SeNPs in cancer cells, as a rule, had a pro-oxidant effect, increasing the production of ROS, pro-inflammatory effect, increasing the expression of serum cytokines (TNF-α, IL-2, and IFN-γ) and the activity of immune cells (macrophages, lymphocytes, and NK cells), caused apoptosis, inducing an increase in the level of caspase, the ratio of PAH/Bcl-2, contributing to the release of cytochrome C, etc. The gene discussed is TNF; the disease is pulmonary arterial hypertension.