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World J Gastrointest Oncol. May 15, 2010; 2(5): 218-221
Published online May 15, 2010. doi: 10.4251/wjgo.v2.i5.218
Tumor stem cell, or its niche, which plays a primary role in tumorigenesis?
Jiang Zhu, Jin Ding, Fei Ding
Jiang Zhu, Jin Ding, Fei Ding, Shanghai Institute of Hematology, Rui-Jin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 20025, China
Author contributions: Zhu J conceived the idea and wrote the manuscript; Ding J and Ding F provided helpful discussions.
Correspondence to: Jiang Zhu, MD, Professor, Shanghai Institute of Hematology, Rui-Jin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 20025, China. zhujiang@shsmu.edu.cn
Telephone: +86-21-64370045 Fax: +86-21-64743206
Received: November 4, 2009
Revised: January 26, 2010
Accepted: February 2, 2010
Published online: May 15, 2010
Abstract

Cancer research over the past decades has focused on neoplastic cells, or a fraction of them, i.e. tumor stem cells, as the ultimate causes of tumorigenesis. However, during recent years, scientists have come to realize that tumorigenesis is not a solo act of neoplastic cells, but rather a cooperative process in which the roles of numerous types of non-neoplastic cells should be recognized. These tumor-residing non-neoplastic cells constitute the so-called tumor-associated stroma, which in certain cases even greatly surpasses the neoplastic cellular compartment that was previously thought of as a sole determiner leading to a seemingly autonomous growth pattern. In this review, we summarize several recent research highlights that have unveiled many previously unappreciated roles for microenvironmental factors, especially during the initiation stage of tumorigenesis. It is becoming increasingly clear that the stroma’s regulatory effects constitute not only an essential force for maintaining tumor growth, but also primary causes initiating tumorigenesis.

Keywords: Tumor stem cells, Stroma, Tumorigenesis, Initiation, Maintenance