The role of depression in the progression of tumor cell inflammation and the potential regulatory mechanisms of aerobic exercise: a narrative review from molecular and cellular perspectives

There is a tight correlation between depression, and tumor progression, particularly via the regulation of the immune system, and inflammatory responses. Chronic inflammation is a member of the core causes in the tumor microenvironment, which can promote tumor initiation, progression, and immune evasion. An increasing body of literature has reported that aerobic exercise (AE), as a non-pharmacological intervention, can display potential in anti-tumor therapy by modulating the immune system, delaying chronic inflammation, and increasing neurotransmitter balance. However, it is worth noting that extreme AE may cause negative influences, such as immunosuppression, which influences its anti-tumor efficacy. Our review aims to investigate how depression influences the inflammatory progression of tumor cells via immune regulation, and the potential regulatory processes of AE in this mechanism. Moreover, we further explore the potential of AE in tumor treatment, and delves into its potential deleterious impacts. via this literature review, together with perspectives from molecular, and cellular biology, notably, our review explores the influences of depression, and AE on the tumor microenvironment, and immune responses. It centers on the contribution of AE in modulating immune cell functions, delaying chronic inflammatory responses, and increasing neurotransmitter balance. Depression promotes inflammatory responses in the tumor microenvironment via neurotransmitter imbalance, abnormal activation of the hypothalamic-pituitary-adrenal axis, and immune system dysregulation, hence triggering tumor growth, and metastasis. AE can positively modulate the immune system, decrease inflammation, as well as improve tumor immune surveillance function. Moderate AE modulates immune responses in the tumor microenvironment in the context of enhancing the activity of immune cells, lowering the levels of pro-inflammatory factors, and improving the production of anti-inflammatory factors, hence blocking the growth, and spread of tumor cells. However, extreme AE may cause immunosuppression, influencing anti-tumor influences, so individualized changes to the intensity, and frequency of exercise interventions are needed.