Prostate Cancer Discovery and Development Program, Thomas Jefferson University, Philadelphia, PA 19107, U.S.A.
Department of Cancer Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, U.S.A.
Biochem J. 2021 Nov 12;478(21):3905-3921. doi: 10.1042/BCJ20210580.
We have previously shown that the αvβ6 integrin plays a key role in promoting prostate cancer (PrCa) and it can be transferred to recipient cells via small extracellular vesicles (sEVs). Furthermore, we have reported in a proteomic analysis that αvβ6 integrin down-regulation increases the expression of IFIT3 (interferon induced protein with tetratricopeptide repeats 3) in PrCa cells and their derived sEVs. IFIT3 is a protein well known for being an antiviral effector, but recently its role in cancer has also been elucidated. To study the relationship between IFIT3 and STAT1 (signal transducer and activator of transcription 1), an upstream regulator of IFIT3, in PrCa cells and their released sEVs, we used CRISPR/Cas9 techniques to down-regulate the expression of the β6 integrin subunit, IFIT3 or STAT1. Our results show that IFIT3 and STAT1 are highly expressed in PrCa cells devoid of the β6 integrin subunit. However, IFIT3 but not STAT1, is present in sEVs derived from PrCa cells lacking the β6 integrin subunit. We demonstrate that loss of IFIT3 generates sEVs enriched in STAT1 but reduces the levels of STAT1 in the cells. As expected, IFIT3 is not detectable in STAT1 negative cells or sEVs. We thus propose that the observed STAT1 enrichment in sEVs is a compensatory mechanism for the loss of IFIT3. Overall, these results provide new insights into the intrinsic role of IFIT3 as a regulator of STAT1 expression in sEVs and in intercellular communication in PrCa.
我们之前已经表明，αvβ6 整合素在促进前列腺癌（PrCa）中起着关键作用，并且它可以通过小细胞外囊泡（sEVs）转移到受体细胞。此外，我们在蛋白质组学分析中报告说，αvβ6 整合素的下调会增加 PrCa 细胞及其衍生的 sEVs 中 IFIT3（干扰素诱导的具有四肽重复的蛋白 3）的表达。IFIT3 是一种众所周知的抗病毒效应蛋白，但最近其在癌症中的作用也已阐明。为了研究 IFIT3 与 STAT1（信号转导和转录激活因子 1）之间的关系，这是 IFIT3 的上游调节剂，在 PrCa 细胞及其释放的 sEVs 中，我们使用 CRISPR/Cas9 技术下调β6 整合素亚基、IFIT3 或 STAT1 的表达。我们的结果表明，IFIT3 和 STAT1 在缺乏β6 整合素亚基的 PrCa 细胞中高度表达。然而，IFIT3 而不是 STAT1，存在于缺乏β6 整合素亚基的 PrCa 细胞衍生的 sEVs 中。我们证明，IFIT3 的缺失会产生富含 STAT1 的 sEVs，但会降低细胞中 STAT1 的水平。正如预期的那样，IFIT3 在 STAT1 阴性细胞或 sEVs 中不可检测到。因此，我们提出观察到的 STAT1 在 sEVs 中的富集是 IFIT3 缺失的补偿机制。总的来说，这些结果为 IFIT3 作为 sEVs 中 STAT1 表达的调节剂以及 PrCa 中细胞间通讯的内在作用提供了新的见解。
