Su Ai-Ling, Tian Chang-Qing, Ou Ying-Jie, Bao Xu-Bin, Huan Xia-Juan, Miao Ze-Hong, Wang Ying-Qing
State Key Laboratory of Drug Research, Cancer Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Haike Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China.
State Key Laboratory of Drug Research, Cancer Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Haike Road, Shanghai 201203, China.
Life Sci. 2023 Nov 1;332:122129. doi: 10.1016/j.lfs.2023.122129. Epub 2023 Sep 26.
Ecto-5'-nucleotidase (CD73), encoded by the NT5E gene, mediates tumor immunosuppression and has been targeted for the development of new anticancer drugs. Proteasome inhibitors impair protein degradation by inhibiting proteasome and have been used in the clinic for cancer therapy. Here we report that proteasome inhibitors reduce the protein and mRNA levels of CD73. Among 127 tested small-molecule drugs, proteasome inhibitors were found to consistently decrease the protein and mRNA levels of CD73 in NSCLC NCI-H1299 cells. This effect was further confirmed in different NSCLC cells exposed to different proteasome inhibitors. In those treated cells, the protein levels of ERK and its active form p-ERK, the vital components in the MAPK pathway, were reduced. Consistently, inhibitors of MEK and ERK, another two members of the MAPK pathway, also lowered the protein and mRNA levels of CD73. Correspondingly, treatments with fibroblast growth factor 2 (FGF2), an activator of the MAPK pathway, enhanced the levels of p-ERK and partly rescued the proteasome inhibitor-driven reduction of CD73 mRNA and protein in NSCLC cells. However, exogenous CD73 overexpression in murine Lewis lung carcinoma (LLC) cells was not lowered either in vitro or in vivo, by the treatments with proteasome inhibitors and basically, did not affect their in vitro proliferative inhibition either. In contrast, CD73 overexpression dramatically reduced the in vivo anticancer activity of Bortezomib in immunocompetent mice, with tumor growth inhibition rates from 52.18 % for LLC/vector down to 8.75 % for LLC/NT5E homografts. These findings give new insights into the anticancer mechanisms of proteasome inhibitors.
由NT5E基因编码的胞外5'-核苷酸酶（CD73）介导肿瘤免疫抑制，一直是新型抗癌药物研发的靶点。蛋白酶体抑制剂通过抑制蛋白酶体来损害蛋白质降解，已在临床上用于癌症治疗。在此我们报告，蛋白酶体抑制剂可降低CD73的蛋白质和mRNA水平。在127种测试的小分子药物中，发现蛋白酶体抑制剂能持续降低非小细胞肺癌NCI-H1299细胞中CD73的蛋白质和mRNA水平。在暴露于不同蛋白酶体抑制剂的不同非小细胞肺癌细胞中，这一效应得到了进一步证实。在这些处理过的细胞中，ERK及其活性形式p-ERK（丝裂原活化蛋白激酶途径中的关键成分）的蛋白质水平降低。同样，丝裂原活化蛋白激酶途径的另外两个成员MEK和ERK的抑制剂也降低了CD73的蛋白质和mRNA水平。相应地，用丝裂原活化蛋白激酶途径的激活剂成纤维细胞生长因子2（FGF2）处理，可提高p-ERK水平，并部分挽救蛋白酶体抑制剂导致的非小细胞肺癌细胞中CD73 mRNA和蛋白质的减少。然而，蛋白酶体抑制剂处理在体外或体内均未降低小鼠Lewis肺癌（LLC）细胞中外源性CD73的过表达，并且基本上也不影响其体外增殖抑制。相反，CD73过表达显著降低了硼替佐米在免疫活性小鼠体内的抗癌活性，LLC/载体移植瘤的肿瘤生长抑制率为52.18%，而LLC/NT5E移植瘤的肿瘤生长抑制率降至8.75%。这些发现为蛋白酶体抑制剂的抗癌机制提供了新的见解。
