Laser Capture Microdissection of Gastric Tissue

LCM was performed for fresh untreated ESD specimens as described previously [13 (link)]. Briefly, specimens were embedded in Tissue-Tek OCT medium (Sakura, Tokyo, Japan), ten serial sections per specimen were cut using a microtome (Leica Biosystems, Deer Park, IL, USA), and transferred to PALM membrane 1.0 PEN slides (Zeiss Microimaging, Munich, Germany). Slides were then stained with hematoxylin and eosin, and coated with Liquid Cover Glass N (Carl Zeiss, Germany). Gastric mucosa (GM), IM, DP, and gastric tumor (GT) cells were delineated using PALM Robosoftware (Zeiss Microimaging), cut out, and collected into 0.5-mL adhesive-cap tubes using a PALM LCM System (Zeiss Microimaging). Genomic DNA of the captured cells was isolated using QIAamp DNA Micro Kit (QIAGEN, Valencia, CA, USA) and its concentration was quantified using PicoGreen dsDNA Quantitation Kit (Molecular Probes, Eugene, OR, USA).