Efficacy of Sijunzi decoction on limb weakness in spleen Qi deficiency model rats through adenosine monophosphate-activated protein kinase/unc-51 like autophagy activating kinase 1 signaling.

OBJECTIVE: To investigate the efficacy of Sijunzi decoction () on limb weakness in a rat model of spleen Qi deficiency (SQD), and to study its effect on mitophagy in skeletal muscle through adenosine monophosphate-activated protein kinase (AMPK) / unc-51 like autophagy activating kinase 1 (ULK1) signaling. METHODS: SQD model rats were produced by fasting combined with forced swimming method for 15 d. After model assessment, rats were randomly divided into four groups of 10 [low/middle/high (L/M/H) Sijunzi decoction dose groups and a normal saline (S) group]. Limb holding power (HP) and body mass (BM) were measured after 2 weeks of treatment. Following euthanasia, quadriceps femoris were dissected and myofiber and mitochondrial morphology were observed by transmission electron microscopy (TEM). Mitochondrial membrane potential (MMP), adenosine triphosphatase (ATP) and reactive oxygen species (ROS) levels were determined using colorimetric methods, and immunoblot analysis of Microtubule-associated protein light chain 3 (LC3) and Sequestosome 1 (p62) was performed to monitor mitophagy and AMPK/ULK1 signaling. RESULTS: Compared with control (C) group rats, in the S group, HP was reduced, the myofiber Z line was disordered, mitochondria were scattered, and numerous vacuoles and mitophagy were observed. MMP and ATP levels were reduced, ROS levels were elevated, and LC3B expression, and p-AMPKα (Thr172)/AMPKα, p-ULK1 (Ser555)/ULK1, and p-Raptor (Ser792)/Raptor ratios were increased, while p62 expression and p-mTOR (Ser2448)/mTOR and p-ULK1 (Ser757)/ULK1 ratios were decreased. After treatment, compared with the S group, HP was improved in M and H groups but not in the L group. Mitophagy was reduced in M, H and L groups but the Z line was disordered and vacuolization remained in the L group. ATP levels were elevated in M, H and L groups, and MMPs were elevat-ed in M and H groups but not in the L group. ROS levels were decreased in M, H and L groups, as were LC3B expression and p-Raptor (Ser792)/Raptor ratios, while p62 expression and p-mTOR (Ser2448)/mTOR and p-ULK1 (Ser757)/ULK1 ratios were increased in M and H groups but not in the L group. p-AMPKα (Thr172)/AMPKα and p-ULK1 (Ser555)/ULK1 ratios were decreased in M, H and L groups. CONCLUSIONS: Sijunzi decoction improved HP, possibly by inhibiting mitophagy via suppression of AMPK/ULK1 signaling. This restored mitochondrial morphology and improved oxidative phosphorylation, which contributed to recovery of limb weakness in SQD model rats.

Deferoxamine Counteracts Cisplatin Resistance in A549 Lung Adenocarcinoma Cells by Increasing Vulnerability to Glutamine Deprivation-Induced Cell Death.

Glutamine, like glucose, is a major nutrient consumed by cancer cells, yet these cells undergo glutamine starvation in the cores of tumors, forcing them to evolve adaptive metabolic responses. Pharmacologically targeting glutamine metabolism or withdrawal has been exploited for therapeutic purposes, but does not always induce cancer cell death. The mechanism by which cancer cells adapt to resist glutamine starvation in cisplatin-resistant non-small-cell lung cancer (NSCLC) also remains uncertain. Here, we report the potential metabolic vulnerabilities of A549/DDP (drug-resistant human lung adenocarcinoma cell lines) cells, which were more easily killed by the iron chelator deferoxamine (DFO) during glutamine deprivation than their parental cisplatin-sensitive A549 cells. We demonstrate that phenotype resistance to cisplatin is accompanied by adaptive responses during glutamine deprivation partly via higher levels of autophagic activity and apoptosis resistance characteristics. Moreover, this adaptation could be explained by sustained glucose instead of glutamine-dominant complex II-dependent oxidative phosphorylation (OXPHOS). Further investigation revealed that cisplatin-resistant cells sustain OXPHOS partly via iron metabolism reprogramming during glutamine deprivation. This reprogramming might be responsible for mitochondrial iron-sulfur [Fe-S] cluster biogenesis, which has become an "Achilles' heel," rendering cancer cells vulnerable to DFO-induced autophagic cell death and apoptosis through c-Jun N-terminal kinase (JNK) signaling. Finally, in vivo studies using xenograft mouse models also confirmed the growth-slowing effect of DFO. In summary, we have elucidated the adaptive responses of cisplatin-resistant NSCLC cells, which balanced stability and plasticity to overcome metabolic reprogramming and permitted them to survive under stress induced by chemotherapy or glutamine starvation. In addition, for the first time, we show that suppressing the growth of cisplatin-resistant NSCLC cells via iron chelator-induced autophagic cell death and apoptosis was possible with DFO treatment. These findings provide a solid basis for targeting mitochondria iron metabolism in cisplatin-resistant NSCLC for therapeutic purposes, and it is plausible to consider that DFO facilitates in the improvement of treatment responses in cisplatin-resistant NSCLC patients.