Table 4.
Protein metabolism
| Cancer and chemotherapy effect | Protein diet effects | |||||||
|---|---|---|---|---|---|---|---|---|
| CTRL | NP16% | P | LP8% | LP12% | NP16% | HP24% | HP32% | |
| Liver | ||||||||
| Protein content | ||||||||
| mg | 600 ± 66 | 557 ± 25 | NS | 500 ± 26 a | 583 ± 26 a | 557 ± 25 a | 597 ± 29 a | 586 ± 34 a |
| g/100 g tissue | 9.8 ± 0.9 | 10.0 ± 0.4 | NS | 9.5 ± 0.4 a | 10.4 ± 0.4 a | 10.0 ± 0.4 a | 10.2 ± 0.4 a | 10.2 ± 0.5 a |
| Protein synthesis | ||||||||
| AU | 0.36 ± 0.17 | 0.19 ± 0.11 | NS | 0.16 ± 0.03 a | 0.17 ± 0.03 a | 0.19 ± 0.10 a | 0.14 ± 0.06 a | 0.13 ± 0.04 a |
| Tibialis | ||||||||
| Protein content | ||||||||
| mg | 58.7 ± 2.4 | 52.6 ± 3.9 | NS | 47.3 ± 2.7 a | 50.9 ± 3.6 a | 52.6 ± 3.9 a | 51.9 ± 3.8 a | 52.1 ± 3.6 a |
| g/100 g muscle | 19.8 ± 0.7 | 18.4 ± 1.1 | NS | 17.2 ± 1.0 a | 17.8 ± 1.2 a | 18.4 ± 1.1 a | 17.7 ± 1.1 a | 18.1 ± 1.1 a |
| Protein synthesis | ||||||||
| AU | 0.74 ± 0.13 | 0.71 ± 0.16 | NS | 0.68 ± 0.11 a | 0.66 ± 0.16 a | 0.71 ± 0.16 a | 0.61 ± 0.10 a | 0.64 ± 0.06 a |
| mTORC1 activation | ||||||||
| 4EBP1 phospho (AU) | 0.21 ± 0.05 | 0.15 ± 0.04 | NS | 0.14 ± 0.05 a | 0.14 ± 0.03 a | 0.15 ± 0.04 a | 0.14 ± 0.02 a | 0.15 ± 0.03 a |
| Proteolyis | ||||||||
| Atrogin‐1 (AU) | 0.18 ± 0.04 | 0.18 ± 0.03 | NS | 0.18 ± 0.04 a | 0.18 ± 0.03 a | 0.18 ± 0.03 a | 0.16 ± 0.03 a | 0.19 ± 0.04 a |
| Murf‐1 (AU) | 0.20 ± 0.09 | 0.20 ± 0.08 | 0.20 ± 0.09 | 0.16 ± 0.05 | 0.20 ± 0.08 | 0.17 ± 0.05 | 0.19 ± 0.07 | |
| Jejunum | ||||||||
| Protein content | ||||||||
| mg/10 cm | 15.0 ± 1.5 | 11.6 ± 0.9 | 0.0440 | 12.5 ± 0.9 a | 12.0 ± 0.6 a | 11.6 ± 0.9 a | 11.3 ± 0.5 a | 11.3 ± 0.9 a |
| g/100 mucosa | 5.3 ± 0.4 | 4.5 ± 0.3 | NS | 4.6 ± 0.2 a | 5.0 ± 0.3 a | 4.5 ± 0.3 a | 4.8 ± 0.2 a | 4.6 ± 0.2 a |
| Protein synthesis | ||||||||
| AU | 0.61 ± 0.22 | 0.31 ± 0.18 | NS | 0.27 ± 0.06 a | 0.20 ± 0.18 a | 0.31 ± 0.18 a | 0.89 ± 0.06 a | 0.28 ± 0.10 a |
| Ileon | ||||||||
| Protein content | ||||||||
| mg/10 cm | 17.5 ± 2.0 | 15.9 ± 1.9 | NS | 15.5 ± 0.9 a | 15.6 ± 1.1 a | 15.9 ± 1.9 a | 14.1 ± 1.3 a | 14.2 ± 0.9 a |
| g/100 g mucosa | 6.9 ± 0.4 | 6.2 ± 0.3 | NS | 6.2 ± 0.2 a | 6.1 ± 0.1 a | 6.2 ± 0.3 a | 6.0 ± 0.3 a | 6.1 ± 0.2 a |
| Protein synthesis | ||||||||
| AU | 1.03 ± 0.40 | 0.99 ± 0.44 | NS | 1.09 ± 0.32 a | 0.81 ± 0.44 a | 0.99 ± 0.44 a | 0.89 ± 0.31 a | 1.31 ± 0.74 a |
Control rats have received the normal‐protein diet (CTRL; n = 8) and tumour‐bearing rats received either the normal‐protein diet (NP16%, n = 14) or a low‐protein diet with 8% protein (LP8%, n = 14), a low‐protein diet with 12% protein (LP12%, n = 14), a high‐protein diet with 24% protein (HP24%, n = 14) or a high‐protein diet with 32% protein (LP32%, n = 14). Two days later, for the tumour‐bearing rats, the first chemotherapy cycle was initiated: irinotecan (CPT‐11; 50 mg/kg) at D0 and 5‐fluorouracil (5‐FU; 50 mg/kg) at D1. One week later, they received the second cycle of chemotherapy (CPT‐11 at D7 and 5‐FU at D8). All rats were then sacrificed at D9 for analysis.
Data are presented as mean ± SEM. Significant differences are grey‐backgrounded. For protein diet effects, values with different superscript letters are statistically different (P < 0.05).