Moreover, following exogenous induction of DNA replication stress, HORMAD1 deleted cells accumulate single stranded DNA (ssDNA). We find that these phenotypes are the result of a lack of RAD51 and BRCA2 loading onto stalled replication forks. Ultimately, loss of HORMAD1 leads to increased DSBs and chromosomal aberrations in response to replication stress. Collectively, our data support a model where HORMAD1 expression is selected to mitigate DNA replication stress, which would otherwise induce deleterious genomic instability.

Absence of MerTK disrupts spermatogenesis in an age-dependent manner

Spermatogenesis is a highly specialized cell differentiation process regulated by the testicular microenvironment. During the process of spermatogenesis, phagocytosis performs an essential role in male germ cell development, and its dysfunction in the testis can cause reproduction defects. MerTK, as a critical protein of phagocytosis, facilitates the removal of apoptotic substrates from the retina and ovaries through cooperation with several phagocytosis receptors. However, its role in mammalian spermatogenesis remains undefined. Here, we found that 30-week-old MerTK^-/- male mice developed oligoasthenospermia due to abnormal spermatogenesis. These mice showed damaged seminiferous tubule structure, as well as altered spermatogonia proliferation and differentiation. We also found that Sertoli cells from MerTK^-/- mice had decreased phagocytic activity on apoptotic germ cells in vitro. Moreover, a transcriptomic analysis demonstrated that the pivotal genes involved in spermatid differentiation and development changed expression. These results indicate that MerTK is crucial for spermatogenesis, as it regulates the crosstalk between germ cells and Sertoli cells. This provides us insight into the molecular mechanism of MerTK on spermatogenesis and its implications for the diagnosis and treatment of human male infertility.

Meiotic Genes and DNA Double Strand Break Repair in Cancer

Tumor cells show widespread genetic alterations that change the expression of genes driving tumor progression, including genes that maintain genomic integrity. In recent years, it has become clear that tumors frequently reactivate genes whose expression is typically restricted to germ cells. As germ cells have specialized pathways to facilitate the exchange of genetic information between homologous chromosomes, their aberrant regulation influences how cancer cells repair DNA double strand breaks (DSB). This drives genomic instability and affects the response of tumor cells to anticancer therapies. Since meiotic genes are usually transcriptionally repressed in somatic cells of healthy tissues, targeting aberrantly expressed meiotic genes may provide a unique opportunity to specifically kill cancer cells whilst sparing the non-transformed somatic cells. In this review, we highlight meiotic genes that have been reported to affect DSB repair in cancers derived from somatic cells. A better understanding of their mechanistic role in the context of homology-directed DNA repair in somatic cancers may provide useful insights to find novel vulnerabilities that can be targeted.

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.

Cancer/testis antigens: from serology to mRNA cancer vaccine

Cancer/testis antigens (CTAs) are a group of tumor antigens expressed in numerous cancer tissues, as well as in the testis and placental tissues. There are over 200 CTAs supported by serology and expression data. The expression patterns of CTAs reflect the similarities between the processes of gametogenesis and tumorigenesis. It is notable that CTAs are highly expressed in three types of cancers (lung cancer, bladder cancer, and skin cancer), all of which have a metal etiology. Here, we review the expression, regulation, and function of CTAs and their translational prospects as cancer biomarkers and treatment targets. Many CTAs are highly immunogenic, tissue-specific, and frequently expressed in cancer tissues but not under physiological conditions, rendering them promising candidates for cancer detection. Some CTAs are associated with clinical outcomes, so they may serve as prognostic biomarkers. A small number of CTAs are membrane-bound, making them ideal targets for chimeric antigen receptor (CAR) T cells. Mounting evidence suggests that CTAs induce humoral or cellular immune responses, providing cancer immunotherapeutic opportunities for T-cell receptors (TCRs), CAR T cell, antibody-based therapy and peptide- or mRNA-based vaccines. Indeed, CTAs are the dominating non-mutated targets in mRNA cancer vaccine development. Clinical trials on CTA TCR and vaccines have shown effectiveness, safety, and tolerance, but these successes are limited to a small number of patients. In-depth studies on CTA expression and function are needed to improve CTA-based immunotherapy.

Therapeutic applications of the cancer immunoediting hypothesis

Since the late 19th century, the immune system has increasingly garnered interest as a novel avenue for cancer therapy, particularly given scientific breakthroughs in recent decades delineating the fundamental role of the immune system in tumorigenesis. The immunoediting hypothesis has articulated this role, describing three phases of the tumor-immune system interaction: Elimination, Equilibrium, and Escape wherein tumors progress from active immunologic surveillance and destruction through dynamic immunologic stasis to unfettered growth. The primary goals of immunotherapy are to restrict and revert progression through these phases, thereby improving the immune system's ability to control tumor growth. In this review, we detail the development and foundation of the cancer immunoediting hypothesis and apply this hypothesis to the dynamic immunotherapy field that includes checkpoint blockade, vaccine therapy, and adoptive cell transfer.

