Amelioration of cancer-induced cachexia by inhibition of NF-kappaB signaling pathway.

摘要

Cachexia is the most debilitating syndrome which manifests itself in several chronic, life-threatening diseases, especially in cancer. Cachexia is of major public health significance for the cancer population because it increases both morbidity and mortality and also reduces quality of life and survival time of cancer patients. Up to two-thirds of patients with advanced neoplasia develop signs and symptoms of cachexia, including anorexia, asthenia and severe unintentional weight loss leading to immobility and cardiac or respiratory failure. Cachexia accounts for more than 20% of all cancer-associated deaths.;In the present study, we established a novel murine model for cancer cachexia induced by the human prostate cancer cell line PC-3. In a novel mouse model of cachexia induced by PC-3 cells, an established androgen-independent cell line derived from a bone metastasis of a human prostatic adenocarcinoma, in BALB/c nude mice we observed body weight loss, a 50% reduction in muscle weights and decreased muscle fiber diameters. Elevated levels of the phosphorylated p65 subunit of the nuclear factor of kappaB (NF-kappaB) were found in tibialis anterior and quadriceps muscles, but not in gastrocnemius muscle. Elevated levels of the muscle specific E3 ligase (MuRF1) confirmed activation of the ubiquitin-proteosome protein degradation pathway in these muscles. In contrast, elevated levels of the phosphorylated eukaryotic initiation factor 2 alpha (p-eIF2-alpha) in gastrocnemius muscle, but not in tibialis anterior and quadriceps muscles, suggested a greater component of cachexia due to decreased protein synthesis in this muscle.;We also utilized a well-established murine model of cancer cachexia induced by murine colon adenocarcinoma cell line (C-26). C-26 tumor-bearing mice were treated with an intramuscular injection of an adeno-associated viral vector serotype 8 (AAV8) carrying the IkappaB super repressor (IkappaBSR) or cellular caspase-8-like inhibitory protein (cFLIP) gene driven by the cytomegalovirus (CMV) or muscle creatine kinase (MCK) promoter. We found that there was an improvement in body weight, individual muscle weight and muscle fiber diameter in mice receiving AAV8-IkappaBSR or AAV8-cFLIP. We also observed a reduction of MuRF1 protein expression, indicating that there was a reduction in muscle protein degradation via the ubiquitin-proteasome system. The result was confirmed by an increased level of myosin heavy chain protein expression. This study suggests the potential for AAV8 carrying IkappaBSR gene mediated gene transfer to prevent or reverse cachectic symptoms in vivo.