Breast cancer patients present pro-tumor biomarkers related to purinergic signaling and oxidative stress.

Breast cancer (BC) is a multifactorial disease characterized by cell cycle disorder and immune evasion. Studies reveal that the purinergic system (PS) is a mediator of the immune system and actively participates in the inflammatory process in cancer. Also, there is growing debate about the role of oxidative stress (OS) markers and interleukins as predictors of BC progression and invasion. Thus, PS and OS markers, in addition to the expression of interleukins and quantification of extracellular ATP, were evaluated in 39 BC patients, before the beginning of surgical or pharmacological treatment, and in 35 control participants, matched by sex and age. The results show reduced ATP and ADP hydrolysis in platelets, apart from increased extracellular ATP in the BC group. Increased AMP hydrolysis was observed in BC patients' peripheral blood mononuclear cells (PBMCs). BC patients presented elevated oxidative parameters (MDA) and reduced antioxidant parameters (SOD and ascorbic acid), and reduction in interleukins TNF, IL-4, and IL-2. In PBMC from the BC group, the expression of P2X7 gene was significantly higher in relation to the expression of CD39 gene. Also, the expression of CD39 was 1.71 fold higher in tumor samples compared to PBMC from the BC group, and it was 0.11 fold lower in PBMC from the BC group compared to the controls. We conclude that ectoenzymes that hydrolyze ATP and ADP, mainly CD39, present reduced activity in the BC group, promoting an increase in extracellular ATP and culminating in a pro-inflammatory environment, favoring cancer progression. The increase in active oxidants and the reduction in antioxidants contributed to the progression of BC in patients. Finally, TNF and IL-4 demonstrated to be promising prognostic markers in BC patients.