Two-stage induced differentiation of OCT4+/Nanog+ stem-like cells in lung adenocarcinoma
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Rong Li1,*, Jinsu Huang1,*, Meili Ma1, Yuqing Lou1, Yanwei Zhang1, Lixia Wu2, David W. Chang3, Picheng Zhao4, Qianggang Dong2, Xifeng Wu3, Baohui Han1
1Department of Pulmonary Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, China
2Cancer Stem Cells Research Group, Shanghai Jiaotong University Cancer Institute, Shanghai 200032, China
3Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
4Department of Pathology and Genomic Medicine, Houston Methodist Hospital Research Institute, Houston, Texas 77030, USA
*Rong Li and Jinsu Huang contributed equally to this work as the first author
Baohui Han, email: firstname.lastname@example.org
Keywords: cancer stem cell, differentiation, lung adenocarcinoma, vitamin D, OCT4
Received: June 15, 2015 Accepted: August 20, 2016 Published: August 31, 2016
Stem-like cells in solid tumors are purported to contribute to cancer development and poor treatment outcome. The abilities to self-renew, differentiate, and resist anticancer therapies are hallmarks of these rare cells, and steering them into lineage commitment may be one strategy to curb cancer development or progression. Vitamin D is a prohormone that can alter cell growth and differentiation and may induce the differentiation cancer stem-like cells. In this study, octamer-binding transcription factor 4 (OCT4)-positive/Nanog homeobox (Nanog)- positive lung adenocarcinoma stem-like cells (LACSCs) were enriched from spheroid cultured SPC-A1 cells and differentiated by a two-stage induction (TSI) method, which involved knockdown of hypoxia-inducible factor 1-alpha (HIF1α) expression (first stage) followed by sequential induction with 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3, VD3) and suberoylanilide hydroxamic acid (SAHA) treatment (second stage). The results showed the HIF1α-knockdowned cells displayed diminished cell invasion and clonogenic activities. Moreover, the TSI cells highly expressed tumor suppressor protein p63 (P63) and forkhead box J1 (FOXJ1) and lost stem cell characteristics, including absent expression of OCT4 and Nanog. These cells regained sensitivity to cisplatin in vitro while losing tumorigenic capacity and decreased tumor cell proliferation in vivo. Our results suggest that induced transdifferentiation of LACSCs by vitamin D and SAHA may become novel therapeutic avenue to alter tumor cell phenotypes and improve patient outcome.
The development and progression of lung cancer may involve rare population of stem-like cells that have the ability to grow, differentiate, and resist drug treatment. However, current therapeutic strategies have mostly focused on tumor characteristics and neglected the potential source of cells that may contribute to poor clinical outcome. We generated lung adenocarcinoma stem-like cells from spheroid culture and induced their transdifferentiation by a two-stage method of knocking down HIF1α expression followed by vitamin Dand suberoylanilide hydroxamic acid (VD3/SAHA) treatment. We observed the induced cells lost stem-like characteristics, regained sensitivity to cisplatin, and displayed reduced tumorigenic capacity. These findings suggest that targeting stem-like cells by reverting them to more specialized state may be an approach to treat lung cancer.
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