부산대학교 도서관

CHO, E., J. STAMPLEY, R. WALL, R. MATTHEWS, E. ZUNICA, J. C. BROWN, N. M. JOHANNSEN, B. A. IRVING, and G. SPIELMANN. Acute Exercise Increases NK Cell Mitochondrial Respiration and Cytotoxicity against Triple-Negative Breast Cancer Cells under Hypoxic Conditions. Med. Sci. Sports Exerc., Vol. 55, No. 12, pp. 2132-2142, 2023. Purpose: Triple-negative breast cancer (TNBC) is an aggressive, highlymetastaticmalignancy with high recurrence rates. Hypoxia is a hallmark of the TNBC tumormicroenvironment, which promotes tumor growth while impairing natural killer (NK) cell cytotoxic functions. Although acute exercise improves NK cell function under normoxic conditions, the effect of exercise onNKcell cytotoxic functions under hypoxic conditions mimickingO2 tensions observed in solid tumors is unknown. Methods: The cytotoxic functions of resting and postexercise NK cells isolated from thirteen young inactive healthy women were assessed against breast cancer cells expressing different levels of hormone receptors (MCF-7 andMDA-MB-231) under normoxic and hypoxic conditions. Mitochondrial respiration and H2O2 efflux rates of the TNBC-activated NK cells were assessed via high-resolution respirometry. Results: Under hypoxia, postexercise NK cells exhibited greater killing of TNBC than resting NK cells. Further, postexercise NK cells were more likely to kill TNBC under hypoxia than normoxic conditions. In addition, mitochondrial respiration associated with oxidative (OXPHOS) capacity of TNBC-activated NKcellswas greater in postexercise cells than resting cells under normoxia, but not under hypoxia. Finally, acute exercise was associated with reduced mitochondrial H2O2 efflux by NK cells in both conditions. Conclusions: Together, we present crucial interrelationships between hypoxia and exercise-induced changes in NK cell functions against TNBC cells. By modulating their mitochondrial bioenergetic functions, we postulate that acute exercise improves NK cell function under hypoxic conditions. Specifically, NK cell O2 and H2O2 flow (pmol·s--1·million NK cells--1) changes in response to 30-min cycling suggest that exercise primes NK cell tumor killing by reducing mitochondrial oxidative stress and, thus, rescuing their function when exposed to harsh hypoxic environments as observed in the microenvironment of breast solid tumors. Key Words: NK CELL CYTOTOXICITY, HYPOXIA ACUTE EXERCISE, TRIPLE-NEGATIVE BREAST CANCER, MITOCHONDRIAL RESPIRATION, MITOCHONDRIAL ROS [ABSTRACT FROM AUTHOR]