Synaptonemal complex proteins modulate the level of genome integrity in cancers

The synaptonemal complex (SC) is a proteinaceous structure that is transiently formed during meiosis to promote homologous recombination between maternal and paternal chromosomes. As this structure is required only for meiotic recombination, the proteins constituting the complex are almost undetectable in normal somatic cells, but they can be expressed under the conditions in which the transcriptional machinery is deregulated. Accumulating evidence indicates that they are epigenetically expressed in cancers of various origin. Not surprisingly, in contrast to their meiotic roles, the somatic roles of the SC proteins remain to be investigated. However, it has recently been reported that SYCP3 and SYCE2 control DNA double‐strand break repair negatively and positively, respectively, suggesting that the ectopic expression of the SC proteins in somatic cells could be associated with the maintenance of genomic instability. Thus, it is highly likely that the investigation of the somatic roles of the SC proteins would improve our understanding of the mechanisms underlying tumor development.

Expression and Prognostic Significance of Cancer/Testis Antigens, MAGE-E1, GAGE, and SOX-6, in Glioblastoma: An Immunohistochemistry Evaluation

Background & Objective:

Glioblastoma is the most common primary malignancy of the brain, the prognosis of which is poor. Immunotherapy with cancer/testis (CT) antigens is a novel therapeutic approach for glioblastoma. This study aimed to investigate the expression rate of MAGE-E1, GAGE, and SOX-6 in glioblastoma tumors using the method of immunohistochemistry (IHC).

Methods:

Expression of MAGE-E1, GAGE, and SOX-6 were determined by IHC in 50 paraffin blocks of glioblastoma. The results were compared between variables including age, gender, tumor location, and Karnofsky performance status (Kps) score. Survival analysis was also performed.

Results:

The expression levels of SOX-6, MAGE-E1, and GAGE were 82%, 78%, and 76%, respectively. The relationship between CT antigens and age, gender, and tumor location was not significant, while the association between MAGE-E1 expression and age was statistically significant (P=0.002). High expression levels of SOX-6 and MAGE-E1 were associated with low Kps scores (P=0.034 and P<0.001, respectively). Survival analysis showed that age >40 and Kps score <80 were associated with significant relationship with shorter survival rate. (P=0.005 and P=0.018, respectively). Expression of MAGE-E1 and GAGE was negatively associated with overall 2-year survival rate (P=0.001 and P=0.021, respectively).

Conclusion:

The expression of all the three CT antigens, especially MAGE-E1 and SOX-6, was high in patients with glioblastoma. It can be concluded that these markers could be ideal targets for immunotherapy in such patients. MAGE-E1 and SOX-6 can be considered as important markers in determining the prognosis of glioblastoma.

Immunology of tissue homeostasis, ovarian cancer growth and regression, and long lasting cancer immune prophylaxis - review of literature

Data on the substantial physiological role of the immune system in the organism's ability to manage proper differentiation and function of normal tissues (tissue homeostasis), and detailed causes of the immune system's essential role for the in-vivo stimulation of cancer growth, are severely lacking. This results in a lack of effective cancer immunotherapy without adverse events, and in the lack of long-lasting cancer immune prophylaxes, particularly in ovarian cancers. Elimination of blood auto-antibodies blocking anti-cancer T cell effectors by intermittent moderate doses of cyclophosphamide, facilitation of the immune system reactivity against alloantigens of cancer cells by two subsequent blood transfusions, and augmentation of anticancer immunity by weekly intradermal injections of bacterial toxins, caused during the subsequent treatment-free period, lasting for two to four weeks, regression of inoperable epithelial ovarian cancers and regeneration of the tremendously metastatically altered abdominal tissues into normal healthy conditions without multivisceral cytoreductive surgery, which can result in life-threatening consequences. An otherwise untreated rectal cancer, progressing over 3 years, regressed after severe toxic dermatitis lasting over one week. This was caused by an accidental consumption of a large raw shiitake mushroom. Subsequent daily consumptions of 2 g Metformin ER and honeybee propolis ethanol extract, and weekly single larger raw shiitake mushroom, which all stimulate immune system reactivity against cancer stem cells, prevented malignant recurrence over the next 29 years without recurring dermatitis, and maintained healthy organism's conditions. These observations indicate that regression of advanced inoperable cancers and long-lasting cancer immune prophylaxis can be reached by simple approaches.

Progress in Neoantigen Targeted Cancer Immunotherapies

Immunotherapies that harness the immune system to kill cancer cells have showed significant therapeutic efficacy in many human malignancies. A growing number of studies have highlighted the relevance of neoantigens in recognizing cancer cells by intrinsic T cells. Cancer neoantigens are a direct consequence of somatic mutations presenting on the surface of individual cancer cells. Neoantigens are fully cancer-specific and exempt from central tolerance. In addition, neoantigens are important targets for checkpoint blockade therapy. Recently, technological innovations have made neoantigen discovery possible in a variety of malignancies, thus providing an impetus to develop novel immunotherapies that selectively enhance T cell reactivity for the destruction of cancer cells while leaving normal tissues unharmed. In this review, we aim to introduce the methods of the identification of neoantigens, the mutational patterns of human cancers, related clinical trials, neoantigen burden and sensitivity to immune checkpoint blockade. Moreover, we focus on relevant challenges of targeting neoantigens for cancer treatment.

