Focus on Breast Cancer
For years scientists have been treating breast cancer as a single disease. However, a new landmark study published in Nature has reclassified breast cancer into ten separate sub-diseases based on their genetic fingerprint. The culmination of decades of research, the study is the largest global study of breast cancer tissue ever performed.
The team, led by the British Columbia Cancer Center in Canada and the Cambridge Cancer Research Institute in the UK, used genome-wide microarrays to analyze the DNA and RNA of 2,000 tumor samples taken from women diagnosed with breast cancer. This huge pool of genetic information (copy number variants, SNPs and gene expression data), as well as survival data, allowed researchers to spot new and previously unacknowledged patterns for ten subtly different cancers that have, historically, been considered as one.
The challenge now is to understand the genetic drivers behind these newly discovered breast cancer variants and to develop new targeted therapies in the future. It could also lead to women with the best prognosis being spared side-effects of chemotherapy. The classification system will likely also form the basis for newer and better ways to diagnose and manage the disease.
Bioline offers a number of reagents that have helped further the study of cancers and, more specifically, breast cancer. So this edition of Bioline Scholar Monthly focuses on the use of Bioline reagents and kits in the field of breast cancer research.
In a diverse cohort of breast cancer patients with a 1–5 year tumor relapse versus those with up to 7 years relapse-free survival, RNA was extracted and subjected to microarray and real-time RT-PCR analysis. Among the 299 genes, five genes which included B cell response genes were found to predict with >85% accuracy relapse-free survival. Real-time RT-PCR confirmed the 5-gene prognostic signature that was distinct from an FDA-cleared 70-gene signature of MammaPrint panel and from the Oncotype DX recurrence score assay panel.
Ascierto, L. M., et al. Breast Can. Res. Treat. 131(3):871-880 (2012) - A signature of immune function genes associated with recurrence-free survival in breast cancer patients.
MicroRNAs (miRNAs) are noncoding RNAs that function as key posttranscriptional regulators of gene expression. This paper found that BRCA1 recognizes the RNA secondary structure and directly binds with primary transcripts of miRNAs via a DNA-binding domain. The findings indicate novel functions of BRCA1 in miRNA biogenesis, which may be linked to its tumor suppressor mechanism and maintenance of genomic stability.
Kawai S. and Amano A. J. Cell Biol. 197 (2):201-208 (2012) - BRCA1 regulates microRNA biogenesis via the DROSHA microprocessor complex.
The bioactive lipid sphingosine 1-phosphate (S1P) uses sphingosine 1-phosphate receptor 4 (S1P4) and human epidermal growth factor receptor 2 (HER2) to stimulate the extracellular signal regulated protein kinase 1/2 (ERK-1/2) pathway in MDA-MB-453 cells. The magnitude of the signaling gain on the ERK-1/2 pathway produced in response to S1P can be increased by HER2 in MDA-MB-453 cells. The linkage of S1P with an oncogene suggests that S1P and specifically S1P4 may have an important role in breast cancer progression.
Long J. S., et al. J. Biol. Chem. 285:35957-35966 (2010) - Sphingosine 1-Phosphate Receptor 4 Uses HER2 (ERBB2) to Regulate Extracellular Signal Regulated Kinase-1/2 in MDA-MB-453 Breast Cancer Cells.
CD44, the transmembrane receptor for hyaluronan, is implicated in tumor cell invasion and metastasis. The expression of CD44 and its variants is associated with poor prognosis in breast cancer. This paper investigated the effect of silibinin (a polyphenolic flavonolignan of the herbal plant of Silybum marianum, milk thistle) on the epidermal growth factor (EGF) ligand-induced CD44 expression in human breast cancer cells. The results suggest that silibinin prevents the EGFR signaling pathway and may be used as an effective drug for the inhibition of metastasis of human breast cancer.
Kim S., et al. Anticancer Res. 31(11): 3767-3773 (2011) - Silibinin Suppresses EGFR Ligand-induced CD44 Expression through Inhibition of EGFR Activity in Breast Cancer Cells.
Human papillomavirus (HPV) and Epstein Barr virus (EBV) have been found in breast carcinomas around the world. In this study, fifty-five BCs from Chile were analyzed for HPV and EBV presence. In addition, HPV- 16 viral load/physical status and E6/E7 expressions were determined. The results suggest that it is unlikely that HPV and/or EBV play a direct role in the etiology of breast carcinomas.
Aguayo F., et al. Infectious Agents and Cancer 6:7 (2011) - Human papillomavirus and Epstein-Barr virus infections in breast cancer from chile.
This study suggests that melatonin may play a role in the desmoplastic reaction in breast cancer through a down regulatory action on the expression of antiadipogenic cytokines, which decrease the levels of these cytokines. Lower levels of cytokines stimulate the differentiation of fibroblasts and decrease both aromatase activity and expression, thereby reducing the number of estrogen-producing cells proximal to malignant cells.
Alonso-González C., et al. J. Pineal Res. 52(3): 282–290, (2012) - Melatonin interferes in the desmoplastic reaction in breast cancer by regulating cytokine production.
Melatonin reduces the development of breast cancer interfering with oestrogen-signalling pathways, and also inhibits aromatase activity and expression. This study shows that melatonin inhibits aromatase activity and expression by regulating the gene expression of specific aromatase promoter regions. A possible mechanism for these effects would be the regulation by melatonin of intracellular cAMP levels, mediated by an inhibition of cyclooxygenase activity and expression.
Martínez-Campa C., et al. British J. Can. 101: 1613–1619 (2009) - Melatonin inhibits aromatase promoter expression by regulating cyclooxygenases expression and activity in breast cancer cells.
Bisphenol A (BPA) has long been suspected to promote carcinogenesis, but the high doses of BPA used in many studies generated conflicting results. This paper shows that BPA at environmentally relevant doses reduces the efficacy of chemotherapeutic agents. These data provide considerable support to the accumulating evidence that BPA is hazardous to human health.
LaPensee E. W., et al. Environ Health Perspect. 117(2): 175–180 (2009) - Bisphenol A at Low Nanomolar Doses Confers Chemoresistance in Estrogen Receptor-a–Positive and –Negative Breast Cancer Cells.
This paper indicates that decreased CDH1, CDH13 and TIMP3 with increased CD44 gene expression levels can be used as an indicator for invasion in both ER-positive and ER-negative breast tumors. In double-negative tumor tissues, CD44 can be considered a marker for aggressive properties. However, additional assays in a larger series of patients with long follow up will be necessary to confirm these results of gene expressions in ER-positive and ER-negative tumors and their relationship with HER2 and ESR1.
Celebiler A., et al. Can. Sci. 100: 2341–2345. (2009) - Predicting invasive phenotype with CDH1, CDH13, CD44, and TIMP3 gene expression in primary breast cancer.