Background Diabetic nephropathy (DN) is a common complication of diabetes. Long non-coding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) is reported to exert a protective role in DN by a previous study. The working mechanism underlying the protective role of CASC2 in DN progression was further explored in this study. Methods The expression of CASC2 and microRNA-135a-5p (miR-135a-5p) was determined by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation ability was assessed by Cell Counting Kit-8 (CCK8) assay and 5-ethynyl-29-deoxyuridine (EDU) assay. Enzyme-linked immunosorbent assay (ELISA) was conducted to analyze the production of inflammatory cytokines in the supernatant. Western blot assay was performed to analyze protein expression. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the target relationship between miR-135a-5p and CASC2 or tissue inhibitors of metalloproteinase 3 (TIMP3). Results High glucose (HG) treatment reduced the expression of CASC2 in human glomerular mesangial cells (HMCs) in a time-dependent manner. CASC2 overexpression suppressed HG-induced proliferation, inflammation and fibrosis in HMCs. miR-135a-5p was validated as a target of CASC2, and CASC2 restrained HG-induced influences in HMCs partly by down-regulating miR-135a-5p. miR-135a-5p bound to the 3ʹ untranslated region (3ʹUTR) of TIMP3, and CASC2 positively regulated TIMP3 expression by sponging miR-135a-5p in HMCs. miR-135a-5p silencing inhibited HG-induced effects in HMCs partly by up-regulating its target TIMP3. CASC2 overexpression suppressed HG-induced activation of Jun N-terminal Kinase (JNK) signaling partly through mediating miR-135a-5p/TIMP3 signaling. Conclusions In conclusion, CASC2 alleviated proliferation, inflammation and fibrosis in DN cell model by sponging miR-135a-5p to induce TIMP3 expression.

Ischemia-reperfusion (I/R) is the most common cause of acute kidney injury (AKI) and can induce apoptosis in renal epithelial tubule cells. Mitochondrial dysfunction is one of the main reasons for I/R-induced apoptosis. Accumulating evidence suggests that PINK1/Parkin-mediated mitophagy possibly plays a renoprotective role in kidney disease by removing impaired mitochondria and preserving a healthy population of mitochondria. Our previous study showed that augmenter of liver regeneration (ALR) alleviates tubular epithelial cells apoptosis in rats with AKI, although the specific mechanism remains unclear. In this study, we investigated the role of ALR in I/Rinduced mitochondrial pathway of apoptosis. We knocked down ALR with short hairpin RNA lentiviral and established an I/R model in human kidney proximal tubular (HK-2) cells in vitro. We observed that the knockdown of ALR aggravated mitochondrial dysfunction and increased the mitochondrial reactive oxygen species (ROS) levels, leading to an increase in cell apoptosis via inhibition of mitophagy. We also found that the PINK1/Parkin pathway was activated by I/R via confocal microscopy and Western blot. Furthermore, the knockdown of ALR suppressed the activation of PINK1 and Parkin. These findings collectively indicate that ALR may protect HK-2 cells from I/R injury by promoting mitophagy, and the mechanism by which ALR regulates mitophagy seems to be related to PINK1 and Parkin. Consequently, ALR may be used as a potential therapeutic agent for AKI in the future.

Multiple myeloma (MM) is the second most common haematological malignancy and remains an incurable disease, with most patients relapsing and requiring further treatment. Augmenter of liver regeneration (ALR) is a vital protein affecting fundamental processes such as energy transduction, cell survival and regeneration. Silencing ALR inhibits cell proliferation and triggers apoptosis in human MM U266 cells. However, little is known about the role of 15-kDa-ALR on MM. In the present study, the role of 15-kDa-ALR in human MM cells was investigated. Blocking extracellular 15-kDa-ALR with an anti-ALR monoclonal antibody (McAb) decreased the proliferation and viability of U266 cells. However, the results of flow cytometry revealed no changes in apoptosis, and the expression levels of Bax, Bcl-2, caspase-3 and cleaved caspase-3 were not affected. However, combined treatment with anti-ALR McAb and epirubicin increased the apoptosis of U266 cells. RNA sequencing results indicated that the ERK1/2, JNK-MAPK and STAT3 signaling pathways, as well as the cell cycle, were associated with the mechanism of action of the anti-ALR McAb, and PCR, western blotting and cell cycle analysis confirmed these results. The present findings suggested that blocking extracellular 15-kDa-ALR in U266 cells with an anti-ALR McAb decreased cell proliferation via the MAPK, STAT3 and cell cycle signaling pathways without increasing apoptosis. Thus, 15-kDa-ALR may be a new therapeutic target for myeloma.

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