Division of Gastrointestinal Surgery, Department of General Surgery, Shanghai Eighth People`s Hospital, Shanghai, China.
Department of Ophthalmology, Shanghai Eighth People`s Hospital, Shanghai, China.
Neoplasma. 2022 May;69(3):640-647. doi: 10.4149/neo_2022_211006N1410. Epub 2022 Mar 16.
Colon cancer is a common cause of death in the world, and its main cause of therapy failure is chemoresistance. Apoptosis is de-regulated in colon cancer and is one key mechanism of cancer treatment. We recently reported that reduced expression of ARHGAP17, a Rho GTPase activating protein, correlated with a poor prognosis of colon cancer patients. Here we investigated the role of ARHGAP17 in apoptosis induced by 5-fluorouracil (5-FU) in human colon cancer cells and in mouse xenograft tumor model. We observed a decreased protein level of ARHGAP17 in 5-FU resistant colon cancer cells (HCT116/5-FU and HCT8/5-FU). While ARHGAP17 knockdown attenuated apoptosis upon 5-FU treatment in HCT116 and HCT8, and ARHGAP17 overexpression in HCT116/5-FU and HCT8/5-FU cells increased apoptosis induced by 5-FU. We also found that ARHGAP17 knockdown led to a high level of active Rac1 in HCT116 and HCT8, but ARHGAP17 overexpression reduced active Rac1 in HCT116/5-FU and HCT8/5-FU cells. However, Rac1 inhibitor abolished the effect of ARHGAP17 knockdown, and Rac1 overexpression diminished the effect of ARHGAP17 overexpression on apoptosis induced by 5-FU. Apoptosis was also confirmed by cleaved Caspase-3 and cleaved PARP. Further, we observed that overexpression of ARHGAP17 promoted 5-FU-induced apoptosis and attenuated tumor growth in vivo. Collectively, our data indicate that ARHGAP17 sensitizes chemotherapy-resistant colon cancer cells to apoptosis induced by 5-FU, which is in part through suppressing Rac1.
结直肠癌是全球常见的死亡原因之一，其治疗失败的主要原因是化疗耐药。结直肠癌中细胞凋亡失调，是癌症治疗的关键机制之一。我们最近报道，Rho GTP 酶激活蛋白 ARHGAP17 的表达降低与结直肠癌患者的预后不良相关。在此，我们研究了 ARHGAP17 在人结肠癌细胞中由 5-氟尿嘧啶（5-FU）诱导的细胞凋亡中的作用及其在小鼠异种移植肿瘤模型中的作用。我们观察到，5-FU 耐药的结肠癌细胞（HCT116/5-FU 和 HCT8/5-FU）中 ARHGAP17 的蛋白水平降低。虽然 ARHGAP17 敲低可减弱 HCT116 和 HCT8 中 5-FU 处理后的细胞凋亡，但在 HCT116/5-FU 和 HCT8/5-FU 细胞中过表达 ARHGAP17 会增加 5-FU 诱导的细胞凋亡。我们还发现，ARHGAP17 敲低导致 HCT116 和 HCT8 中活性 Rac1 水平升高，但 ARHGAP17 过表达降低了 HCT116/5-FU 和 HCT8/5-FU 细胞中的活性 Rac1。然而，Rac1 抑制剂消除了 ARHGAP17 敲低的作用，而 Rac1 过表达减弱了 ARHGAP17 过表达对 5-FU 诱导的细胞凋亡的影响。通过切割 Caspase-3 和切割 PARP 也证实了细胞凋亡。此外，我们观察到 ARHGAP17 的过表达促进了 5-FU 诱导的细胞凋亡，并减轻了体内肿瘤的生长。总之，我们的数据表明，ARHGAP17 使化疗耐药的结肠癌细胞对 5-FU 诱导的细胞凋亡敏感，部分原因是通过抑制 Rac1。
