Department of Tropical Medicine and Parasitology, Seoul National University College of Medicine, and Institute of Endemic Diseases, Seoul 03080, Korea.
Seoul National University Bundang Hospital, Seongnam 13620, Korea.
Int J Mol Sci. 2020 Sep 10;21(18):6642. doi: 10.3390/ijms21186642.
Nuclear factor kappa B (NF-κB) activation is a well-known mechanism by which chemoresistance to anticancer agents is reported. It is well-known that irinotecan as a chemotherapeutic drug against non-small-cell lung carcinoma (NSCLC) has limited anticancer effect due to NF-κB activation. In this study, we propose the novel role of GRA16, a dense granule protein of , as an anticancer agent to increase the effectiveness of chemotherapy via the inhibition of NF-κB activation. To demonstrate this, H1299 cells were stably transfected with GRA16. The anticancer effects of GRA16 were demonstrated as a reduction in tumor size in a mouse xenograft model. GRA16 directly elevated B55 regulatory subunit of protein phosphatase 2A (PP2A-B55) expression in tumor cells, thereby decreasing GWL protein levels and ENSA phosphorylation. This cascade, in turn, induced PP2A-B55 activation and suppressed AKT/ERK phosphorylation and cyclin B1 levels, suggesting reduced cell survival and arrested cell cycle. Moreover, PP2A-B55 activation and AKT phosphorylation inhibition led to NF-κB inactivation via the reduction in inhibitory kappa B kinase beta (IKKβ) levels, de-phosphorylation of inhibitor of kappa B alpha (IκBα), and reduction in the nuclear transit of NF-κB p65. Furthermore, this molecular mechanism was examined under irinotecan treatment. The PP2A-B55/AKT/NF-κB p65 pathway-mediated anticancer effects were only induced in the presence of GRA16, but not in the presence of irinotecan. Moreover, GRA16 synergistically promoted the anticancer effects of irinotecan via the induction of the sub-G phase and reduction of cell proliferation. Collectively, irinotecan and GRA16 co-treatment promotes the anticancer effects of irinotecan via NF-κB inhibition and cell cycle arrest induced by GRA16, subsequently increasing the chemotherapeutic effect of irinotecan to NSCLC cells via NF-κB inhibition.
核因子 kappa B（NF-κB）的激活是一种众所周知的机制，据报道，它可以使抗癌药物产生耐药性。众所周知，伊立替康作为一种针对非小细胞肺癌（NSCLC）的化疗药物，由于 NF-κB 的激活，其抗癌效果有限。在这项研究中，我们提出了一种新的观点，即致密颗粒蛋白 GRA16 作为一种抗癌药物，通过抑制 NF-κB 的激活来增加化疗的效果。为了证明这一点，我们使用 GRA16 稳定转染了 H1299 细胞。在小鼠异种移植模型中，GRA16 减少肿瘤大小，证明了 GRA16 的抗癌作用。GRA16 直接上调肿瘤细胞中蛋白磷酸酶 2A 的 B55 调节亚基（PP2A-B55）的表达，从而降低 GWL 蛋白水平和 ENSA 磷酸化。这一级联反应反过来又诱导 PP2A-B55 的激活，并抑制 AKT/ERK 磷酸化和细胞周期蛋白 B1 的水平，提示细胞存活减少和细胞周期停滞。此外，PP2A-B55 的激活和 AKT 磷酸化的抑制导致 NF-κB 的失活，这是通过降低抑制性 κB 激酶β（IKKβ）的水平、磷酸化抑制剂 κBα（IκBα）的去磷酸化以及 NF-κB p65 的核转位来实现的。此外，还在伊立替康治疗下检查了这种分子机制。只有在存在 GRA16 的情况下，才能诱导出 PP2A-B55/AKT/NF-κB p65 通路介导的抗癌作用，而在存在伊立替康的情况下则不能。此外，GRA16 通过诱导亚 G1 期和减少细胞增殖，与伊立替康协同促进抗癌作用。总的来说，伊立替康和 GRA16 的联合治疗通过 GRA16 诱导的 NF-κB 抑制和细胞周期阻滞，促进伊立替康的抗癌作用，随后通过 NF-κB 抑制增加伊立替康对 NSCLC 细胞的化疗效果。
