Department of Clinical Laboratory and Molecular Biology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China.
Oncol Rep. 2021 Apr;45(4). doi: 10.3892/or.2021.7958. Epub 2021 Mar 2.
The cell surface glycoprotein CD44 displays different active statuses; however, it remains unknown whether the activation process of CD44 is critical for tumor development and progression. The aim of the present study was to investigate whether breast cancer (BCa) cells with different activation states of CD44 show similar or distinct functional characteristics and to further examine the mechanisms regulating CD44 activities. A feature for the 'activated' state of CD44 is that it can bind to its principal ligand hyaluronan (HA). The binding of CD44 with HA is usually influenced by CD44 alternative splicing, resulting in multiple CD44 isoforms that determine CD44 activities. Flow cytometry was used to sort BCa cell subsets based on CD44‑HA binding abilities (HA vs. HA). Subsequently, cell proliferation and colony formation assays were performed , and CD44 expression patterns were analyzed via western blotting. The results demonstrated that the CD44 variant isoform 10 (CD44v10) was highly expressed in a HA binding subset of BCa cells, which exhibited a significantly higher proliferation capacity compared with the HA binding subpopulation. Knockdown of CD44v10 isoform in HA binding subpopulation induced an increase in HA binding ability and markedly inhibited proliferation. Furthermore, the mechanistic analysis identified that CD44v10 facilitated cell proliferation via activation of ERK/p38 MAPK and AKT/mTOR signaling. Moreover, the knockdown of CD44v10 expression downregulated the phosphorylation of ERK, AKT and mTOR, while no alteration was observed in p38 phosphorylation. Collectively, the present study identified a subset of fast‑growing BCa cells characterized by CD44v10 expression, which may serve as a specific therapeutic target for BCa.
细胞表面糖蛋白 CD44 呈现不同的活性状态；然而，CD44 的激活过程是否对肿瘤的发生和发展至关重要仍不清楚。本研究旨在探讨具有不同 CD44 激活状态的乳腺癌（BCa）细胞是否表现出相似或不同的功能特征，并进一步研究调节 CD44 活性的机制。CD44 处于“激活”状态的一个特征是它可以与主要配体透明质酸（HA）结合。CD44 与 HA 的结合通常受 CD44 选择性剪接的影响，导致决定 CD44 活性的多种 CD44 同工型。本研究采用流式细胞术根据 CD44-HA 结合能力（HA vs. HA）对 BCa 细胞亚群进行分选。随后，进行细胞增殖和集落形成实验，并通过 Western blot 分析 CD44 表达模式。结果表明，CD44 变体 10 异构体（CD44v10）在 BCa 细胞中高表达，与 HA 结合亚群相比，该亚群具有更高的增殖能力。在 HA 结合亚群中敲低 CD44v10 异构体可增加 HA 结合能力，并显著抑制增殖。此外，机制分析表明，CD44v10 通过激活 ERK/p38 MAPK 和 AKT/mTOR 信号通路促进细胞增殖。此外，敲低 CD44v10 表达可下调 ERK、AKT 和 mTOR 的磷酸化，但 p38 磷酸化无变化。综上所述，本研究鉴定了具有 CD44v10 表达特征的快速生长的 BCa 细胞亚群，这可能成为 BCa 的特定治疗靶点。
