Abstract
The objective of this systematic review was to investigate the expression of angiotensin converting enzyme 2 (ACE 2) in the head and neck region. We examined the evidence of the association of ACE 2 expression in oral tissues, salivary glands, and head and neck carcinoma. We searched Pub Med/Medline, Biorxiv, and Google Scholar to identify relevant literature. Studies reporting ACE 2 expression in human oral tissues and with a focus on head and neck carcinoma samples were included. From 110 studies, we extracted 15 studies analyzing the distribution and expression of ACE 2 in different head and neck tissues - olfactory mucosa and nasopharynx n=5, oral mucosa n=5, salivary gland n=5, head and neck squamous cell carcinoma patients n=3. ACE 2 was found to be expressed at a 4.43-fold increase in the head and neck region (OR, 4.43; 95% CI, 3.76-5.22; I(2)= 97%, P(h)=<0.00001) when compared with controls (other tissues except for head and neck region). RNA expression of ACE 2 was 60% higher in head and neck squamous cell carcinoma patients than that in the normal tissues (OR=0.60, 95% CI, 0.04-9.26, P(h)=0.00001). In conclusion, the meta-analysis of the studies indicated that ACE 2 is highly expressed in olfactory mucosa, nasopharynx, oral mucosa, and salivary glands. Furthermore, the results indicate that ACE 2 expression is increased in patients with head and neck cancer.