Targeting MAGE-C1/CT7 expression increases cell sensitivity to the proteasome inhibitor bortezomib in multiple myeloma cell lines.

The MAGE-C1/CT7 encodes a cancer/testis antigen (CTA), is located on the chromosomal region Xq26-27 and is highly polymorphic in humans. MAGE-C1/CT7 is frequently expressed in multiple myeloma (MM) that may be a potential target for immunotherapy in this still incurable disease. MAGEC1/CT7 expression is restricted to malignant plasma cells and it has been suggested that MAGE-C1/CT7 might play a pathogenic role in MM; however, the exact function this protein in the pathophysiology of MM is not yet understood. Our objectives were (1) to clarify the role of MAGE-C1/CT7 in the control of cellular proliferation and cell cycle in myeloma and (2) to evaluate the impact of silencing MAGE-C1/CT7 on myeloma cells treated with bortezomib. Myeloma cell line SKO-007 was transduced for stable expression of shRNA-MAGE-C1/CT7. Downregulation of MAGE-C1/CT7 was confirmed by real time quantitative PCR and western blot. Functional assays included cell proliferation, cell invasion, cell cycle analysis and apoptosis. Western blot showed a 70-80% decrease in MAGE-C1/CT7 protein expression in inhibited cells (shRNA-MAGE-C1/CT7) when compared with controls. Functional assays did not indicate a difference in cell proliferation and DNA synthesis when inhibited cells were compared with controls. However, we found a decreased percentage of cells in the G2/M phase of the cell cycle among inhibited cells, but not in the controls (p<0.05). When myeloma cells were treated with bortezomib, we observed a 48% reduction of cells in the G2/M phase among inhibited cells while controls showed 13% (empty vector) and 9% (ineffective shRNA) reduction, respectively (p<0.01). Furthermore, inhibited cells treated with bortezomib showed an increased percentage of apoptotic cells (Annexin V+/PI-) in comparison with bortezomib-treated controls (p<0.001). We found that MAGE-C1/CT7 protects SKO-007 cells against bortezomib-induced apoptosis. Therefore, we could speculate that MAGE-C1/CT7 gene therapy could be a strategy for future therapies in MM, in particular in combination with proteasome inhibitors.

MAGE-A inhibits apoptosis in proliferating myeloma cells through repression of Bax and maintenance of survivin.

PURPOSE: The type I Melanoma Antigen GEnes (MAGEs) are commonly expressed in cancers, fueling speculation that they may be therapeutic targets with oncogenic potential. They form complexes with RING domain proteins that have E3 ubiquitin ligase activity and promote p53 degradation. MAGE-A3 was detected in tumor specimens from patients with multiple myeloma and its expression correlated with higher frequencies of Ki-67(+) malignant cells. In this report, we examine the mechanistic role of MAGE-A in promoting survival of proliferating multiple myeloma cells. EXPERIMENTAL DESIGN: The impact of MAGE-A3 expression on survival and proliferation in vivo was examined by immunohistochemical analysis in an independent set of tumor specimens segregated into two groups: newly diagnosed, untreated patients and patients who had relapsed after chemotherapy. The mechanisms of MAGE-A3 activity were investigated in vitro by silencing its expression by short hairpin RNA interference in myeloma cell lines and primary cells and assessing the resultant effects on proliferation and apoptosis. RESULTS: MAGE-A3 was detected in a significantly higher percentage of relapsed patients compared with newly diagnosed, establishing a novel correlation with progression of disease. Silencing of MAGE-A showed that it was dispensable for cell cycling, but was required for survival of proliferating myeloma cells. Loss of MAGE-A led to apoptosis mediated by p53-dependent activation of proapoptotic Bax expression and by reduction of survivin expression through both p53-dependent and -independent mechanisms. CONCLUSIONS: These data support a role for MAGE-A in the pathogenesis and progression of multiple myeloma by inhibiting apoptosis in proliferating myeloma cells through two novel mechanisms.

Evaluation of LAGE-1 and NY-ESO-1 expression in multiple myeloma patients to explore possible benefits of their homology for immunotherapy.

Due to the high homology between the LAGE-1 and NY-ESO-1 proteins, we hypothesized that an anti-NY-ESO-1 vaccine might elicit LAGE-1 immunity and hence may be effective in multiple myeloma (MM) patients with LAGE-1-positive/NY-ESO-1-negative tumors. Therefore, we set out to evaluate LAGE-1 and NY-ESO-1 mRNA and protein expression in MM patients in a bid to evaluate possible benefits of their homology for immunotherapy. LAGE-1 (a and b isoforms) and NY-ESO-1 mRNA expression was studied in 18 normal tissues and 50 bone marrow MM samples by RT-PCR. LAGE-1 and NY-ESO-1 protein expression was analyzed by immunohistochemistry (IHC) in 27 MM specimens using mAbs 219-510-23 and E978. Spontaneous serological immune response against both antigens was analyzed by ELISA in sera from 33 MM patients. LAGE-1 (a and b isoforms) was positive in 42% and NY-ESO-1 in 26% of the MM samples analyzed by RT-PCR. Both genes were found to be expressed in 18% of the cases, while at least one of the genes was found to be expressed in 50% of the cases. In LAGE-1 positive samples, 81% were positive for LAGE-1a and 19% were positive for both LAGE-1a and -1b. LAGE-1 and NY-ESO-1 protein expression could only be detected in two cases by IHC and there was a clear strong spontaneous antibody response to LAGE-1 and NY-ESO-1 in only one MM patient. In conclusion, LAGE-1a and NY-ESO-1 homology cannot be easily exploited in an anti-NY-ESO-1 vaccine given the low frequency of protein expression detected by IHC or serum analysis.

