Original Research Article

ACE2 in tumor cells and tumor vasculature: Negligible intercellular transfer from cancer cells into endothelial cells

¹ State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
² Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
³ Department of Pathology, Guangzhou Concord Cancer Center, Guangzhou 510555, PR China
⁴ Department of Radiation Oncology, Guangzhou Concord Cancer Center, Guangzhou 510555, PR China

^* Corresponding author: qianchn@sysucc.org.cn

Received: 1 March 2021
Accepted: 6 July 2021

Abstract

Cancer patients are more susceptible to severe coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Angiotensin-converting enzyme 2 (ACE2) is the functional host receptor for SARS-CoV-2 entering into human cells. Bioinformatics’ analyses have revealed that ACE2 is upregulated in some cancer cells. In the present study, we evaluated ACE2 protein expression levels in several common malignancies compared to non-cancerous normal tissues. ACE2 expression was elevated in colorectal adenocarcinoma, pancreatic adenocarcinoma, gastric adenocarcinoma, and papillary renal cell carcinoma cancer. Yet, it was suppressed in chromophobe renal cell carcinoma, testicular germ cell tumors, and papillary thyroid carcinoma. Two tumor tissue microarrays were used to evaluate the prognostic value of ACE2 expression in patients with gastric adenocarcinoma, and colorectal adenocarcinoma without COVID-19. No significant survival benefit was found for patients with overexpression of ACE2 in the tumor. In the tumor vasculature, ACE2 expression was observed in only 54% of the tumor micro-vessels. Using an in vitro co-culture of endothelial cells and tumor cells overexpressing fusion protein ACE2-red fluorescent protein, we did not observe any clear and convincing intercellular transfer of ACE2 from cancer cells into endothelial cells. In summary, alteration of ACE2 expression was found in common malignancies, but there is no evidence of intercellular transfer of ACE2 from cancer cells to endothelial cells.