Cancer Research Center, School of Medicine, Xiamen University, Xiamen, China.
CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Shanghai, 200031, China.
J Cell Biochem. 2021 Apr;122(3-4):472-484. doi: 10.1002/jcb.29875. Epub 2021 Jan 5.
HnRNPA2/B1 is highly expressed in many tumors. However, the role of hnRNPA2/B1 in breast cancer is not clear. In this study, we found the proliferation rate was decreased after knockout of hnRNPA2/B1 by CRISPR-CAS9 in MCF-7 cells, as demonstrated by the reduced expression of CDK4 and p-AKT, and the increased expression of P27. Besides this, the western blot results showed that knockout of hnRNPA2/B1 increased the rate of apoptosis and declined autophagy. By in vivo assay, we found that knockout of hnRNPA2/B1 suppressed tumor growth in a xenograft mouse model. Immunohistochemical staining results confirmed knockout of hnRNPA2/B1 impaired tumor angiogenesis, as illustrated by downregulated expression of VEGF-A. Besides this, interacting proteins with hnRNPA2/B1 were identified by mass spectrometry and the PPI network was constructed. GO analysis suggests that the Interacting proteins are mainly enriched in the Wnt signaling pathway, tumor necrosis factor-mediated signaling pathway, translation, and so on. We then identified hnRNPA2/B1 interacted with signal transducer and activator of transcription 3 (STAT3), as supported by the colocalization of hnRNPA2/B1 and STAT3. Meanwhile, knockout of hnRNPA2/B1 inhibited the phosphorylation of STAT3. Collectively, our results demonstrate that hnRNPA2/B1 promotes tumor cell growth in vitro and in vivo by activating the STAT3 pathway, regulating apoptosis and autophagy.
hnRNPA2/B1 在许多肿瘤中高度表达。然而，hnRNPA2/B1 在乳腺癌中的作用尚不清楚。在这项研究中，我们通过 CRISPR-CAS9 敲除 MCF-7 细胞中的 hnRNPA2/B1 发现，细胞增殖率降低，这表现为 CDK4 和 p-AKT 的表达减少，而 P27 的表达增加。除此之外，Western blot 结果表明，hnRNPA2/B1 的敲除增加了细胞凋亡率并降低了自噬水平。通过体内实验，我们发现 hnRNPA2/B1 的敲除抑制了异种移植小鼠模型中的肿瘤生长。免疫组织化学染色结果证实 hnRNPA2/B1 的敲除损害了肿瘤血管生成，表现为 VEGF-A 的表达下调。除此之外，通过质谱法鉴定出与 hnRNPA2/B1 相互作用的蛋白质，并构建了 PPI 网络。GO 分析表明，这些相互作用的蛋白质主要富集在 Wnt 信号通路、肿瘤坏死因子介导的信号通路、翻译等通路中。我们随后鉴定出 hnRNPA2/B1 与信号转导和转录激活因子 3（STAT3）相互作用，这得到了 hnRNPA2/B1 和 STAT3 共定位的支持。同时，hnRNPA2/B1 的敲除抑制了 STAT3 的磷酸化。综上所述，我们的研究结果表明 hnRNPA2/B1 通过激活 STAT3 通路、调节细胞凋亡和自噬来促进肿瘤细胞在体外和体内的生长。