Efficacy of co-immunization with the DNA and peptide vaccines containing SYCP1 and ACRBP epitopes in a murine triple-negative breast cancer model

Multiepitope cancer vaccines have gained lots of attention for prophylactic and therapeutic purposes in cancer patients. In our previous study, multiepitope DNA and peptide cancer vaccines consisted of the most immunodominant epitopes of ACRBP and SYCP1 antigens were designed by bioinformatic tools. In this study, the effect of prophylactic co-immunization with these DNA and peptide cancer vaccines in the 4T1 breast cancer animal model was assessed. Serum levels of the peptide-specific IgG total, IgG2a and IgG1 were measured by enzyme-linked immunosorbent assay (ELISA). Also, the efficacy of the immunized mice splenocytes' for producing interleukin-4 (IL-4) and interferon-γ (IFN-γ) was evaluated. The co-immunization caused a significant (P < .05) increase in the serum levels of IgG1 and IgG2a. The co-immunized mice splenocytes exhibited significantly enhanced IL-4 (6.6-fold) and IFN-γ (19-fold) production. Also, their lymphocytes exhibited higher proliferation rate (3-fold) and granzyme B production (6.5-fold) in comparison with the control. The prophylactic co-immunization significantly decreased the breast tumors' volume (78%) and increased the tumor-bearing mice survival time (37.5%) in comparison with the control. Taking together, prophylactic co-immunization with these multiepitope DNA and peptide cancer vaccines can activate the immune system against breast cancer. However, further experiments are needed to evaluate their efficacy from different angles.

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.

Production, purification, and in vivo evaluation of a novel multiepitope peptide vaccine consisted of immunodominant epitopes of SYCP1 and ACRBP antigens as a prophylactic melanoma vaccine

Melanoma cells are significantly resistance to the current treatments. Therefore, the best option for high-risk populations is prevention. Recently, many preventive cancer vaccines have been developed. In our previous study, several bioinformatic tools were employed for selection of the most immunodominant epitopes of acrosin binding protein (ACRBP) and synaptonemal complex protein 1 (SYCP1) antigens to design multiepitope DNA and peptide cancer vaccines. In the current study, the final construct of the multiepitope DNA vaccine was placed into a pcDNA3.1 vector and then, subcloned into a pET-28a (+) expression vector for transfecting BL21 E. coli strain. The recombinant multiepitope peptide vaccine, weighing 6.35 kDa, was purified by Fast protein liquid chromatography technique (FPLC) and detected by western blotting. Subsequently, C57BL/6 mice were immunized by a mixture of the peptide vaccine and incomplete Freund's adjuvant (IFA) (four vaccinations with one-week intervals). Two weeks after the last vaccination, the serum levels of the peptide-specific IgG total, IgG2a, and IgG1 were measured by enzyme-linked immunosorbent assays (ELISA). Also, the immunized mice splenocytes efficacy for producing interleukin-4 (IL-4) and interferon-γ (IFN-γ) after stimulation with the peptide vaccine was evaluated. At last, the prophylactic effect of the peptide vaccine immunization was evaluated in B16-F10 murine melanoma model. The peptide vaccine immunization caused a significant increase in the serum levels of IgG1, IgG2a, and IgG2a. Also, the immunized mice splenocytes exhibited significantly higher ability to produce IL-4 (10-fold) and IFN-γ (16-fold) after stimulation with the peptide vaccine, in comparison with the PBS and IFA groups. The peptide immunized mice exhibited 50.2% and 43% decrease in the mean tumors' volume in comparison with PBS and IFA groups. Also, the mean survival time for the peptide immunized mice was 33 ± 1.3 days which was 5 and 6 days more than the PBS and IFA groups, respectively. The obtained results exhibit high efficacy of the designed multiepitope peptide vaccine for the immune system activation and anti-tumor prophylactic effects in the murine melanoma model.

Gemcitabine, vinorelbine and cyclooxygenase inhibitors in the treatment of glioblastoma. Ultrastructural analyses in C6 glioma in vitro

OBJECTIVES

To define ultrastructural features accompanying to antitumor effects of gemcitabine, vinorelbine and cyclooxygenase inhibitors in C6 glioma cells in vitro. Vinorelbine is a semisynthetic vinca alkaloid and recent studies showed its antitumor activity in pediatric optic and pontine gliomas. Vinorelbine infusion induces a severe tumor site-pain in systemic cancers, but it is unknown whether algesia and inflammation contribute to its antitumor effects. Gemcitabine is a nucleoside-chemotherapeutic which was recently shown to act as a radiosensitizer in high-grade glioma. Some studies showed synergism of anti-inflammatory cyclooxygenase-inhibitors with microtubule inhibitors and gemcitabine. DMSO is a solvent and blocks both cylooxygenase and ribonucleotide reductase, another target of gemcitabine. Rofecoxib is withdrawn from the market, yet we used it for investigational purposes, since it blocks cylooxygenase-2 1000-times more potently than cylooxygenase -1 and is also a selective inhibitor of crinophagy.

