Chen Xi, Wu Hongjin, Feng Jia, Li Ying, Lv Jiao, Shi Weikai, Fan Weiwei, Xiao Li, Sun Danmeng, Jiang Mingfeng, Shi Ming
School of Life Science and Technology, Harbin Institute of Technology, Harbin, 150001, China.
Department of Clinical Laboratory, Hangzhou Cancer Hospital, Hangzhou,, 320000, Zhejiang, China.
BMC Cancer. 2021 Jan 5;21(1):24. doi: 10.1186/s12885-020-07728-x.
The growth- and plasticity-associated protein-43 (GAP43) is biasedly expressed in indigestive system and nervous system. Recent study has shown that GAP43 is responsible for the development of neuronal growth and axonal regeneration in normal nervous tissue, while serves as a specific biomarker of relapsed or refractory neuroblastoma. However, its expression pattern and function in digestive system cancer remains to be clarified.
In this study, we examined the GAP43 status with qRT-PCR and bisulfite genomic sequencing in colorectal cancer (CRC). We investigated the effect of overexpressed GAP43 in CRC cells with RNA-seq. The RNA-seq data was analyzed with DAVID and IPA.
GAP43 was downregulated in CRC compared to the adjacent tissues. DNA methylase inhibitor 5-Aza-CdR treatment could significantly induce GAP43, indicated that the silencing of GAP43 gene in CRC is closely related to DNA methylation. Bisulfite genomic sequencing confirmed the promoter methylation of GAP43 in CRC. To explore the transcriptional alterations by overexpressed GAP43 in CRC, we performed RNA-seq and found that upregulated genes were significantly enriched in the signaling pathways of ABC transporters and ECM-receptor interaction, while downregulated genes were significantly enriched in Ribosome signaling pathway. Further Ingenuity Pathway Analysis (IPA) showed that EIF2 signaling pathway was significantly repressed by overexpression of GAP43.
Our findings provide a novel mechanistic insight of GAP43 in CRC. Transcriptome profiling of overexpressed GAP43 in CRC uncovered the functional roles of GAP43 in the development of human CRC.
生长与可塑性相关蛋白43（GAP43）在消化系统和神经系统中呈偏向性表达。最近的研究表明，GAP43在正常神经组织中负责神经元生长和轴突再生的发育，同时作为复发或难治性神经母细胞瘤的特异性生物标志物。然而，其在消化系统癌症中的表达模式和功能仍有待阐明。
在本研究中，我们通过qRT-PCR和亚硫酸氢盐基因组测序检测了结直肠癌（CRC）中GAP43的状态。我们用RNA测序研究了CRC细胞中过表达GAP43的影响。RNA测序数据用DAVID和IPA进行分析。
与相邻组织相比，GAP43在CRC中表达下调。DNA甲基化酶抑制剂5-Aza-CdR处理可显著诱导GAP43，表明CRC中GAP43基因的沉默与DNA甲基化密切相关。亚硫酸氢盐基因组测序证实了CRC中GAP43的启动子甲基化。为了探索CRC中过表达GAP43引起的转录变化，我们进行了RNA测序，发现上调的基因在ABC转运蛋白和ECM-受体相互作用的信号通路中显著富集，而下调的基因在核糖体信号通路中显著富集。进一步的Ingenuity通路分析（IPA）表明，GAP43的过表达显著抑制了EIF2信号通路。
我们的研究结果为GAP43在CRC中的作用提供了新的机制性见解。CRC中过表达GAP43的转录组分析揭示了GAP43在人类CRC发生发展中的功能作用。
