Increased expression of a set of genes enriched in oxygen binding function discloses a predisposition of breast cancer bone metastases to generate metastasis spread in multiple organs

Abstract

Bone is the preferential site of distant metastasis in breast carcinoma (BrCa). Patients with metastasis restricted to bone (BO) usually show a longer overall survival compared to patients who rapidly develop multiple metastases also involving liver and lung. Hence, molecular predisposition to generate bone and visceral metastases (BV) represents a clear indication of poor clinical outcome. We performed microarray analysis with two different chip platforms, Affymetrix and Agilent, on bone metastasis samples from BO and BV patients. The unsupervised hierarchical clustering of the resulting transcriptomes correlated with the clinical progression, segregating the BO from the BV profiles. Matching the twofold significantly regulated genes from Affymetrix and Agilent chips resulted in a 15-gene signature with 13 upregulated and two downregulated genes in BV versus BO bone metastasis samples. In order to validate the resulting signature, we isolated different MDA-MB-231 clonal subpopulations that metastasize only in the bone (MDA-BO) or in bone and visceral tissues (MDA-BV). Six of the signature genes were also significantly upregulated in MDA-BV compared to MDA-BO clones. A group of upregulated genes, including Hemoglobin B (HBB), were involved in oxygen metabolism, and in vitro functional analysis of HBB revealed that its expression in the MDA subpopulations was associated with a reduced production of hydrogen peroxide. Expression of HBB was detected in primary BrCa tissue but not in normal breast epithelial cells. Metastatic lymph nodes were frequently more positive for HBB compared to the corresponding primary tumors, whereas BO metastases had a lower expression than BV metastases, suggesting a positive correlation between HBB and ability of bone metastasis to rapidly spread to other organs. We propose that HBB, along with other genes involved in oxygen metabolism, confers a more aggressive metastatic phenotype in BrCa cells disseminated to bone. ß

Combined Genome and Transcriptome Analysis of Single Disseminated Cancer Cells from Bone Marrow of Prostate Cancer Patients Reveals Unexpected Transcriptomes

“…Likewise attempts to reconstruct cancer cell transcriptomes from unpurified CTCs by transcript subtraction need to be viewed with caution (38). Our findings are consistent with previous observations, such as a transcriptome study of 15 single prostate CTCs from one M1-stage patient revealing low-level expression of EPCAM, PTPRC (CD45), and CD34 (39), expression of hemoglobins in breast cancer epithelial cells (40,41) and ovarian cancer epithelial cells transdifferentiating into erythroid cells expressing hemoglobins (42). The observed expression of hematopoietic and erythroid transcripts by bone marrow-DCCs may reflect adaptation to the specific environment.…”

Oligo- and Polymetastatic Progression in Lung Metastasis(es) Patients Is Associated with Specific MicroRNAs

“…Our current analysis, based on the rate of progression of metastasis emphasizes growth properties of different metastatic clones [29]–[32]. However, differences in the ability to colonize the lung microenvironment following primary tumor resection may also account for observed differences between oligo- and poly- metastatic phenotypes [33].…”

Intratumoral acidosis fosters cancer-induced bone pain through the activation of the mesenchymal tumor-associated stroma in bone metastasis from breast carcinoma

“…Such acidification might promote the pathogenic process in bone; however, the association between the ability to localize in the bone and the ability to secrete high levels of protons has never been evaluated. We compared the MDA cell line with the bmMDA clone, which is more prone to form BM when injected into the left ventricle of nude mice [ 16 ]. Compared with the parental MDA cells, the bmMDA cells showed higher mRNA (Figure 1A ) expression of key regulators of intracellular pH [ 12 , 17 ], such as carbonic anhydrase 9 (CA9; mRNA p = 0.0209) and monocarboxylate transporter 4 (MCT4; mRNA p =0.0209, protein p =0.0495), and glucose transporter 1 (GLUT-1; mRNA p =0.045), an indirect marker of glycolysis.…”