Department of Pathology, Case Western Reserve University, Cleveland, Ohio.
Pediatric Hematology and Oncology, The Angie Fowler Adolescent & Young Adult Cancer Institute, University Hospitals Rainbow Babies & Children's Hospital, Cleveland, Ohio.
Cancer Res Commun. 2023 May 5;3(5):793-806. doi: 10.1158/2767-9764.CRC-22-0497. eCollection 2023 May.
Natural killer (NK) cells are innate lymphocytes with cytotoxic activity. Understanding the factors regulating cytotoxicity is crucial for improving NK-cell adoptive therapies. Here, we studied a previously unknown role of p35 (CDK5R1), a coactivator of cyclin-dependent kinase 5 (CDK5) in NK-cell function. p35 expression was thought to be neuronal-specific and the majority of studies are still focused on neuronal cells. Here, we show that CDK5 and p35 are expressed in NK cells and are kinase-active. NK cells from p35 knockout mice were analyzed and showed significantly increased cytotoxicity against murine cancer cells, while they did not show any differences in cell numbers or maturation stages. We confirmed this using human NK cells transduced with p35 short hairpin RNA (shRNA), showing similar increase in cytotoxicity against human cancer cells. Overexpression of p35 in NK cells resulted in moderate decrease in cytotoxicity, while expressing a kinase-dead mutant of CDK5 displayed increased cytotoxicity. Together, these data suggest that p35 negatively regulates NK-cell cytotoxicity. Surprisingly, we found that TGFβ, a known negative regulator of NK-cell cytotoxicity, induces p35 expression in NK cells. NK cells cultured with TGFβ exhibit reduced cytotoxicity, while NK cells transduced with p35 shRNA or mutant CDK5 expression exhibited partial reversal of this inhibitory effect pointing to an interesting hypothesis that p35 plays an important role in TGFβ-mediated NK-cell exhaustion.
This study reports a role for p35 in NK-cell cytotoxicity and this might help to improve NK-cell adoptive therapy.
自然杀伤 (NK) 细胞是具有细胞毒性的先天淋巴细胞。了解调节细胞毒性的因素对于改善 NK 细胞过继疗法至关重要。在这里，我们研究了 p35（CDK5R1）的一个先前未知的作用，p35 是周期蛋白依赖性激酶 5 (CDK5) 的共激活因子，在 NK 细胞功能中起作用。p35 的表达被认为是神经元特异性的，大多数研究仍集中在神经元细胞上。在这里，我们表明 CDK5 和 p35 在 NK 细胞中表达，并且是激酶活性的。分析 p35 敲除小鼠的 NK 细胞显示对鼠癌细胞的细胞毒性显著增加，而它们在细胞数量或成熟阶段没有任何差异。我们使用转导了 p35 短发夹 RNA (shRNA) 的人 NK 细胞证实了这一点，显示对人癌细胞的细胞毒性相似增加。在 NK 细胞中过表达 p35 导致细胞毒性适度降低，而表达 CDK5 的激酶失活突变体则显示出增加的细胞毒性。总的来说，这些数据表明 p35 负调节 NK 细胞的细胞毒性。令人惊讶的是，我们发现 TGFβ，一种已知的 NK 细胞细胞毒性的负调节剂，在 NK 细胞中诱导 p35 的表达。用 TGFβ 培养的 NK 细胞表现出降低的细胞毒性，而转导了 p35 shRNA 或突变 CDK5 表达的 NK 细胞则表现出这种抑制作用的部分逆转，这表明一个有趣的假设，即 p35 在 TGFβ 介导的 NK 细胞耗竭中起重要作用。
本研究报告了 p35 在 NK 细胞细胞毒性中的作用，这可能有助于改善 NK 细胞过继疗法。