METHODS

Plating efficacy, 3D-spheroid S-phase analysis with BrdU labelling and transmission electron microscopical analyses were performed.

RESULTS

Vinorelbine induced frequent mitotic slippage/apoptosis and autophagy. Despite both DMSO and rofecoxib induced autophagy alone and in synergy, they reduced mitotic catastrophe and autophagy triggered by vinorelbine, which was also reflected by reduced inhibition of spheroid S-phase. Gemcitabine induced karyolysis and margination of coarse chromatin towards the nuclear membrane, abundant autophagy, gutta adipis formation and decrease in mitochondria, which were enhanced by DMSO and rofecoxib.

CONCLUSIONS

Detailed ultrastructural analysis of the effects of chemotherapeutic drugs may provide a broader insight about their actions and pave to develop better strategies in treatment of glioblastoma.

SYCP2 expression is a novel prognostic biomarker in luminal A/B breast cancer

Aim: To explore the prognostic value of synaptonemal complex protein-2 (SYCP2) in different subtypes of breast cancer. Patients & materials: In silico bioinformatic analysis was conducted using large databases. Results: SYCP2 was only significantly upregulated in luminal B tumors compared with the adjacent normal tissues. SYCP2 expression was an independent indicator of shorter overall survival in luminal A patients (hazard ratio: 2.269; 95% CI: 1.059–4.862; p = 0.035) and luminal B patients (hazard ratio: 2.546; 95% CI: 1.020–6.355; p = 0.045). Its expression was negatively correlated with the methylation status of multiple CpG sites (cg22214414, cg23241473 and cg07347645) in both luminal A and luminal B tumors. Conclusion: Increased SYCP2 expression might be an independent indicator of shorter overall survival in both luminal A and luminal B patients.

Emerging Role and Future Directions of Immunotherapy in Advanced Ovarian Cancer

Clinical progress in cancer immunotherapy has been slow; however, within the last 5 years, breakthrough successes have brought immunotherapy to the forefront in cancer therapy. Promising results have been observed in solid tumors and hematologic malignancies. Most treatment modalities have shown limited efficacy as monotherapy. The complex nature of cancer and the immunosuppressive microenvironment emphasizes the need to personalize immunotherapy by manipulating the patient's own immune system. For successful and long-lasting cure of cancer, a multimodal approach is essential, combining antitumor cell therapy with manipulation of multiple pathways in the tumor microenvironment to ameliorate tumor-induced immunosuppression.

HORMAD1 Is a Negative Prognostic Indicator in Lung Adenocarcinoma and Specifies Resistance to Oxidative and Genotoxic Stress

Cancer testis antigens (CTA) are expressed in testis and placenta and anomalously activated in a variety of tumors. The mechanistic contribution of CTAs to neoplastic phenotypes remains largely unknown. Using a chemigenomics approach, we find that the CTA HORMAD1 correlates with resistance to the mitochondrial complex I inhibitor piericidin A in non-small cell lung cancer (NSCLC). Resistance was due to a reductive intracellular environment that attenuated the accumulation of free radicals. In human lung adenocarcinoma (LUAD) tumors, patients expressing high HORMAD1 exhibited elevated mutational burden and reduced survival. HORMAD1 tumors were enriched for genes essential for homologous recombination (HR), and HORMAD1 promoted RAD51-filament formation, but not DNA resection, during HR. Accordingly, HORMAD1 loss enhanced sensitivity to γ-irradiation and PARP inhibition, and HORMAD1 depletion significantly reduced tumor growth in vivo These results suggest that HORMAD1 expression specifies a novel subtype of LUAD, which has adapted to mitigate DNA damage. In this setting, HORMAD1 could represent a direct target for intervention to enhance sensitivity to DNA-damaging agents or as an immunotherapeutic target in patients.Significance: This study uses a chemigenomics approach to demonstrate that anomalous expression of the CTA HORMAD1 specifies resistance to oxidative stress and promotes HR to support tumor cell survival in NSCLC. Cancer Res; 78(21); 6196-208. ©2018 AACR.

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.

