Evaluation of COVID-19 based on ACE2 expression in normal and cancer patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is now a serious public health problem. Angiotensin-converting enzyme 2 (ACE2) recognized as the receptor of SARS-CoV is also necessary for SARS-CoV-2. However, the impact of ACE2 on SARS-CoV-2 susceptibility and the situation of malignant tumor patients in this outbreak are unclear. So, it is important to understand the expressions of ACE2 in different normal tissues and cancers. The results showed that the kidneys, duodenum, intestine, gallbladder and testis had the highest ACE2 expressions, followed by the colon, rectum and seminal vesicles. The lungs had a very low expression. ACE2 expressions were upregulated in renal cancer, gastrointestinal tumor and lung cancer. ACE2 expression levels may affect SARS-CoV-2 infection and severity. A total of 3,421 cases with COVID-19 have been collected. Among them, 43 cases (1.26%) had malignant tumor coexisting conditions. The rate of severe events for malignant tumor patients was 39.02% (16/41), while the rate of severe events for all patients was 10.79% (194/1,798). The clinical symptoms and signs were studied for the following three systems: respiratory (31-92%), digestive (10-13%) and urinary systems (3.38%). It seems that symptom severity is not related to protein expression levels. This might be the reason for SARS-CoV-2 showing higher regeneration index and susceptibility. More research is needed to explore the mechanisms and treatments.