School of Life Sciences, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Gwangju, 61005, Korea.
Immune Synapse and Cell Therapy Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea.
J Hematol Oncol. 2021 Mar 17;14(1):43. doi: 10.1186/s13045-021-01058-6.
Transgelin-2 is a 22 kDa actin-binding protein that has been proposed to act as an oncogenic factor, capable of contributing to tumorigenesis in a wide range of human malignancies. However, little is known whether this tiny protein also plays an important role in immunity, thereby keeping body from the cancer development and metastasis. Here, we investigated the functions of transgelin-2 in dendritic cell (DC) immunity. Further, we investigated whether the non-viral transduction of cell-permeable transgelin-2 peptide potentially enhance DC-based cancer immunotherapy.
To understand the functions of transgelin-2 in DCs, we utilized bone marrow-derived DCs (BMDCs) purified from transgelin-2 knockout (Tagln2) mice. To observe the dynamic cellular mechanism of transgelin-2, we utilized confocal microscopy and flow cytometry. To monitor DC migration and cognate T-DC interaction in vivo, we used intravital two-photon microscopy. For the solid and metastasis tumor models, OVA B16F10 melanoma were inoculated into the C57BL/6 mice via intravenously (i.v.) and subcutaneously (s.c.), respectively. OTI TCR T cells were used for the adoptive transfer experiments. Cell-permeable, de-ubiquitinated recombinant transgelin-2 was purified from Escherichia coli and applied for DC-based adoptive immunotherapy.
We found that transgelin-2 is remarkably expressed in BMDCs during maturation and lipopolysaccharide activation, suggesting that this protein plays a role in DC-based immunity. Although Tagln2 BMDCs exhibited no changes in maturation, they showed significant defects in their abilities to home to draining lymph nodes (LNs) and prime T cells to produce antigen-specific T cell clones, and these changes were associated with a failure to suppress tumor growth and metastasis of OVA B16F10 melanoma cells in mice. Tagln2 BMDCs had defects in filopodia-like membrane protrusion and podosome formation due to the attenuation of the signals that modulate actin remodeling in vitro and formed short, unstable contacts with cognate CD4 T cells in vivo. Strikingly, non-viral transduction of cell-permeable, de-ubiquitinated recombinant transgelin-2 potentiated DC functions to suppress tumor growth and metastasis.
This work demonstrates that transgelin-2 is an essential protein for both cancer and immunity. Therefore, transgelin-2 can act as a double-edged sword depending on how we apply this protein to cancer therapy. Engineering and clinical application of this protein may unveil a new era in DC-based cancer immunotherapy. Our findings indicate that cell-permeable transgelin-2 have a potential clinical value as a cancer immunotherapy based on DCs.
转凝胶蛋白-2 是一种 22kDa 的肌动蛋白结合蛋白，据推测它作为致癌因子，能够在多种人类恶性肿瘤中促进肿瘤发生。然而，人们对于这种微小蛋白是否在免疫中也发挥着重要作用，从而使机体免受癌症发展和转移，知之甚少。在这里，我们研究了转凝胶蛋白-2 在树突状细胞（DC）免疫中的功能。此外，我们还研究了细胞通透性转凝胶蛋白-2 肽的非病毒转导是否能增强基于 DC 的癌症免疫治疗。
为了了解转凝胶蛋白-2 在 DC 中的功能，我们利用从转凝胶蛋白-2 敲除（Tagln2）小鼠中纯化的骨髓来源的 DC（BMDC）。为了观察转凝胶蛋白-2 的动态细胞机制，我们利用共聚焦显微镜和流式细胞术。为了监测体内 DC 迁移和同源 T-DC 相互作用，我们使用活体双光子显微镜。对于实体瘤和转移瘤模型，OVA B16F10 黑色素瘤通过静脉（i.v.）和皮下（s.c.）分别接种到 C57BL/6 小鼠中。OTI TCR T 细胞用于过继转移实验。从大肠杆菌中纯化出细胞通透性、去泛素化的重组转凝胶蛋白-2，并用于基于 DC 的过继免疫治疗。
我们发现，转凝胶蛋白-2 在 BMDC 成熟和脂多糖激活过程中显著表达，提示该蛋白在基于 DC 的免疫中发挥作用。尽管 Tagln2 BMDC 在成熟过程中没有变化，但它们在归巢引流淋巴结（LNs）和激活 T 细胞产生抗原特异性 T 细胞克隆的能力上存在显著缺陷，这些变化与抑制 OVA B16F10 黑色素瘤细胞在小鼠中的生长和转移有关。Tagln2 BMDC 在体外调节肌动蛋白重塑的信号减弱，导致丝状伪足样膜突起和破骨细胞形成缺陷，在体内与同源 CD4 T 细胞形成短而不稳定的接触。引人注目的是，细胞通透性、去泛素化的重组转凝胶蛋白-2 的非病毒转导增强了 DC 的功能，从而抑制肿瘤生长和转移。
这项工作表明，转凝胶蛋白-2 是癌症和免疫的必需蛋白。因此，转凝胶蛋白-2 可以根据我们对癌症治疗的应用方式成为一把双刃剑。该蛋白的工程和临床应用可能会开启基于 DC 的癌症免疫治疗的新时代。我们的研究结果表明，细胞通透性转凝胶蛋白-2 具有作为基于 DC 的癌症免疫疗法的潜在临床价值。
