Oncotarget

Research Papers:

Biomolecular characterization of exosomes released from cancer stem cells: Possible implications for biomarker and treatment of cancer

Dhruv Kumar _, Dwijendra Gupta, Sharmila Shankar and Rakesh K. Srivastava

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Oncotarget. 2015; 6:3280-3291. https://doi.org/10.18632/oncotarget.2462

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Abstract

Dhruv Kumar1, Dwijendra Gupta2, Sharmila Shankar3, Rakesh K. Srivastava1

1Department of Pharmacology, Toxicology and Therapeutics, and Medicine, The University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS, 66160, USA

2Center of Bioinformatics and Department of Biochemistry, University of Allahabad, Allahabad, India

3Kansas City VA Medical Center, 4801 Linwood Boulevard, Kansas City, MO 64128, USA

Correspondence to:

Dr. Rakesh K. Srivastava, email: rsrivastava.lab@gmail.com

Dr. Sharmila Shankar, email: sharmila.shankar@va.gov

Keywords: CSCs, Rotenone, CD9, CD63, CD81, Alix, Atg7, LC3.

Abbreviations: Atg, Autophagy related gene; CSC, Cancer Stem Cell; DAPI, 4',6-diamidino-2-phenylindole; FBS, Fetal bovine serum; LC3, Microtubule-associated protein 1 light chain 3; miRNA, micro RNA

Received: July 03, 2014     Accepted: September 06, 2014     Published: September 17, 2014

ABSTRACT

Cancer recognized as one of the leading irrepressible health issues is contributing to increasing mortality-rate day-by-day. The tumor microenvironment is an important field of cancer to understand the detection, treatment and prevention of cancer. Recently, cancer stem cell (CSC) research has shown promising results aiming towards cancer diagnostics and treatment. Here, we found that prostate and breast cancer stem cells secreted vesicles of endosomal origin, called exosomes showed strong connection between autophagy and exosomes released from CSCs. Exosomes may serve as vesicles to communicate with neoplastic cells (autocrine and paracrine manner) and normal cells (paracrine and endocrine manner) and thereby suppress immune systems and regulate neoplastic growth, and metastasis. They can also be used as biomarkers for various cancers. We detected tetraspanin proteins (CD9, CD63, CD81), Alix and tumor susceptibility gene-101 (TSG101) of exosomal markers from rotenone treated CSCs. We have also detected the induction of autophagy genes, Atg7 and conversion of autophagy marker (LC3-I to LC3-II), and tetraspanin proteins (CD9, CD63, CD81) in rotenone treated CSCs by western blotting. The mRNA expression of CD9, CD63, CD81 and TSG101 analyzed by qRT-PCR showed that the rotenone induced the expression of CD9, CD63, CD81 and TSG101 in CSCs. Electron microscopy of rotenone treated CSCs showed the mitochondrial damage of CSCs as confirmed by the release of exosomes from CSCs. The constituents of exosomes may be useful to understand the mechanism of exosomes formation, release and function, and also serve as a useful biomarker and provide novel therapeutic strategies for the treatment and prevention of cancer.


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