Classical gene amplifications in human breast cancer are not associated with distant solid metastases

Combined analysis of copy number alterations by single-nucleotide polymorphism array and MYC status in non-metastatic breast cancer patients: comparison according to the circulating tumor cell status

Recent technological advances have made it possible to detect circulating tumor cells (CTCs) as a prognostic marker in operable breast cancer patients. Whether the presence of CTCs in cancer patients correlates with molecular alterations in the primary tumor has not been widely explored. We identified 14 primary breast cancer specimens with known CTC status, in order to evaluate the presence of differential genetic aberrations by using SNP array assay. There was a global increase of altered genome, CNA, and copy-neutral loss of heterozygosity (cn-LOH) observed in the CTC-positive (CTC(+)) versus CTC-negative (CTC(-)) cases. As the preliminary results showed a higher proportion of copy number alteration (CNA) at 8q24 (MYC loci) and the available evidence supporting the role of MYC in the processes cancer metastases is conflicting, MYC status was determined in tissue microarray sections in a larger series of patients (n = 49) with known CTC status using FISH. MYC was altered in 62% (16/26) CTC(+) patients and in 43% (6/14) CTC(-) patients (p = 0.25). Based on the observation in our study, future studies involving a larger number of patients should be performed in order to definitively define if this correlation exists.

Extra copies of c-mycare more pronounced in nodular melanomas than in superficial spreading melanomas as revealed by fluorescence in situ hybridisation

BACKGROUND

Amplification of c-myc is a common genetic alteration and associated with a poor prognosis in a variety of cancers. Extra copies of the gene have been found in large numbers of melanoma metastases, but only few primary tumours have been studied. We investigated the c-myc copy number alterations in two different subtypes of primary melanomas with different biological behaviours.

METHODS

Fluorescence in situ hybridisation was performed using c-myc and centromeric 8 (C8) probes on 68 lesions (28 nodular melanomas [NMs], 26 superficial spreading melanomas [SSMs], and 14 metastases). To assess the ploidy pattern, copy number distribution of seven different chromosomes was also investigated.

RESULTS

All tumours showed aneuploid populations for at least three chromosomes. Whereas 61% of the NMs exhibited extra c-myc copies, only 27% of SSMs showed increased gene dosage. The c-myc/C8 ratio exceeding 1.5 was significantly higher in NMs (P = 0.01). High level amplification was seen only in NMs. An elevated c-myc/C8 ratio was higher than 1.5 in only four metastases.

CONCLUSION

Our data show that c-myc copy number alterations differ in the two melanoma subtypes and are associated with the advanced stage of the disease. The less frequent amplification of the c-myc gene in metastatic lesions indicates that it may play an important role in the development of an invasive potential rather than in the metastatic process.

Molecular alterations in sporadic breast cancer

Breast cancer is a genetic disease. Like other human cancers, it is thought to occur as the result of progressive accumulation of genetic aberrations. These aberrations result in a deviation of the gene expression profiles from that of the normal progenitor cell. In up to 99% of cases, breast cancer is due to solely somatic genetic aberrations without germ-line ones. Considerable progress have already been made in understanding the genetic mechanisms underlying the development and progression of breast cancer. Several extensively studied genes are now well known to be involved. Unfortunately, our ability to make clinically useful interventions on the basis of these data is limited. Because of the involvement of multiple genes and complex pathways in a single cancer cell, the molecular dysfunctioning underlying breast cancer remains to be completely clarified. In a next future, studying the global gene expression of different types of tumors will allow the development of expression profiles unique for a breast cancer, its stage and prognostic category, leading to diagnostic assays and the identification of new therapeutic targets.

Mammaglobin, a potential marker of breast cancer nodal metastasis

The Mammaglobin gene, a breast-specific member of the uteroglobin gene family, has been previously identified as being overexpressed in some breast tumours, but the cellular origin and relationship to tumour progression are unknown. Using a subtractive hybridization approach, mammaglobin mRNA has also been found to be overexpressed in the in situ compared to the invasive element within an individual breast tumour. Further study by in situ hybridization performed in 13 breast tumours, selected to include normal, in situ, and invasive primary tumour elements, and in most cases axillary lymph node metastases, revealed that mammaglobin expression occurs in all elements, is restricted to epithelial cells, and is significantly increased in tumour cells compared with normal cells ( p< 0.04). Analysis of mammaglobin expression within 20 independent primary breast tumours and their corresponding axillary lymph nodes revealed that all 13 lymph nodes positive and none of the seven nodes negative for metastatic breast carcinoma by histology were mammaglobin-positive by reverse transcription-polymerase chain reaction (RT-PCR) ( p=0.0001). These results suggest that mammaglobin could be a marker of axillary lymph node breast metastases.

Immunohistochemical detection of p53 and c-myc proteins in canine mammary tumours

The objectives of this study were to detect by immunohistochemical means, nuclear accumulations of p53 and c-myc proteins in mammary tumours of dogs. Moderate or intense p53 protein nuclear labelling was shown by each of five osteosarcomas. In contrast, focal immunoreactivity was shown by three of five adenocarcinomas and two of three malignant myoepitheliomas. Six benign mixed tumours and three myoepitheliomas showed no detectable immunoreactivity. On the other hand, three patterns of c-myc protein nuclear reactivity were observed in these tumours. Osteosarcomas, adenocarcinomas, malignant myoepitheliomas and myoepitheliomas showed intense or moderate reactivity. In benign mixed tumours, the epithelial component showed moderate or intense reactivity, and the myoepithelial component showed focal or moderate reactivity. These results demonstrated that p53 protein was expressed only in the osteosarcomas, but that c-myc expression was detectable in both the epithelial and myoepithelial components.