Number of expressed cancer/testis antigens identifies focal adhesion pathway genes as possible targets for multiple myeloma therapy.

Considering that the importance of cancer/testis (CT) antigens in multiple myeloma (MM) biology is still under investigation, the present study aimed to: (1) identify genes differentially expressed in MM using microarray analysis of plasma cell samples, separated according to the number of expressed CTs; (2) examine possible pathways related to MM pathogenesis; (3) validate the expression of candidate genes by quantitative real-time PCR (RQ-PCR). Three samples predominantly positive (>6 expressed), including the U266 cell line, and three samples predominantly negative (0 or 1 expressed CT for the 13 analyzed CT antigens), were submitted for microarray analysis. Validation by RQ-PCR from 24 MM samples showed that the ITGA5 gene was downregulated in predominantly positive (>6 expressed CTs, p = 0.0030) and in tumor versus normal plasma cells (p = 0.0182). The RhoD gene was overexpressed in tumor plasma cells when compared to normal plasma cells (p = 0.0339). Results of the microarray analysis corroborate the hypothesis that MM could be separated into predominantly positive and predominantly negative expression. The differential expression of ITGA5 and RhoD suggests disruption of the focal adhesion pathway in MM and offers a new target field to be explored in this disease.

Comparative expression of a set of genes to an internal housekeeping control in CDNA amplified and not amplified by PolyAPCR in non-Hodgkin's lymphoma samples obtained from fine-needle aspiration cytology.

AIM: We aimed to evaluate the amount and quality of the RNA obtained from lymph nodes of non-Hodgkin lymphomas (NHLs) patients using fine-needle aspiration cytology (FNAC), and to develop strategies to overcome eventual technical drawbacks. MATERIALS AND METHODS: Twenty-six patients with NHL and 10 tonsils from children submitted to tonsillectomy underwent FNAC. The aspirates were performed using both cytoaspirator (sample A) and syringe and needle (sample B). The RNA was extracted using Trizol reagent and transcribed with the Superscript kit (Invitrogen). The quality of RNA was verified through the amplification of a beta-actin 155-bp fragment. RESULTS: Fifty-two NHL and 20 tonsil samples were analyzed. The total amount of RNA in the tonsil samples varied from <1.0 to 6.2 microg with cytoaspirator (A) and from <1.0 to 4.7 microg with syringe and needle (B). The total amount of RNA obtained from NHL varied from <1.0 to 6.5 microg with cytoaspirator (A) and <1.0 to 5.5 microg with syringe and needle. In an attempt to increase the amounts of RNA in each sample, we standardized the polyAPCR technique, which increased by 10 times the amount of cDNA in most of the test and control samples. The efficiency of the reaction was verified through the amplification of beta-actin, in which 100% of the test and control samples were amplified. When polyAPCR cDNA and nonamplified cDNA samples were paired to be evaluated by real-time PCR, using glyceraldehyde-3-phosphate dehydrogenase as the constitutive gene and nuclear factor-kappa B and NFkappaBIA as target genes, there was equivalence in the amplifications of 100% of the 15 evaluated samples. CONCLUSIONS: Our results showed that FNAC, obtained either by cytoaspirator or syringe and needle, is a good source of small amounts of RNA. The polyAPCR technique significantly increased the amount of genomic material, which might be a cDNA source for future gene expression studies.

Frequency and prognostic relevance of cancer testis antigen 45 expression in multiple myeloma.

OBJECTIVE: This study aims to analyze the expression of cancer testis antigen 45 (CT45) in normal tissues and in plasma cell disorders and to identify possible associations with clinical data and prognosis in multiple myeloma (MM) patients. MATERIALS AND METHODS: Expression of CT45 was studied in 20 normal tissues (testis, placenta, skeletal muscle, bladder, lung, spleen, heart, brain and fetal brain, thymus, uterus, stomach, mammary gland, pancreas, prostate, small intestine, kidney, adrenal gland, spinal cord, colon, and one pool of 10 normal bone marrow samples) and bone marrow aspirates from 3 monoclonal gammopathies of undetermined significance, 5 solitary plasmacytomas, 61 newly diagnosed MM patients and MM cell line U266 by reverse transcriptase polymerase chain reaction. RESULTS: CT45 was positive in 3 of 20 (15%) normal tissues tested: lung, brain (both fetal and adult), and spinal cord. Among monoclonal gammopathies, CT45 was positive in 2 of 5 (40%) solitary plasmacytomas bone marrow aspirates, 10 of 61 (16%) MM bone marrow aspirates, and in the U266 MM cell line. CONCLUSIONS: We did not find associations between bone marrow histology and CT45 expression. However, we demonstrated for the first time that positive expression of CT45 was associated with poor prognostic (International Staging System) and poor outcomes in MM patients, meaning that CT45-positive cases presented seven times more chance of worse evolution than the negative ones.