Somatic role of SYCE2: an insulator that dissociates HP1α from H3K9me3 and potentiates DNA repair

The synaptonemal complex is a proteinaceous structure essential for meiotic recombination, and its components have been assumed to play a role exclusively in the germ line. However, SYCE2, a component constituting the synaptonemal complex, is expressed at varying levels in somatic cells. Considering its potent protein-binding activities, it may be possible that SYCE2 plays a somatic role by affecting nuclear functions. Here, we show that SYCE2 constitutively insulates HP1α from trimethylated histone H3 lysine 9 (H3K9me3) to promote DNA double-strand break repair. Unlike other HP1α-binding proteins, which use the canonical PXVXL motifs for their bindings, SYCE2 interacts with the chromoshadow domain of HP1α through its N-terminal hydrophobic sequence. SYCE2 reduces HP1α-H3K9me3 binding without affecting H3K9me3 levels and potentiates ataxia telangiectasia mutated-mediated double-strand break repair activity even in the absence of exogenous DNA damage. Such a somatic role of SYCE2 is ubiquitously observed even if its expression levels are low. These findings suggest that SYCE2 plays a somatic role in the link between the nuclear microenvironment and the DNA damage response potentials as a scaffold of HP1α localization.

Generation of haploid spermatids from chicken embryonal primordial germ cells

In vitro production of functional spermatids has special significance in the research of spermatogenesis and the treatment of male infertility. Primordial germ cells (PGCs) are the precursors of oocyte and sperm, which generate the totipotent cells. Studies have shown that PGCs have the potential ability to develop meiotic spermatids in vitro. Here we have shown that retinoic acid (RA) leads to PGC differentiation, and SCF can improve the efficiency of induction. We indicate an efficient approach to produce haploid spermatids from chicken PGCs in the presence of RA and stem cell factor (SCF). Real-time RT-PCR assays showed that RA and SCF induced a remarkable increase in expression of SYCP1, ACR, BOULE and DCM1 of meiotic germ cells and haploid germ cells, respectively. DNA content assays revealed that RA and SCF induced a remarkable increase of haploid cells. This study provides a theoretical basis and a great animal model for spermatogenesis study.

KIF-2C expression is correlated with poor prognosis of operable esophageal squamous cell carcinoma male patients

To determine the prognostic significance of Kinesin family member 2C (KIF-2C) expression in patients with operable esophageal squamous cell carcinoma (ESCC), we conducted an immunohistochemical analysis of KIF-2C expression in 415 surgically resected primary tumor tissues and 40 adjacent non-cancerous tissues from patients with operable ESCC. The median duration of postoperative follow-up was 76.0 months. Higher KIF-2C expression was associated with significantly increased risks of higher pathologic tumor (pT) status (P=0.038) and poorer tumor differentiation (P=0.022). For the entire cohort, KIF-2C expression was not an independent factor significantly associated with overall survival (OS) (P=0.097) or disease-free survival (DFS) (P=0.152). In female patients, KIF-2C expression had no effect on OS (P=0.880) and DFS (P=0.864). However, OS (hazard ratio (HR)=1.480, P=0.013) and DFS (HR=1.418, P=0.024) were worse for male patients with high KIF-2C expression compared with male patients with low KIF-2C expression. Moreover, the OS and DFS of male patients with high KIF-2C expression were also significantly shorter compared with female patients with low KIF-2C expression (P=0.022, P=0.029) and female patients with high KIF-2C expression (P=0.014, P=0.018). Based on these findings, KIF-2C expression in tumor tissues promises to serve as an independent prognostic marker for male, but not female, patients with operable ESCC. Prognosis was worse for male patients with high KIF-2C expression compared with patients with the same pathologic tumor-node-metastasis (pTNM) stage.

Proteomic Differences in Feline Fibrosarcomas Grown Using Doxorubicin-Sensitive and -Resistant Cell Lines in the Chick Embryo Model

Proteomic analyses are rapid and powerful tools that are used to increase the understanding of cancer pathogenesis, discover cancer biomarkers and predictive markers, and select and monitor novel targets for cancer therapy. Feline injection-site sarcomas (FISS) are aggressive skin tumours with high recurrence rates, despite treatment with surgery, radiotherapy, and chemotherapy. Doxorubicin is a drug of choice for soft tissue sarcomas, including FISS. However, multidrug resistance is one of the major causes of chemotherapy failure. The main aim of the present study was to identify proteins that differentiate doxorubicin-resistant from doxorubicin-sensitive FISS using two-dimensional gel electrophoresis (2DE), followed by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Using the three-dimensional (3D) preclinical in ovo model, which resembles features of spontaneous fibrosarcomas, three significantly (p ≤ 0.05) differentially expressed proteins were identified in tumours grown from doxorubicin-resistant fibrosarcoma cell lines (FFS1 and FFS3) in comparison to the doxorubicin-sensitive one (FFS5): Annexin A5 (ANXA5), Annexin A3 (ANXA3), and meiosis-specific nuclear structural protein 1 (MNS1). Moreover, nine other proteins were significantly differentially expressed in tumours grown from the high doxorubicin-resistant cell line (FFS1) in comparison to sensitive one (FFS5). This study may be the first proteomic fingerprinting of FISS reported, identifying potential candidates for specific predictive biomarkers and research targets for doxorubicin-resistant FISS.

