Moderate swimming suppressed the growth and metastasis of the transplanted liver cancer in mice model: with reference to nervous system.
Level 5 - mechanism / opinion, no new human data
Preclinical animal and in vitro laboratory study
PubMed 26686088 · doi:10.1038/onc.2015.484
What was done
Researchers evaluated the impact of varying durations of swimming exercise on liver cancer progression in mouse models. C57BL/6 mice bearing transplanted liver cancer underwent moderate swimming (8 minutes/day for 9 weeks) or overload swimming (16 or 32 minutes/day for 9 weeks). Nude mice orthotopically implanted with human liver cancer cell lines were treated with dopamine, with or without dopamine D2 receptor (DR2) blockade. In vitro experiments examined downstream signaling, including extracellular signal-regulated kinase (ERK) phosphorylation and transforming growth factor-beta (TGF-β1)-induced epithelial-mesenchymal transition (EMT).
What was found
The abstract reports directions of effect without numerical values for tumor volumes, metastasis counts, or survival durations. Moderate swimming (8 min/day) increased dopamine levels in the prefrontal cortex, serum, and tumor tissue, suppressed tumor growth, reduced lung metastasis, and extended survival in mice. Conversely, overload swimming (16 and 32 min/day) accelerated tumor growth and metastasis. Dopamine treatment in nude mice suppressed tumor growth and lung metastasis through the DR2 receptor, an effect abolished by DR2 blockade. Both moderate swimming and dopamine treatment inhibited TGF-β1-induced EMT in vivo, and DR2 activation suppressed ERK phosphorylation and TGF-β1 expression in vitro.
Why it matters
This study identifies a neurobiological mechanism linking physical activity to tumor suppression, demonstrating that moderate exercise acts via dopamine D2 receptor signaling to inhibit liver cancer progression, while excessive exercise may be harmful in animal models.
Limits
The abstract provides no exact quantitative metrics, effect sizes, or animal sample sizes (n is not reported). The findings are strictly preclinical in mouse models and cell lines, so it remains unknown whether these dopamine-mediated exercise effects or the threshold between moderate and overload exercise translate to human hepatocellular carcinoma.
Cited by
- supports Preclinical animal trials demonstrate that exercise as a monotherapy slows the growth and metastatic spread of implanted cancer tumors in mice.