Pyrroloquinoline quinone ameliorates diabetic cardiomyopathy by inhibiting the pyroptosis signaling pathway in C57BL/6 mice and AC16 cells.

PURPOSE: Diabetic cardiomyopathy (DCM), a common complication of diabetes mellitus and is characterized by myocardial hypertrophy and myocardial fibrosis. Pyrroloquinoline quinone (PQQ), a natural nutrient, exerts strong protection against various myocardial diseases. Pyroptosis, a type of inflammation-related programmed cell death, is vital to the development of DCM. However, the protective effects of PQQ against DCM and the associated mechanisms are not clear. This study aimed to investigate whether PQQ protected against DCM and to determine the underlying molecular mechanism. METHODS: Diabetes was induced in mice by intraperitoneal injection of streptozotocin, after which the mice were administered PQQ orally (10, 20, or 40 mg/kg body weight/day) for 12 weeks. AC16 human myocardial cells were divided into the following groups and treated accordingly: control (5.5 mmol/L glucose), high glucose (35 mmol/L glucose), and HG + PQQ groups (1 and 10 nmol/L PQQ). Cells were treated for 24 h. RESULTS: PQQ reduced myocardial hypertrophy and the area of myocardial fibrosis, which was accompanied by an increase in antioxidant function and a decrease in inflammatory cytokine levels. Moreover, myocardial hypertrophy-(ANP and BNP), myocardial fibrosis-(collagen I and TGF-ß1), and pyroptosis-related protein levels decreased in the PQQ treatment groups. Furthermore, PQQ abolished mitochondrial dysfunction and the activation of NF-κB/IκB, and decreased NLRP3 inflammation-mediated pyroptosis in AC16 cells under high-glucose conditions. CONCLUSION: PQQ improved DCM in diabetic mice by inhibiting NF-κB/NLRP3 inflammasome-mediated cell pyroptosis. Long-term dietary supplementation with PQQ may be greatly beneficial for the treatment of DCM. Diagram of the underlying mechanism of the effects of PQQ on DCM. PQQ inhibits ROS generation and NF-κB activation, which stimulates activation of the NLRP3 inflammasome and regulates the expression of caspase-1, IL-1ß, and IL-18. The up-regulated inflammatory cytokines trigger myocardial hypertrophy and cardiac fibrosis and promote the pathological process of DCM.

GDF11/BMP11 as a novel tumor marker for liver cancer.

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11, a member of the transforming growth factor-ß superfamily, has been reported to be involved in colorectal cancer. However, the roles of GDF11 in Chinese patients with liver cancer and the underlying mechanisms have remained elusive. The present study assessed the expression of GDF11 in 10 paired samples of cancerous and normal tissues from Chinese liver cancer patients. The results indicated that the expression of GDF11 was significantly lower in cancerous tissues than in normal tissues. In vitro, the expression of GDF11 was reduced in a panel of liver cancer cell lines compared with that in a normal liver cell line at the mRNA and protein level. Treatment with GDF11 reduced the viability of HepG2 for up to 72 h and GDF11 treatment reduced the viability of SMMC-7721 after 48 and 72 h. Furthermore, GDF11 activated Smad2/3 signaling in HepG2 cells. In conclusion, GDF11 has a tumor suppressor role in liver cancer, exerts its effects through Smad2/3 signaling and may serve as a novel tumor marker in liver cancer diagnosis.