Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
Chronic Kidney Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
Life Sci. 2020 Oct 1;258:118094. doi: 10.1016/j.lfs.2020.118094. Epub 2020 Jul 13.
Docosahexaenoic acid (DHA) as an omega 3 free fatty acid has been reported to exert anti-angiogenesis effects. However, our current understanding regarding the precise mechanisms of such effects is still limited. Exosomes secreted by cancer cells may act as angiogenesis promoters. The aim of the study was to determine altered expression levels of HIF-1α, TGF-β, VEGFR, Snail1, Snail2 and SOX2 and their regulating microRNAs in MDA-MB-231 and BT-474 cell lines after treatment with DHA in both normoxic and hypoxic conditions.
Human breast cancer cell lines including MDA-MB-231 and BT-474 were treated for 24 h with 100 uM DHA under normoxic and hypoxic conditions. Exosomes were isolated from untreated and treated cells and characterized by transmission electron microscopy (TEM) and western blotting. RNAs from cells and isolated exosomes were extracted and cDNAs were synthesized. Expression levels of miRNAs and their pro-angiogenic target genes were analyzed using quantitative real-time PCR (qRT-PCR).
We showed significant decrease in the expression of pro-angiogenic genes including HIF1-α, TGF-β, SOX2, Snail1, Snail2 and VEGFR in cells and also their secreted exosomes after treatment with DHA in normoxic and hypoxic conditions. Also the expression levels of tumor suppressor miRs including miR-101, miR-199, miR-342 were increased and the expression levels of oncomiRs including mir-382 and miR-21 were decreased after treatment with DHA in cells and exosomes.
DHA can alter the expression of pro-angiogenic genes and microRNA contents in breast cancer cells and their derived-exosomes in favor of the inhibition of angiogenesis. Our data demonstrated new insight into DHA's anti-cancer action to target not only breast cancer cells but also their derived exosomes to suppress tumor angiogenesis.
二十二碳六烯酸（DHA）作为一种ω-3 游离脂肪酸，已被报道具有抗血管生成作用。然而，我们目前对这种作用的确切机制的理解仍然有限。癌细胞分泌的外泌体可能作为血管生成促进剂。本研究的目的是确定在常氧和缺氧条件下，DHA 处理 MDA-MB-231 和 BT-474 细胞系后，HIF-1α、TGF-β、VEGFR、Snail1、Snail2 和 SOX2 的表达水平及其调节 microRNA 的变化。
用 100 uM DHA 在常氧和缺氧条件下处理人乳腺癌细胞系 MDA-MB-231 和 BT-474 24 小时。用透射电子显微镜（TEM）和 Western blot 法分离未经处理和处理过的细胞的外泌体并进行鉴定。从细胞和分离的外泌体中提取 RNA 并合成 cDNA。用实时定量 PCR（qRT-PCR）分析 miRNA 和其促血管生成靶基因的表达水平。
我们发现，在常氧和缺氧条件下，DHA 处理后，细胞及其分泌的外泌体中促血管生成基因（包括 HIF1-α、TGF-β、SOX2、Snail1、Snail2 和 VEGFR）的表达显著降低。此外，在细胞和外泌体中，肿瘤抑制 microRNA，如 miR-101、miR-199、miR-342 的表达水平增加，而致癌 microRNA，如 miR-382 和 miR-21 的表达水平降低。
DHA 可以改变乳腺癌细胞及其衍生外泌体中促血管生成基因和 microRNA 含量的表达，有利于抑制血管生成。我们的数据为 DHA 的抗癌作用提供了新的见解，不仅可以靶向乳腺癌细胞，还可以靶向其衍生的外泌体，以抑制肿瘤血管生成。
