Exosomes from Bone Marrow Mesenchymal Stem Cells Contain a MicroRNA that Promotes Dormancy in Metastatic Breast Cancer Cells

Makiko Ono, Nobuyoshi Kosaka, Naoomi Tominaga, Yusuke Yoshioka, Fumitaka Takeshita, Ryou-u Takahashi, Masayuki Yoshida, Hitoshi Tsuda, Kenji Tamura, Takahiro Ochiya.

Sci Signal. 2014; 7: 332-ra63

Speaker: Ming-Che, Tsai (蔡明哲)                              Time: 13:00~14:00, Mar 18, 2015

Commentator: Dr. Hsiao-Sheng Liu (劉校生 博士)    Place: Room 601

Abstract:

Breast cancer is one of the most common cancers in the world; in 2012 alone it resulted in about 1.68 million cases and 52.2 thousands deaths. Although the mortality of this disease has been decreased due to early detection surgery and chemotherapy, however, there are some patients that still have tumor regrowth after treatments. This phenomenon implies there are some breast cancer cells which may survive somewhere in the body and may turn into a quiescent state for a very long time causing cancer dormancy, while waiting for the appropriate environmental situation to reemerge again. Clinical reports showed that disseminated breast cancer cells can be detected in the bone marrow (BM) during early stages of breast cancer and is a strong prognostic factor. Bone marrow mesenchymal stem cells (BM-MSCs) is known to be one of the stem cell niches of regulating hematopoietic stem cells, it is thought that cancer stem cells (CSCs) may originate form a niche similar to that of hematopoietic stem cells; indeed, some reports have demonstrated the existence of niche-regulating CSCs.¹ In this study, the author demonstrated that the exosomes from BM-MSCs which contained miR-23b were taken up by established human breast cancer cell line (BM2), resulting in a observed cell cycle regulation decrease by changes in MARCKS gene expression of BM2 cells.² In conclusion, the author showed how cancer cells maintain a dormant state before cancer recurrence, with this finding it is suggested that targeting molecules secreted through exosomes from metastatic niches may prevent or delay cancer recurrence.

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