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

Cancer-testis antigens MAGE-C1/CT7 and MAGE-A3 promote the survival of multiple myeloma cells

BACKGROUND

Multiple myeloma is a life-threatening disease and despite the introduction of stem cell transplantation and novel agents such as thalidomide, lenalidomide, and bortezomib most patients will relapse and develop chemoresistant disease. Therefore, alternative therapeutic modes for myeloma are needed and cancer-testis antigens such as MAGE-C1/CT7 and MAGE-A3 have been suggested to represent a class of tumor-specific proteins particularly suited for targeted immunotherapies. Surprisingly, the biological role of cancer-testis genes in myeloma remains poorly understood.

DESIGN AND METHODS

We performed the first investigation of the function of two cancer-testis antigens most commonly expressed in myeloma, MAGE-C1/CT7 and MAGE-A3, using an RNA interference-based gene silencing model in myeloma cell lines. Functional assays were used to determine changes in proliferation, cell adhesion, chemosensitivity, colony formation, and apoptosis resulting from gene-specific silencing.

RESULTS

We show that the investigated genes are not involved in regulating cell proliferation or adhesion; however, they play an important role in promoting the survival of myeloma cells. Accordingly, knock-down of MAGE-C1/CT7 and MAGE-A3 led to the induction of apoptosis in the malignant plasma cells and, importantly, both genes were also essential for the survival of clonogenic myeloma precursors. Finally, silencing of cancer-testis genes further improved the response of myeloma cells to conventional therapies.

CONCLUSIONS

Cancer-testis antigens such as MAGE-C1/CT7 and MAGE-A3 play an important role in promoting the survival of myeloma cells and clonogenic precursors by reducing the rate of spontaneous and chemotherapy-induced apoptosis and might, therefore, represent attractive targets for novel myeloma-specific therapies.

Cancer/testis (CT) antigens: potential targets for immunotherapy

Cancer/testis (CT) antigens are protein antigens with normal expression restricted to adult testicular germ cells, and yet are aberrantly activated and expressed in a proportion of various types of human cancer. At least a subset of this group of antigens has been found to elicit spontaneous humoral and cell-mediated immune responses in cancer patients, raising the possibility that these antigens could be cancer vaccine targets. More than 100 CT antigen genes have been reported in the literature, with approximately 30 being members of multigene families on the X chromosome, so-called CT-X genes. Most CT-X genes are expressed at the spermatogonia stage of spermatogenesis, and their functions are mostly unknown. In cancer, the frequency of CT antigen expression is highly variable among different tumor types, but is more often expressed in high-grade late-stage cases in general. Cancer vaccine trials based on CT antigens MAGE-A3 and NY-ESO-1 are currently ongoing, and these antigens may also play a role in antigen-specific adoptive T-cell transfer and in the immunomodulation approach of cancer therapy.

Cancer/testis antigens can be immunological targets in clonogenic CD133+ melanoma cells

"Cancer stem cells" that resist conventional treatments may be a cause of therapeutic failure in melanoma. We report a subpopulation of clonogenic melanoma cells that are characterized by high prominin-1/CD133 expression in melanoma and melanoma cell lines. These cells have enhanced clonogenicity and self-renewal in vitro, and serve as a limited in vitro model for melanoma stem cells. In some cases clonogenic CD133(+) melanoma cells show increased expression of some cancer/testis (CT) antigens. The expression of NY-ESO-1 in an HLA-A2 expressing cell line allowed CD133(+) clonogenic melanoma cells to be targeted for killing in vitro by NY-ESO-1-specific CD8(+) T-lymphocytes. Our in vitro findings raise the hypothesis that if melanoma stem cells express CT antigens in vivo that immune targeting of these antigens may be a viable clinical strategy for the adjuvant treatment of melanoma.

Clinical significance of cancer/testis antigens expression in patients with non-small cell lung cancer

Cancer/testis antigens (CT antigens) are thought to be suitable targets for antigen-specific immunotherapy, because of the cancer-specific expression except for the testis among various normal tissues and no-expression of HLA class I in the testis. In the present study, the expressions of CT antigens (MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1) in non-small cell lung cancer (NSCLC) were analyzed by RT-PCR. The subjects were 239 patients with NSCLC who underwent surgery from 2001 to 2005 in our department. The expression rates of MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1 were 23.8%, 20.1%, 10.5% and 32.6% in patients with NSCLC, respectively. MAGE-A4 was expressed more frequently in male (25.3%) than in female (10.6%) (p<0.01). The positive proportion of MAGE-A4 was higher in stages II-IV (30.6%) than in stage I (12.8%) (p<0.01). Both of MAGE-A3 and MAGE-A4 were expressed more frequently in squamous cell carcinoma than in adenocarcinoma (p<0.01). Such tendency was not observed among NY-ESO-1 and KK-LC-1 expression. KK-LC-1 was expressed in 32.1% of patients with adenocarcinoma and in 36.5% of patients with squamous cell carcinoma. Patients with positive MAGE-A4 expression showed significantly poorer overall survival than those without MAGE-A4 expression (p=0.013), and such effect on survival was also observed, when the analysis was limited to patients at stage I (p=0.0037). Expression of MAGE-A3, NY-ESO-1 or KK-LC-1 did not affect survival of patients with NSCLC significantly, however, expression of at least one of such CT antigens negatively affect survival of patients with NSCLC (p=0.045).

