Background: Currently, many detection methods have high sensitivity to the diagnosis of lung cancer. However, some postoperative patients with pulmonary nodule were eventually diagnosed as benign nodules. The ideal evaluation of an individual with a pulmonary nodule would expedite therapy for a malignant nodule and minimize testing for those with a benign nodule.Methods: This case-control study is designed to explore the relationship between ACE1 rs4646994 polymorphism and the risk of lung cancer in patients with pulmonary nodules, 400 individuals with lung cancer and benign pulmonary nodules were included. A DNA extraction kit was used to extract plasm DNA from peripheral blood. The relationship between ACE1 rs4646994 and the risk of lung cancer in patients with pulmonary nodules was determined by chi-square test, logistic regression analysis and cross analysis. Results: The results showed that the DD genotype of ACE1 rs4646994 may increase the risk of lung cancer in patients with pulmonary nodules, and this correlation was more significant in the female subgroup. In the age stratification analysis, it was found that the risk of lung cancer was significantly increased in the DD genotype of ACE1 rs4646994 in the older subgroup (> 45 years). In addition, the possibility of EGFR mutation in lung adenocarcinoma patients with ACE1 rs4646994 DD genotype was lower than that of II or ID genotype carriers. Conclusions: Our study indicated that ACE1 rs4646994 polymorphism increases the risk of lung cancer in patients with pulmonary nodules from China.

Angiotensin-converting enzyme (ACE)1, ACE2, and renin are components of the renin-angiotensin system (RAS), which regulates blood pressure. ACE2 also serves as a receptor for SARS-CoV-2 and together with the transmembrane serine protease 2 (TMPRSS-2), mediates viral cell-endocytosis. As the placenta expresses all these factors, it acts as a target for SARS-CoV-2 and also as a source of blood pressure modulators. An ACE1/ACE2 ratio imbalance can lead to RAS dysregulation and a bad prognosis in COVID-19 patients. Calcitriol, the vitamin D active metabolite, negatively regulates RAS, reduces inflammation, and enhances antiviral immunity, thereby playing a protective role against COVID-19 severity. Placental calcitriol has been inversely correlated with maternal blood pressure; however, its regulatory role in RAS components and SARS-CoV-2 receptors within the fetomaternal unit has been barely explored. Therefore, we investigated the effects of calcitriol on placental RAS components. Calcitriol downregulated ACE1, ACE2, TMPRSS-2, and renin gene expression in cultured syncytiotrophoblasts and the extravillous trophoblast cell line HTR-8/SVneo. The ACE1/ACE2 ratio was also downregulated by calcitriol. Similar results were obtained in syncytiotrophoblasts treated with calcidiol, the precursor of calcitriol. Altogether, these results support that vitamin D is essential in restricting SARS-CoV-2 placental infection while helping to regulate maternal blood pressure during pregnancy.

Respiratory transmission is the primary route of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Angiotensin I converting enzyme 2 (ACE2) is the known receptor of SARS-CoV-2 surface spike glycoprotein for entry into human cells. A recent study reported absent to low expression of ACE2 in a variety of human lung epithelial cell samples. Three bioprojects (PRJEB4337, PRJNA270632 and PRJNA280600) invariably found abundant expression of ACE1 (a homolog of ACE2 and also known as ACE) in human lungs compared to very low expression of ACE2. In fact, ACE1 has a wider and more abundant tissue distribution compared to ACE2. Although it is not obvious from the primary sequence alignment of ACE1 and ACE2, comparison of X-ray crystallographic structures show striking similarities in the regions of the peptidase domains (PD) of these proteins, which is known (for ACE2) to interact with the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. Critical amino acids in ACE2 that mediate interaction with the viral spike protein are present and organized in the same order in the PD of ACE1. In silico analysis predicts comparable interaction of SARS-CoV-2 spike protein with ACE1 and ACE2. In addition, this study predicts from a list of 1263 already approved drugs that may interact with ACE2 and/or ACE1, potentially interfere with the entry of SARS-CoV-2 inside the host cells and alleviate the symptoms of Coronavirus disease (COVID-19).