Lipid Profiles for HER2-positive Breast Cancer

Background: Accumulating data indicate that human epidermal growth factor receptor-2 (HER2)-positive breast cancer is a heterogeneous disease. We undertook a study to correlate lipid profiles with heterogeneous clinicopathological features of HER2-positive breast cancer. Materials and Methods: Histology-directed matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS) analyses were performed on 22 retrospective frozen tissue samples collected from patients with HER2-positive metastatic breast cancer, in order to correlate lipid profiles with clinicopathological characterisitics. Additionally, a pair of tumor and adjacent normal tissue was profiled to identify cancer-associated changes in lipid profiles. Results: Sphingomyelin 34:1, phosphatidylcholine (PC) 32:0, and PC 34:1, and PC 36:2 were overexpressed in HER2-positive breast cancer compared to adjacent normal tissue (HER2 signature). Lipid MALDI-MS profiles were different between Ki-67-high and Ki-67-low tumors. The proliferation signature (Ki-67-high vs. Ki-67-low) and the HER2 signature (cancer vs. normal) did not significantly overlap with each other. Conclusion: For the first time to our knowledge, this study describes lipid profiles correlated with various clinicopathological characteristics of HER2-positive breast cancer. Lipid profiling might be helpful for the molecular characterization of this disease. Matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry (MS) imaging has been demonstrated to be useful for molecular profiling of common solid tumors (1). In this approach, thin sections of frozen tissues are obtained from surgical resections or biopsies, and mass spectra were obtained from discrete tumor locations on the tissue. We previously reported that protein and lipid MALDI-MS profiles can classify breast cancers according to intrinsic