Objective:To investigate whether astaxanthin (AST) down-regulates dynamin-related protein 1 (Drp1) through activating the silent mating type information regulation 2 homolog-1 (SIRT1) signaling pathway, thereby attenuating contrast-induced acute kidney injury.Methods:Forty adult male Sprague-Dawley rats weighing 160-180 g were randomly divided into five groups: sham surgery group (Sham group), contrast medium injury group (CM group), astaxanthin-intervention group (AST+CM group), SIRT1 inhibitor Ex527 intervention group (Ex527+CM group), and astaxanthin combined with Ex527 intervention group (AST+Ex527+CM group). After 72 hours of modeling, heart blood was removed and kidney tissues were collected for follow-up testing. Serum creatinine (Scr), blood urea nitrogen (BUN), and oxidative stress-related indexes total superoxide dismutase (T-SOD) and malondialdehyde (MDA) were measured by biochemistry; hematoxylin and eosin staining was performed to observe the pathological changes in the kidney; mitochondrial morphology and number were observed by transmission electron microscopy; reactive oxygen species (ROS) levels were detected by ROS staining in frozen sections; TUNEL staining was performed to detect apoptosis level. The expression levels of SIRT1, p53, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), Drp1 and apoptosis-related proteins Bcl-2 and Bax were detected by Western blotting.Results:(1) Compared with the CM group, Scr and BUN level were significantly lower, T-SOD level was higher and MDA level was lower in the AST+CM group, while T-SOD level decreased and MDA level increased after the combination of Ex527 (all P<0.05). (2) ROS expression was lower in the AST+CM group compared to the CM group and higher after the combination of Ex527 (both P<0.05). (3) The number of apoptotic cells was significantly reduced in the AST+CM group compared to the CM group and increased after the combination of Ex527 (both P<0.05). (4) The protein expression levels of SIRT1, PGC-1α and Bcl-2 were increased and the protein expression levels of p53, Drp1 and Bax were decreased (all P<0.05) in the AST+CM group compared with the CM group, and the protein expression levels of SIRT1, PGC-1α and Bcl-2 were decreased and the protein expression levels of p53, Drp1 and Bax were increased when Ex527 was combined (all P<0.05). Conclusion:Astaxanthin can inhibit Drp1-mediated mitochondrial fission by activating the SIRT1 pathway, thereby reducing contrast-induced acute kidney injury in rats.

Programmed cell death 4 (PDCD4) is a RNA-binding protein that acts as a tumor suppressor in many cancer types, including colorectal cancer (CRC). During CRC carcinogenesis, PDCD4 protein levels remarkably decrease, but the underlying molecular mechanism for decreased PDCD4 expression is not fully understood. In this study, we performed bioinformatics analysis to identify miRNAs that potentially target PDCD4. We demonstrated miR-181b as a direct regulator of PDCD4. We further showed that activation of IL6/STAT3 signaling pathway increased miR-181b expression and consequently resulted in downregulation of PDCD4 in CRC cells. In addition, we investigated the biological effects of PDCD4 inhibition by miR-181b both in vitro and in vivo and found that miR-181b could promote cell proliferation and migration and suppress apoptosis in CRC cells and accelerate tumor growth in xenograft mice, potentially through targeting PDCD4. Taken together, this study highlights an oncomiR role for miR-181b in regulating PDCD4 in CRC and suggests that miR-181b may be a novel molecular therapeutic target for CRC.
Animals ; Apoptosis Regulatory Proteins ; genetics ; metabolism ; Caco-2 Cells ; Cell Proliferation ; Colorectal Neoplasms ; genetics ; metabolism ; pathology ; Heterografts ; Humans ; Male ; Mice ; Mice, Nude ; Mice, SCID ; MicroRNAs ; genetics ; metabolism ; Neoplasm Proteins ; genetics ; metabolism ; Neoplasm Transplantation ; RNA, Neoplasm ; genetics ; metabolism ; RNA-Binding Proteins ; genetics ; metabolism