Silencing of augmenter of liver regeneration inhibited cell proliferation and triggered apoptosis in U266 human multiple myeloma cells

Abstract

Augmenter of liver regeneration (ALR) is a thermostable cytokine that was originally identified to promote the growth of hepatocytes. This study was conducted to explore the expression and function of ALR in multiple myeloma (MM), a common hematologic malignancy. Real-time PCR and western blot analysis were performed to detect the expression of ALR in U266 human MM cells and healthy peripheral blood mononuclear cells (PBMCs). U266 MM cells were exposed to 20 or 40 μg/mL of recombinant ALR and tested for cell proliferation. Small interfering RNA-mediated silencing of ALR was done to investigate the role of ALR in cell proliferation, apoptosis, and cytokine production. Compared to PBMCs, U266 MM cells exhibited significantly higher levels of ALR at both the mRNA and protein levels. The addition of recombinant ALR protein significantly promoted the proliferation of U266 cells. In contrast, knockdown of ALR led to a significant decline in the viability and proliferation of U266 cells. Annexin-V/PI staining analysis demonstrated that ALR downregulation increased apoptosis in U266 MM cells, compared to control cells (20.1±1.1 vs 9.1±0.3%, P<0.05). Moreover, ALR depletion reduced the Bcl-2 mRNA level by 40% and raised the Bax mRNA level by 2-fold. Additionally, conditioned medium from ALR-depleted U266 cells had significantly lower concentrations of interleukin-6 than control cells (P<0.05). Taken together, ALR contributed to the proliferation and survival of U266 MM cells, and targeting ALR may have therapeutic potential in the treatment of MM.

Blocking the short isoform of augmenter of liver regeneration inhibits proliferation of human multiple myeloma U266 cells via the MAPK/STAT3/cell cycle signaling pathway

“…This may be due to the fact that, in the present study, there were no injury factors such as TNFα, lipopolysaccharide or ischemia reperfusion, which may cause apoptosis; hence, blocking extracellular 15-kDa-ALR with antibodies alone may not be sufficient to stimulate apoptosis. However, a previous study revealed that silencing ALR triggered apoptosis in U266 cells without injury factors (15). Small hairpin RNA was used for silencing ALR expression in a previous study (15), which influenced 23-and 15-kDa-ALR at the same time.…”

“…However, a previous study revealed that silencing ALR triggered apoptosis in U266 cells without injury factors (15). Small hairpin RNA was used for silencing ALR expression in a previous study (15), which influenced 23-and 15-kDa-ALR at the same time. The 23-kDa-ALR is located in mitochondria and is involved in the process of oxidative phosphorylation, which is essential for life.…”

“…A previous study has demonstrated that silencing ALR can influence proliferation and apoptosis in human MM U266 cells (15). However, little is known about the role of 15-kDa-ALR in MM.…”

Augmenter of liver regeneration enhances cell proliferation through the microRNA‐26a/Akt/cyclin D1 pathway in hepatic cells

“…5 It was shown that silencing of ALR inhibited cell proliferation and triggered apoptosis in U266 human multiple myeloma cells. 6 It was also shown that hepatic deficiency of ALR enhanced alcohol-induced liver injury and promoted fibrosis in mice. 7 Although, several studies have shown the role of ALR in proliferation, there is a scarce data available to show the molecular mechanisms by which it exerts its effects on hepatocytes.…”

“…It was shown that liver‐specific deletion of ALR resulted in hepatic necrosis, inflammation, and liver fibrosis of mice at 4–8 weeks after birth . It was shown that silencing of ALR inhibited cell proliferation and triggered apoptosis in U266 human multiple myeloma cells . It was also shown that hepatic deficiency of ALR enhanced alcohol‐induced liver injury and promoted fibrosis in mice .…”