Abstract 4959: High-resolution MALDI imaging mass spectrometry demonstrated the correlation between phosphatidylinositol profiles and invasion/metastasis in human breast cancer

Abstract

Abstract High-resolution matrix-assisted laser desorption/ionization imaging mass spectrometry (HR-MALDI IMS) is an emerging application for lipid research that provides a detailed histological distribution of ionized lipids within tissue section. Phosphatidylinositol (PI) is one of the major classes of membrane phospholipid. The cellular membrane fluidity and signal transduction activity could be modulated by the alteration of fatty acid composition of PIs. Especially, PI-3kinase pathway, which can be activated by the phosphorylation of PIs, has become a great concern in breast cancer treatment. Although the amount of PIs is known to increase in human breast cancer tissues, it remains unclear how PIs are distributed in cancerous tissues. In this study, we investigated the detailed spatial distribution of PIs in breast tissues obtained from 24 patients, including 23 invasive ductal carcinoma (IDC), 4 ductal carcinoma in situ (DCIS), and 4 fibrocystic change lesions by using HR-MALDI IMS. The distribution of PIs was visualized at the resolution of 10um. 10 PIs with different fatty acid composition were detected in breast tissues. High-resolution analysis revealed the fatty acid composition of PIs was altered specifically in cancer cell clusters compared to stromal cells and non-malignant epithelia. PIs carrying monounsaturated fatty acid (MUFA) and PIs carrying polyunsaturated fatty acid (PUFA) showed the specific localization to cancer cell clusters. However, the proportion of PIs carrying MUFA and PIs carrying PUFA showed a clear inverse correlation in cancer cells. When we compared the PI profiles of IDC, DCIS, and FC, it was suggested that the accumulation of PIs carrying PUFA was occurred during the step of invasion. Moreover, lymph node metastasis well correlated with the accumulation of PIs carrying PUFA in cancer cells. HR-MALDI IMS firstly demonstrated the possible association between the PI profiles of breast cancer cells and their invasion/metastasis ability. Although this is a preliminary study, HR-MALDI IMS could be a useful modality to visualize the reprogramming of the lipid metabolism which reflects the cancer cell phenotype. Citation Format: Masahiro Kawashima, Nobuko Kawaguchi-Sakita, Masahiro Sugimoto, Taka-Aki Sato, Koichi Tanaka, Masakazu Toi. High-resolution MALDI imaging mass spectrometry demonstrated the correlation between phosphatidylinositol profiles and invasion/metastasis in human breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4959. doi:10.1158/1538-7445.AM2014-4959