Expression of cancer/testis antigens in prostate cancer is associated with disease progression

An overview of cancer/testis antigens expression in classical Hodgkin's lymphoma (cHL) identifies MAGE-A family and MAGE-C1 as the most frequently expressed antigens in a set of Brazilian cHL patients

ABSTRACT: BACKGROUND: Cancer/testis antigens are considered potential targets for immunotherapy due to their tumor-associated expression pattern. Although recent studies have demonstrated high expression of CT45 in classical Hodgkin's lymphomas (cHL), less is known about the expression pattern of other families of CTAs in cHL. We aim to evaluate the expression of MAGE-A family, MAGE-C1/CT7, MAGE-C2/CT10, NY-ESO1 and GAGE family in cHL and to correlate their expression with clinical and prognostic factors in cHL. METHODS: Tissue microarray was generated from 38 cHL archival cases from Pathology Department of Universidade Federal de Sao Paulo. Immunohistochemistry (IHC) was done using the following panel of antibodies: MAGE-A family (MA454, M3H67, 57B and 6C1), GAGE (#26), NY-ESO-1 (E978), MAGE-C1/CT7 (CT7-33) and MAGE-C2/CT10 (CT10#5). RESULTS: We found CTA expression in 21.1% of our cHL series. Among the tested CTAs, only MAGE-A family 7/38 (18.4%) and MAGE-C1/CT7 5/38 (13.2%) were positive in our cHL samples. We found higher CTA positivity in advanced stage (28.6%) compared to early stage (11.8%) disease, but this difference was not statistically significant. Analysis of other clinicopathological subgroups of cHL including histological subtypes, EBV status and response to treatment also did not demonstrate statistical significant differences in CTA expression. CONCLUSION: We found CTA expression in 21.1% of cHL samples using our panel. Our preliminary findings suggest that from all CTAs included in this study, MAGE-A family and MAGE-C1/CT7 are the most interesting ones to be explored in further studies.

Cancer/Testis Antigens as potential predictors of biochemical recurrence of prostate cancer following radical prostatectomy

Background

The Cancer/Testis Antigens (CTAs) are an important group of proteins that are typically restricted to the testis in the normal adult but are aberrantly expressed in several types of cancers. As a result of their restricted expression patterns, the CTAs could serve as unique biomarkers for cancer diagnosis/prognosis. The aim of this study was to identify promising CTAs that are associated with prostate cancer (PCa) recurrence following radical prostatectomy (RP).

Methods

The expression of 5 CTAs was measured by quantitative multiplex real-time PCR using prostate tissue samples obtained from 72 patients with apparently clinically localized PCa with a median of two years follow-up (range, 1 to 14 years).

Results

The expression of CTAs namely, CEP55, NUF2, PBK and TTK were significantly higher while PAGE4 was significantly lower in patients with recurrent disease. All CTAs with the exception of TTK were significantly correlated with the prostatectomy Gleason score, but none were correlated with age, stage, or preoperative PSA levels. In univariate proportional hazards models, CEP55 (HR = 3.59, 95% CI: 1.50-8.60), p = 0.004; NUF2 (HR = 2.28, 95% CI: 1.11-4.67), p = 0.024; and PAGE4 (HR = 0.44, 95% CI: 0.21-0.93), p = 0.031 were significantly associated with the risk of PCa recurrence. However, the results were no longer significant after adjustment for prostatectomy Gleason score.

Conclusions

To our knowledge, this is the first study to identify CTAs as biomarkers that can differentiate patients with recurrent and non-recurrent disease following RP and underscores its potential impact on PCa prognosis and treatment.