Immunotherapy in ovarian cancer

Immunological destruction of tumors is a multistep, coordinated process that can be modulated or targeted at several critical points to elicit tumor rejection. These steps in the cancer immunity cycle include: (i) generation of sufficient numbers of effector T cells with high avidity recognition of tumor antigens in vivo; (ii) trafficking and infiltration into the tumor; (iii) overcoming inhibitory networks in the tumor microenvironment; (iv) direct recognition of tumor antigens and generation of an effector anti-tumor response; and (v) persistence of the anti-tumor T cells. In an effort to understand whether the immune system plays a role in controlling ovarian cancer, our group and others demonstrated that the presence of tumor infiltrating lymphocytes (TILs) is associated with improved clinical outcome in ovarian cancer patients. Recently, we hypothesized that the quality of infiltrating T cells could also be a critical determinant of outcome in ovarian cancer patients. In the past decade, several immune-based interventions have gained regulatory approval in many solid tumors and hematologic malignancies. These interventions include immune checkpoint blockade, cancer vaccines, and adoptive cell therapy. There are currently no approved immune therapies for ovarian cancer. Immunotherapy in ovarian cancer will have to consider the immune suppressive networks within the ovarian tumor microenvironment; therefore, a major direction is to develop biomarkers that would predict responsiveness to different types of immunotherapies, and allow for treatment selection based on the results. Moreover, such biomarkers would allow rational combination of immunotherapies, while minimizing toxicities. In this review, the current understanding of the host immune response in ovarian cancer patients will be briefly reviewed, progress in immune therapies, and future directions for exploiting immune based strategies for long lasting durable cure.

Identification of novel serum autoantibodies against EID3 in non-functional pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pNETs) are relatively rare heterogenous tumors, comprising only 1–2% of all pancreatic neoplasms. The majority of pNETs are non-functional tumors (NF-pNETs) that do not produce hormones, and as such, do not cause any hormone-related symptoms. As a result, these tumors are often diagnosed at an advanced stage because patients do not present with specific symptoms. Although tumor markers are used to help diagnosis and predict some types of cancers, chromogranin A, a widely used tumor marker of pNETs, has significant limitations. To identify novel NF-pNET-associated antigens, we performed serological identification of antigens by recombinant cDNA expression cloning (SEREX) and identified five tumor antigens (phosphatase and tensin homolog, EP300-interacting inhibitor of differentiation 3 [EID3], EH domain-containing protein 1, galactoside-binding soluble 9, and BRCA1-associated protein). Further analysis using the AlphaLISA^® immunoassay to compare serum antibody levels revealed that antibody levels against the EID3 antigen was significantly higher in the patient group than in the healthy donor group (n = 25, both groups). In addition, higher serum anti-EID3 antibody levels in NF-pNET patients correlated with shorter disease-free survival. The AUC calculated by ROC analysis was 0.784 with moderate diagnostic accuracy. In conclusion, serum anti-EID3 antibody levels may be useful as a tumor marker for prediction of tumor recurrence in NF-pNETs.

Identification of tumor antigens in malignant mesothelioma

Serological analysis of recombinant tumor cDNA expression library (SEREX) is a powerful and widely used method to explore the cancer immune environment. In the present study, immunoscreening of normal testicular tissues and malignant mesothelioma (MM) cancer MSTO-211H cell line cDNA libraries with sera from 5 MM patients led to the isolation of 16 independent antigens, which were designated ‘Korea Pusan-Malignant Mesothelioma’ (KP-MM)-1 to −16. In total, 3/16 antigens were identified using the results of previous SEREX analyses, and 13 were newly identified. Of these, KP-MM-8, which was subsequently identified as amyotrophic lateral sclerosis 2 chromosome region candidate 11, was shown to be tissue-restricted. Reverse transcription-polymerase chain reaction demonstrated KP-MM-8 to be expressed strongly only in the normal testis, and weakly in the spleen, prostate, ovary, heart and skeletal muscle. In addition, KP-MM-8 mRNA was identified in MM cell lines, and in various other cancer cell lines, including MM (3/4), lung cancer (5/7), melanoma (5/7) and liver cancer (5/5) cell lines. Additionally, 2/16 antigens (KP-MM-2 and KP-MM-6) exclusively reacted with sera from cancer patients. However, KP-MM-8 reacted with 1 of 8 MM sera. Notably, 8/8 patients with MM and 8/8 normal individuals exhibited antibodies reactive to KP-MM-5, which was identified as cell division cycle 25B, a known oncogene. Overall, this data suggests that KP-MM-8 may be considered as a cancer/testis-like antigen and KP-MM-5 as an immunogenic tumor antigen in MM patients.

Hypothesis about Transdifferentiation As Backbone of Malignancy

Background

Cancer is mainly watched through the prism of random mutations and related corruption of signaling pathways. However, it would seem puzzling to explain the tumor organization, pugnacity and steady evolution of the tumorous disease and, moreover, a systematic ascendancy over the healthy tissues, only through stochastic genomic alterations.

