The association between large tumor size and metastatic risk in a majority of clinical cancers has led to questions as to whether these observations are causally related or whether one is simply a ...marker for the other. This is partly due to an uncertainty about how metastasis-promoting gene expression changes can arise in primary tumors. We investigated this question through the analysis of a previously defined "lung metastasis gene-expression signature" (LMS) that mediates experimental breast cancer metastasis selectively to the lung and is expressed by primary human breast cancer with a high risk for developing lung metastasis. Experimentally, we demonstrate that the LMS promotes primary tumor growth that enriches for LMS⁺ cells, and it allows for intravasation after reaching a critical tumor size. Clinically, this corresponds to LMS⁺ tumors being larger at diagnosis compared with LMS⁻ tumors and to a marked rise in the incidence of metastasis after LMS⁺ tumors reach 2 cm. Patients with LMS-expressing primary tumors selectively fail in the lung compared with the bone or other visceral sites and have a worse overall survival. The mechanistic linkage between metastasis gene expression, accelerated tumor growth, and likelihood of metastatic recurrence provided by the LMS may help to explain observations of prognostic gene signatures in primary cancer and how tumor growth can both lead to metastasis and be a marker for cells destined to metastasize.
MicroRNAs (miRNAs) are small RNA molecules that modulate gene expression and which have been implicated in cancer. We evaluated whether five candidate predictive miRNAs, derived from a pilot study in ...which 249 miRNAs were assayed, were associated with clinical benefit of tamoxifen therapy in advanced breast cancer. These five miRNAs were measured in an independent series of 246 estrogen receptor (ER)-positive primary breast tumors of patients who received tamoxifen for advanced disease by quantitative Real Time PCR. Univariate analysis showed that higher expression levels of hsa-miR-30a-3p, hsa-miR-30c, and hsa-miR-182 were significantly associated with benefit of tamoxifen treatment and with longer PFS (all
P
-values <0.01). In multivariate analysis, corrected for the traditional predictive factors, only hsa-miRNA-30c was an independent predictor (
P
-value <0.01). Finally, in an attempt to understand the biology connected to this miRNA, Global testing pathway analysis showed an association of hsa-miRNA-30c expression with HER and RAC1 signaling pathways. We identified hsa-miRNA-30c as an independent predictor for clinical benefit of tamoxifen therapy in patients with advanced breast cancer. Assessment of tumor levels and connected pathways could be helpful to improve treatment strategies.
Abstract BACKGROUND: Preclinical and clinical studies have reported that human epidermal growth factor receptor 2 (HER2) overexpression yields resistance to endocrine therapies. Here the prevalence ...and prognostic impact of HER2-positive circulating tumor cells (CTCs) were investigated retrospectively in metastatic breast cancer (MBC) patients with a HER2-negative primary tumor receiving endocrine therapy. Additionally, the prevalence and prognostic significance of HER2-positive CTCs were explored in a chemotherapy cohort, as well as the prognostic impact of the estrogen receptor (ER) CTC status in both cohorts. METHODS: Included were MBC patients with a HER2-negative primary tumor, with ≥1 detectable CTC, starting a new line of treatment. CTCs were enumerated using the CellSearch system, characterized for HER2 with the CellSearch anti-HER2 phenotyping reagent, and characterized for ER mRNA expression. Primary end point was progression-free rate after 6 months (PFR6months) of endocrine treatment in HER2-positive versus HER2-negative CTC patients. RESULTS: HER2-positive CTCs were present in 29% of all patients. In the endocrine cohort ( n = 72), the PFR6months was 53% for HER2-positive versus 68% for HER2-negative CTC patients ( P = .23). In the chemotherapy cohort ( n = 82), no prognostic value of HER2-positive CTCs on PFR6months was observed either. Discordances in ER status between the primary tumor and CTCs occurred in 25% of all patients but had no prognostic value in exploratory survival analyses. CONCLUSION: Discordances regarding HER2 status and ER status between CTCs and the primary tumor occurred frequently but had no prognostic impact in our MBC patient cohorts.
Proliferation and tumor differentiation captured by the genomic grade index (GGI) are important prognostic indicators in breast cancer (BC) especially for the estrogen receptor positive (ER+) ...disease. The aims of this study were to convert this microarray index to a qRT-PCR assay (PCR-GGI), which could be realized on formalin fixed paraffin embedded samples (FFPE), and to assess its prognostic performance and predictive value of clinical benefit in early and advanced ER+ BC patients treated with tamoxifen.
The accuracy and concordance of the PCR-GGI with the GGI was assessed using BC patients for which frozen and FFPE tissues as well as microarray data were available (n = 19). The evaluation of the prognostic value of the PCR-GGI was assessed on FFPE material using a consecutive series of 212 systemically treated early BC patients. The predictive performance for tamoxifen benefit was assessed using two ER+ BC populations treated either with adjuvant tamoxifen only (n = 77+139) or first-line tamoxifen for advanced disease (n = 270).
