Abstract 4899: Surface marker screening revealed the marker distinguishes gastric cancer stem cells in CD44 negative population.

Abstract

Abstract Background: Gastric cancer (GC) is the second leading cause of cancer-related deaths in the world. Reportedly, cancer tissue is maintained by a small fraction of cancer cells called cancer stem cells (CSCs). CSCs are considered to initiate therapy resistance, recurrence and metastasis. Although several reports have shown that GC is maintained by CSCs, detailed mechanism of gastric CSCs (GCSCs) maintenance is unclear. It has been shown that high aldehyde dehydrogenase (ALDH) activity is one of the markers for GCSCs by several groups including us. To elucidate the molecular mechanism which regulate GCSCs, we performed screening to identify the novel marker which is able to distinguish GSCSs with high specificity. Materials and methods: We performed flowcytometric screening of 8 common CSC markers (CD44, CD133, EpCAM, CD90, CD13, CD117 and ALDH) for 6 GC cell lines (MKN45, AGS, GSU, NUGC3, MKN1 and MKN7). Fresh surgically removed GC specimens were obtained with informed patient consent. To obtain xenograft, tissues were dissociated with mechanical and enzymatic digestion, filtered to remove clumps, and injected subcutaneously to flank of NOD/SCID mice. Cells were stain with ALDEFLUOR assay kit for 45 minutes at 37°C detection of ALDH activity. Result: Among 8 common CSC makers tested, we decided to focus on ALDH activity because the cell populations with high ALDH activities (ALDHhigh cells) were detected in the most of the cell lines and the fresh tumor tested. ALDHhigh cells showed higher ability of sphere formation, tumorigenicity in NOD/SCID mice, and chemoresistance. Notch1, a critical regulator in maintenance of normal gastric stem/progenitor cell, was highly expressed in ALDHhigh cells. We identified several cell surface markers in the course of searching for markers selectively overexpressed in ALDHhigh cells of GC xenograft. By staining GC cells with several markers including CD44, GCSCs in CD44- fraction became distinguishable. Expression of the several surface markers was highly increased after treatment of chemotherapeutic agents. Our data suggest that the cell populations distinguished by CD44 are heterogenous in terms of chemoresistance and tumorigenicity. Conlcusion: High ALDH activity is a marker for GCSCs and analysis of ALDH high cells revealed that fresh gastric cancer samples contain CD44- gastric cancer stem cells. Citation Format: Shimpei Nishikawa, Hideshi Ishii, Masamitsu Konno, Naotsugu Haraguchi, Yoshihiro Kano, Atsushi Hamabe, Shinichiro Hasegawa, Hisataka Ogawa, Takahito Fukusumi, Katsuya Ohta, Toshihiro Kudo, Daisuke Sakai, Shuji Takiguchi, Taroh Satoh, Masaki Mori, Yuichiro Doki. Surface marker screening revealed the marker distinguishes gastric cancer stem cells in CD44 negative population. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4899. doi:10.1158/1538-7445.AM2013-4899