Seventeen-gene signature from enriched Her2/Neu mammary tumor-initiating cells predicts clinical outcome for human HER2 ⁺ :ERα ⁻ breast cancer

Abstract

Human Epidermal Growth Factor Receptor 2-positive (HER2 + ) breast cancer (BC) is a highly aggressive disease commonly treated with chemotherapy and anti-HER2 drugs, including trastuzumab. There is currently no way to predict which HER2 + BC patients will benefit from these treatments. Previous prognostic signatures for HER2 + BC were developed irrespective of the subtype or the hierarchical organization of cancer in which only a fraction of cells, tumor-initiating cells (TICs), can sustain tumor growth. Here, we used serial dilution and single-cell transplantation assays to identify MMTV-Her2/Neu mouse mammary TICs as CD24 + :JAG1 − at a frequency of 2-4.5%. A 17-gene Her2-TICenriched signature (HTICS), generated on the basis of differentially expressed genes in TIC versus non-TIC fractions and trained on one HER2 + BC cohort, predicted clinical outcome on multiple independent HER2 + cohorts. HTICS included up-regulated genes involved in S/G2/ M transition and down-regulated genes involved in immune response. Its prognostic power was independent of other predictors, stratified lymph node + HER2 + BC into low and high-risk subgroups, and was specific for HER2 + :estrogen receptor alpha-negative (ERα − ) patients (10-y overall survival of 83.6% for HTICS − and 24.0% for HTICS + tumors; hazard ratio = 5.57; P = 0.002). Whereas HTICS was specific to HER2 + :ERα − tumors, a previously reported stroma-derived signature was predictive for HER2 + :ERα + BC. Retrospective analyses revealed that patients with HTICS + HER2 + :ERα − tumors resisted chemotherapy but responded to chemotherapy plus trastuzumab. HTICS is, therefore, a powerful prognostic signature for HER2 + :ERα − BC that can be used to identify high risk patients that would benefit from anti-HER2 therapy. , and triple-negative (basal-like, Claudin-low) tumors. HER2 + BC is caused by overexpression/amplification of the HER2/ERBB2/NEU tyrosine kinase receptor and constitutes 15-20% of cases. Approximately 50% of these are ERα + tumors, and 50% are ERα − . Current treatment of HER2 + BC involves chemotherapy plus trastuzumab (Herceptin; Genentech), a monoclonal antibody directed against HER2 (1-3). Despite improvement in disease-free survival (DFS) over a 4-y follow-up (4), the cost of trastuzumab, adverse effects such as cardiac failure, and emergence of drug-resistance metastases represent serious limitations for its use, particularly in lowincome countries (5). A prognostic signature that can predict clinical outcome from tumor biopsies at time of presentation may help prioritize patients for anti-HER2 therapy.Because BC consists of several different subtypes, each with distinct pathological features and clinical behaviors, predictive prognostic signatures may need to be developed for each subtype.In addition, many types of cancer exhibit hierarchical organization whereby only a fraction of cells, termed tumor-initiating cells (TICs), sustains growth, whereas the remaining tumor cells, which descend from TICs, have lost their tumorigenic potential (6). HER2/...

shRNA Kinome Screen Identifies TBK1 as a Therapeutic Target for HER2+ Breast Cancer

“…However, the importance of Atg1 and TBK1 in HER2 þ breast cancer in which RAS is activated at a significantly lower level is largely unknown. To investigate the role of these factors in HER2 þ breast cancer, we first analyzed their expression in primary and secondary (transplanted) mammary Her2/Neu tumors (19). Both Atg1/ Ulk1 and Tbk1 were readily detected by RNA microarray (Supplementary Fig.…”

“…This model was also used to identify TICs and tumorsphere-forming units (TFU; refs. 9,18), and to generate a powerful prognostic signature for HER2 þ breast cancer (19), demonstrating its utility in modeling the human disease. Here, we show that following several passages of Her2/Neu tumor cells as adherent or nonadherent cells, they become enriched for p53 mutations, and that tumorsphere but not monolayer cells maintain TICs.…”

“…RNA extracted from TBK1-IItreated HCC1954 cells was subject to transcriptional profiling and global gene set enrichment analysis (GSEA; ref. 40), followed by "functional enrichment maps" to visualize the results (19,41). Lists of genes/pathways that were highly up-or downregulated are shown in Supplementary Table S4A and S4B.…”

mda-7/IL-24 Expression Inhibits Breast Cancer through Upregulation of Growth Arrest-Specific Gene 3 (gas3) and Disruption of β1 Integrin Function

“…The correlation between IL-20R1 and GAS3 genes was assessed by Pearson Correlation method with median-centered, log-2-transformed, and Robust Multi-array Average normalized microarray gene expression values. Kaplan-Meier curves and HRs were generated as described (16).…”

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“…Approximately 15%-30% of patients with stage I breast cancer and up to 40% of stage II node-negative patients will have a recurrence with local therapy alone. The disparity in outcomes within groups of similar histopathologic characteristics speaks to the incredible heterogeneity of this disease [3,4]. How to better define and identify these higher risk individuals has been an area of intense investigation for more than a decade [5].…”