Expression of the SARS-CoV-2 receptor ACE2 reveals the susceptibility of COVID-19 in non-small cell lung cancer

Recent studies have revealed that cancer patients had a higher risk of having coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), compared to patients without cancer. The expression of angiotensin-converting enzyme 2 (ACE2), the receptor of SARS-CoV-2, was aberrantly expressed in many tumors. In this study, by exploring the TCGA and GTEx public databases, we investigated ACE2 expression and its association with prognosis in non-small cell lung cancer (NSCLC), the most susceptible caner type. We found that lung was one of the major organs with highly expressed ACE2. Furthermore, ACE2 expression was significantly elevated in lung adenocarcioma (LUAD) and lung squamous cell carcinoma (LUSC) compared to normal tissues. DNA methylation might be one possible mechanism leading to ACE2 upregulation. Despite that, the AEC2 expression was not statistically associated with disease-free survival (DFS) and overall survival (OS) for LUAD patients, and higher ACE2 expression was associated with prolonged DFS in LUSC patients. Taken together, we observed ACE2 was highly expressed in LUAD and LUSC despite the controversial role of ACE2 expression in predicting prognosis in these two common lung cancer types.