Department of Respiratory Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China.
Department of Laboratory Medicine, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China.
Life Sci. 2020 Apr 1;246:117428. doi: 10.1016/j.lfs.2020.117428. Epub 2020 Feb 11.
Arl4c is overexpressed in several cancer tissues and is involved in cancer development. Nevertheless, the exact mechanism that regulates Arl4c expression in lung cancer has not been fully elucidated. The aim of this study was to investigate the regulatory mechanism of Arl4c and to explore potential chemotherapeutic drugs targeting Arl4c.
Immunohistochemistry was used to examine Arl4c expression levels in human lung adenocarcinoma cancer specimens. Protein expression was detected by western blot. Overexpression of Arl4c-Flag protein was used to detect the ubiquitination of Arl4c. A short interfering RNA against Arl4c was used for gene silencing.
Arl4c was overexpressed in lung cancer tissues, and knockdown of Arl4c expression by siRNA decreased lung cancer A549 and 95-D cell proliferation. In addition, Arl4c expression was downregulated via inhibition of the AKT pathway in A549 and 95-D cells, whereas exposure to benzo (a) pyrene (a carcinogen in smoke) increased Arl4c expression in 16HBE cells via AKT activation. Finally, we found that chemotherapy drug hydroxycamptothecin (HCPT) could decrease Arl4c expression levels by inhibiting the activation of the AKT pathway in A549 and 95-D cells. Moreover, accumulation of ubiquitinated Arl4c protein was increased by HCPT and LY294002 (an AKT inhibitor) treatment whereas the proteasome inhibitor MG-132 attenuated the inhibitory effect of HCPT and LY294002 on Arl4c expression.
Here, we highlighted the AKT pathway as an important regulatory pathway for Arl4c expression in lung cancer cells and identified HCPT as a promising drug for lung adenocarcinoma treatment that functioned by targeting Arl4c expression.
Arl4c 在几种癌症组织中过表达，并参与癌症的发生。然而，调控肺癌中 Arl4c 表达的确切机制尚未完全阐明。本研究旨在探讨 Arl4c 的调控机制，并探索针对 Arl4c 的潜在化疗药物。
采用免疫组织化学法检测人肺腺癌组织标本中 Arl4c 的表达水平。采用 Western blot 检测蛋白表达。用 Arl4c-Flag 蛋白过表达检测 Arl4c 的泛素化。用针对 Arl4c 的 siRNA 进行基因沉默。
Arl4c 在肺癌组织中过表达，siRNA 下调 Arl4c 表达可降低肺癌 A549 和 95-D 细胞的增殖。此外，在 A549 和 95-D 细胞中，通过抑制 AKT 通路可下调 Arl4c 的表达，而暴露于苯并（a）芘（烟雾中的致癌物质）可通过 AKT 激活增加 16HBE 细胞中的 Arl4c 表达。最后，我们发现化疗药物羟基喜树碱（HCPT）可通过抑制 AKT 通路的激活降低 A549 和 95-D 细胞中的 Arl4c 表达水平。此外，HCPT 和 LY294002（AKT 抑制剂）处理可增加泛素化 Arl4c 蛋白的积累，而蛋白酶体抑制剂 MG-132 可减弱 HCPT 和 LY294002 对 Arl4c 表达的抑制作用。
本研究强调 AKT 通路是肺癌细胞中 Arl4c 表达的重要调控通路，并发现 HCPT 是一种有前途的治疗肺腺癌的药物，通过靶向 Arl4c 表达发挥作用。
