Long noncoding RNA LINC00657 induced by SP1 contributes to the non-small cell lung cancer progression through targeting miR-26b-5p/COMMD8 axis

Non-small-cell lung cancer (NSCLC) is a kind of lung cancer with high incidence and poor outcomes all over the world. Studies have validated that the upregulation of long noncoding RNA LINC00657 is related to several cancers. Nevertheless, the underlying regulatory mechanism of LINC00657 in NSCLC has not been well elucidated. In the present study, quantitative reverse-transcription polymerase chain reaction (RT-qPCR) revealed that LINC00657 level was apparently elevated in NSCLC cells. Loss-of function assays demonstrated that LINC00657 silence retarded cell proliferation and migration in NSCLC cells. Moreover, the chromatin immunoprecipitation result identified the transcription factor SP1 could bind with LINC00657 promoter, and RT-qPCR proved SP1 positively regulated LINC00657 expression in NSCLC cells. In addition, the mechanistic investigations unveiled that LINC00657 was an endogenous sponge of miR-26b-5p and therefore boosted the expression of copper metabolism MURR1 domain-containing 8 (COMMD8), one of the targets of miR-26b-5p. Besides, miR-26b-5p could negatively regulate LINC00657 or COMMD8 in NSCLC cells. With the application of rescue assays, we uncovered that overexpression of COMMD8 partly mitigated the impairment of LINC00657 repression on NSCLC cell proliferation and migration. Together, our study illustrated that SP1-stimulated LINC00657 promoted NSCLC progression through targeting miR-26b-5p/COMMD8 axis, offering a novel potential therapeutic target for NSCLC.