整合素受体长期以来一直被视为破坏癌症特征的一个潜在吸引人的靶点。有关整合素抑制剂作为化疗的辅助治疗的有希望的初步研究结果并未转化为临床成功。然而，整合素抑制对肿瘤免疫细胞相互作用的影响仍然大部分未被探索。进一步的研究可以揭示整合素信号传导与免疫检查点表达之间的连接，为使用整合素抑制剂使本来耐药的肿瘤对免疫治疗产生敏感性开辟道路。将荧光标记的野生型HCT-116结直肠癌细胞和TALL-104 T细胞进行共培养，并使用GLPG-0187，一种小分子整合素抑制剂，以不同剂量进行处理。该实验显示剂量依赖性的癌细胞杀伤作用，表明整合素抑制可能使癌细胞对免疫细胞产生敏感。假设的机制涉及肿瘤细胞中TGF-β介导的PD-L1上调。为了研究这一机制，对WT和p53-/- HCT-116细胞进行预处理，然后与潜在的TGF-β处理。Western blot分析表明，添加潜在的TGF-β增加了癌细胞中PD-L1的表达。此外，低剂量的整合素抑制剂挽救了这些效应，使PD-L1表达恢复到对照水平。这表明，整合素抑制的免疫刺激效应可能是通过降低癌细胞上的免疫检查点PD-L1表达来实现的。必须注意的是，药物的高剂量并未减少PD-L1的表达。这可能是由于非特异性作用与所提出的通路相冲突，然而这些发现仍在积极调查中。正在进行的蛋白质组实验将包括更大范围的药物和潜在TGF-β剂量。探测TGF-β的附加下游标志物和PD-L1的上游标志物将有助于进一步阐明这一机制。进一步的共培养实验还将包括抗PD-L1和抗PD-1治疗，以研究整合素抑制作为免疫检查点阻断的辅助治疗的可行性。AJCR版权所有©2023。

Integrin receptors have long posed as a potentially attractive target for disrupting cancer hallmarks. Promising preliminary findings with integrin inhibition as an adjuvant to chemotherapy have not translated to clinical success. However, the effect of integrin inhibition on tumor-immune cell interactions remains largely unexplored. Further investigation could shed light on a connection between integrin signaling and immune checkpoint expression, opening the path for using integrin inhibitors to sensitize otherwise resistant tumors to immunotherapy. Fluorescently labeled wild-type HCT-116 colorectal cancer cells and TALL-104 T-cells were co-cultured and treated with GLPG-0187, a small molecule integrin inhibitor, at various doses. This assay revealed dose dependent cancer cell killing, indicating that integrin inhibition may be sensitizing cancer cells to immune cells. The hypothesized mechanism involves TGF-β-mediated PD-L1 upregulation in cancer cells. To investigate this mechanism, both WT and p53-/- HCT-116 cells were pre-treated with GLPG-0187 and subsequently with latent-TGF-β. Western blot analysis demonstrated that the addition of latent-TGF-β increased the expression of PD-L1 in cancer cells. Additionally, a low dose of integrin inhibitor rescued these effects, returning PD-L1 expression back to control levels. This indicates that the immunostimulatory effects of integrin inhibition may be due to downregulation of immune checkpoint PD-L1 on cancer cells. It must be noted that the higher dose of the drug did not reduce PD-L1 expression. This could potentially be due to off-target effects conflicting with the proposed pathway; however, these findings are still under active investigation. Ongoing proteomic experiments will include a larger range of both drug and latent-TGF-β doses. Probing for additional downstream markers of TGF-β and up-stream markers of PD-L1 will help to further elucidate this mechanism. Further co-culture experiments will also include anti-PD-L1 and anti-PD-1 therapy to investigate the viability of integrin inhibition as an adjuvant to immune checkpoint blockade.AJCR Copyright © 2023.