Cancer progression in COVID-19: integrating the roles of renin angiotensin aldosterone system, angiopoietin-2, heat shock protein-27 and epithelial mesenchymal transition.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has affected millions worldwide and has been found to cause severe disease in patients with underlying comorbidities. In patients with known malignancies, in addition to constraints in routine healthcare, the risk of being susceptible to developing severe forms of the disease is of grave concern. While follow-up studies on survivors of the severe acute respiratory syndrome (SARS) 2003 outbreak revealed increased susceptibility to infections, tumours and cardiovascular abnormalities, recent studies implicating angiopoietin 2 in induction of inflammatory intussusceptive angiogenesis and diffuse alveolar damage in COVID-19 patients raises the possibility of progression of carcinogenetic processes in patients with known malignancies. Angiotensin converting enzyme-2 (ACE-2) mediated cellular entry of SARS-Cov2 leads to receptor shedding of ACE-2 and disrupts the renin angiotensin aldosterone axis (RAAS). This augments the pro-inflammatory and proliferative effects of RAAS, while attenuating the anti-inflammatory and anti-proliferative angiotensin 1-7 /Mas pathway. Angiopoietin-2, a molecule responsible for angiogenesis and cancer progression which corelates with tumour load in certain cancers, is upregulated by angiotensin 2-AT1 Receptor axis. Tumour microenvironment-comprising of various cells, blood vessels and extra cellular matrix which express the RAAS peptides-plays a key role in cancer initiation, progression and metastasis. Angiotensin 2 induces the formation of a desmoplastic environment, favouring cancer cell growth. ACE-2 downregulation causes bradykinin accumulation which may exert its proliferative action via mitogen activated protein kinase pathways which has established roles in cancers of breast and kidney. In addition to cytokine storm causing organ damage, acute inflammation in COVID-19 may also cause epithelial mesenchymal transition and heat shock protein 27 phosphorylation, both of which are key mediators in cancer signalling pathways. We hypothesise that SARS-Cov2, by impacting the RAAS and immune system, has the potential to cause tumour cell proliferation, apoptosis evasion and metastasis, thereby increasing the possibility of cancer progression in patients with known malignancies.