The cancer/testis antigen prostate-associated gene 4 (PAGE4) is a highly intrinsically disordered protein

The cancer/testis antigens (CTAs) are an important group of heterogeneous proteins that are predominantly expressed in the testis in the normal human adult but are aberrantly expressed in several types of cancers. Prostate-associated gene 4 (PAGE4) is a member of the CT-X family of CTAs that in addition to testis, is highly expressed in the fetal prostate, and may also play an important role both in benign and malignant prostate diseases. However, the function of this gene remains poorly understood. Here, we show that PAGE4 is a highly (100%) intrinsically disordered protein (IDP). The primary protein sequence conforms to the features of a typical IDP sequence and the secondary structure prediction algorithm metaPrDOS strongly supported this prediction. Furthermore, SDS-gel electrophoresis and analytical size exclusion chromatography of the recombinant protein revealed an anomalous behavior characteristic of IDPs. UV circular dichroism (CD) and NMR spectroscopy confirmed that PAGE4 is indeed a highly disordered protein. In further bioinformatic analysis, the PredictNLS algorithm uncovered a potential nuclear localization signal, whereas the algorithm DBS-Pred returned a 99.1% probability that PAGE4 is a DNA-binding protein. Consistent with this prediction, biochemical experiments showed that PAGE4 preferentially binds a GC-rich sequence. Silencing PAGE4 expression induced cell death via apoptosis and in mice carrying PCa xenografts, siRNA-mediated knockdown of the PAGE4 mRNA attenuated tumor growth in vivo. Furthermore, overexpressing PAGE4 protected cells from stress-induced death. To our knowledge, PAGE4 is the first example of a CTA that is an IDP with an anti-apoptotic function.

Autoantibodies to tumor-associated antigens in breast carcinoma

Autoantibodies (AAbs) to tumor-associated antigens (TAAs) have been identified in the circulation of patients with cancer. This paper will focus on recent knowledge related to circulating AAbs to TAAs in breast carcinoma. So far, the following TAAs have been identified to elicit circulating AAbs in breast carcinoma: p53, MUC-1, heat shock proteins (HSP-27, HSP-60, and HSP-90), HER2/neu/c-erb B2, GIPC-1, c-myc, c-myb, cancer-testis antigens (NY-ESO-1), BRCA1, BRCA2, endostatin, lipophilin B, cyclin B1, cyclin D1, fibulin, insulin-like growth factor binding protein 2 (IGFBP-2), topoisomerase II alpha (TOPO2α), and cathepsin D. Measurement of serum AAbs to one specific TAA only is of little value for screening and early diagnosis of breast carcinoma; however, assessment of AAbs to a panel of TAAs may have promising diagnostic potential.

BORIS/CTCFL expression is insufficient for cancer-germline antigen gene expression and DNA hypomethylation in ovarian cell lines

Expression of the cancer-germline (CG) (or cancer-testis) antigen gene BORIS/CTCFL has been proposed to mediate activation of CG antigen genes in cancer. Consistent with this idea, we have observed that BORIS is frequently expressed in ovarian cancer, often in conjunction with other CG genes. Here we assessed the role of BORIS in CG antigen gene regulation and DNA methylation using normal and cancerous ovarian cell lines, and the CG genes MAGE-A1, NY-ESO-1, and XAGE-1 as models. Adenoviral vectored BORIS was expressed at robust levels and exhibited predominant nuclear localization in ovarian cells. However, BORIS expression in immortalized ovarian surface epithelial cells or ovarian cancer cell lines did not induce CG antigen gene expression or lead to CG antigen promoter DNA hypomethylation. BORIS overexpression also did not alter global DNA methylation, as assessed by genomic 5-methyl-deoxycytidine levels and LINE-1 methylation. We used decitabine to further assess the role of BORIS in CG gene activation and found that decitabine treatment induced BORIS and other CG genes with similar kinetics, suggesting that BORIS induction does not account for the induction of other CG genes by decitabine in ovarian cancer cells. In agreement, siRNA knockdown of BORIS did not block decitabine-mediated induction of CG genes or DNA hypomethylation in ovarian cancer cells treated with this agent. We conclude that BORIS is insufficient for CG antigen gene expression and DNA hypomethylation in ovarian cell lines, and that additional factors are likely required for CG antigen expression in ovarian cancer.