The PCR-GGI is based on the expression of 8 genes (4 representative of the GGI and 4 reference genes). A significant correlation was observed between the microarray-derived GGI and the qRT-PCR assay using frozen (rho = 0.95, p < 10E-06) and FFPE material (rho = 0.89, p < 10E-06). The prognostic performance of the PCR-GGI was confirmed on FFPE samples (HRunivar. = 1.89; 95CI:1.01-3.54, p = 0.05). The PCR-GGI further identified two subgroups of patients with statistically different time to distant metastasis free survival (DMFS) across the two cohorts of ER+ BC patients treated with adjuvant tamoxifen. Additionally, the PCR-GGI was associated with response to tamoxifen in the advanced setting (HRunivar. = 1.98; 95CI:1.51-2.59, p = 6.9E-07).
PCR-GGI recapitulates in an accurate and reproducible manner the performances of the GGI using frozen and FFPE samples.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Breast tumors often display extreme genetic heterogeneity characterized by hundreds of gross chromosomal aberrations and tens of thousands of somatic mutations. Tumor evolution is thought to be ...ongoing and driven by multiple mutagenic processes. A major outstanding question is whether primary tumors have preexisting mutations for therapy resistance or whether additional DNA damage and mutagenesis are necessary. Drug resistance is a key measure of tumor evolvability. If a resistance mutation preexists at the time of primary tumor presentation, then the intended therapy is likely to fail. However, if resistance does not preexist, then ongoing mutational processes still have the potential to undermine therapeutic efficacy. The antiviral enzyme APOBEC3B (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3B) preferentially deaminates DNA C-to-U, which results in signature C-to-T and C-to-G mutations commonly observed in breast tumors. We use clinical data and xenograft experiments to ask whether APOBEC3B contributes to ongoing breast tumor evolution and resistance to the selective estrogen receptor modulator, tamoxifen. First, APOBEC3B levels in primary estrogen receptor-positive (ER
) breast tumors inversely correlate with the clinical benefit of tamoxifen in the treatment of metastatic ER
disease. Second, APOBEC3B depletion in an ER
breast cancer cell line results in prolonged tamoxifen responses in murine xenograft experiments. Third, APOBEC3B overexpression accelerates the development of tamoxifen resistance in murine xenograft experiments by a mechanism that requires the enzyme's catalytic activity. These studies combine to indicate that APOBEC3B promotes drug resistance in breast cancer and that inhibiting APOBEC3B-dependent tumor evolvability may be an effective strategy to improve efficacies of targeted cancer therapies.
We previously identified in a single-center study a 76-gene prognostic signature for lymph node-negative (LNN) breast cancer patients. The aim of this study was to validate this gene signature in an ...independent more diverse population of LNN patients from multiple institutions.
Using custom-designed DNA chips we analyzed the expression of the 76 genes in RNA of frozen tumor samples from 180 LNN patients who did not receive adjuvant systemic treatment.
In this independent validation, the 76-gene signature was highly informative in identifying patients with distant metastasis within 5 years (hazard ratio, HR, 7.41; 95% CI, 2.63 to 20.9), even when corrected for traditional prognostic factors in multivariate analysis (HR, 11.36; 95% CI, 2.67 to 48.4). The actuarial 5- and 10-year distant metastasis-free survival were 96% (95% CI, 89% to 99%) and 94% (95% CI, 83% to 98%), respectively, for the good profile group and 74% (95% CI, 64% to 81%) and 65% (53% to 74%), respectively for the poor profile group. The sensitivity for 5-yr distant metastasis-free survival was 90%, and the specificity was 50%. The positive and negative predictive values were 38% (95% CI, 29% to 47%) and 94% (95% CI, 86% to 97%), respectively. The 76-gene signature was confirmed as a strong prognostic factor in subgroups of estrogen receptor-positive patients, pre- and postmenopausal patients, and patients with tumor sizes 20 mm or smaller. The subgroup of patients with estrogen receptor-negative tumors was considered too small to perform a separate analysis.
Our data provide a strong methodologic and clinical multicenter validation of the predefined prognostic 76-gene signature in LNN breast cancer patients.
The biology of tumors relapsing to bone is poorly understood. In this study, we initiated a search for genes that are implicated in tumors relapsing to bone in breast cancer.
We analyzed 107 primary ...breast tumors in patients who were all lymph node negative at the time of diagnosis and all had experienced relapse. Total RNA isolated from frozen tumor samples was used to gather gene expression data using oligo microarrays.
A panel of 69 genes was found significantly differentially expressed between patients who experienced relapse to bone versus those who experienced relapse elsewhere in the body. The most differentially expressed gene, TFF1, was confirmed by quantitative reverse transcriptase polymerase chain reaction in an independent cohort (n = 122; P = .0015). Our differentially expressed genes, combined with a recently reported gene set relevant to tumors relapsing to bone in an animal model system, pointed to the involvement of the fibroblast growth factor receptor signaling pathway in preference of tumor cells that relapse to bone. Given that patients who experience relapse to bone may benefit from bisphosphonate therapy, we developed a classifier of 31 genes, which in an independent validation set correctly predicts all tumors relapsing to bone with a specificity of 50%.
