Laboratory of Pharmacoimmunology, Integrated Research Institute of Pharmaceutical Sciences and BK21 FOUR Team for Advanced Program for SmartPharma Leaders, College of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Bucheon-si, Gyeonggi-do 14662, Republic of Korea.
Laboratory of Pharmacoimmunology, Integrated Research Institute of Pharmaceutical Sciences and BK21 FOUR Team for Advanced Program for SmartPharma Leaders, College of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Bucheon-si, Gyeonggi-do 14662, Republic of Korea.
Life Sci. 2023 May 1;320:121559. doi: 10.1016/j.lfs.2023.121559. Epub 2023 Mar 8.
In this study, we investigated the inhibition of IL-2 activity and anticancer efficacy of chelerythrine (CHE), a natural small molecule that targets IL-2 and inhibits CD25 binding, and elucidated the mechanism underlying the action of CHE on immune cells.
CHE was discovered by competitive binding ELISA and SPR analysis. The effect of CHE on IL-2 activity was evaluated in CTLL-2, HEK-Blue reporter and immune cells, and in ex vivo generation of regulatory T cells (Treg cells). The antitumor activity of CHE was evaluated in B16F10 tumor-bearing C57BL/6 or BALB/c nude mice.
We identified that CHE, which acts as an IL-2 inhibitor, selectively inhibits the interaction between IL-2 and IL-2Rα and directly binds to IL-2. CHE inhibited the proliferation and signaling of CTLL-2 cells and suppressed IL-2 activity in HEK-Blue reporter and immune cells. CHE prevented the conversion of naive CD4 T cells into CD4CD25Foxp3 Treg cells in response to IL-2. CHE reduced tumor growth in C57BL/6 mice but not in T-cell-deficient mice, upregulated the expression of IFN-γ and cytotoxic molecules, and limited Foxp3 expression. Furthermore, the combination of CHE and a PD-1 inhibitor synergistically increased antitumor activity in melanoma-bearing mice and almost completely regressed the implanted tumors.
We found that CHE, which targets IL-2 and inhibits its binding to CD25, exhibits T cell-mediated antitumor activity and that combination therapy with CHE and PD-1 inhibitor induced synergistic antitumor effects, suggesting that CHE may be a promising anticancer agent for melanoma monotherapy and combination therapy.
在这项研究中，我们研究了白屈菜红碱（CHE）对白细胞介素-2（IL-2）活性的抑制作用及其抗癌功效， CHE 是一种靶向 IL-2 并抑制 CD25 结合的天然小分子，并阐明了 CHE 对免疫细胞作用的机制。
通过竞争性结合 ELISA 和 SPR 分析发现 CHE。通过 CHE 在 CTLL-2、HEK-Blue 报告细胞和免疫细胞中的作用，以及体外调节性 T 细胞（Treg 细胞）的生成，评估 CHE 对 IL-2 活性的影响。通过 B16F10 荷瘤 C57BL/6 或 BALB/c 裸鼠评估 CHE 的抗肿瘤活性。
我们发现 CHE 作为 IL-2 抑制剂，选择性抑制 IL-2 与 IL-2Rα 的相互作用，并直接与 IL-2 结合。CHE 抑制 CTLL-2 细胞的增殖和信号转导，抑制 HEK-Blue 报告细胞和免疫细胞中的 IL-2 活性。CHE 阻止了幼稚 CD4 T 细胞在 IL-2 刺激下向 CD4CD25Foxp3 Treg 细胞的转化。CHE 减少了 C57BL/6 小鼠的肿瘤生长，但在 T 细胞缺陷小鼠中没有减少，增加了 IFN-γ 和细胞毒性分子的表达，并限制了 Foxp3 的表达。此外，CHE 与 PD-1 抑制剂联合使用在荷瘤小鼠中协同增强了抗肿瘤活性，并几乎完全消退了植入的肿瘤。
我们发现靶向 IL-2 并抑制其与 CD25 结合的 CHE 具有 T 细胞介导的抗肿瘤活性，并且 CHE 与 PD-1 抑制剂的联合治疗诱导了协同的抗肿瘤作用，这表明 CHE 可能是治疗黑色素瘤的一种有前途的单药和联合治疗药物。
