Abstract 4570: Using laser capture microdissection functionally coupled with mass spectrometry for an enhanced study of solid tumor heterogeneity via tissue proteomics

• Published in: Cancer research (Chicago, Ill.) Vol. 70; no. 8_Supplement; p. 4570
• Main Authors: Johann, Donald J., Mukherjee, Sumana, Rodriquez-Canales, Jaime, Hanson, Jeffrey, Prieto, DaRue, Veenstra, Timothy D., Emmert-Buck, Michael, Blonder, Josip
• Format: Journal Article
• Language: English
• Published: 15.04.2010
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM10-4570

Abstract Introduction Examining solid tumor heterogeneity using a tissue proteomics approach, which relies on a functional coupling between Laser Capture Microdissection (LCM) and biological mass spectrometry (MS), is the purpose of this research study. A common characteristic of solid tumors is a heterogeneous architecture, which enables distinct cellular morphologies and molecular behaviors. This diverse composition of cells, specifically cancer cells proper along with both modified and unmodified stromal elements, collectively forms a microenvironment that serves to nurture the malignant process. Methods Using LCM, homogeneous regions of cells exhibiting uniform histology were isolated and captured from fresh frozen tissue specimens, which were obtained from a human lesion of breast carcinoma metastasis. All slides were reviewed by a pathologist and the LCM session planned. Multiple specimens each containing ∼ 50,000 cells were collected by LCM. Specimens were processed directly on LCM caps, using sonication in buffered methanol to lyse captured cells, solubilize, and digest extracted proteins. Preliminary results Prepared samples were analyzed by LC-MS/MS resulting in more than 500 unique protein identifications. High confidence measures were employed by including only proteins identified by ≥ 2 unique peptides. Decoy database searching revealed a false-positive rate between 5 and 10%. Machine learning methods assisted with molecular profiling activities to better discern the concurrent expression of multiple cellular phenotypes due to the heterogeneity of the solid tumor. Cross validation via Western Blot analysis confirmed specific linkage of 12 validated proteins to underlying pathology and their potential role in solid tumor heterogeneity. Summary and conclusion Solid tumors are composed of an assortment of cell types, which have diverse morphologies, as well as distinct molecular phenotypes. Tumor heterogeneity may be viewed as a memory of the malignant process and thus a novel proteomic study may yield insights regarding cancer development and more effective treatment. The biological background of such heterogeneity is not well understood. With continued research and optimization of this method including analysis of additional clinical specimens, this approach may lead to an improved understanding of tumor heterogeneity, and serve as a platform for solid tumor biomarker discovery. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4570.