SAGE analysis highlights the importance of p53csv, ddx5, mapkapk2 and ranbp2 to multiple myeloma tumorigenesis.

Serial analysis of gene expression (SAGE) allows a comprehensive profiling of gene expression within a given tissue and also an assessment of transcript abundance. We generated SAGE libraries from normal and neoplastic plasma cells to identify genes differentially expressed in multiple myeloma (MM). Normal plasma cells were obtained from palatine tonsils and MM SAGE library was generated from bone marrow plasma cells of MM patients. We obtained 29,918 SAGE tags from normal and 10,340 tags from tumor libraries. Computer-generated genomic analysis identified 46 upregulated genes in the MM library. Ten upregulated genes were selected for further investigation. Differential expression was validated by quantitative real-time PCR in purified plasma cells of 31 patients and three controls. P53CSV, DDX5, MAPKAPK2 and RANBP2 were found to be upregulated in at least 50% of the MM cases tested. All of them were also found upregulated in MM when compared to normal plasma cells in a meta-analysis using ONCOMINE microarray database. Antibodies specific to DDX5, RANBP2 and MAPKAPK2 were used in a TMA containing 57 MM cases and confirmed the expression of these proteins in 74%, 96%, and 21% of the MM samples, respectively. Analysis of differential expression using SAGE could identify genes important for myeloma tumorigenesis (P53CSV, DDX5, MAPKPK2 and RANBP2) and that could potentially be useful as therapeutic targets.

Prognostic impact of cancer/testis antigen expression in advanced stage multiple myeloma patients.

This study aims to analyze the expression of 14 cancer/testis (CT) antigens in multiple myeloma (MM) to identify possible prognostic markers and therapeutic targets. The expression of MAGEA1, MAGEA2, MAGEA3/6, MAGEA4, MAGEA10, MAGEA12, BAGE1, MAGEC1/CT7, the GAGE family, LAGE-1, PRAME, NY-ESO-1, SPA17 and SSX1 was studied by RT-PCR in 15 normal tissues, a pool of 10 normal bone marrow samples, 3 normal tonsils and bone marrow aspirates from 6 normal donors, 3 monoclonal gammopathies of undetermined significance (MGUS), 5 solitary plasmacytomas, 39 MM samples (95% advanced stage) and the MM cell line U266. MAGEC1/CT7 was expressed in bone marrow aspirates from one MGUS and one plasmacytoma. The frequencies at which CT antigen were found to be expressed in MM patients were MAGEC1/CT7 77%, LAGE-1 49%, MAGEA3/6 41%, MAGEA2 36%, GAGE family 33%, NY-ESO-1 33%, BAGE-1 28%, MAGEA1 26%, PRAME 23%, SSX-1 26%, MAGEA12 20.5%, MAGEA4 0%, and MAGEA10 0%. Cox's regression model showed that GAGE family expression and having >6 CT antigens expressed were independent prognostic factors when all patients were analyzed. However, MAGEC1/CT7 expression was the only independent prognostic factor when non-transplanted patients where analyzed. Based on our findings, MAGEC1/CT7, MAGEA3/6 and LAGE-1 are good candidates for immunotherapy, since together they cover 85% of our MM cases. Furthermore, expression of the GAGE family, >6 CT antigens and MAGEC1/CT7 seem to have impact on MM prognosis.

Physical interaction of two cancer-testis antigens, MAGE-C1 (CT7) and NY-ESO-1 (CT6).

Cancer/testis (CT) antigens are the protein products of germ line-associated genes that are activated in a wide variety of tumors and can elicit autologous cellular and humoral immune responses. CT antigens can be divided between those that are encoded on the X chromosome (CT-X antigens) and those that are not (non-X CT antigens). Among the CT-X antigens, the melanoma antigen gene (MAGE) family, defined by a shared MAGE homology domain (MHD), is the largest. CT-X genes are frequently expressed in a coordinate manner in cancer cells, and their expression appears to be modulated by epigenetic mechanisms. The expression of CT-X genes is associated with advanced disease and poor outcome in different tumor types. We used the yeast two-hybrid system to identify putative MHD-interacting proteins. The MHD of MAGE-C1 (CT7) was used as bait to screen a human testis cDNA library. This study identified NY-ESO-1 (CT6) as a MAGE-C1 binding partner. Immunoprecipitation and immunofluorescence staining confirmed MAGE-C1 interaction with NY-ESO-1, and cytoplasmic co-localization of both proteins in melanoma cells. Co-expression of these two genes was found to occur in cancer cell lines from different origins, as well as in primary tumors (multiple myeloma and non-small cell lung cancer samples). This is the first report of direct interaction between two CT antigens and may be pertinent in the light of the frequently coordinated expression of these proteins.