Our study identifies a panel of genes relevant to bone metastasis in breast cancer. The subsequently developed classifier of tumors relapsing to bone could, after thorough confirmation on an extended number of independent samples, and in combination with our previously developed high-risk profile, provide a diagnostic tool for the recommendation of adjuvant bisphosphonate therapy in addition to endocrine therapy or chemotherapy.
Detection of circulating tumor cells (CTCs) in whole blood from metastatic cancer patients by the CellSearch™ CTC Test (Veridex LLC, Warren, NJ, USA) has been shown to have clinical relevance. In ...addition to enumeration, there is great interest in molecular characterization of these CTCs. We aimed to establish a robust method to perform mRNA expression analysis of multiple genes by a real-time reverse transcriptase (RT)-PCR on small numbers of CTCs enriched from whole blood by the CellSearch™ system. Despite the 4 log depletion of leukocytes after CellSearch enrichment, the CTC-enriched fractions still contained leukocytes, in particular B-lymphocytes, which severely interfered with our CTC-specific gene expression profiling. After extensive washing and leukocyte-specific depletion by anti-CD45 coated magnetic beads prior to CellSearch™ enrichment, the number of leukocytes present in the enriched fraction was still high (range 60-929). However, by using a set of genes with no or minor expression by leukocytes, we succeeded to perform quantitative gene expression profiling specific for as little as one breast cancer CTC present in a CTC-enriched environment typically containing over 800 contaminating leukocytes. Our method allows molecular characterization specific for as little as one CTC, and can be used to expand the understanding of the biology of metastasis and, potentially, to improve patient management.
Published prognostic gene signatures in breast cancer have few genes in common. Here we provide a rationale for this observation by studying the prognostic power and the underlying biological ...pathways of different gene signatures.
Gene signatures to predict the development of metastases in estrogen receptor-positive and estrogen receptor-negative tumors were identified using 500 re-sampled training sets and mapping to Gene Ontology Biological Process to identify over-represented pathways. The Global Test program confirmed that gene expression profilings in the common pathways were associated with the metastasis of the patients.
The apoptotic pathway and cell division, or cell growth regulation and G-protein coupled receptor signal transduction, were most significantly associated with the metastatic capability of estrogen receptor-positive or estrogen-negative tumors, respectively. A gene signature derived of the common pathways predicted metastasis in an independent cohort. Mapping of the pathways represented by different published prognostic signatures showed that they share 53% of the identified pathways.
We show that divergent gene sets classifying patients for the same clinical endpoint represent similar biological processes and that pathway-derived signatures can be used to predict prognosis. Furthermore, our study reveals that the underlying biology related to aggressiveness of estrogen receptor subgroups of breast cancer is quite different.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Increased APOBEC3B mRNA levels are associated with a hypermutator phenotype and poor prognosis in ER-positive breast cancer patients. In addition, a 29.5 kb deletion polymorphism of APOBEC3B, ...resulting in an APOBEC3A-B hybrid transcript, has been associated with an increased breast cancer risk and the hypermutator phenotype. Here we evaluated whether the APOBEC3B deletion polymorphism also associates with clinical outcome of breast cancer. Copy number analysis was performed by quantitative PCR (qPCR) in primary tumors of 1,756 Dutch breast cancer patients. The APOBEC3B deletion was found in 187 patients of whom 16 carried a two-copy deletion and 171 carried a one-copy deletion. The prognostic value of the APOBEC3B deletion for the natural course of the disease was evaluated among 1,076 lymph-node negative (LNN) patients who did not receive adjuvant systemic treatment. No association was found between APOBEC3B copy number values and the length of metastasis-free survival (MFS; hazard ratio (HR) = 1.00, 95% confidence interval (CI) = 0.90-1.11, P = 0.96). Subgroup analysis by ER status also did not reveal an association between APOBEC3B copy number values and the length of MFS. The predictive value of the APOBEC3B deletion was assessed among 329 ER-positive breast cancer patients who received tamoxifen as the first-line therapy for recurrent disease and 226 breast cancer patients who received first-line chemotherapy for recurrent disease. No association between APOBEC3B copy number values and the overall response rate (ORR) to either tamoxifen (odds ratio (OR) = 0.88, 95% CI = 0.69-1.13, P = 0.31) or chemotherapy (OR = 0.97, 95% CI = 0.71-1.33, P = 0.87) was found. Thus, in contrast to APOBEC3B mRNA levels, the APOBEC3B deletion polymorphism has neither a prognostic nor a predictive value for breast cancer patients. Although a correlation exists between APOBEC3B copy number and mRNA expression, it is relatively weak. This suggests that other mechanisms exist that may affect and therefore determine the prognostic value of APOBEC3B mRNA levels.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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