Angiotensin-converting enzyme 2 (ACE2) plays a pivotal role in the renin–angiotensin system and is closely related to coronavirus disease of 2019. However, the role of ACE2 in cancers remains unclear. We explored the pan-cancer expression patterns and prognostic value of ACE2 across multiple databases, including Oncomine, PrognoScan, Gene Expression Profiling Interactive Analysis, and Kaplan–Meier Plotter. Then, we investigated the correlations between ACE2 expression and immune infiltration in cancers. We found that tumor tissues had higher expression levels of ACE2 compared with normal tissue in the kidney and the liver and lower expression levels in the lung. High expression levels of ACE2 were beneficial to survival in ovarian serous cystadenocarcinoma, liver hepatocellular carcinoma, kidney renal papillary cell carcinoma, and kidney renal clear cell carcinoma, although this was not the case in lung squamous cell carcinoma. For those with a better prognosis, there were significant positive correlations between ACE2 expression and immune infiltrates, including B cells, CD8 + T cells, CD4 + T cells, neutrophils, macrophages, and dendritic cells. In conclusion, ACE2 could serve as a pan-cancer prognostic biomarker and is correlated with immune infiltrates.

血管紧张素转换酶2（ACE2）在肾素-血管紧张素系统中起关键作用，并与2019年的冠状病毒疾病密切相关。但是，尚不清楚ACE2在癌症中的作用。我们探讨了跨多个数据库（包括Oncomine，PrognoScan，Gene Expression Profiling Interactive Analysis和Kaplan-Meier Plotter）的ACE2的全癌表达模式和预后价值。然后，我们调查了ACE2表达与免疫浸润之间的相关性。我们发现，与肾脏和肝脏中的正常组织相比，肿瘤组织具有较高的ACE2表达水平，而在肺中则具有较低的表达水平。ACE2的高表达水平有助于卵巢浆液性囊腺癌，肝肝细胞癌，肾肾乳头状细胞癌，肾肾透明细胞癌，尽管在肺鳞状细胞癌中并非如此。对于预后较好的患者，ACE2表达与免疫浸润之间存在显着正相关，包括B细胞，CD8 + T细胞，CD4 + T细胞，嗜中性粒细胞，巨噬细胞和树突状细胞。总之，ACE2可以作为全癌预后的生物标志物，并与免疫浸润相关。