Malignancy specific properties

Considering the core characteristics of cancer cells, it appears that two major sets of properties are emerging, corresponding to well-identified physiological phenotypes, i.e., (1) the trophoblastic logistical functions for cell survival, protection, expansion, migration, and host-tissue conditioning for angiogenesis and immune tolerance and (2) the sexual functions for genome maintenance. To explain the resurgence of these trophoblastic and sexual phenotypes, a particular cell reprogramming, to be called “malignant transdifferentiation” in view of its key role in the precancer-to-cancer shift, appears to be a convincing hypothesis.

Perspectives

The concept of malignant transdifferentiation, in addition to oncogenic mutations, would determine a more rational approach of oncogenesis and would open so far unexplored ways of therapeutic actions. Indeed, the trophoblastic phenotype would be a good candidate for therapeutic purposes because, on the one hand, it covers numerous properties that all are vital for the tumor, and on the other hand, it can be targeted with potentially no risk of affecting the healthy tissues as it is not expressed there after birth.

Crystal Structure of C-Terminal Coiled-Coil Domain of SYCP1 Reveals Non-Canonical Anti-Parallel Dimeric Structure of Transverse Filament at the Synaptonemal Complex

The synaptonemal complex protein 1 (SYCP1) is the main structural element of transverse filaments (TFs) of the synaptonemal complex (SC), which is a meiosis-specific complex structure formed at the synapse of homologue chromosomes to hold them together. The N-terminal domain of SYCP1 is known to be located within the central elements (CEs), whereas the C-terminal domain is located toward lateral elements (LEs). SYCP1 is a well-known meiosis marker that is also known to be a prognostic marker in the early stage of several cancers including breast, gliomas, and ovarian cancers. The structure of SC, especially the TF structure formed mainly by SYCP1, remains unclear without any structural information. To elucidate a molecular basis of SC formation and function, we first solved the crystal structure of C-terminal coiled-coil domain of SYCP1. The coiled-coil domain of SYCP1 forms asymmetric, anti-parallel dimers in solution.

Ectopic Expression of Testis Germ Cell Proteins in Cancer and Its Potential Role in Genomic Instability

Genomic instability is a hallmark of human cancer and an enabling factor for the genetic alterations that drive cancer development. The processes involved in genomic instability resemble those of meiosis, where genetic material is interchanged between homologous chromosomes. In most types of human cancer, epigenetic changes, including hypomethylation of gene promoters, lead to the ectopic expression of a large number of proteins normally restricted to the germ cells of the testis. Due to the similarities between meiosis and genomic instability, it has been proposed that activation of meiotic programs may drive genomic instability in cancer cells. Some germ cell proteins with ectopic expression in cancer cells indeed seem to promote genomic instability, while others reduce polyploidy and maintain mitotic fidelity. Furthermore, oncogenic germ cell proteins may indirectly contribute to genomic instability through induction of replication stress, similar to classic oncogenes. Thus, current evidence suggests that testis germ cell proteins are implicated in cancer development by regulating genomic instability during tumorigenesis, and these proteins therefore represent promising targets for novel therapeutic strategies.

Genome management and mismanagement--cell-level opportunities and challenges of whole-genome duplication

Whole-genome duplication (WGD) doubles the DNA content in the nucleus and leads to polyploidy. In this review, Yant and Bomblies discuss both the adaptive potential and problems associated with WGD, focusing primarily on cellular effects.

Whole-genome duplication (WGD) doubles the DNA content in the nucleus and leads to polyploidy. In whole-organism polyploids, WGD has been implicated in adaptability and the evolution of increased genome complexity, but polyploidy can also arise in somatic cells of otherwise diploid plants and animals, where it plays important roles in development and likely environmental responses. As with whole organisms, WGD can also promote adaptability and diversity in proliferating cell lineages, although whether WGD is beneficial is clearly context-dependent. WGD is also sometimes associated with aging and disease and may be a facilitator of dangerous genetic and karyotypic diversity in tumorigenesis. Scaling changes can affect cell physiology, but problems associated with WGD in large part seem to arise from problems with chromosome segregation in polyploid cells. Here we discuss both the adaptive potential and problems associated with WGD, focusing primarily on cellular effects. We see value in recognizing polyploidy as a key player in generating diversity in development and cell lineage evolution, with intriguing parallels across kingdoms.

Antigen Selection for Enhanced Affinity T-Cell Receptor-Based Cancer Therapies

Evidence of adaptive immune responses in the prevention of cancer has been accumulating for decades. Spontaneous T-cell responses occur in multiple indications, bringing the study of de novo expressed cancer antigens to the fore and highlighting their potential as targets for cancer immunotherapy. Circumventing the immune-suppressive mechanisms that maintain tumor tolerance and driving an antitumor cytotoxic T-cell response in cancer patients may eradicate the tumor or block disease progression. Multiple strategies are being pursued to harness the cytotoxic potential of T cells clinically. Highly promising results are now emerging. The focus of this review is the target discovery process for cancer immune therapeutics based on affinity-matured T-cell receptors (TCRs). Target cancer antigens in the context of adoptive cell transfer technologies and soluble biologic agents are discussed. To appreciate the impact of TCR-based technology and understand the TCR discovery process, it is necessary to understand key differences between TCR-based therapy and other immunotherapy approaches. The review first summarizes key advances in the cancer immunotherapy field and then discusses the opportunities that TCR technology provides. The nature and breadth of molecular targets that are tractable to this approach are discussed, together with the challenges associated with finding them.