Kruppel-associated box domain-associated protein-1 as a latency regulator for Kaposi's sarcoma-associated herpesvirus and its modulation by the viral protein kinase

Kaposi's sarcoma-associated herpesvirus (KSHV) has been linked to the development of Kaposi's sarcoma, a major AIDS-associated malignancy, and to hematologic malignancies, including primary effusion lymphoma and multicentric Castleman's disease. Like other herpesviruses, KSHV is capable of both latent and lytic replication. Understanding the molecular details associated with this transition from latency to lytic replication is key to controlling virus spread and can affect the development of intervention strategies. Here, we report that Kruppel-associated box domain-associated protein-1 (KAP-1)/transcriptional intermediary factor 1beta, a cellular transcriptional repressor that controls chromosomal remodeling, participates in the process of switching viral latency to lytic replication. Knockdown of KAP-1 by small interfering RNA leads to KSHV reactivation mediated by K-Rta, a key transcriptional regulator. In cells harboring latent KSHV, KAP-1 was associated with the majority of viral lytic-gene promoters. K-Rta overexpression induced the viral lytic cycle with concomitant reduction of KAP-1 binding to viral promoters. Association of KAP-1 with heterochromatin was modulated by both sumoylation and phosphorylation. During lytic replication of KSHV, KAP-1 was phosphorylated at Ser(824). Several lines of evidence directly linked the viral protein kinase to this post-translational modification. Additional studies showed that this phosphorylation of KAP-1 produced a decrease in its sumoylation, consequently decreasing the ability of KAP-1 to condense chromatin on viral promoters. In summary, the cellular transcriptional repressor KAP-1 plays a role in regulating KSHV latency, and viral protein kinase modulates the chromatin remodeling function of this repressor.

Coordinated activation of candidate proto-oncogenes and cancer testes antigens via promoter demethylation in head and neck cancer and lung cancer

Background

Epigenetic alterations have been implicated in the pathogenesis of solid tumors, however, proto-oncogenes activated by promoter demethylation have been sporadically reported. We used an integrative method to analyze expression in primary head and neck squamous cell carcinoma (HNSCC) and pharmacologically demethylated cell lines to identify aberrantly demethylated and expressed candidate proto-oncogenes and cancer testes antigens in HNSCC.

Methodology/Principal Findings

We noted coordinated promoter demethylation and simultaneous transcriptional upregulation of proto-oncogene candidates with promoter homology, and phylogenetic footprinting of these promoters demonstrated potential recognition sites for the transcription factor BORIS. Aberrant BORIS expression correlated with upregulation of candidate proto-oncogenes in multiple human malignancies including primary non-small cell lung cancers and HNSCC, induced coordinated proto-oncogene specific promoter demethylation and expression in non-tumorigenic cells, and transformed NIH3T3 cells.

Conclusions/Significance

Coordinated, epigenetic unmasking of multiple genes with growth promoting activity occurs in aerodigestive cancers, and BORIS is implicated in the coordinated promoter demethylation and reactivation of epigenetically silenced genes in human cancers.

Mage-b vaccine delivered by recombinant Listeria monocytogenes is highly effective against breast cancer metastases

New therapies are needed that target breast cancer metastases. In previous studies, we have shown that vaccination with pcDNA3.1-Mage-b DNA vaccine is effective against breast cancer metastases. In the study presented here, we have further enhanced the efficacy of Mage-b vaccination through the improved delivery of the vaccine using recombinant Listeria monocytogenes (LM). Three overlapping fragments of Mage-b as well as the complete protein-encoding region of Mage-b have been expressed as a fusion protein with a truncated non-cytolytic form of listeriolysin O (LLO) in recombinant LM. These different Mage-b vaccine strains were preventively tested for their efficacy against breast cancer metastases in a syngeneic mouse tumour model 4T1. The LM-LLO-Mage-b/2nd, expressing position 311–660 of the cDNA of Mage-b, was the most effective vaccine strain against metastases in the 4T1 mouse breast tumour model. Vaccination with LM-LLO-Mage-b/2nd dramatically reduced the number of metastases by 96% compared with the saline group and by 88% compared with the vector control group (LM-LLO), and this correlated with strong Mage-b-specific CD8 T-cell responses in the spleen, after restimulation with Mage-b. However, no effect of LM-LLO-Mage-b/2nd was observed on 4T1 primary tumours, which may be the result of a complete absence of Mage-b-specific immune responses in the draining lymph nodes. Vaccination with LM-LLO-Mage-b/2nd could be an excellent follow-up after removal of the primary tumour, to eliminate metastases and residual tumour cells.

