Exercise regulates breast cancer cell viability: systemic training adaptations versus acute exercise responses

Area of Science:

• Exercise physiology
• Cancer biology
• Cellular mechanisms

Background:

• Exercise is known to decrease breast cancer risk and recurrence.
• The precise mechanisms underlying this protective effect remain largely unknown.
• Systemic adaptations to exercise training have been hypothesized as potential mediators.

Purpose of the Study:

• To investigate whether systemic adaptations to exercise training or acute exercise responses affect breast cancer cell viability.
• To determine if serum from breast cancer survivors after a training intervention or acute exercise session can regulate cancer cell growth in vitro.

Main Methods:

• Blood samples were collected from breast cancer survivors undergoing a 6-month training program or a 2-hour acute exercise session.
• Systemic factors and training parameters were analyzed.
• Pre- and post-exercise sera were used to stimulate breast cancer cell lines (MCF-7, MDA-MB-231) in vitro.

Main Results:

• Six months of training improved cardiorespiratory fitness and muscle strength but did not affect breast cancer cell viability.
• Acute exercise led to significant increases in serum lactate, epinephrine, norepinephrine, and IL-6.
• Serum from after acute exercise reduced the viability of both MCF-7 and MDA-MB-231 breast cancer cells.

Conclusions:

• Acute exercise significantly reduces breast cancer cell viability in vitro, whereas long-term training adaptations do not.
• These findings challenge the notion that baseline risk factor reductions mediate exercise's protective effects against breast cancer.
• The study proposes that the cumulative impact of repeated acute exercise responses may be responsible for exercise's cancer-protective benefits.