Department of Orthopedics, Τhe First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China.
Department of Orthopedics, The Second Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China.
Int J Mol Med. 2018 Apr;41(4):1845-1854. doi: 10.3892/ijmm.2018.3433. Epub 2018 Jan 29.
Honokiol (HNK) is a small biphenolic compound, which exerts antineoplastic effects in various types of cancer. However, the mechanism underlying the antitumor effects of HNK in osteosarcoma (OS) cells is not yet fully understood. Emerging evidence has indicated that microRNAs (miRNAs/miRs) serve key roles in numerous pathological processes, including cancer. It has previously been reported that Chinese medicinal herbs harbor anticancer properties via modulating miRNA expression. Therefore, the present study aimed to determine whether HNK could suppress OS cell growth by regulating miRNA expression. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis were used to evaluate the cell proliferation and apoptosis in human OS cells after treatment with HNK, respectively. The results demonstrated that HNK inhibits proliferation and induces apoptosis of human OS cells in a dose‑dependent manner. Furthermore, HNK‑induced apoptosis was characterized by upregulation of proapoptotic proteins, including cleaved‑caspase‑3, cleaved‑poly (ADP‑ribose) polymerase and B‑cell lymphoma 2 (Bcl‑2)‑associated X protein, and downregulation of the anti‑apoptotic protein Bcl‑2. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) verified that HNK was able to induce aberrant expression of miRNAs in human OS cells, and miR‑21 was one of the miRNAs that was most significantly downregulated. To further investigate miR‑21 function, the present study validated that HNK reduces miR‑21 levels in a dose‑dependent manner. In addition, restoration of miR‑21 expression abrogated the suppressive effects of HNK on OS cells. Luciferase assay and western blot analysis identified that miR‑21 inhibits the expression of phosphatase and tensin homolog (PTEN) by directly targeting its 3'-UTR. Notably, HNK was able to suppress the phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT) signaling pathway; however, it was reactivated by miR‑21 overexpression. Taken together, these data indicated that HNK may inhibit proliferation and induce apoptosis of human OS cells by modulating the miR‑21/PTEN/PI3K/AKT signaling pathway. Therefore, miR‑21 may be considered a potential therapeutic target for the treatment of osteosarcoma with HNK.
和厚朴酚（HNK）是一种小分子双酚化合物，它在多种类型的癌症中具有抗肿瘤作用。然而，HNK 对骨肉瘤（OS）细胞的抗肿瘤作用的机制尚不完全清楚。新出现的证据表明，microRNAs（miRNAs/miRs）在包括癌症在内的许多病理过程中发挥关键作用。先前有报道称，中草药通过调节 miRNA 表达具有抗癌特性。因此，本研究旨在确定 HNK 是否可以通过调节 miRNA 表达来抑制 OS 细胞的生长。使用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）测定法和流式细胞术分析分别评估 HNK 处理后人类 OS 细胞的细胞增殖和细胞凋亡。结果表明，HNK 以剂量依赖性方式抑制人骨肉瘤细胞的增殖并诱导其凋亡。此外，HNK 诱导的细胞凋亡的特征是促凋亡蛋白，包括 cleaved-caspase-3、cleaved-poly（ADP-ribose）polymerase 和 B 细胞淋巴瘤 2（Bcl-2）相关 X 蛋白的上调，以及抗凋亡蛋白 Bcl-2 的下调。逆转录-定量聚合酶链反应（RT-qPCR）验证了 HNK 能够诱导人骨肉瘤细胞中 miRNA 的异常表达，并且 miR-21 是下调最显著的 miRNA 之一。为了进一步研究 miR-21 的功能，本研究验证了 HNK 以剂量依赖性方式降低 miR-21 水平。此外，恢复 miR-21 的表达可消除 HNK 对 OS 细胞的抑制作用。荧光素酶测定和 Western blot 分析表明，miR-21 通过直接靶向其 3'-UTR 抑制磷酸酶和张力蛋白同源物（PTEN）的表达。值得注意的是，HNK 能够抑制磷酸肌醇 3-激酶（PI3K）/蛋白激酶 B（AKT）信号通路；然而，miR-21 的过表达使其重新激活。综上所述，这些数据表明，HNK 可能通过调节 miR-21/PTEN/PI3K/AKT 信号通路抑制人骨肉瘤细胞的增殖并诱导其凋亡。因此，miR-21 可能被认为是用 HNK 治疗骨肉瘤的潜在治疗靶点。
