Circular RNA (circRNA) is a type of noncoding RNA that can interact with miRNAs 
to regulate gene expression. However, little is known concerning circRNA, which 
is crucial in the pathogenesis of lung cancer. To date, limited studies have 
explored the role of circ_0044516 in lung cancer progression. Recently, we 
observed that circ_0044516 expression levels were obviously elevated in lung 
cancer tissues and cells. A549 and SPCA1 cells were transfected with 
circ_0044516 siRNA. We observed that knockdown of circ_0044516 dramatically 
repressed cell proliferation, increased cell apoptosis, and repressed the cell 
cycle. Moreover, A549 and SPCA1 cell migration and invasion abilities were 
greatly repressed by circ_0044516 siRNA. Due to accumulating evidence 
demonstrating the vital role of cancer stem cells, their mechanism of 
involvement has drawn increasing attention in tumor progression and metastasis 
research. We also found that cancer stem cell properties were restrained by 
silencing circ_0044516 in A549 and SPC-A1 cells. Moreover, in vivo xenograft 
experiments showed that circ_0044516 downregulation reduced tumor growth. 
Mechanistically, in lung cancer and using bioinformatics, we demonstrated that 
circ_0044516 sponges miR-136 targeting MAT2A. Furthermore, rescue assays were 
carried out to identify that circ_0044516 modulates cell proliferation, 
invasion, and stemness by regulating miR-136 and MAT2A in lung cancer. In 
summary, our study revealed that the circ_0044516/miR-136/MAT2A axis is involved 
in lung cancer progression. Our findings may provide novel targets for diagnosis 
and therapeutic intervention in lung cancer patients.