The novel protein complex with SMARCAD1/KIAA1122 binds to the vicinity of TSS

The SMARCAD1/KIAA1122 protein is structurally classified into the SWI2/SNF2 superfamily of DNA-dependent ATPases that are catalytic subunits of chromatin-remodeling complexes. Although the importance of other members of the SWR1-like subfamily in chromatin remodeling (EP400, INOC1, and SRCAP) has already been elucidated, the biological function of SMARCAD1/KIAA1122 in transcriptional regulation remains to be clarified. To gain insight into the role of this protein, we generated a specific antibody against SMARCAD1/KIAA1122 and used it for chromatin and protein immunoprecipitation assays. We employed high-resolution genome tiling microarrays in chromatin immunoprecipitation and found the binding sites of SMARCAD1/KIAA1122 in the vicinity of the transcriptional start site of 69 candidate target genes. In the protein immunoprecipitation assay, we found that endogenous SMARCAD1/KIAA1122 binds with TRIM28, a recently highlighted transcriptional regulator in the cancer field. From these findings, we propose a novel model for gene regulation via the SMARCAD1/KIAA1122 protein complex.

Epigenetic dysregulation in thyroid neoplasia

Gain-of-function mutations in oncogenes have aided our understanding of the molecular mechanisms of thyroid carcinogenesis. Mutations or deletions cause inactivation of tumor suppressor genes in thyroid carcinomas. However, recent advances have disclosed the significance of epigenetic events in the development and progression of human tumorigenesis. Indeed, various tumor-suppressor genes and thyroid hormone-related genes are epigenetically silenced in thyroid tumors. This article reviews the evidence for epigenetic gene dysregulation in follicular cell-derived thyroid carcinomas including papillary thyroid carcinoma, follicular thyroid carcinoma, and undifferentiated thyroid carcinoma. The authors also discuss future applications of epigenetics as ancillary diagnostic tools and in the design of targeted therapies for thyroid cancer.

Alpha-fetoprotein and other tumour-associated antigens for immunotherapy of hepatocellular cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer death, with few treatment options for advanced disease.

OBJECTIVES

Here, we review the aetiology of HCC and focus on recent data on tumour-associated antigens (TAA) for HCC, their functions and potential use as immunological targets for immune-based therapy for HCC. In addition, we examine some aspects of antigen presentation within the liver.

RESULTS/CONCLUSIONS

alpha-Fetoprotein (AFP) has been investigated for many years as a TAA, and has been tested in recent clinical trials. More recently, additional TAA have been identified and new therapeutic approaches have been investigated which may be testable clinically in this difficult disease setting.

Adenovirus targeting to HLA-A1/MAGE-A1-positive tumor cells by fusing a single-chain T-cell receptor with minor capsid protein IX

Adenovirus vectors have great potential in cancer gene therapy. Targeting of cancer-testis (CT) antigens, which are specifically presented at the surface of tumor cells by human leukocyte antigen (HLA) class I molecules, is an attractive option. In this study, a single-chain T-cell receptor (scTCR) directed against the CT antigen melanoma-associated antigen (MAGE)-A1 in complex with the HLA class I molecule of haplotype HLA-A1 is fused with the C terminus of the adenovirus minor capsid protein IX. Propagation of a protein-IX (pIX)-gene-deleted human adenovirus 5 (HAdV-5) vector on cells that constitutively express the pIXscTCR fusion protein yielded viral particles with the pIXscTCR fusion protein incorporated in their capsid. Generated particles specifically transduced melanoma cell lines expressing the HLA-A1/MAGE-A1 target complex with at least 10-fold higher efficiency than control viruses. Whereas loading of HLA-A1-positive cells with MAGE-A1 peptides leads to enhanced transduction of the cells, the efficiency of virus transduction is strongly reduced if the HLA-A1 molecules are not accessible at the target cell. Taken together, these data provide proof of principle that pIXscTCR fusions can be used to target HAdV-5 vectors to tumor cells expressing intracellular CT antigens.

Marked clinical and immunological response of MAGE-A3 peptides vaccination in a patient with adenocarcinoma of the lung case report: A case report

A 56-year patient was diagnosed adenocarcinoma of the right lung and underwent lower lobectomy. Pleural dissemination was observed, and the pathological stage was T4N0M0. Systemic chemotherapy was performed with paclitaxel and vinorelbine after the surgery. Because multiple pulmonary and liver metastases were appeared 1 year after the surgery, the second line chemotherapy (CDDP and 5FU) was performed. The response of the chemotherapy was not observed, and thus the patient was enrolled in the clinical trial of MAGE-A3 peptide vaccine with OK-432. The peptide (300 mg) was injected subcutaneously at the upper thigh or upper arm a total of 6 times over 2 months (days 1, 8, 15, 22, 36, and 50) with OK432. During two courses of the vaccinations, the tumor markers (CA19-9 and CEA) decreased markedly. Furthermore, the tumor size of the lung and liver metastases decreased to 30% of their pre-treatment size. The delayed type hypersensitive reaction became positive after the first course of vaccinations. The precursor CTL for the peptide in the peripheral blood had increased after the vaccination. MAGE-A3 peptide vaccination with OK-432 has a potential to induce immunological response and clinical response in advanced lung cancer patients.