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Proc Natl Acad Sci U S A. 2017 Jul 18;114(29):E5930-E5939. doi: 10.1073/pnas.1705206114. Epub 2017 Jul 6.

BRAFV600 inhibition alters the microRNA cargo in the vesicular secretome of malignant melanoma cells.

Author information

1
Krefting Research Center, Department of Internal Medicine and Clinical Nutrition, University of Gothenburg, Gothenburg 405 30, Sweden.
2
Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia.
3
Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC 3010, Australia.
4
Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden.
5
Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, 790-784, Republic of Korea.
6
Krefting Research Center, Department of Internal Medicine and Clinical Nutrition, University of Gothenburg, Gothenburg 405 30, Sweden; jan.lotvall@gu.se.
7
Codiak BioSciences, Cambridge, MA 02139.

Abstract

The BRAF inhibitors vemurafenib and dabrafenib can be used to treat patients with metastatic melanomas harboring BRAFV600 mutations. Initial antitumoral responses are often seen, but drug-resistant clones with reactivation of the MEK-ERK pathway soon appear. Recently, the secretome of tumor-derived extracellular vesicles (EVs) has been ascribed important functions in cancers. To elucidate the possible functions of EVs in BRAF-mutant melanoma, we determined the RNA content of the EVs, including apoptotic bodies, microvesicles, and exosomes, released from such cancer cells after vemurafenib treatment. We found that vemurafenib significantly increased the total RNA and protein content of the released EVs and caused significant changes in the RNA profiles. RNA sequencing and quantitative PCR show that cells and EVs from vemurafenib-treated cell cultures and tumor tissues harvested from cell-derived and patient-derived xenografts harbor unique miRNAs, especially increased expression of miR-211-5p. Mechanistically, the expression of miR-211-5p as a result of BRAF inhibition was induced by increased expression of MITF that regulates the TRPM1 gene resulting in activation of the survival pathway. In addition, transfection of miR-211 in melanoma cells reduced the sensitivity to vemurafenib treatment, whereas miR-211-5p inhibition in a vemurafenib resistant cell line affected the proliferation negatively. Taken together, our results show that vemurafenib treatment induces miR-211-5p up-regulation in melanoma cells both in vitro and in vivo, as well as in subsets of EVs, suggesting that EVs may provide a tool to understand malignant melanoma progression.

KEYWORDS:

cancer; extracellular vesicles; noncoding RNAs; small RNAs

PMID:
28684402
PMCID:
PMC5530690
DOI:
10.1073/pnas.1705206114
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Conflict of interest statement: J.L. has written several patents in the field of extracellular vesicles as therapeutics and is currently an employee of Codiak BioSciences, in parallel with his position at the University of Gothenburg. R.O.B. has received honoraria from Roche for lectures.

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