Department of Biomedical Sciences, Division of Medical Life Sciences, Hirosaki University School of Health Sciences, Hirosaki, Aomori 036-8564, Japan.
Oncol Rep. 2012 Nov;28(5):1551-8. doi: 10.3892/or.2012.1967. Epub 2012 Aug 10.
Exosomes are microvesicles that are released from various cells into the extracellular space. It has been reported that the components within exosomes vary according to the type of secreted cell. In the present study, we investigated the tetraspanin family proteins CD63, CD9 and CD81 as useful collection markers of exosomes derived from the three colorectal cancer (CRC) cell lines HCT-15, SW480 and WiDr. In addition, we aimed to detect the mRNAs, microRNAs and natural antisense RNAs within the exosomes secreted from the three CRC cell lines. Furthermore, we examined whether exosomes containing their RNAs were transferred into the hepatoma cell line HepG2 and lung cancer cell line A549. CD81 was detected in exosomes secreted from the three CRC cell lines. This result indicates that CD81 can be a collection marker of exosomes derived from the three CRC cell lines. When the RNA species within exosomes derived from the three CRC cell lines were examined, the mRNAs of housekeeping genes such as ACTB and GAPDH, the microRNAs such as miR-21, miR-192 and miR-221, and the natural antisense RNAs of LRRC24, MDM2 and CDKN1A genes, were detected. We discovered their natural antisense RNAs within exosomes for the first time in the present study. Furthermore, PKH67-labeled exosomes derived from the CRC cell lines were taken up into HepG2 and A549 cells. These findings indicate that the intracellular RNAs enclosed within exosomes are secreted to the outside, and exosomes derived from the CRC cell lines are transferred into HepG2 and A549 cells. In conclusion, we reveal that exosomes derived from the CRC cell lines contain mRNAs, microRNAs and natural antisense RNAs, and can be delivered into HepG2 and A549 cells. These findings indicate that exosomal RNAs can shuttle between cells, and may be involved in the regulation of gene expression in recipient cells.
外泌体是从各种细胞释放到细胞外空间的微囊泡。据报道，外泌体中的成分根据分泌细胞的类型而有所不同。在本研究中，我们研究了四跨膜蛋白家族蛋白 CD63、CD9 和 CD81 作为三种结直肠癌（CRC）细胞系 HCT-15、SW480 和 WiDr 来源的外泌体的有用收集标记物。此外，我们旨在检测三种 CRC 细胞系分泌的外泌体中的 mRNAs、microRNAs 和天然反义 RNA。此外，我们检查了含有其 RNA 的外泌体是否转移到肝癌细胞系 HepG2 和肺癌细胞系 A549 中。在三种 CRC 细胞系分泌的外泌体中检测到 CD81。这一结果表明 CD81 可以作为三种 CRC 细胞系来源的外泌体的收集标记物。当检查三种 CRC 细胞系来源的外泌体中的 RNA 种类时，检测到管家基因如 ACTB 和 GAPDH 的 mRNAs、miR-21、miR-192 和 miR-221 等 microRNAs 以及 LRRC24、MDM2 和 CDKN1A 基因的天然反义 RNA。我们首次在本研究中发现了它们的外泌体中的天然反义 RNA。此外，PKH67 标记的来自 CRC 细胞系的外泌体被摄取到 HepG2 和 A549 细胞中。这些发现表明，外泌体中包含的细胞内 RNA 被分泌到细胞外，并且来自 CRC 细胞系的外泌体被转移到 HepG2 和 A549 细胞中。总之，我们揭示了来自 CRC 细胞系的外泌体含有 mRNAs、microRNAs 和天然反义 RNA，并且可以递送到 HepG2 和 A549 细胞中。这些发现表明外泌体 RNA 可以在细胞之间穿梭，并且可能参与受体内基因表达的调控。
