Potential mouse tumor model for pre-clinical testing of mage-specific breast cancer vaccines

Expression pattern analysis of the MAGE family genes in breast cancer patients and hypomethylation activation in the MCF-7 cells

Melanoma antigen gene (MAGE) families are cancer-testis genes that normally show expression in the testes. However, their expressions have been linked with various types of human cancers, including BC. Therefore, the primary purposes of the present research were to assess the expression of MAGE-A, -B, and -C genes in Saudi female patients with BC and determine their regulation via the epigenetic mechanism. Ten BC samples were analyzed for the expression levels of nine MAGE-A genes, six MAGE-B genes, and three MAGE-C genes using the RT-PCR technique. All 18 evaluated genes except for MAGE-A1, -A3, -A4, and -B5 showed weak band expressions in some BC specimens. MAGE-A6 and -B2 were expressed in 40 % of the BC tissue samples, and MAGE-A9, -A10, and -B6 were expressed in 30 %. The lowest expression levels were found for MAGE-A11, -B1, -B3, -B4, -C1, and -C2 in 10 % of the BC specimens and for MAGE-A9,--B2, and --C3 in 20 % of the samples. The most frequently expressed gene was MAGE-A8 (found in 70 % of the BC samples), which suggests that it may serve as - a marker for screening of BC. In vitro treatment, the 5-aza-2'-deoxycytidine agent led to a significant rise in mRNA expressions for all tested genes related to the MAGE-A family, except for MAGE-A10. By contrast, among the genes in the MAGE-B and -C families, only MAGE-B1 and -C2 exhibited detectable mRNA expression levels after treatment.

Prognostic roles of MAGE family members in breast cancer based on KM-Plotter Data

Breast cancer is the second leading cause of cancer-associated mortality among women worldwide, and the prevalence and mortality rates associated with this disease are high in Western countries. The melanoma-associated antigen (MAGE) family proteins are well-known tumor-specific antigens; this family includes >60 proteins that serve an important part in cell cycle withdrawal, neuronal differentiation and apoptosis. The aim of the present study was to identify a biomarker within the MAGE family that is specific for breast cancer. In the present study, the prognostic role of MAGE mRNA expression was investigated in patients with breast cancer using the Kaplan-Meier plotter database. The prognostic value of MAGE members in the different intrinsic subtypes of breast cancer was further investigated, as well as the clinicopathological features of the disease. The results of the present study indicated that patients with breast cancer that had high mRNA expression levels of MAGEA5, MAGEA8, MAGEB4 and MAGEB6 had an improved relapse-free survival, whereas those with high mRNA expression levels of MAGEB18 and MAGED4 did not. These results suggested that MAGEA5, MAGEA8, MAGEB4 and MAGEB6 may have roles as tumor suppressors in the occurrence and development of breast cancer, whereas MAGEB18 and MAGED4 may possess carcinogenic potential. MAGED2, MAGED3 and MAGEF1 had different effects depending on the type of breast cancer. In particular, high MAGEC3 mRNA expression was associated with worse RFS in lymph node-positive breast cancer, but with improved RFS in lymph node-negative breast cancer. In patients with wild-type TP53 and patients with different pathological grades of breast cancer, MAGEE2, MAGEH1 and MAGEL2 were more worthy of attention as potential prognostic factors. The results of the present study may help to elucidate the role of MAGE family members in the development of breast cancer, and may promote further research that identifies MAGE-targeting reagents for the treatment of breast cancer.

Prevention of metastases with a Mage-b DNA vaccine in a mouse breast tumor model: potential for breast cancer therapy

Anti-tumor vaccines are a relatively non-toxic alternative to conventional chemotherapeutic strategies to control breast cancer. Immunization with tumor-associated antigens (TAAs) triggers anti-tumor cytotoxic T lymphocytes (CTL), which can limit tumor progression. Here we report on the development and effectiveness of a TAA-based DNA vaccine encoding Mage-b1/2, the mouse homologue of the human MAGE-B1/2. As model system, we used immune competent Balb/c mice with syngeneic non-metastatic (64pT) or metastatic (4TO7cg) breast tumors. First, the presence of Mage-btranscripts in the 64pT and 4TO7cg breast tumors and metastases was demonstrated by RT-PCR, Southern blotting, and DNA sequencing. A DNA-based vaccine was developed from transcripts of one of the 64pT tumors, encoding the complete Mage-b1/2 protein, and subsequently tested for its preventive efficacy in both breast tumor models. Mice were immunized two times intramuscularly with the vaccine (pcDNA3.1-Mage-b1/2-V5), the control vector (pcDNA3.1-V5), or saline. Two weeks after the last immunization, the syngeneic 4TO7cg or 64pT tumor cell lines were injected in a mammary fat pad. Mice were monitored during the next 4 weeks for tumor formation, latency and size, and subsequently sacrificed for analysis. While the Mage-b1/2 vaccine had only a minor effect on the latency and growth of primary tumors, a significant and reproducible reduction in the number of 4TO7cg metastases was observed (vaccine versus control vector, p=0.0329; vaccine versus saline, p=0.0128). The observed protective efficacy of the Mage-b DNA vaccine correlated with high levels of vaccine-induced IFNgamma in spleen and lymph nodes upon re-stimulation in vitro. These results demonstrate the potential of TAA-based DNA vaccines in controlling metastatic disease in breast cancer patients.

The promise of genetically engineered mice for cancer prevention studies

Sophisticated genetic technologies have led to the development of mouse models of human cancers that recapitulate important features of human oncogenesis. Many of these genetically engineered mouse models promise to be very relevant and relatively rapid systems for determining the efficacy of chemopreventive agents and their mechanisms of action. The validation of such models for chemoprevention will help the selection of appropriate agents for large-scale clinical trials and allow the testing of combination therapies.

Behavior of metastatic and nonmetastatic breast tumors in old mice

Breast cancer incidence and mortality increase with age. A better understanding of the biological behavior of metastatic and nonmetastatic breast tumors in older subjects may help to develop improved breast cancer therapies. In this study, we used syngeneic metastatic (4TO7cg) and nonmetastatic (64pT) mouse breast tumor models at three age levels to evaluate various characteristics that are considered to be important for effective anti-breast cancer immunotherapy. These included tumor size and growth, metastases, vascularization, gene expression levels of the tumor-associated antigen (TAA) Mage-b (homologous to human MAGE-B) in primary breast tumors and metastases, and the presence of CD4(+) and CD8(+) T cells in the inguinal lymph nodes at the site of the tumor. The primary breast tumors and metastases were generated by injection of mouse mammary tumor cell lines 4TO7cg or 64pT into a mammary fat pad of normal 3-, 9-, or 21/24-month old BALB/c mice. In the nonmetastatic breast tumor model, significantly smaller tumors were observed in old compared with young mice. This was associated with a significant increase in the percentage of CD8(+) T cells in inguinal lymph nodes and significantly higher Mage-b expression levels in the primary tumors at old age. In the metastatic (4TO7cg) breast tumor model, a less pronounced, not statistically significant, smaller tumor size was found in the old mice, without a difference in the percentage of CD8(+) T cells or Mage-b expression levels. However, in this mouse model almost all metastases showed high levels of Mage-b expression (2- to 3-fold higher than the primary tumors in the same animals) regardless of age. These results indicate that the metastatic and nonmetastatic breast tumor models could be useful model systems to analyze how breast cancer vaccines for humans can be tailored to old age.