Circulating cell-free cancer-testis MAGE-A RNA, BORIS RNA, let-7b and miR-202 in the blood of patients with breast cancer and benign breast diseases

BACKGROUND

MAGE-A (melanoma-associated antigen-A) are promising targets for specific immunotherapy and their expression may be induced by the epigenetic factor BORIS.

METHODS

To determine their relevance for breast cancer, we quantified the levels of MAGE-A1, -A2, -A3, -A12 and BORIS mRNA, as well as microRNAs let-7b and miR-202 in pre- and postoperative serum of 102 and 34 breast cancer patients, respectively, and in serum of 26 patients with benign breast diseases and 37 healthy women by real-time PCR. The mean follow-up time of the cancer patients was 6.2 years.

RESULTS

The serum levels of MAGE-A and BORIS mRNA, as well as let-7b were significantly higher in patients with invasive carcinomas than in patients with benign breast diseases or healthy women (P<0.001), whereas the levels of miR-202 were elevated in both patient cohorts (P<0.001). In uni- and multivariate analyses, high levels of miR-202 significantly correlated with poor overall survival (P=0.0001). Transfection of breast cancer cells with synthetic microRNAs and their inhibitors showed that let-7b and miR-202 did not affect the protein expression of MAGE-A1.

CONCLUSIONS

Based on their cancer-specific increase in breast cancer patients, circulating MAGE-A and BORIS mRNAs may be further explored for early detection of breast cancer and monitoring of MAGE-directed immunotherapies. Moreover, serum miR-202 is associated with prognosis.

A non-BRCA1/2 hereditary breast cancer sub-group defined by aCGH profiling of genetically related patients

Germline mutations in BRCA1 and BRCA2 explain approximately 25% of all familial breast cancers. Despite intense efforts to find additional high-risk breast cancer genes (BRCAx) using linkage analysis, none have been reported thus far. Here we explore the hypothesis that BRCAx breast tumors from genetically related patients share a somatic genetic etiology that might be revealed by array comparative genomic hybridization (aCGH) profiling. As BRCA1 and BRCA2 tumors can be identified on the basis of specific genomic profiles, the same may be true for a subset of BRCAx families. Analyses used aCGH to compare 58 non-BRCA1/2 familial breast tumors (designated BRCAx) to sporadic (non-familiar) controls, BRCA1 and BRCA2 tumors. The selection criteria for BRCAx families included at least three cases of breast cancer diagnosed before the age of 60 in the family, and the absence of ovarian or male breast cancer. Hierarchical cluster analysis was performed to determine sub-groups within the BRCAx tumor class and family heterogeneity. Analysis of aCGH profiles of BRCAx tumors indicated that they constitute a heterogeneous class, but are distinct from both sporadic and BRCA1/2 tumors. The BRCAx class could be divided into sub-groups. One subgroup was characterized by a gain of chromosome 22. Tumors from family members were classified within the same sub-group in agreement with the hypothesis that tumors from the same family would harbor a similar genetic background. This approach provides a method to target a sub-group of BRCAx families for further linkage analysis studies.

A multiplex PCR predictor for aCGH success of FFPE samples

Formalin-fixed, paraffin-embedded (FFPE) tissue archives are the largest and longest time-spanning collections of patient material in pathology archives. Methods to disclose information with molecular techniques, such as array comparative genomic hybridisation (aCGH) have rapidly developed but are still not optimal. Array comparative genomic hybridisation is one efficient method for finding tumour suppressors and oncogenes in solid tumours, and also for classification of tumours. The fastest way of analysing large numbers of tumours is through the use of archival tissue samples with first, the huge advantage of larger median follow-up time of patients studied and second, the advantage of being able to locate and analyse multiple tumours, even across generations, from related individuals (families). Unfortunately, DNA from archival tissues is not always suitable for molecular analysis due to insufficient quality. Until now, this quality remained undefined. We report the optimisation of a genomic-DNA isolation procedure from FFPE pathology archives in combination with a subsequent multiplex PCR-based quality-control that simply identified all samples refractory to further DNA-based analyses.