Targeting cancer testis antigens for biomarkers and immunotherapy in colorectal cancer: Current status and challenges

Colorectal cancer ranks third among the estimated cancer cases and cancer related mortalities in United States in 2014. Early detection and efficient therapy remains a significant clinical challenge for this disease. Therefore, there is a need to identify novel tumor associated molecules to target for biomarker development and immunotherapy. In this regard, cancer testis antigens have emerged as a potential targets for developing novel clinical biomarkers and immunotherapy for various malignancies. These germ cell specific proteins exhibit aberrant expression in cancer cells and contribute in tumorigenesis. Owing to their unique expression profile and immunogenicity in cancer patients, cancer testis antigens are clinically referred as the most promising tumor associated antigens. Several cancer testis antigens have been studied in colorectal cancer but none of them could be used in clinical practice. This review is an attempt to address the promising cancer testis antigens in colorectal cancer and their possible clinical implications as biomarkers and immunotherapeutic targets with particular focus on challenges and future interventions.

X-ray crystallographic studies of the middle part of the human synaptonemal complex protein 1 coiled-coil domain

The synaptonemal complex is a meiosis-specific complex structure formed at the synapse of homologous chromosomes to hold them together during meiosis. Synaptonemal complex protein 1 (SYCP1) is one of the components of the syneptonemal complex. In this study, the short form of the coiled-coil domain of SYCP1 was overexpressed in Escherichia coli with an engineered C-terminal His tag. The short form of the coiled-coil domain of SYCP1 was then purified to homogeneity and crystallized at 293 K. X-ray diffraction data were collected to a resolution of 3.0 Å from a crystal belonging to space group I4, with unit-cell parameters a = 41.95, b = 41.95, c = 318.78 Å. The asymmetric unit was estimated to contain two molecules.

Meta-analysis of expression of l(3)mbt tumor-associated germline genes supports the model that a soma-to-germline transition is a hallmark of human cancers

Evidence is starting to emerge indicating that tumorigenesis in metazoans involves a soma-to-germline transition, which may contribute to the acquisition of neoplastic characteristics. Here, we have meta-analyzed gene expression profiles of the human orthologs of Drosophila melanogaster germline genes that are ectopically expressed in l(3)mbt brain tumors using gene expression datasets derived from a large cohort of human tumors. We find these germline genes, some of which drive oncogenesis in D. melanogaster, are similarly ectopically activated in a wide range of human cancers. Some of these genes normally have expression restricted to the germline, making them of particular clinical interest. Importantly, these analyses provide additional support to the emerging model that proposes a soma-to-germline transition is a general hallmark of a wide range of human tumors. This has implications for our understanding of human oncogenesis and the development of new therapeutic and biomarker targets with clinical potential.

Immunotherapy for prostate cancer: lessons from responses to tumor-associated antigens

Prostate cancer (PCa) is the most common cancer in men and the second most common cause of cancer-related death in men. In recent years, novel therapeutic options for PCa have been developed and studied extensively in clinical trials. Sipuleucel-T is the first cell-based immunotherapeutic vaccine for treatment of cancer. This vaccine consists of autologous mononuclear cells stimulated and loaded with an immunostimulatory fusion protein containing the prostate tumor antigen prostate acid posphatase. The choice of antigen might be key for the efficiency of cell-based immunotherapy. Depending on the treatment strategy, target antigens should be immunogenic, abundantly expressed by tumor cells, and preferably functionally important for the tumor to prevent loss of antigen expression. Autoimmune responses have been reported against several antigens expressed in the prostate, indicating that PCa is a suitable target for immunotherapy. In this review, we will discuss PCa antigens that exhibit immunogenic features and/or have been targeted in immunotherapeutic settings with promising results, and we highlight the hurdles and opportunities for cancer immunotherapy.

A novel cohort of cancer-testis biomarker genes revealed through meta-analysis of clinical data sets

The identification of cancer-specific biomolecules is of fundamental importance to the development of diagnostic and/or prognostic markers, which may also serve as therapeutic targets. Some antigenic proteins are only normally present in male gametogenic tissues in the testis and not in normal somatic cells. When these proteins are aberrantly produced in cancer they are referred to as cancer/testis (CT) antigens (CTAs). Some CTA genes have been proven to encode immunogenic proteins that have been used as successful immunotherapy targets for various forms of cancer and have been implicated as drug targets. Here, a targeted in silico analysis of cancer expressed sequence tag (EST) data sets resulted in the identification of a significant number of novel CT genes. The expression profiles of these genes were validated in a range of normal and cancerous cell types. Subsequent meta-analysis of gene expression microarray data sets demonstrates that these genes are clinically relevant as cancer-specific biomarkers, which could pave the way for the discovery of new therapies and/or diagnostic/prognostic monitoring technologies.