Cancer cachexia shrinks heart muscle cells and leaves lasting damage after the tumor signals stop
In a human stem cell heart model, cachexia signals shrank cardiac cells and impaired function that persisted a week after the stimuli were removed.
Riepilogo
Cancer cachexia, the severe involuntary wasting seen in many cancer patients, harms the heart as well as skeletal muscle. Researchers grew human heart muscle cells from induced pluripotent stem cells and exposed them to signals from colon cancer cells. The heart cells shrank, contracted more weakly, relaxed more slowly, and consumed more oxygen. The team traced this to a shutdown of the AKT/mTORC1 growth pathway, which activated FOXO proteins that drive muscle breakdown. A protein called Atrogin-1 rose and lowered calcineurin A, blocking NFAT, a signal that supports cell growth. When the cancer signals were removed, Atrogin-1 and the cell-recycling (autophagy) markers returned to normal within a week. However, the weakened contraction and altered energy use did not recover in that time. The findings point to a specific signaling chain as a possible drug target and suggest that cardiac damage in cancer patients and survivors may linger after the tumor stress ends.
Riepilogo Dettagliato
Cancer cachexia is a wasting syndrome that causes involuntary loss of body mass, profound skeletal muscle loss, and high mortality. The heart is also affected, and cardiac muscle wasting is common in cancer patients and survivors. Because heart function underpins physical capacity and long-term healthspan, understanding how cachexia damages cardiac muscle matters for people living with and after cancer.
The researchers built a human model using cardiac muscle cells derived from induced pluripotent stem cells (hiPSC-CMs). They exposed these cells to conditioned media or Transwell coculture with C26 or HCT116 tumor cells to mimic cachexia. They then measured cell size, contraction and relaxation, oxygen consumption, and key signaling proteins.
Cachectic cells showed atrophy, reduced contraction amplitude, prolonged relaxation time, and higher oxygen consumption, indicating wasting, contractile dysfunction, and metabolic dysregulation. Signaling through AKT/mTORC1/S6 was suppressed: total and phosphorylated AKT fell, the p-S6/S6 ratio dropped, and RPTOR was downregulated. This coincided with activation of FOXO1/3 and nuclear translocation of FOXO1, promoting atrophic remodeling. Atrogin-1 rose and reduced calcineurin A, which impaired NFAT nuclear translocation and dampened growth signaling. Autophagic flux increased, with a higher LC3BII/LC3BI ratio.
After the cachexia-inducing stimuli were withdrawn, Atrogin-1 and autophagy markers normalized within one week. Contractile and metabolic impairments persisted, indicating delayed functional recovery. The authors propose the FOXO/Atrogin-1/calcineurin A/NFAT axis, within broader AKT/mTORC1 suppression, as a central regulator of cachexia-induced cardiac wasting and a tractable therapeutic target.
The work is preclinical. Isolated stem cell-derived heart cells lack the complexity of a whole organism, and tumor cell lines cannot capture the full range of human cancers. The short recovery window leaves open whether function eventually returns. This summary is based on the abstract only, so detailed methods, effect sizes, and statistics were not available for review.
Risultati Principali
- Cachexia signals made human stem cell-derived heart cells shrink, contract more weakly, relax more slowly, and use more oxygen.
- AKT/mTORC1/S6 signaling was suppressed, activating FOXO1/3 and promoting atrophic remodeling in heart muscle cells.
- Atrogin-1 upregulation lowered calcineurin A and blocked NFAT nuclear translocation, dampening growth signaling.
- Atrogin-1 and autophagy markers normalized within one week of stimulus withdrawal, but contractile and metabolic defects persisted.
- The FOXO/Atrogin-1/calcineurin A/NFAT axis is proposed as a tractable therapeutic target for cardiac wasting.
Metodologia
The team created a human iPSC-derived cardiac myocyte platform modeling cancer cachexia using conditioned media and Transwell coculture with C26 or HCT116 tumor cells. Readouts included cell atrophy, contraction and relaxation, oxygen consumption rate, and signaling and autophagy markers. A withdrawal experiment tested recovery after removing the cachexia-inducing stimuli.
Limitazioni dello Studio
This summary is based on the abstract only, as the full paper was not available. The study is in vitro, using stem cell-derived heart cells and tumor cell lines (C26, HCT116), so it may not reflect cachexia in patients or animals. Recovery was assessed over a short window, so long-term reversibility remains unknown.
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