Plasma exosome microRNAs are indicative of breast cancer.
microRNAs are promising candidate breast cancer biomarkers due to their cancer-specific expression profiles. However, efforts to develop circulating breast cancer biomarkers are challenged by the heterogeneity of microRNAs in the blood. To overcome this challenge, we aimed to develop a molecular profile of microRNAs specifically secreted from breast cancer cells. Our first step towards this direction relates to capturing and analyzing the contents of exosomes, which are small secretory vesicles that selectively encapsulate microRNAs indicative of their cell of origin. To our knowledge, circulating exosome microRNAs have not been well-evaluated as biomarkers for breast cancer diagnosis or monitoring.



Exosomes were collected from the conditioned media of human breast cancer cell lines, mouse plasma of patient-derived orthotopic xenograft models (PDX), and human plasma samples. Exosomes were verified by electron microscopy, nanoparticle tracking analysis, and western blot. Cellular and exosome microRNAs from breast cancer cell lines were profiled by next-generation small RNA sequencing. Plasma exosome microRNA expression was analyzed by qRT-PCR analysis.



Small RNA sequencing and qRT-PCR analysis showed that several microRNAs are selectively encapsulated or highly enriched in breast cancer exosomes. Importantly, the selectively enriched exosome microRNA, human miR-1246, was detected at significantly higher levels in exosomes isolated from PDX mouse plasma, indicating that tumor exosome microRNAs are released into the circulation and can serve as plasma biomarkers for breast cancer. This observation was extended to human plasma samples where miR-1246 and miR-21 were detected at significantly higher levels in the plasma exosomes of 16 patients with breast cancer as compared to the plasma exosomes of healthy control subjects. Receiver operating characteristic curve analysis indicated that the combination of plasma exosome miR-1246 and miR-21 is a better indicator of breast cancer than their individual levels.



Our results demonstrate that certain microRNA species, such as miR-21 and miR-1246, are selectively enriched in human breast cancer exosomes and significantly elevated in the plasma of patients with breast cancer. These findings indicate a potential new strategy to selectively analyze plasma breast cancer microRNAs indicative of the presence of breast cancer.
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.|Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA.
Bethany N
BN
Hannafon
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
Yvonne D
YD
Trigoso
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
Cameron L
CL
Calloway
Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.|Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA.
Y Daniel
YD
Zhao
Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA.
David H
DH
Lum
Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, 84112, USA.
Alana L
AL
Welm
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.|Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA.
Zhizhuang J
ZJ
Zhao
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
Kenneth E
KE
Blick
Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.|Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA.
William C
WC
Dooley
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA. weiqun-ding@ouhsc.edu.|Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA. weiqun-ding@ouhsc.edu.
W Q
WQ
Ding
D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000378:metabolism; D004195:Disease Models, Animal; D055354:Exosomes / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D064593:Heterografts; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D012372:ROC Curve
D014408:Biomarkers, Tumor; D017077:Culture Media, Conditioned; D035683:MicroRNAs
Biomarker; Breast cancer; Exosomes; Patient-derived xenograft; microRNA